WO2010016265A1

WO2010016265A1 - Corrosion testing method

Info

Publication number: WO2010016265A1
Application number: PCT/JP2009/003784
Authority: WO
Inventors: 西川太一郎; 草刈美里; 大塚保之; 山野能章; 西村直也; 佐倉一成; 野村良行; 古川欣吾; 伊藤貴章
Original assignee: 住友電気工業株式会社; 株式会社オートネットワーク技術研究所; 住友電装株式会社
Priority date: 2008-08-08
Filing date: 2009-08-06
Publication date: 2010-02-11

Abstract

Disclosed is a corrosion testing method suitable for the evaluation of corrosion resistance of a member constituting an electric and electronic equipment such as an electric wire with a terminal that is utilized under such an environment that corrosion proceeds relatively mildly. In the corrosion testing method, for example, granules of a nonmetallic insulating material and an electrolyte-containing fluid are brought into contact with a sample (1) that comprises a terminal member (11) mounted on the end of an electric wire (10) comprising an insulating layer (10i) provided on the outer circumference of a conductor (10c). In this state, the sample (1) is held for a predetermined period of time to corrode the sample (1). More specifically, an electrolyte-supported material comprising the granules with an electrolyte deposited on the surface thereof is provided. The electrolyte-supported material is spread on the sample (1), and the sample (1), with which the electrolyte-supported material is in contact, is held in a constant temperature and humidity state within a thermo-hygrostat for a predetermined period of time. An electrolyte-containing fluid produced from the electrolyte in the electrolyte-supported material and moisture contained in an atmosphere in the thermo-hygrostat is brought into contact with the sample (1), whereby the terminal member (11) is corroded by utilizing the fluid.

Description

Corrosion test method

The present invention relates to a corrosion test method for examining the corrosion resistance of a member made of a metal material. In particular, the present invention relates to a corrosion test method suitable for a metal member disposed in an environment where corrosion is relatively difficult to proceed, such as in a living space of a vehicle.

Structural members of electrical and electronic equipment include metal members made of various metal materials such as wiring conductors, terminals connected to the wiring, and housings for storing various components. As a corrosion test method for investigating the corrosion resistance of industrial products composed of such various metal materials, a JIS standard salt spray test is known. In this test, the test piece is exposed to an atmosphere sprayed with a corrosive solution such as an aqueous sodium chloride solution at 35 ° C., and the corrosion state of the test piece after a predetermined time (for example, several hundred hours) is confirmed visually. Evaluate the corrosion resistance. In addition, there is a salt water immersion test in which a test piece is immersed in an aqueous sodium chloride solution for a predetermined time and then the corrosion state of the test piece exposed from the aqueous solution is examined.

In Patent Document 1, as a method for corrosion testing of overhead power transmission lines, a sample is placed in the air above the surface of an acidic corrosive solution such as hydrochloric acid or sulfuric acid, and the sample is corroded in a humid atmosphere. Disclosure.

JP 2008-128763 A

The conventional corrosion test methods such as the salt water spray test and the salt water immersion test may not be suitable as a simulation test in an actual environment.

In the corrosion test method such as the salt spray test, the corrosion solution contacts the sample and corrodes the sample for a long time of several hundred hours, so that the metal constituting the sample remains in its composition (in the case of an alloy, the alloy Elution) or the sample is greatly damaged, and corrosion is likely to proceed. Therefore, the corrosion test method such as the salt spray test is positioned as an accelerated test that simulates an environment where the progress of corrosion is fast, for example, an engine room of a car or the outdoors (particularly in a coastal area).

On the other hand, in an actual environment, the corrosive solution may be difficult to contact the metal member continuously for a long time. For example, metal members disposed in indoor environments such as living spaces of vehicles such as automobiles, houses, and interiors of buildings are usually difficult to continuously contact rain, seawater, corrosive gases, etc. Compared with the case where it is arrange | positioned outdoors etc., it is thought that corrosion does not advance easily. In fact, there are many examples of metal members that have been evaluated as having a very fast progress of corrosion when the salt spray test is performed, and that can be used without problems for over 10 years in the actual usage environment. Further, as a result of investigation by the present inventors, the corrosion situation of the sample in which only the corrosion solution such as NaCl solution was continuously in contact with the corrosion situation of the actual product collected from the living space of the vehicle was different. Therefore, for example, when the corrosion resistance of the metal member placed in the indoor environment is evaluated using the salt spray test or the like, an appropriate evaluation may not be obtained.

Moreover, in the metal member placed in an environment where the progress of corrosion is relatively slow as described above, corrosion may occur partially. For example, in the case where members (conductors and terminals) made of a metal material are arranged close to each other like an electric wire with a terminal, the terminal may be corroded mainly as compared with a conductor included in the electric wire. However, when the salt spray test is performed on the electric wire with terminal, both the conductor and the terminal included in the electric wire are corroded. Therefore, in a conventional corrosion test method such as a salt spray test, an environment in which the terminal mainly corrodes is not simulated, and it is very difficult to appropriately evaluate the corrosion state of such an environment.

Furthermore, in recent years, since various metal materials have been used for components such as in-vehicle systems of automobiles, electric corrosion (electric corrosion) can occur between members made of different metal materials. However, the evaluation of corrosion resistance for metal members that can cause electric corrosion has hardly been performed, and the corrosion test method has not been clarified. In addition, when a salt spray test is performed on a metal member that can cause such electrolytic corrosion, damage to the test piece due to electrolytic corrosion is too great, and the corrosion resistance cannot be evaluated substantially. In fact, the JIS standard salt spray test stipulates that it is desirable not to test different metal specimens at the same time.

On the other hand, the corrosion test method described in Patent Document 1 is a method that reproduces the actual environment of an overhead power transmission line, that is, an outdoor environment exposed to rainwater or strong wind, and relatively progress of corrosion like the indoor environment described above. However, it is not a method that simulates a slow environment.

Thus, in the conventional corrosion test methods such as the salt spray test method, there are environments and conditions where it is difficult to obtain an appropriate evaluation. Therefore, it is desired to develop a corrosion test method that simulates an environment in which an appropriate evaluation cannot be obtained by a corrosion test method such as a salt spray test, for example, an environment in which corrosion proceeds relatively slowly.

Therefore, an object of the present invention is to provide a corrosion test method capable of evaluating corrosion resistance by simulating an environment where the progress of corrosion is relatively slow.

The present inventors, among the constituent members of electrical and electronic equipment arranged in the living space of an aged automobile of 10 years or more, particularly in places where metal members made of different metals may be arranged adjacent to each other. The state of corrosion of the placed objects was examined. Specifically, for a wire harness (a group of electric wires bundled with terminals attached to ends of a plurality of electric wires), the corrosion condition of the terminals and locations where the terminals are connected in the electric wires and the vicinity thereof were examined. As a result, a portion where the corrosion was relatively advanced (hereinafter referred to as a corrosion-promoted portion) was found in a part of the surveyed portion. Further, the corrosion progressing portion was markedly attached with dust such as sand and dust, and chlorine (Cl), sodium (Na) and the like were attached to the dust.

Especially, the corrosion status of the above terminals was examined. The terminal is inserted into one connector having a plurality of fitting holes into which a plurality of terminals can be respectively inserted. That is, the terminal is used in an environment where a plurality of terminals are densely arranged in a narrow space. Each of the above terminals is made of brass, and there are gaps and chippings in some of the copper parts that have become copper due to dezincification (Zn) corrosion and dezincification corrosion. There were few missing points and almost no defects were observed. In particular, dezincification corrosion occurred from the surface side of the terminal toward the inside (the side in contact with the electric wire). Moreover, there was almost no corrosion of the copper constituting the conductor. From this, it can be considered that the environment in which the terminal is used is an environment in which dezincification corrosion is more likely to occur than corrosion in which brass itself is eluted. On the other hand, in the test method in which only the corrosive solution is brought into contact with the sample for a long time, such as the salt spray test described above, as shown in a test example to be described later, brass itself is eluted, not only brass terminals but also copper conductors. Was also corroded. Therefore, the corrosion test under this condition cannot be said to be an accelerated corrosion test method that reproduces the usage environment of the terminal. Therefore, the present inventors further examined the environment of the collected terminals in order to obtain appropriate corrosion test conditions, and in places where dezincification corrosion occurred in the surface side region of the terminals, sand, dust, etc. The dust was noticeably attached, and chlorine (Cl), sodium (Na), and the like were attached to the dust. In addition, the dust adheres so as to connect the terminals inserted in the adjacent fitting holes of the connector.

The reason why the corrosion progressed in the corrosion progressing part (the part where the dust is attached) compared to the part where the dust is not attached is estimated as follows. Further, the reason why the zinc terminal corrosion of the brass terminal compared to the copper conductor is estimated from the above collected terminal state as follows.

If an electrolyte such as sodium chloride (NaCl), especially a hygroscopic electrolyte, adheres to the surface of the dust, the dew point of the attached portion of the electrolyte in the dust and the atmosphere in the vicinity thereof will decrease. Moisture inside is easily adsorbed. As a result of the dew point being lowered, the adhering part and the atmosphere in the vicinity thereof easily adsorb moisture. As a result, the adhering part and the vicinity thereof easily adsorb moisture in the atmosphere including the electrolyte. That is, the electrolyte is more easily attached. As the electrolyte adheres over time, the electrolyte on the surface of the dust concentrates (increases) due to repeated temperature changes and dry and wet conditions with the electrolyte attached. It is presumed that the concentrated electrolyte adsorbs moisture to become an electrolytic solution, acts on corrosion, and the corrosion progressing portion is generated.

In addition, since the generated electrolytic solution is interposed between adjacent terminals, a minute current (leakage current) can flow between terminals to which a voltage is applied. Here, the dust is generally made of a non-metallic insulating material, and when such an insulator is interposed between the terminals, the current flowing between the terminals becomes minute even when the electrolyte is present. Conceivable. In particular, in the environment where the electrolyte is generated by the dust adhering to the electrolyte as described above, the leakage current is generated when the electrolyte is generated and is present between the terminals. It is considered that it varies depending on the amount of the electrolyte. That is, it is considered that the leakage current between the terminals is unstable in generation state and magnitude. With such a leakage current, it is presumed that corrosion that causes the brass itself constituting the terminal to elute hardly occurs, and dezincification corrosion that elutes zinc in the brass tends to occur. Further, it is presumed that this leakage current hardly affected the corrosion of the conductor made of copper.

For these reasons, in conditions where corrosion is relatively difficult to proceed, such as in automobile living spaces and indoors, the conditions under which corrosion progresses are as follows: 1. Granules made of non-metallic insulating material such as dust come into contact with metal members. 2. It is conceivable that 2. an electrolyte and moisture exist, and a fluid containing the electrolyte composed of these contacts the metal member.

Therefore, in the present invention, as an accelerated corrosion test method simulating an environment where corrosion is relatively difficult to proceed, such as in a vehicle's living space or indoors, the use of a granular material made of a nonmetallic insulating material and a fluid containing an electrolyte is used. suggest.

The corrosion test method of the present invention relates to a method for investigating the corrosion state of a sample having a portion made of a metal material. The sample is made of a granular material made of a non-metal insulating material and a fluid containing an electrolyte. A step of holding the contacted state for a predetermined time.

As a more specific form of the present invention, the above-mentioned granular material (electrolyte carrier) to which an electrolyte is attached and the moisture in the atmosphere are used to generate a fluid containing the electrolyte during the test (hereinafter referred to as corrosion). And a form using a fluid containing the above-described granular material and electrolyte prepared before the test (hereinafter referred to as a corrosive liquid utilization form). Moreover, the said sample includes the electric wire with a terminal which attached the terminal member to the edge part of the electric wire which provides an outer periphery of a conductor with an insulating layer.

The corrosion test method of the present invention having the above-described configuration can slow the progress of corrosion of a sample as compared with a conventional corrosion test such as a salt spray test. Therefore, it is expected that the corrosion test method of the present invention can be suitably used as an accelerated test that simulates an environment where the progress of corrosion is relatively slow. Further, the corrosion test method of the present invention can suppress excessive corrosion even when a sample made of a different metal is used, and can evaluate the corrosion resistance of this sample. Therefore, the corrosion test method of the present invention is expected to be able to appropriately evaluate the corrosion resistance even when it is considered that appropriate evaluation is difficult in the conventional salt spray test or the like.

As an environment in which corrosion is relatively difficult to proceed, it is proposed that the following form be adopted, particularly when an accelerated corrosion test is performed that simulates an environment in which corrosion is caused by leakage current. Specifically, an electric wire with a terminal in which a terminal member is attached to an end portion of an electric wire having an insulating layer on the outer periphery of a conductor, and a fluid containing the electrolyte between the sample and a separately prepared electrode material The present invention proposes a mode in which the granular material made of the non-metal insulating material is interposed and power is supplied to the sample and the electrode material.

Specifically, the above-described form involving the supply of power includes the following steps.
A step of preparing the sample and the electrode material and arranging the terminal member of the sample and the electrode material apart from each other.
The sample terminal member and the electrode material are maintained while a state in which the granular material made of the nonmetallic insulating material and the fluid containing the electrolyte are interposed between the terminal member of the sample and the electrode material. Supplying electric power to the sample and the electrode material for a predetermined time so that a current flows between them.
And after the said predetermined time progress, the corrosion condition of the terminal member of the said sample is evaluated.

As a more specific form of the corrosion test that simulates the environment in which corrosion can occur due to the leakage current, while holding the electrolyte carrier between the sample and the electrode material in a constant temperature and humidity state, A corrosive solution generating mode for supplying electric power to the sample and the electrode material is proposed. As another form, a form using a corrosive liquid using a fluid containing a granular material made of the non-metal insulating material and an electrolyte prepared before the test is proposed.

In the above-mentioned corrosive liquid generation form that involves the supply of electric power, the corrosion test is performed as follows. An electrolyte carrier having an electrolyte attached to a surface of a plurality of the granular materials is prepared, and the terminal member of the sample and the electrode material which are arranged apart from each other are in contact with each other and between the terminal member and the electrode material. The electrolyte carrier is disposed so as to be interposed between the two. Then, electric power is supplied to the sample and the electrode material for a predetermined time while maintaining the sample on which the electrolyte carrier is disposed and the electrode material in a constant temperature and humidity state. By holding the electrolyte carrier in a constant temperature and humidity state, a fluid containing an electrolyte is generated and interposed between the sample and the electrode material.

In the mode of using the corrosive liquid with the supply of electric power, the sample and the electrode material are supplied with electric power for a predetermined time while the terminal member of the sample and the electrode material that are spaced apart are immersed in the produced fluid. Supply.

According to the above configuration, while using a fluid containing an electrolyte, such as salt water (NaCl aqueous solution), by simultaneously interposing a granular material made of a nonmetallic insulating material between the sample and the electrode material, Compared to a conventional corrosion test method such as a salt spray test, the progress of corrosion of the sample can be slowed (moderated). For example, a corrosive state in which a part of the sample is mainly corroded and the remaining part is hardly corroded can be obtained. Therefore, according to the above configuration, it is used for an accelerated corrosion test that simulates an environment in which an appropriate evaluation is difficult in a corrosion test such as a conventional salt spray test, that is, an environment in which corrosion proceeds relatively slowly, It is expected that the corrosion resistance of the metal member can be appropriately evaluated. Examples of the corrosive environment include an environment in which corrosion occurs due to leakage current generated between a plurality of terminal members arranged densely in a narrow space.

Hereinafter, the present invention will be described in more detail.
[sample]
Samples to which the corrosion test method of the present invention is applied include various members having a portion made of a metal material, typically the above-described electric wires with terminals. As such an electric wire with a terminal, what is typically used for wire harnesses, such as a car, an airplane, and an industrial robot, can be used. In other words, the sample can be of the same specifications (material, size (wire diameter, thickness, etc.), shape, etc.) as the wires and terminal members actually used in the wire harness, etc. The specification of is not particularly limited. A sample imitating a desired electric wire or terminal member may be separately produced and used. Examples of the material of the conductor and the terminal member include copper, copper alloy, aluminum, and aluminum alloy. The copper alloy constituting the terminal member is typically brass, Cu—Sn—Fe—P alloy, or Cu—Ni—Si alloy. When a terminal member made of brass is used as a constituent element of a sample, the state of dezincification corrosion can be examined by the present invention. Examples of the conductor of the electric wire include a single wire, a stranded wire, a compression stranded wire, and the like, and there are various materials and thicknesses of the insulating layer. Examples of the terminal member include various forms such as a male mold, a female mold, a crimping mold, and a welding mold. The length of the electric wire used for the sample can be appropriately selected in consideration of the length required for the attachment of the terminal member, the attachment of the power supply means to be described later, and the arrangement to the constant temperature and humidity means to be described later. it can. In the present invention involving power supply, at least one of the above samples, that is, one in which one terminal member is attached to one end of one electric wire is prepared, and the power supply means described later Connect to the positive electrode side.

[Electrode material]
In the embodiment in which power is supplied in the present invention, a circuit for leakage current is constituted by the sample, the electrode material, and a fluid containing an electrolyte described later. As will be described in a test example to be described later, it is a sample connected to the positive electrode side of the power supply means that can be corroded by a leakage current. Therefore, the electrode material connected to the negative electrode side of the power supply means can be made conductive, that is, various forms formed from a conductive material can be used. For example, a pair of samples having the same form as the sample, that is, a sample made of the electric wire with terminal may be prepared, and one of them may be used as an electrode material. In addition, a plate material or a bar material made of a conductive material can be used as the electrode material. The conductive material constituting the plate or bar may be the same as or different from the constituent material of the sample terminal member. For example, when the terminal member of the sample is made of brass, a plate or bar made of brass or copper can be used.

[Granular]
In the present invention, a fluid containing an electrolyte is used as a corrosive liquid, and a plurality of granular bodies made of a non-metal insulating material are used as a simulated body of dust such as sand and dust. By using such a granular material, it is expected that an environment close to the surrounding environment of the terminal to which dust such as sand and dust adheres can be simulated. Further, in the embodiment in which power is supplied in the present invention, a material that has a large resistance when power is supplied, typically the granular material made of an electrically insulating material, is interposed between the sample and the electrode material. Thus, even if a fluid containing an electrolyte is present between the two, it is expected that the leakage current flowing between the two can be easily weakened and an environment where the progress of corrosion is slow can be simulated more appropriately.

In the case of a granular material made of a material that is soluble in a solvent, it may not be used for the resistance as described above, or depending on the material, the progress of corrosion of the sample may be accelerated. In a granular material made of metal, the granular material itself may corrode. Moreover, in the form which supplies the said electric power, there exists a possibility of short-circuiting between a sample and an electrode material if it is a granular body which consists of good conductors like a metal. Therefore, in any case, it is difficult to appropriately simulate an environment in which the progress of corrosion is slow, such as a corrosive environment due to a leak current, and it is difficult to properly grasp the corrosion state of the sample. Therefore, in the present invention, the constituent material of the granular material is an insulating material that is substantially insoluble in a solvent, is non-metallic, and has high electrical insulation (or a large electrical resistance value).

Specific examples of the constituent material of the granular material include inorganic materials such as ceramics, organic materials such as resins, and salts that are difficult or insoluble in a solvent (typically water). Ceramics include, for example, silicon carbide (SiC), silicon dioxide (SiO ₂ ), alumina (Al ₂ O ₃ ), iron oxide, silicon nitride, titanium boride, beryllium oxide, talc, kaolinite (kaolin, white porcelain), etc. Is mentioned. Ceramics generally do not dissolve in water, are excellent in heat resistance and water resistance, hardly change in quality even when kept in a high-temperature and high-humidity state, and are excellent in durability, and can be reused. In addition, the ceramics listed above generally have a high insulating property, and if a granular material made of such a ceramic having excellent insulating properties is used, almost no current flows in the granular material itself when power is supplied to the sample. There is no flow. In particular, SiC and SiO ₂ are commercially available in powder or fibrous form and can be easily obtained. Examples of the salt that is insoluble in water include calcium carbonate (CaCO ₃ ). A plurality of types of granular materials of different materials may be used in combination.

The shape of the granule is not particularly limited. It may be particulate or fibrous, and may be angular or rounded. For example, in the above-described corrosive liquid generation mode, when an angular granule is used, the amount of moisture retained tends to be larger than when a rounded product is used. A desired shape can be appropriately selected according to the dust to be simulated. When the size of the granular material (in the case of particles: average particle diameter, in the case of fibers: average short diameter) is 200 μm or less, it is considered that it is easy to use. In particular, it is considered that the granular materials made of the above-described ceramics and salts and having a size of about 1 μm or more and 150 μm or less are readily available and easy to use. A plurality of types of granular materials having different sizes may be used in combination.

[Electrolytes]
For example, Na, Cl, Mg, K, Ca, SO ₄ ^2- , SO ₃ ^2- , NO ₃ ^- and NH ₄ ⁺ can be selected for the electrolyte contained in the fluid and the electrolyte adhering to the granular material. And those containing one or more elements or ions. _{_{Typically, NaCl, MgCl 2, CaCO 3}} , KCl, Na 2 SO 4, H 2 SO 3, Cu (NO 3) 2, NH 4 Cl, FeCl 3, and one or more selected from FeCl ₂ Compounds. In the present invention, the fluid containing an electrolyte may contain one or more kinds of electrolytes. The compounds are typically present as ions in the fluid.

[Electrolyte carrier]
In the corrosive liquid generation mode, the granular material functions as a holding member for the electrolyte (or ions). Therefore, the shape, size, etc. of the granular material can be appropriately selected as long as the electrolyte can be retained. As described above, when the size of the granular material is 200 μm or less, it is easy to sprinkle the granular material on the sample or the electrode material, and it is easy to contact each granular material with the sample or the electrode material. However, if it is too small, the granular material covers the surface of the sample and the electrode material without gaps, so that moisture (dissolved oxygen) in the atmosphere that causes corrosion or the electrolyte of the electrolyte carrier is dissolved in this moisture. There is a risk of preventing the sample or electrode material from coming into contact with the liquid (fluid containing electrolyte). That is, the desired corrosion is not performed and the corrosion resistance may not be evaluated. Therefore, in this embodiment, the size of the granular material is preferably 1 μm or more.

The electrolyte (compound) adhering to the surface of the granular material in the electrolyte carrier may be one or more of the above-described electrolytes. Elements such as Na, Cl, Mg, K, and Ca are contained in seawater, and the actual environment (e.g., by using an electrolyte carrier in which a compound containing these elements adheres to the surface of the granular material) The environment can be made closer to the coast.

(Production method)
In order to produce an electrolyte carrier in which an electrolyte is adhered to a granular material, a solution containing the above electrolyte (typically, an aqueous solution or an acid solution described later) is produced, and this solution is applied to the granular material, followed by drying. Can be mentioned. Since the above-listed compounds such as NaCl are commercially available and can be easily obtained, the above solution can be easily prepared. Moreover, you may utilize commercially available solutions, such as artificial seawater, as a solution containing Na, Cl, Mg, K, Ca, etc. The attached amount of the electrolyte can be adjusted by, for example, the concentration of the solution, and the attached amount tends to increase as the concentration increases. The adhesion amount (ion concentration) of the electrolyte can be appropriately selected depending on the environment to be simulated. For example, when the mass of the electrolyte carrier is 100% by mass, the same level of results as in the case of using the corrosive liquid is obtained when the amount of the deposited electrolyte is 0.005% by mass or more. The adhesion amount of the electrolyte is more preferably 0.05% by mass or more, and no upper limit is particularly set. In addition, an electrolyte carrier that contains moisture without being dried may be used for the corrosion test. However, it is considered that the electrolyte carrier is more easily placed on the sample after drying. In the corrosive liquid generation mode, moisture is supplied from the atmosphere by holding the sample in a constant temperature and humidity state, so the electrolyte carrier may be in a dry state.

(Arrangement on the sample)
As described above, the electrolyte carrier is placed between the particles constituting the prepared electrolyte carrier so that the sample or electrode material can contact the moisture in the atmosphere or the generated electrolyte solution. It is good to arrange on the material. Specifically, it is preferable to sprinkle evenly to such an extent that the gap is formed and a part of the sample can be visually observed. In the form involving the concentration of the solution (amount of electrolyte attached), temperature and humidity in the atmosphere, and power supply, although depending on the test conditions such as power conditions, the thickness of the electrolyte carrier to be sprinkled is preferably 1 mm or less . The amount of the electrolyte carrier may be adjusted according to conditions such as the amount of electrolyte deposited (solution concentration), temperature and humidity in a constant temperature and humidity atmosphere, and power conditions. In particular, in the form involving power supply, an appropriate gap is provided between the sample terminal member and the electrode material so that the terminal member of the sample and the electrode material are not in direct contact (short-circuited state). And the electrode material are disposed, and the electrolyte carrier is disposed so as to fill the gap. The distance between the terminal member of the sample and the electrode material may be adjusted according to the actual environment.

(Generation of fluid containing electrolyte)
In the corrosive liquid generation mode, the fluid containing the electrolyte is generated by the moisture in the constant temperature and humidity atmosphere and the electrolyte in the electrolyte carrier as described above, and is interposed between the sample and the electrode material. Is done. Thus, it is expected that the environment of the aged automobile described above can be reproduced more faithfully by generating a fluid (aqueous solution) containing an electrolyte during the test.

[Fluid containing electrolyte in the form of using corrosive liquid]
In particular, in the form of using the corrosive liquid, an aqueous solution containing an electrolyte in which the fluid solvent is typically water (pure water) can be used as the fluid containing the electrolyte. The aqueous solution may be neutral, acidic, or alkaline, and a neutral aqueous solution such as an NaCl aqueous solution is easy to handle. In addition, the aqueous solution is relatively easy to produce and obtain, and is excellent in convenience when performing a corrosion test. When seawater or artificial seawater is used as an aqueous solution containing elements such as Na, Cl, Mg, K, and Ca, it is easy to obtain and simulates an environment that is closer to the actual environment (for example, at the beach). It is thought that you can. When using the NaCl aqueous solution for the fluid, the concentration of NaCl is preferably 0.005% by mass or more, and it is considered that 0.05% by mass to 27% by mass is easy to use.

And, in the form of using the corrosive liquid, in addition to the electrolyte, a fluid containing a granular material made of the nonmetallic insulating material is used. In an actual environment, dust such as sand and dust is usually present. Therefore, it is expected that an environment closer to the actual environment can be simulated by using a fluid containing a granular material imitating the dust. As such a fluid, for example, mud containing clay mineral such as kaolinite can be used. In particular, in the form of using the corrosive liquid with power supply, the electrolyte and the granular material are interposed between the terminal member and the electrode material by immersing the terminal member and the electrode material of the sample in the fluid in a separated state. The fluid containing the body can be easily interposed. In addition, a granular material made of a non-metallic insulating material is interposed between the terminal member of the sample and the electrode material, so that the terminal material and the electrode material are short-circuited by the granular material. In addition, it is considered that the current flowing between the two is likely to be minute. In this way, in the form of using the corrosive liquid, the presence of particulates in the fluid can simulate the environment in which the corrosion progresses slowly compared to salt spray tests that simply use a corrosive solution such as NaCl aqueous solution. It is done. Further, in the form of using the corrosive liquid, the preparation of the fluid is easy, and the workability of the test is excellent.

[Power requirements]
As one aspect of the present invention, when a step of supplying electric power is provided, a form in which a constant voltage is applied to the sample and the electrode material for a predetermined time can be cited. The magnitude of the voltage to be applied can be appropriately selected according to the actual environment. For example, when a terminal member used for an automobile wire harness or the like is used as a sample, the applied voltage may be 12V used for a power source of the automobile. In the corrosion test method of the present invention, insulation is provided between the sample and the electrode material by using a fluid containing granular materials as described above or by generating an electrolytic solution during the test using an electrolyte carrier. There is a thing in between and there is little quantity of electrolyte solution. For this reason, when a constant voltage is applied to the sample and the electrode material, the leakage current generated between them can be kept small, and the environment where corrosion proceeds relatively slowly, particularly where the leakage current causes corrosion. It is thought that it can be simulated well.

In addition, according to the above configuration, by using a constant voltage, it is possible to reproduce a corrosive environment that matches a real environment in which a predetermined constant voltage is applied and used. For example, a terminal member provided in a wire harness of an automobile is generally used by applying a constant voltage of 12V. Therefore, according to the said structure, it can utilize suitably as a corrosion test imitating the case where a constant voltage is applied in a real environment.

Furthermore, when the present inventors investigated, even if it supplied the constant current of a specific magnitude | size to the said sample and electrode material, the corrosion very similar to the corrosion state of the terminal extract | collected from the aged car mentioned above was carried out. The knowledge that it will be in a state was obtained. In particular, the knowledge that a corrosive state similar to that of the collected terminal can be obtained by setting the magnitude of the current in a specific range and the charge amount (charge amount = current value × time) in a specific range. Obtained. In the case of constant current, since the amount of charge becomes constant when the energization time is constant, the amount of charge can be controlled with high accuracy, and therefore, it is expected that the reproducibility of the corrosive environment under a predetermined condition is high. From the above, in the case where the present invention includes a step of supplying electric power, even in a method in which a constant current is passed through the sample and the electrode material, the corrosion occurs in an environment where corrosion progresses relatively slowly, in particular, leakage current. It is expected that it can be suitably used for a corrosion test that simulates such an environment.

When supplying the constant current, it is preferable that the current value and the amount of charge per unit area are within a specific range with respect to the exposed area of the terminal member of the sample. Specifically, the current value is less than 0.19 mA / mm ² (excluding 0 mA / mm ² ), the charge amount is 20 C / mm ² or less (excluding 0 C / mm ² ), that is, the energization time is equal to 20 C charge amount. It is preferable to set the time to be / mm ² or less. When an accelerated test is desired, the current value is preferably 0.001 mA / mm ² or more and the charge amount is preferably 0.125 C / mm ² or more. In particular, the current value: 0.005 mA / mm ² or more 0.15 mA / mm ² or less, the charge quantity: 0.15C / mm ² or more 15C / mm ² or less being more preferred. In addition, when energizing such a weak current, the above-described non-metallic insulating material granular material is not interposed between the sample and the electrode material, and only the corrosive solution such as the NaCl aqueous solution is used. Corrosion state similar to terminals collected from aged automobiles can be obtained.

[Samples with plating]
Some components such as an in-vehicle system of an automobile are plated. There is a possibility that the plating composition may change due to thermal degradation (thermal diffusion of base metal) depending on the usage environment. Due to this change in the composition, the corrosion resistance of the plated member may change. However, the evaluation of the corrosion resistance for the plated member, particularly the evaluation of the corrosion resistance of the deteriorated plating has not been carried out, and the corrosion test method has not been clarified.

On the other hand, when the present inventors examined the corrosion status of the terminal with plating disposed in the living space of the above-mentioned automobile, the base metal constituting the terminal diffuses during plating, and this base material A portion where the metal and the metal composing the alloy were alloyed was observed during the plating. This alloying is considered to have occurred due to thermal degradation. In general, corrosion of an alloy proceeds faster than pure metal. Therefore, in particular, when examining the corrosion resistance of a metal member having a plated portion, such as a terminal with plating, when the sample is heat treated to alloy the plating, the actual environment, that is, an environment in which corrosion is relatively difficult to proceed. It is considered that an accelerated test simulating a state in which corrosion is relatively easy to proceed (for example, a state in which the corrosion is arranged in an automobile living space and alloyed as described above) can be realized. Therefore, when evaluating the corrosion resistance of a metal member having a plated part, prepare a sample having a plated part plated on the surface of the base material, and appropriately heat-treat this sample to alloy the plated part, Proposed to be used in the above-mentioned form of the corrosive liquid.

The heat treatment conditions can be set in consideration of the composition of the plating, the composition of the base material to be plated, the assumed degree of thermal degradation, and the like. For example, when the base material is copper or a copper alloy and the plating is tin, the heat treatment conditions include a heating temperature: 100 to 200 ° C. and a heating time: 2 to 600 hours. Depending on the type of plating, heat treatment such as post-plating reflow treatment may be performed. Due to the reflow treatment, a part of the plating, particularly a region on the base material side, may be alloyed. On the other hand, in the present invention, heat treatment is further performed so that the alloy region in the plating is increased more than in the case of only the reflow treatment, and thermal degradation is acceleratedly simulated. All of the plating may be fully alloyed.

[Corrosion test system]
In the above-described corrosion test method of the present invention, when the above-described form of the corrosive liquid is formed, an electrolyte carrier and constant temperature and humidity means are used. Moreover, when it is set as the form accompanied by supply of electric power, a power supply means is further utilized. For example, the following system can be suitably used in a corrosive liquid generation mode involving supply of electric power. This corrosion test system relates to a system for examining the corrosion state of a sample in which a terminal member is attached to an end of an electric wire having an insulating layer on the outer periphery of a conductor. This system includes an electrolyte carrier having a plurality of granules made of a non-metal insulating material and an electrolyte attached to the surfaces of the granules, and a constant temperature and humidity means for holding the sample and the electrode material at constant temperature and humidity. And a power supply means for supplying power to the sample and the electrode material. The terminal member and the electrode material of the sample are arranged in a separated state. The electrolyte carrier is in contact with the terminal member and the electrode material of the sample, and is interposed between the terminal member and the electrode material of the sample that are separated from each other. The power supply means uses the fluid containing the electrolyte interposed between the terminal member of the sample and the electrode material held in a constant temperature and humidity state, and the terminal member of the sample, the electrode material, Power is supplied for a predetermined time so that a current flows during the period. This power supply means is attached to the electric wire of the sample and the electrode material.

The following system can be used suitably in the corrosive liquid utilization mode that involves the supply of electric power. This corrosion test system relates to a system for examining the corrosion state of a sample in which a terminal member is attached to an end of an electric wire having an insulating layer on the outer periphery of a conductor. The system includes a fluid containing a granular material made of a non-metal insulating material and an electrolyte, a fluid tank in which the fluid is stored, and a power supply unit that supplies power to the sample and the electrode material. . The sample and the electrode material are immersed in the fluid tank in a separated state. The power supply means utilizes the fluid interposed between the terminal member of the sample and the electrode material so that a current flows between the terminal member of the sample and the electrode material. And power is supplied to the electrode material for a predetermined time. This power supply means is attached to the electric wire of the sample and the electrode material. As the fluid tank, an appropriate one capable of storing the fluid can be used.

(Constant temperature and humidity means)
In particular, in the form of the corrosive solution, the sample or electrode material is kept at a constant temperature and humidity in a state where the electrolyte carrier is sprinkled on the sample or an electrolyte carrier is interposed between the terminal member of the sample and the electrode material. By charging the means and maintaining the set temperature and humidity, corrosion is accelerated. By inserting the sample or electrode material into the constant temperature and humidity means, the moisture in the atmosphere of the constant temperature and humidity means, or the electrolytic solution generated by the contact of the moisture with the electrolyte carrier contacts the sample or the electrode material. The state can be maintained. In particular, if the sample and the electrode material are kept in a constant temperature and humidity state to some extent before the power supply, the electrolyte is generated, and therefore, a leak current is likely to occur with the start of power supply. That is, the time for starting the supply of electric power may be different from the time for starting the holding of the constant temperature and humidity, and the supply time and the holding time of the constant temperature and humidity state may be different. As the constant temperature and humidity means, a commercially available constant temperature and humidity device can be used. Temperature, humidity, and holding time can be appropriately selected. It is considered that the higher the temperature and the higher the humidity, the faster the progress of corrosion. It is preferable that the holding time be equal to or longer than the power supply time so that the temperature and humidity are maintained at least during power supply. Further, when the test time is 30 days (720 hours) or less, particularly 10 days (240 hours) or less, and further 2 days (48 hours) or less, the test time is short and the evaluation is easy. A cycle test in which temperature, humidity, voltage, current, and the like are changed at regular intervals can also be performed.

Even in the case of using a corrosive liquid, if the temperature and humidity are maintained, the temperature of the fluid becomes uniform, reducing the effects of convection, fluctuations in the electrolyte concentration of the fluid due to evaporation of moisture, and moisture depletion. This is expected to reduce the fear of In the case of maintaining a constant temperature and humidity state, the system used in this embodiment may be provided with a constant temperature and humidity means. Moreover, after supplying electric power, it may hold | maintain to constant temperature and humidity for a fixed time in the state which stopped supplying electric power, and you may evaluate a corrosion condition. Or you may perform the cycle test which repeats alternately supply of electric power, and holding | maintenance of constant temperature and humidity in the state which stopped supply of electric power.

(Power supply means)
In the above corrosive liquid generation mode, leakage current is generated between the terminal member and the electrode material by supplying electric power, maintaining a constant temperature and humidity state (moisture supply), and interposing an electrolyte carrier (electrolyte supply). The terminal member of the sample is corroded by this leakage current. In the above-mentioned form of using the corrosive liquid, the current flowing between the terminal member and the electrode material is weakened by the supply of electric power, the intervening electrolyte, and the intervening granular material, which is an insulator. The terminal member of the sample is corroded. A commercially available apparatus can be used as the power supply means. When applying a constant voltage, a device capable of applying a constant voltage can be used, and when applying a constant current, a device capable of supplying a constant current can be used.

According to the corrosion test method of the present invention, it can correspond to an accelerated corrosion test that simulates an environment in which corrosion progresses relatively slowly, for example, an environment in which corrosion due to leakage current can occur, and evaluates corrosion resistance in the environment. can do.

FIG. 1 (I) is a schematic configuration diagram showing the vicinity of a terminal member of a terminal-attached electric wire used for a sample, and FIG. 1 (II) is a schematic diagram of a ZZ cross section of FIG. 1 (I). Fig. 2 is a micrograph (200x) showing the corrosion status of the terminal part in the ZZ section of the electric wire with terminal. Fig. 2 (I) shows the actual sample No. 1-100 and Fig. 2 (II) shows the conductor. Material: Copper-Terminal material: Brass Sample No. 1-1 is a sample using an electrolyte carrier (sand No. 3) prepared for a corrosion test using a solution with a concentration of 2% by mass. . Fig. 3 is an SEM photograph (20,000 times) near the plated part of the plated terminal. Fig. 3 (I) shows the actual sample No. 1-102, and Fig. 3 (II) shows the sample No. before the heat treatment. .1-5-1 and FIG. 3 (III) show Sample No. 1-5-1 after the heat treatment. FIG. 4 is a schematic configuration diagram of a corrosion test system with power supply. FIG. 4 (I) shows a form of generating a corrosive liquid, and FIG. 4 (II) shows a form of using a corrosive liquid. FIG. 5 is a micrograph (25 times) of a sample terminal member subjected to a corrosion test using an electrolyte carrier or mud while applying a constant voltage, and an XX cross-section of an actual sample terminal member. (I) is sample No. 2-1, FIG. 5 (II) is sample No. 2-2, FIG. 5 (III) is sample No. 2-3, and FIG. 5 (IV) is actual sample No. 2-100. Indicates. FIG. 6 is a micrograph (25 times or 200 times) of a sample of a terminal member of a sample subjected to a corrosion test with a constant voltage applied using a corrosive solution without using a granular material. I) is sample No. 2-200, Fig. 6 (II) is sample No. 2-201, Fig. 6 (III) is sample No. 2-202, Fig. 6 (IV) is sample No. 2-203, Fig. 6 6 (IV ') is a partially enlarged photograph of sample No. 2-203 (200x), Fig. 6 (V) is sample No. 2-204, Fig. 6 (VI) is sample No. 2-205, Fig. 6 ( VI ′) shows a partially enlarged photograph (200 ×) of Sample No. 2-205. FIG. 7 is a principle explanatory diagram for explaining the principle of the corrosion test method of the present invention involving the supply of electric power. FIG. 8 is a photomicrograph (25 ×) of the terminal member of the sample subjected to the corrosion test using the electrolyte carrier while applying a constant current.

(Test Example 1: Corrosion test without power supply)
(Test Example 1-1)
Prepare a plurality of terminal-attached wires with terminal members attached to the end of the wire as samples, prepare various electrolyte carriers, and perform corrosion tests on the samples. The corrosion test method was evaluated by comparing the corrosion state of the sample).

[Actual sample]
As an actual sample to be compared, we prepared a copper wire placed in the living space of an ordinary car that was used for 10 to less than 20 years in an environment where dust is present, and a brass terminal connected to one end of this wire ( Actual sample No.1-100).

[sample]
Sample 1 used in this test is a terminal-attached electric wire (crimped electric wire) in which a terminal member 11 is connected to one end of an electric wire 10 as shown in FIG. The electric wire 10 includes a conductor 10c formed by twisting a plurality of metal strands made of a conductive material, and an insulating layer 10i made of an insulating material covering the outer periphery of the conductor 10c, and strips off the insulating layer 10i on one end side. The conductor 10c is exposed. A terminal member 11 is attached to the exposed portion. The terminal member 11 is formed by making appropriate cuts on both edge sides of a metal plate made of a conductive material and bending the section. Specifically, the terminal member 11 is a terminal portion 12 (a flat male terminal portion having a rectangular plate shape or a rectangular tubular shape) formed by appropriately bending both ends on one end side of the plate material so that the edge side is in contact. Female terminal part), an insulation barrel part 13 formed by bending both sections of the other end of the plate so as to sandwich the insulating layer 10i part of the electric wire 10, and a terminal part 12 and an insulation barrel part 13 And a wire barrel portion 14 formed by bending both sections of a middle portion of the plate so that the conductor 10c exposed between the insulating layers 10i is vertically attached to sandwich the conductor 10c. . Most of the exposed conductor 10c is covered with the wire barrel portion 14 and a part of the pole is exposed.

[Electrolyte carrier]
<Dust collected from the actual environment>
In this test, an electrolyte carrier was further used. In preparing the electrolyte carrier, first, the dust that had fallen into the automobile from which the actual sample No. 1-100 was collected was collected, and the type and concentration of ions adhering to the surface were examined (measurement method is The same as the electrolyte carrier described later). As a result, the presence of a plurality of ions was recognized as shown in Table 1. Therefore, this dust was used as an electrolyte carrier (sand No. 10). This sand dust was a mixture of sand having an average particle size of several μm to 100 μm and dust having an average particle size of about 10 μm. When this dust was analyzed by EDX, the main elements were C, O, Si, and Ca (14.1 to 24.1% by mass, respectively), and other elements included Na, Mg, Al, S, Cl, K, and Fe. (1.4-5.5% by mass respectively). Therefore, this dust is considered to include ceramics such as SiO _2.

<Produced electrolyte carrier>
NaCl as an electrolyte and ultrapure water as a solvent were prepared, neutral aqueous solutions having a concentration of 0.5 to 26% by mass were prepared, and 200 g of each aqueous solution was prepared. In addition, 200 g of an acidic aqueous solution (about pH 5) in which H ₂ SO ₃ was added in addition to NaCl as an electrolyte was prepared (solvent: ultrapure water). 100 g of silica (SiO ₂ ) powder having an average particle diameter of about 100 μm was prepared as a granular body made of a nonmetallic insulating material. The silica powder used had an angular shape. The electrolyte, solvent, and granular material used are all commercially available products.

The prepared silica powder is placed on a filter paper, and the prepared electrolyte aqueous solution is dropped from above the silica powder, and then charged in a thermostatic chamber heated to 150 ° C., dried, and the powder obtained after drying Was used as an electrolyte support (sand No. 1 to 7).

In each prepared electrolyte carrier (sand No. 1 to 7, 10), the ion concentration (mass ppm) of the substance adhering to the surface of the granular material was examined. For the measurement of ion concentration, 0.5 g each of the prepared electrolyte carrier and the collected sand dust are taken, mixed in 50 ml of ultrapure water, kept at 90 ° C. for 1 h, and the extracted substances are extracted. Was analyzed by ion chromatography. The results are shown in Table 1. The ion concentration shown in Table 1 is a ratio to the mass of the electrolyte carrier or dust.

[Corrosion test]
As a sample, an electric wire with a terminal shown in Table 2 below was prepared (copper alloy: Cu—Ni—Si alloy). Then, the prepared electrolyte carrier (sand Nos. 1 to 7, 10) is sprinkled on each sample No. 1-1 to 1-4, and the sample in a state where the electrolyte carrier is in contact with the sample is 60 ° C. The sample was placed in a thermo-hygrostat set to 95% RH, taken out of the thermo-hygrostat after 12 days (288 hours), and the corrosion state of each sample from which the electrolyte carrier was removed was evaluated. Each electrolyte carrier was sprinkled so that a part of each sample could be visually confirmed (thickness of 1 mm or less).

[Comparative sample]
A sample subjected to a salt water immersion test was prepared as a comparative sample. Specifically, a 5% by mass NaCl aqueous solution was prepared using the same electrolyte and solvent as described above, and the conductor material: copper-terminal material: brass with terminal (sample No. 1 in Table 2). (Corresponding to 1) was immersed in this aqueous solution (not containing a granular material made of a nonmetallic insulating material), kept at 60 ° C. for 2 days, and then dried for 5 days (Sample No. 1). -200).

[Evaluation]
In the evaluation, a cross section of the wire barrel portion 14 in which the conductor is covered with the terminal (corresponding to the ZZ cross section in FIG. 1 (I), hereinafter referred to as the ZZ cross section; see FIG. 1 (II)), the conductor is covered with the terminal. The cross section of the missing portion (corresponding to the WW cross section in FIG. 1 (I), hereinafter referred to as the WW cross section) was observed by optical microscope observation (200 times) and appearance observation. The results are shown in Table 3. In Table 3, “◯” indicates corrosion, “Δ” indicates dezincification corrosion, and “-” indicates no corrosion.

Dezincification (Zn) corrosion is observed on a part of the outer side of the terminal (the part surrounded by the dotted square in Fig. 1 (II)) in the ZZ cross section of actual sample No. 1-100 (see Fig. 2 (I)) In the WW cross section, corrosion (black part) was observed on a part of the outside of the terminal. In addition, pitting corrosion was observed in a part of the conductor of the W-W cross section. No corrosion was observed on the conductor of the Z-Z cross section and on the inner side of the terminal (contact side with the conductor) in both cross sections.

On the other hand, when the ZZ cross section and WW cross section of sample No.1-200 subjected to the salt water immersion test were observed in the same manner as actual sample No.1-100, dezincification corrosion of brass terminals was observed over almost the entire surface. It was. Further, when the appearance was observed, it was confirmed that Sample No. 1-200 was corroded more severely than the most corroded portion in the conductor of Actual Sample No. 1-100.

On the other hand, the result of the corrosion test using the electrolyte carrier was almost the same as that of the actual sample No. 1-100. Specifically, in the sample No. 1-1 in which the conductor material is copper and the terminal material is brass, the electrolyte carrier prepared using a solution having a solution concentration of 2, 10, 26% by mass (each sand No. 3 , No.6, No.7), dezincification corrosion was observed on a part of the outside of the brass terminal (see FIG. 2 (II): the photograph is sand No. 3). Also, on the WW cross section of sample No.1-1, use the electrolyte carrier (sand No.2-7) prepared using a solution with a solution concentration of 1% by mass or more and the collected dust (sand No.10). In some cases, corrosion was observed on a part of the conductor.

For sample No. 1-2, which is a conductor material: copper-terminal material: copper alloy, when using an electrolyte carrier (sand No. 1 to 5) prepared using a low-concentration solution, and the collected sand ( When sample No. 10) was used, almost no corrosion was observed. However, corrosion was observed when an electrolyte carrier (sand No. 6, 7) prepared using a high concentration solution was used.

Corrosion was hardly observed in the Z-Z section of sample No.1-3, where the conductor material was aluminum and the terminal material was brass. However, in the W-W cross section of sample No. 1-3, corrosion was observed on a part of the conductor in any of the electrolyte carriers (sand Nos. 1 to 7, 10).

In the Z-Z section of sample No.1-4, which is conductor material: aluminum-terminal material: copper alloy, corrosion was observed on a part of the conductor when the collected sand dust (sand No. 10) was used. In addition, in the W-W cross section of sample No. 1-4, corrosion was observed on a part of the conductor in any of the electrolyte carriers (sand Nos. 1 to 7, 10).

From the above results, it can be seen that the corrosion test using the electrolyte carrier is almost equivalent to the corrosion state of actual sample No. 1-100. Moreover, it turns out that the corrosion test using the produced electrolyte carrier is in the same situation as the corrosion test using the collected dust, although the ion concentration is different. Therefore, the corrosion test method using a specific electrolyte carrier is a test method simulating an actual environment, and the concentration (ion concentration) and type of solution, constant temperature and humidity conditions, test time (especially in a constant temperature and humidity state). It is expected that the environment closer to the actual environment can be simulated by adjusting the retention time. For example, from this test result, the electrolyte carrier produced using a solution having a low ion concentration can be made to be approximately the same as the ion concentration attached to the collected sand dust, and can simulate an environment closer to the actual environment. In addition, it is expected that an accelerated test can be performed. In addition, for example, if an electrolyte carrier prepared using a high-concentration solution used in this test or a solution with a higher ion concentration is used, it is expected that the test time can be shortened (acceleration test can be accelerated). Is done. And the corrosion test method using such a specific electrolyte carrier is a component of various electrical and electronic devices used in an indoor environment where corrosion is likely to occur due to adhesion of dust such as sand and dust, In particular, it is expected to be suitably used for evaluating the corrosion resistance of metal members made of different metals.

(Test Example 1-2)
Prepare sand No. 1 (solution concentration: 0.5% by mass), sand No. 2 (same: 1% by mass), sand No. 10 (collected sand dust) prepared in Test Example 1-1, and test time of 6 A corrosion test was conducted in the same manner as in Test Example 1 except that the date was changed to 144 days. The results are shown in Table 4. The evaluation of the corrosion status in the table is the same as in Table 3.

As a result, almost no corrosion was observed in the sample No. 1-1 in which the conductor material: copper-terminal material: brass. In contrast, sample No. 1-2, which is a conductor material: copper-terminal material: copper alloy, and sample No. 1-3, which is a conductor material: aluminum-terminal material: brass, have a solution concentration of 1% by mass. When the electrolyte carrier (sand No. 2) was used, corrosion of the conductor was observed. In sample No.1-4, which is a conductor material: aluminum-terminal material: copper alloy, no matter what electrolyte support (sand No.1, 2) was used, corrosion of the conductor was observed. However, no dezincification corrosion was observed in any of the samples.

From the above evaluation, it can be seen that the electrolyte carrier produced from the collected sand dust has a fast progress of corrosion. Therefore, from the results of Test Example 1-1 and Test Example 1-2, it was confirmed that an acceleration test can be performed by using a specific electrolyte carrier. However, in this Test Example 1-2, since dezincification corrosion was not observed, a more precise evaluation of corrosion resistance was desired, and the solution of Table 4 was used, and the same as in Test Example 1-1. In the case of the constant temperature and humidity conditions, it is considered that the test time is preferably about the same as in Test Example 1-1.

(Test Example 1-3)
Various electrolyte solutions were prepared to prepare an electrolyte carrier, and the ion concentration of substances adhering to the surface of the granular material was measured.

For the preparation of the electrolyte carrier, prepare the same silica powder used in Test Example 1-1, prepare the electrolyte and solvent ultrapure water shown in Table 1, and have the concentrations shown in Table 1. An aqueous solution was prepared. Then, in the same manner as in Test Example 1-1, the prepared silica powder was placed on a filter paper, each prepared aqueous solution was dropped thereon, and then dried at 150 ° C. to prepare an electrolyte carrier. In addition, an electrolyte carrier was prepared by dropping artificial seawater (Daigo Artificial Seawater SP, manufactured by Nippon Pharmaceutical Co., Ltd.) from the silica powder and then drying at 150 ° C. An extract was prepared from the prepared electrolyte carrier in the same manner as in Test Example 1-1, and analyzed using an ion chromatograph. The results are shown in Table 1.

As shown in Table 1, it can be seen that there is a correlation between the concentration of the electrolyte solution and the amount of ions adhering to the electrolyte carrier. Specifically, it can be seen that the higher the concentration, the greater the amount of ions. It can also be seen that the amount of ions (Cl ⁻ , Na ⁺ ) adhering to the electrolyte carrier used in Test Examples 1-1 and 1-2 is larger than the collected dust. From this, it is expected that the electrolyte carrier used in Test Examples 1-1 and 1-2 can be used for the acceleration test. Also, when preparing the electrolyte carrier, the amount of ions adhering to the electrolyte carrier can be adjusted by adjusting the concentration of the solution, simulating the environment according to the actual environment, or increasing the speed of the acceleration test Expected to speed up.

(Test Example 1-4)
As the electrolyte carrier, particles having different sizes and shapes were produced, and the change in weight after the constant temperature and humidity of the electrolyte carrier was examined.

The granular material was made of silica and prepared so as to have a mass ratio shown in Table 5 with an angular shape having an average particle size of 105 μm and 20 μm and a round shape with an average particle size of 20 μm. Then, an electrolyte shown in Table 5 was prepared, and an aqueous solution was prepared using ultrapure water so as to have a concentration shown in Table 5 (Na concentration in Sample Nos. 1-4-1 to 1-4-4 is Sample No. 1-4-7 (same as Na concentration of Na ₂ SO ₄ (12% by mass)) In addition, the same solution as the artificial seawater used in Test Example 1-3 was prepared as an electrolyte solution.

As in Test Example 1-1, each prepared silica powder was placed on a filter paper, and each aqueous solution prepared from it was dropped, and then dried at 150 ° C. to prepare an electrolyte carrier, each weight Was measured. Also, put each dried electrolyte carrier in a constant temperature and humidity device set at 60 ° C and 95% RH, take it out from the constant temperature and humidity device after 3 hours, measure the weight of each electrolyte carrier, and before and after constant temperature and humidity The weight difference was determined. The results are shown in Table 5. A positive number shown in “Amount of increase in mass after constant temperature and humidity” in Table 5 indicates an increase, and a negative number indicates a decrease.

As shown in Table 5, the mass after constant temperature and humidity varies depending on the type and concentration of the solution, and when hygroscopic salts such as NaCl adhere to it or a high concentration solution is used, It can be seen that the mass of the glass tends to increase. The increased mass is thought to be mainly due to moisture adhesion. Therefore, it is considered that the amount of moisture attached can be adjusted by selecting the material of the electrolyte to be attached or adjusting the concentration of the solution. In this test, the material whose mass is reduced is within the range of measurement error, and it is considered that an electrolyte containing corrosion-promoting ions such as Cl 2 ⁻ can be used for the corrosion test.

Also, as shown in Table 5, when the same material electrolyte was used and the shape of the granular material was the same, the increase in mass was almost the same regardless of the size of the granular material. Furthermore, when the same concentration of electrolyte was used with the same material electrolyte, the amount of moisture adhered was larger in the angularly shaped granular material.

(Test Example 1-5)
A sample having a plated portion was prepared and heat-treated, and the situation after the heat treatment of this sample was compared with the situation of an actual product (actual sample) over time.

[Actual sample]
As a real sample, a brass terminal connected to one end of a copper electric wire arranged in the living space of the above-mentioned ordinary automobile and having a tin plating made of pure Sn on the surface was prepared (Sample No. 1-102). . The cross section of the plated terminal was observed with an SEM (scanning electron microscope) (20,000 times), and the composition of the plated portion was analyzed with an EDX apparatus (energy dispersive X-ray analyzer). The results are shown in Table 6. In actual sample No. 1-102, the composition was examined at two points as shown in FIG. 3 (I), specifically, the point [i] on the surface side and the point [ii] on the side close to the terminal base metal. It was. In the SEM micrographs of FIGS. 3 (I) to (III), the lower side is the terminal base material, the upper layer is the plated portion, and the upper dark black layer is the background.

[Preparation sample]
A copper alloy terminal (copper alloy: Cu—Ni—Si alloy) with tin plating made of pure Sn on the surface was prepared, and heat treatment was performed at 150 ° C. for 120 hours (Sample No. 1-5-1). Before and after the heat treatment, the cross section of this sample was subjected to SEM observation (20,000 times) in the same manner as the actual sample No. 1-102, and the composition was examined. The results are shown in Table 6. Sample No.1-5-1 was reflow-treated after tin plating, and before the heat treatment at 150 ° C. × 120 h, as shown in FIG. 3 (II), the surface side point [1] and the terminal base material The composition of the point [2] near the surface and the composition of the surface [3] after the heat treatment as shown in FIG. 3 (III) were examined. Note that K and L in the element column of Table 6 indicate trajectories of characteristic X-rays.

As shown in Table 6 and Fig. 3 (I), in the plating part of actual sample No. 1-102, a part where the element of the terminal base material (here Cu) diffuses and is alloyed during plating is observed. . In particular, it is recognized that the portion close to the terminal base material in the plated portion has a high atomic ratio of elements of the terminal base material, and the alloying is proceeding. On the other hand, after plating and before heat treatment, the surface side of the plating part of sample No.1-5-1 does not show the element of the terminal base material (Cu here), whereas the terminal base material in the plating part It can be seen that the portion close to が has a high atomic ratio of the terminal base material element (Cu), and the terminal base material element (Cu) is diffused and alloyed during plating. When heat treatment was applied to this sample No.1-5-1, as shown in Table 6 and Fig. 3 (III), the atomic ratio of the element (Cu) in the terminal base metal also increased at the surface side of the plated part. It can be seen that the entire plating is alloyed. From this, it can be said that alloying due to thermal deterioration can be accelerated and simulated by performing heat treatment on the plated portion.

When performing a corrosion test on a metal member having a plated part based on the results of the above test, prepare a sample that is appropriately heat-treated on the plated part, and investigate the corrosion state by sprinkling the above-mentioned electrolyte carrier on this sample. Therefore, it is expected that an accelerated test can be performed in addition to simulating an environment that is more appropriate to the actual environment. In addition, in a test involving the supply of electric power, which will be described later, when a metal member having a plated portion is used as a sample, it is expected that an environment more suitable for the actual environment can be simulated by appropriately applying the heat treatment. .

(Test Example 2: Corrosion test for supplying power (constant voltage))
Prepare a plurality of electric wires with terminals used in Test Example 1 above as samples, conduct corrosion tests under various conditions, and compare the corrosion status of each sample with the corrosion status of the actual product (actual sample) over time. The corrosion test method was evaluated. In this test, power is supplied.

[Actual sample]
As an actual sample to be compared, a copper wire with a brass terminal arranged in the living space of a normal automobile similar to Test Example 1-1 was prepared (actual sample No. 2-100).

<Corrosion test>
Here, the corrosion test using the electrolyte carrier described later (corrosion liquid generation form (form I)), the corrosion test using mud (corrosion liquid utilization form (form II)), and only the NaCl aqueous solution without using particulates. Three corrosion tests were carried out with the corrosion test using A (form α). First, a sample, a cavity, a constant temperature and humidity device, a power supply device, an electrolyte carrier used in the above-mentioned form I, and a fluid tank used in the above-described forms II and α, which are commonly used in these three corrosion tests, will be described.

<Sample>
For Forms I, II, and α, a pair of samples having the same configuration as Sample 1 (FIG. 1 (I)) used in Test Example 1-1 was prepared, and a corrosion test was performed.

Here, as the wire 10, the conductor is made of pure copper, a wire conductor cross-sectional area 0.5 mm ^2, AVSS are utilized in automobiles, such as (automobile ultrathin low pressure lines, JASO D611 conforming product) wires (insulation Layer material: vinyl chloride, thickness: about 0.3 mm) was cut to an appropriate length and used. The conductor may be uncompressed or compressed. As the terminal member 11, a 2.3 type female terminal whose base material is made of brass and whose surface is tin-plated is used. As described above, in the forms I, II, and α, samples were prepared using electric wires and terminals having the same material and size.

<Cavity>
In each of the forms I, II, and α, a pair of samples 1 were used in the cavity 5 for use. As shown in FIG. 4, the cavity 5 is a member having a quadrangular prism shape, and includes a plurality of insertion holes 50 into which the terminal portion 12 portion of the sample 1 and the vicinity thereof are inserted. The cavity 5 simulates an F connector to which a terminal of an automobile wire harness is connected. Each insertion hole 50 is provided so that the axial directions of the plurality of samples 1 are parallel. Therefore, when one sample 1 is inserted into one insertion hole 50 and another sample 1 is inserted into the insertion hole adjacent to this insertion hole, both samples 1 are arranged in parallel as shown in FIG. It is maintained in a state of being arranged with an interval of. Here, the cavity 5 is formed of polybutylene terephthalate (PBT) resin, and the center-to-center distance between adjacent insertion holes 50 (the distance between the pair of terminal members 11) is about 3 mm. Then, the terminal portions 12 of the pair of samples 1 are respectively inserted into the adjacent insertion holes 50 of the cavity 5 and used for the corrosion tests of forms I, II, and α. By using the cavity 5, it is possible to simulate an environment that is more suitable for the actual environment in which the wire harness is used. Instead of using the cavity 5, the pair of samples may be arranged in a separated state. In the form I, a sample separated on an insulating plate or the like may be placed. The insertion hole of the cavity may be a through hole or a non-through hole. Here, it is a through hole.

<Constant temperature and humidity device and power supply device>
In any of the forms I, II, and α, the sample 1 mounted in the cavity 5 is placed in the constant temperature and humidity device 2 and maintained at a predetermined temperature and humidity. Further, the power supply device 3 is connected to the other end side of the electric wire 10 of the pair of samples 1, and a voltage is applied to the sample 1. Here, a lead wire was separately connected to the other end of the electric wire 10 to connect the power supply device 3. Of course, the electric wire 10 may be directly connected to the power supply device 3. Both the constant temperature and humidity device 2 and the power supply device 3 were commercially available.

<Fluid tank>
In the forms II and α, the sample 1 mounted in the cavity 5 is arranged in a fluid tank 7 in which a fluid 6 containing an electrolyte is stored as shown in FIG. 4 (II). As the fluid tank 7, an appropriate one capable of storing the predetermined fluid 6 can be used. In FIG. 4, the same reference numerals as those in FIG.

<Electrolyte carrier>
In Form I, an electrolyte support 4 was further used. The electrolyte carrier 4 was produced as follows with reference to the dust that had fallen into the automobile from which the actual sample No. 2-100 was collected. 200 g of artificial seawater (NaCl concentration: 26% by mass, aqueous solution containing electrolyte (Na, Cl)), heavy calcium carbonate (JIS Z 8901 (2006) with an average particle size of 10 μm or less), powder for testing 100 g of 1-16 kinds of powder (granular material) was prepared. The powder used was approximately the same size as the dust. Both the artificial seawater and the granular material are commercially available products.

Place the prepared calcium carbonate powder on the filter paper, drop the prepared artificial seawater from above the powder, place it in a thermostatic bath heated to 150 ° C. and dry it. An electrolyte carrier was obtained. In the obtained electrolyte support, the ion concentration (mass ppm) of the substance adhering to the surface of the granular material was examined in the same manner as in Test Example 1-1. As a result, the results are the same as those shown in Table 1 (total ion concentration: about 1.1% by mass> 0.05% by mass), and the produced electrolyte support was composed of a plurality of types of ions (Cl ⁻ , Na ⁺ , Mg ²⁺ , K ⁺ , Ca ²⁺ ). Moreover, it has confirmed that these ions were the same kind as the ion adhering to the dust which fell in the motor vehicle which collected the said real sample.

<Form I: Corrosion test using electrolyte carrier>
In Form I, the corrosion test was performed according to the following procedure.

(1) A pair of samples 1 is prepared, and the terminal portion 12 of each sample 1 is inserted into the adjacent insertion hole 50 of the cavity 5. By this step, the terminal members 11 of both samples 1 are arranged in parallel with a predetermined interval.

(2) Filling the insertion hole 50 of the cavity 5 into which the sample 1 is inserted with the prepared electrolyte carrier 4 and arranging the electrolyte carrier 4 so as to fill a part of the electric wire 10 exposed from the insertion hole 50 To do. In FIG. 4 (I), the electrolyte carrier 4 is disposed in a portion surrounded by a one-dot chain line. By this step, at least the insulation barrel portion 13 and the wire barrel portion 14 of the terminal member 11 of each sample 1 are in contact with the powder of the electrolyte carrier 4, and the electrolyte carrier 4 is between the terminal members 11 of both samples 1. Intervene. Here, a part of the electric wire 10 is also covered with the electrolyte carrier 4, and the electrolyte carrier 4 is present between the two samples 1, so that even if there is a cavity wall between the two samples 1, one terminal member 11 A leakage current may flow from the other terminal member 11 to the other terminal member 11. In addition, since the insertion hole 50 of the cavity 5 is a through hole, it is inserted into an adjacent insertion hole by an electrolyte carrier existing in the vicinity of one opening of the through hole (the opening where the sample is not inserted). The electrolyte carrier can also be interposed between the terminal portions of the both terminal members.

(3) Connect the power supply device 3 to the other end of the pair of samples 1. This connection can be made at any time before the voltage is applied to the sample 1, and before placing the electrolyte carrier 4 on the sample 1, even after holding a constant temperature and humidity state for a predetermined time (30 minutes) to be described later. Good.

(4) The sample 1 and the cavity 5 on which the electrolyte carrier 4 is arranged are placed in the constant temperature and humidity device 2. After charging the constant temperature and humidity device 2, the sample 1 is held in a constant temperature and humidity state for a predetermined time. Here, it was held for 30 minutes. The constant temperature and humidity conditions were temperature: 38 ° C. and humidity: 95% RH.

(5) After a predetermined time (30 minutes), a constant voltage is applied to the sample 1 by the power supply device 3 while maintaining the constant temperature and humidity state for a predetermined time. The constant temperature and humidity conditions are: temperature: 38 ° C, humidity: 95% RH, applied voltage: applied voltage: 12V, applied time: 20 hours (sample No. 2-1), 40 hours (sample No. 2- 2). Here, the applied voltage was set to 12 V, imitating the power supply voltage of the automobile wire harness. The current flowing between the two terminal members 11 during the charging time was measured and found to be several mA (less than 10 mA). Further, when the electric (charge) amount (C, Coulomb) was determined from the measured current and the charging time, it was Sample No. 2-1: 29.3C and Sample No. 2-2: 42.1C.

(6) After a predetermined time (20 hours or 40 hours) has elapsed, the charging is stopped, and the sample 1 is taken out of the thermo-hygrostat 2 and the electrolyte carrier 4 is removed.

《Form II: Corrosion test using mud》
In Form II, the corrosion test was performed according to the following procedure. In Form II, mud prepared by mixing kaolin (30 g) in a NaCl aqueous solution (50 ml) having a NaCl concentration of 5% by mass was prepared as a fluid containing a granular material made of a nonmetallic insulating material and an electrolyte. Then, as shown in FIG. 4 (II), the sample 1 placed in the cavity 5 is placed in the fluid tank 7, and then the fluid 6 (here, the above mud) is injected into the fluid tank 7, The entire terminal member 11 and a part of the electric wire 10 are immersed in the fluid 6.

The sample 1 and the fluid tank 7 are placed in a constant temperature and humidity device (not shown in FIG. 4 (II)) and maintained in a constant temperature and humidity state of 30 ° C. and 95% RH. In this state, a constant voltage is applied to the sample 1 by the power supply device 3 for a predetermined time within 30 minutes after injecting the fluid 6 into the fluid tank 7 in which the sample 1 is arranged. The voltage application conditions were an applied voltage of 12 V and a voltage application time of 13 hours (Sample No. 2-3). The amount of electricity obtained in the same manner as in Form I was 122.3C. After a predetermined time has elapsed, the application of electricity is stopped, the sample 1 is taken out of the constant temperature and humidity device, and mud is removed. You may remove mud using a brush etc. suitably.

<< Form α: Corrosion test using NaCl aqueous solution >>
In the form α, only an aqueous NaCl solution is used without using an electrolyte carrier or a granular material. Specifically, as shown in FIG. 4 (II), the sample 1 inserted into the cavity 5 is placed in the fluid tank 7, and then the fluid 6 (here, the concentration of NaCl is 5% by mass). NaCl terminal solution) is filled, and the entire terminal member 11 and a part of the electric wire 10 are immersed in the fluid 6. Further, the opening was closed with an insulating tape (not shown) so that the fluid 6 would not enter from one opening of the insertion hole 50 of the cavity 5 (the opening where the sample 1 was not inserted). The same applies to Form II).

The sample 1 and the fluid tank 7 were placed in a constant temperature and humidity device, and the sample 1 was immersed in the fluid 6 for constant temperature and humidity, and a constant current was passed for a predetermined time. Here, the initial voltage when applying power was set to 1.3 V or more. Then, by setting the current value to 20 mA (fixed value) and changing the energization time, sample Nos. 2-200 to 2-205 having different amounts of electricity were obtained. The constant temperature and humidity conditions were temperature: 38 ° C. and humidity: 95% RH.

In Embodiments II and α, the fluid tank 7 is inserted into a constant temperature and humidity device, but it may not be charged depending on temperature and humidity. By inserting the thermostatic / humidity device, the temperature of the fluid becomes uniform, and the effects of convection can be reduced, and the possibility that moisture is evaporated and depleted can be reduced.

<Observation results>
The corrosion status of each of the actual samples Nos. 2-100 and Nos. 2-1 to 2-3 subjected to the corrosion tests of Forms I, II, and α was evaluated. For the evaluation of each of the actual sample and each sample, a cross section (corresponding to a cross section cut along XX in FIG. 1 (I)) of the insulation barrel portion orthogonal to the axial direction was obtained with an optical microscope (25 times or 200 times). )). FIG. 5 shows observation images of Sample Nos. 2-1, 2-2, and 2-3 and Actual Sample No. 2-100, and FIG. 6 shows Samples No. 2-200 to 2-205. In FIGS. 5 and 6 and FIG. 8 described later, a plurality of round lumps existing in the central portion are each strand constituting the conductor of the electric wire, and a strip-shaped lumps existing on the outer periphery of the strand indicate a terminal member. Actual sample No. 2-100 shows the XX cross section in a state where a part of the terminal member is removed. Further, in the terminal members of FIGS. 5 and 6 and FIG. 8 to be described later, a dark color portion indicates copper, and a light color portion indicates brass.

In any of the forms I, II, and α, the observed image is observed from the two terminal members arranged in parallel on the positive electrode side (+ side). The terminal member arranged on the negative electrode side (− side) was not corroded like the terminal member arranged on the positive electrode side (+ side) in any of the corrosion tests of forms I, II and α. Note that a brass plate, a copper rod, or the like can be used as an object to be connected to the negative electrode side (-side) instead of the sample having the terminal member.

In the actual sample No. 2-100, as shown in FIG. 5 (IV), it can be seen that there are portions where the brass has changed to copper, that is, portions where dezincification corrosion has occurred, over the entire terminal member. Moreover, it turns out that the dent and the space | gap have arisen in the part which has become the copper by dezincification corrosion. However, there are almost no defects or voids in the brass part. It can also be seen that the conductor is hardly corroded.

On the other hand, Sample No. 2-1 (formation time: 20 hours) of Form I using an electrolyte carrier is a copper that has been dezincified and turned into copper as shown in FIG. 5 (I). It turns out that the part exists widely. Moreover, it turns out that a part of this copper part lose | deletes and the dent and the space | gap have arisen. It can also be seen that there is almost no defect in the brass part. In Sample No. 2-2, where the charging time was increased to 40 hours, as shown in Fig. 5 (II), there were more copper parts that became copper due to dezincification corrosion. It can be seen that dezincification corrosion occurs throughout. And it turns out that the defect | deletion in a brass part is hardly seen. In addition, Sample No. 2-3 using mud, like Sample No. 2-1 and 2-2, dezincification corrosion occurred over the entire terminal member, and there were almost no defects in the brass part. I understand that there is no. Further, it can be seen that the conductors of all of sample Nos. 2-1 to 2-3 are hardly corroded.

On the other hand, sample Nos. 2-200 to 2-204, which were subjected to the corrosion test of form α in which the sample was immersed in a NaCl solution containing no granular material, had almost no dezincification corrosion on the terminal member, and the brass itself It can be seen that dents and voids are generated by elution. For example, as shown in FIG. 6 (IV ′) in which a portion surrounded by a white rectangular frame in Sample No. 2-203 in FIG. 6 (IV) is enlarged, brass itself is deficient. That is, these sample Nos. 2-200 to 2-204 have an electric quantity of 0.3C (sample No. 2-200), compared with samples Nos. 2-1 to 2-3 of Forms I and II. Despite being as low as 1.5C (Sample No. 2-201), 5.8C (Sample No. 2-202), 10C (Sample No. 2-203), and 20C (Sample No. 2-204), the brass itself It can be seen that is eluted. Sample No. 2-205 (quantity of electricity: 50C), which has a larger amount of electricity than Sample Nos. 2-1 to 2-3 of Forms I and II, is surrounded by a white rectangular frame in Fig. 6 (VI). As shown in FIG. 6 (VI ′) in which the portion is enlarged, dezincification corrosion is very slight.

Based on the above, the corrosion test of Forms I and II using an electrolyte carrier and mud and applying a constant voltage is very good with the actual sample No.2-100. It is similar and can be said to have high reproducibility. In addition, although the produced electrolyte carrier contains ions similar to the collected dust, although the ion concentration is different, the form I using this electrolyte carrier is the environment surrounding the actual sample No. 2-100. It can be said that it can be suitably used as a simulated acceleration test. Furthermore, since the produced mud contains the same granular material as the collected dust, form II using this mud can also be suitably used as an accelerated test that simulates the surrounding environment of actual sample No. 2-100. It can be said. On the other hand, in the corrosion test of Form α in which the sample is immersed in a NaCl solution, the corrosion state of the actual sample No. 2-100 is not similar at all, and it can be said that the reproducibility is poor.

From the above, it is presumed that the Form I using the electrolyte carrier and the Form II using mud are corroded by the following principle. As shown in FIG. 7, a pair of electrode members 60 made of a conductive material are inserted into a pair of containers 61 filled with an electrolyte and moisture, respectively, and brought into contact with the electrolyte and moisture, and resistance is passed between both containers 61. A resistor 62 having a large value is arranged. In this state, a voltage having a certain magnitude is applied to both electrode members 60. Then, only a very small current flows between the electrode members 60 due to the interposition of the resistor 62. It is presumed that corrosion was caused by such a very small current. In particular, by using a variable resistor, even if the amount of electricity in a predetermined time is the same, the current value in a certain time can be changed. It is presumed that such a fluctuating and weak current caused corrosion more suited to the actual environment.

As described above, the corrosion test method using an electrolyte carrier or a fluid containing the specific granular material and applying a constant voltage is, for example, an indoor environment where dust such as sand and dust is generated. It is expected that it can be suitably used for evaluating the corrosion resistance of various metal members used in an environment where they adhere and corrode due to leakage current. In addition, the type and amount of the electrolyte in the electrolyte carrier, the size of the granular material used for the electrolyte carrier, the amount of the electrolyte carrier used, the size and amount of the granular material mixed with the fluid, the electrolyte concentration of the fluid, the constant temperature It is expected that an environment closer to the actual environment can be simulated by adjusting the constant humidity conditions (temperature, humidity), voltage value (current value), charging time (charge amount), and the like. In addition, by increasing the ion concentration of the solution used when preparing the electrolyte carrier, increasing the temperature and humidity in a constant temperature and humidity state, and increasing the voltage value during current application (current value during energization) It is expected that the test time can be shortened (accelerated test speeding up). These points are the same when energizing a constant current described later. In addition, for example, when the temperature is 75 ° C under constant temperature and humidity conditions and the charging time is 4 hours, the corrosion situation is very similar to when the temperature is 38 ° C and the charging time is 40 hours. When the temperature was 75 ° C., the charging time was 8 hours, and 13 hours, the dezincification corrosion amount was further increased. Therefore, further acceleration of the test can be expected by increasing the temperature under constant temperature and humidity conditions.

Furthermore, it is expected that this corrosion test method can be suitably used as an accelerated test that simulates an environment in which terminal members are mainly corroded and conductors are hardly corroded. It is expected that the corrosion status of the terminal member can be evaluated even when the constituent metal of the conductor is different from the constituent metal of the terminal member because the conductor is less corroded. The same applies to the case where a constant current described later is applied.

(Test Example 3: Corrosion test with power supply (constant current))
Sample 1, the electrolyte carrier 4 and the fluid used in Test Example 2 were prepared, a similar corrosion test system was constructed, and a constant voltage was replaced with a constant current to conduct a corrosion test. In this test, a corrosion test was performed in the same manner as in Test Example 2 except that the power supply conditions were changed.

<Form I: Corrosion test using electrolyte carrier>
In the same manner as in Form I of Test Example 2, the sample 1 and the cavity 5 in which the electrolyte carrier 4 is arranged are loaded into the constant temperature and humidity device 2, and the sample 1 is kept in a constant temperature and humidity state for a predetermined time (here, 30 Min) Hold. The temperature and humidity conditions were temperature: 75 ° C. and humidity: 95% RH.

After a predetermined time (30 minutes) has passed, a current of a certain magnitude shown in Table 7 is passed through the sample 1 for a predetermined time by the power supply device 3 while maintaining the constant temperature and humidity condition of the above constant temperature and humidity conditions. Here, the energization time was adjusted so that the charge amount was 50C. After a predetermined time has elapsed, the energization is stopped, the sample 1 is taken out from the constant temperature and humidity device 2, and the electrolyte carrier 4 is removed.

<Form II: Corrosion test using mud>
In the same manner as in Form II of Test Example 2, after placing Sample 1 placed in cavity 5 in fluid tank 7, fluid 6 (mud used in Form II of Test Example 2) was injected into fluid tank 7. Then, the entire terminal member 11 of the sample 1 and a part of the electric wire 10 are immersed in the fluid 6.

The sample 1 and the fluid tank 7 are charged into a constant temperature and humidity device, and kept at a constant temperature and humidity state of 30 ° C. and 95% RH. In this state, within 30 minutes after injecting the fluid 6 into the fluid tank 7 in which the sample 1 is arranged, the power supply device 3 starts to supply a current having the magnitude shown in Table 1, and the constant current is applied to the sample 1 For a predetermined time. Here, the energization time was adjusted so that the charge amount was 250C. After a predetermined time has elapsed, the energization is stopped, the sample 1 is taken out from the constant temperature and humidity device, and mud is removed.

<Observation results>
The actual sample No. 2-100 used in Test Example 2 was used as a comparison object, and the corrosion status of each sample No. 3-1 and 3-2 subjected to the corrosion test of the above forms I and II was evaluated. The evaluation was performed by observing the XX cross section of each sample with an optical microscope (25 times) in the same manner as in Test Example 2. In the same manner as in Test Example 2, the observed image is observed on the positive electrode side (+ side).

Further, with respect to Sample Nos. 3-1, 3-2, when the voltage between the pair of terminal members was measured after the start of energization, the voltage gradually increased immediately after the start of energization, and thereafter became a constant value. Table 7 shows these constant voltage values as system voltages.

It can be seen that Sample No. 3-1 has a portion where dezincification corrosion has occurred over the entire terminal member as shown in FIG. 8, or a portion where a portion of the copper portion is missing. In Sample No. 3-1, it can be seen that there are almost no defects or voids in the brass portion, and the conductor is hardly corroded. Sample No. 3-2 was also in the same corrosion state as Sample No. 3-1. From these results, the corrosion test performed on sample Nos. 3-1 and 3-2 reproduces the corrosion environment of actual sample No. 2-100 well, and accelerated corrosion test of such a corrosive environment It can be said that it corresponds to.

In addition, the corrosion state was examined by applying a constant current in the same manner using a 5 mass% NaCl solution without using the granular material used in Forms I and II. Here, the charge amount was fixed at 50 C, and the current values were changed to 0.2 mA, 1 mA, 3 mA, and 5 mA. Current per unit area to the exposed area (here was about 26 mm ² in) of the terminal members each ^{0.2mA: 0.0075mA / mm 2, 1mA} : 0.038mA / mm 2, 3mA: 0.11mA /

mm

2, 5 mA: 0.19 mA / mm ² . As a result, in a sample in which a constant current was applied so that the current per unit area of the terminal member was less than 0.19 mA / mm ² and the charge amount per unit area of the terminal member was 20 C / mm ² or less, It was very similar to the corrosion state of sample No.2-100. On the other hand, in the 0.19 mA / mm ² sample, there was almost no dezincification corrosion, and the brass itself was eluted to form dents and voids, and corrosion of the conductor was also observed.

From the above test results, when the current value per unit area in the exposed area of the terminal member is small, brass itself constituting the terminal member does not flow out, and dezincification tends to occur, and when the current value is large, It can be said that the brass constituting the terminal member tends to flow out. One possible cause of this result is that the electrode potential of the anode (brass) varies depending on the current value. Actually, the anode potential was measured using a brass plate as follows. A reference electrode (Ag / AgCl) is prepared and immersed in a fluid (5% NaCl solution, 38 ° C.) containing an electrolyte together with a pair of brass plates. A voltmeter is attached to the reference electrode and the brass plate of the anode, and in this state, a charge amount: 50 C and a current value (constant): 2 mA or 50 mA are passed through the pair of brass plates. The anode potential during energization was measured with the voltmeter. Then, the sample set to 2 mA (current value per exposed area of the brass plate: 0.0077 mA / mm ² ) took a substantially constant potential during the energization time (25000 seconds) (40 mV), but the sample set to 50 mA ( The electric current value per exposed area of the brass plate: 0.19 mA / mm ² ) had a large potential fluctuation range (110 to 160 mV) during the energization time (1000 seconds).

Based on the above, energization satisfying a condition that a specific granular material and a fluid containing an electrolyte are interposed between the terminal member of the sample and the electrode material, and less than 0.19 mA / mm ² and 20 C / mm ² or less. Under certain conditions, a corrosion test method in which a weak current having a certain magnitude is applied is expected to be suitably used as an accelerated test that simulates an actual environment such as an environment in which corrosion due to leakage current occurs. In addition, this corrosion test method has a constant electric current, which makes it easy to control the amount of charge, easily forms the same corrosive environment, and has excellent reproducibility. It is expected that it can be suitably used as a test method.

In Test Examples 2 and 3 described above, heavy calcium carbonate was used for the granular material of the electrolyte carrier, but silica may be used as in Test Example 1, or kaolin mixed in the fluid may be used. In addition, ceramics such as alumina described above may be used.

The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention. For example, the composition, shape and size of the granular material, the type of electrolyte to be attached to the granular material constituting the electrolyte carrier, and the type of electrolyte to be contained in the fluid, etc., and the test conditions (constant temperature) The temperature and humidity of constant humidity, the magnitude of voltage / current, the power supply time, etc.) can be changed as appropriate.

The corrosion test method of the present invention is a corrosion resistance of components of electric and electronic equipment used in an environment where the progress of corrosion is considered to be relatively gradual, for example, in an indoor environment such as an automobile living space, a house, or a building interior. When evaluating the corrosion resistance of a metal member that can cause electrolytic corrosion, it can be suitably used when evaluating the corrosion resistance of a metal member that can be corroded by a leakage current in the above-described component member.

1 Sample 2 Constant temperature and humidity device 3 Power supply device 4 Electrolyte carrier 5 Cavity 50 Insert hole 6 Fluid 7 Fluid tank 10 Electric wire 10c Conductor 10i Insulating layer 11 Terminal member 12 Terminal portion 13 Insulation barrel portion 14 Wire barrel portion 60 Electrode member 61 Container 62 Resistor

Claims

A corrosion test method for investigating the corrosion status of a sample having a part made of a metal material,
A corrosion test method comprising the step of holding a state in which the sample is made in contact with a granular material made of a nonmetallic insulating material and a fluid containing an electrolyte for a predetermined time.
The sample is obtained by attaching a terminal member to an end of an electric wire having an insulating layer on the outer periphery of a conductor. The sample and an electrode material are prepared, and the terminal member and the electrode material of the sample are separated from each other. And arranging the process,
The sample terminal member and the electrode material are maintained while the state where the granular material made of the nonmetallic insulating material and the fluid containing the electrolyte are interposed between the terminal member of the sample and the electrode material. 2. The corrosion test method according to claim 1, further comprising a step of supplying electric power to the sample and the electrode material for a predetermined time so that a current flows between the sample and the electrode material.
Preparing an electrolyte carrier in which an electrolyte is attached to the surfaces of the plurality of granular bodies;
The electrolyte carrier is disposed so as to be in contact with the terminal member and the electrode material of the sample that are spaced apart and interposed between the terminal member and the electrode material,
While maintaining the sample and the electrode material in which the electrolyte carrier is arranged in a constant temperature and humidity state, power is supplied to the sample and the electrode material for a predetermined time,
3. The fluid containing the electrolyte is generated by holding the electrolyte carrier in a constant temperature and humidity state, and is interposed between the sample and the electrode material. Corrosion test method.
3. The corrosion test method according to claim 1, wherein the fluid includes the granular material.
3. The corrosion test method according to claim 2, wherein, in the step of supplying electric power, a constant voltage is applied to the sample and the electrode material for a predetermined time.
In the step of supplying power, a constant current is passed through the sample and the electrode material,
3. The corrosion test method according to claim 2, wherein the energization is performed for a time in a range in which a current value is less than 0.19 mA / mm 2 and a charge amount is 20 C / mm 2 or less.
The corrosion test method according to claim 1 or 2, wherein the electrolyte contains one or more selected from Na, Cl, Mg, K, and Ca.
The corrosion test method according to claim 1 or 2, wherein the terminal member is made of brass.