JP2020038178A - Exfoliation sensor and exfoliation detection system - Google Patents

Abstract

To provide an exfoliation sensor that is able to detect exfoliation that may arise in a joining interface between a metal and a resin.SOLUTION: An exfoliation sensor 1 comprises: a metal tester 11 made of a first metal; a separator 12 disposed on the metal tester, made of an insulation material, and permeable to liquid; an auxiliary electrode 13 made of a second metal disposed on the separator; and a resin tester 14 made of a resin, encapsulating the auxiliary electrode liquid-tightly together with the separator, and joined to the metal tester. According to the exfoliation sensor of the present invention, exfoliation that may occur in a joining interface between the metal tester and the resin tester can be detected by measuring an electrical characteristic between the metal tester and the auxiliary electrode. The presence or absence of exfoliation, which may occur in a joining interface, can be detected, for example, by measuring a resistance value if the first metal and the second metal are materials of the same kind and by measuring an electrical current value if the first metal and the second metal are materials of different kinds.SELECTED DRAWING: Figure 1A

Description

  The present invention relates to a sensor and the like that can detect peeling that can occur at a bonding interface between a metal and a resin.

  In order to achieve weight reduction, high functionality, high productivity, and the like, a member (hereinafter simply referred to as a “joined body”) in which metal and resin, which are dissimilar materials, are joined is often used. There is a joined body in which a metal and a resin are directly joined, and there is a joined body composed of metals or a metal / resin joined via an adhesive. Considering that most of the adhesives are made of resin, all of the joined bodies have in common that the metal and the resin are joined at both interfaces.

  In order to ensure the reliability of such a bonded body and to evaluate the reliability, it is necessary to accurately grasp the separation between the metal and the resin at the bonded interface. A technique for detecting peeling is described in, for example, the following patent documents.

JP 2001-2384 A JP-A-2004-361132 Japanese Patent No. 5624250

  Patent Document 1 proposes a separation detection method using an optical fiber sensor. Patent Documents 2 and 3 propose a peeling inspection method using ultrasonic waves. Such a method tends to increase the size or complexity of the measurement system. In addition, in the conventional method, when exposed to a severe corrosive environment or the like where peeling easily occurs (hereinafter simply referred to as “peeling environment”), it is difficult to secure stable monitoring over a long period of time due to deterioration of the sensor. .

  The present invention has been made in view of such circumstances, and provides a different type of peel sensor and the like from the related art.

  As a result of intensive research to solve this problem, the inventor of the present invention has conceived of detecting peeling at a bonding interface by an electrochemical method, and has realized a new type of peeling sensor. By developing these results, the present invention described below has been completed.

《Peeling sensor》
(1) The present invention provides a metal test piece made of a first metal, a separator provided on the metal test piece and made of an insulating material and having liquid permeability, and a second test piece provided on the separator. An auxiliary electrode made of a metal; a resin specimen made of a resin, which encloses the separator and the auxiliary electrode in a liquid-tight manner and is joined to the metal specimen; and wherein the metal specimen and the resin specimen are provided. This is a peeling sensor capable of detecting peeling that may occur at the bonding interface of the above.

(2) By using the peeling sensor of the present invention, it is possible to detect peeling that may occur at a bonding interface between a metal (test body) and a resin (test body) as a material to be tested (test object) without requiring a large-scale device or the like. it can. Further, the peeling sensor of the present invention has a relatively simple structure and electrochemically detects peeling, so that long-term monitoring can be stably performed even in a severe peeling environment.

  The mechanism by which the peeling sensor of the present invention detects peeling at the bonding interface is considered as follows. The resin specimen is joined to the metal specimen while enclosing the separator and the auxiliary electrode in a liquid-tight manner. When no separation occurs at the bonding interface between the resin specimen and the metal specimen, the separator is in a state of being shielded from the outside (external environment). The metal test piece and the auxiliary electrode are insulated by this separator, and no electrical conduction occurs between them.

  On the other hand, when peeling occurs at the joint interface between the resin specimen and the metal specimen, a liquid or its vapor enters the separator from the outside through a gap formed at the peeled portion. Since the separator has liquid permeability, the liquid or vapor (especially condensed liquid, dew condensation liquid, etc.) that has entered communicates inside the separator. As a result, the electrical characteristics between the metal test piece serving as the working electrode and the auxiliary electrode change. For example, the electrical resistance between the two is reduced, and conduction between the two via a liquid or the like becomes possible. When the first metal and the second metal have different standard electrode potentials and the liquid in the separator acts as an electrolyte, an oxidation-reduction reaction (electrode reaction) may occur between the metal test body (working electrode) and the auxiliary electrode. That is, a battery (a local battery, a galvanic battery, etc.) is formed between the metal specimen and the auxiliary electrode. Also in this case, conduction can be achieved between the two via the liquid or the like that has entered the separator.

  In any case, when peeling occurs at the joint interface between the resin specimen and the metal specimen, the separator comes into communication with the outside world, and the electrical characteristics between the metal specimen and the auxiliary electrode on both sides of the separator are reduced. Can change. By measuring (or monitoring) this electrical characteristic, it is possible to detect peeling occurring at the bonding interface.

<< Peeling detection system / peeling detection method >>
The present invention can be further understood as a peel detection system or a peel detection method. For example, the present invention can also be grasped as a peeling detection system including the peeling sensor described above and a measuring unit that measures an electrical characteristic between the metal specimen and the auxiliary electrode. Further, it can be understood as a peeling detection method including a measuring step of measuring an electrical characteristic between the metal test piece and the auxiliary electrode using the above-described peeling sensor.

《Other》
(1) The present invention only needs to detect (detect) the presence or absence of peeling at the bonding interface. For this reason, the measurement of the electrical characteristics (resistance, voltage, or current) by the external circuit connected to the peeling sensor is not limited to a specific numerical measurement, and may only be able to specify a change exceeding a threshold. Therefore, “measurement” referred to in this specification includes not only measurement but also simple detection or detection.

  Further, the peeling sensor of the present invention may be used for evaluation of the bonding property between a metal material and a resin material, or used for monitoring a peeling occurring on a member which is attached to a practical member for a long time. May be done. Therefore, “measurement” as used herein includes such monitoring.

(2) Unless otherwise specified, “x to y” in this specification includes a lower limit x and an upper limit y. A range such as “ab” may be newly established as a new lower limit or an upper limit of various numerical values or any numerical value included in the numerical range described in this specification.

It is a longitudinal cross-sectional view which shows a peeling detection system typically. It is a top view which shows a peeling sensor typically. It is explanatory drawing of the principle which peeling is detected by a peeling sensor. It is a graph which shows the electric current value which arises in the peeling sensor after a combined cycle peeling test. It is a top view which shows the modification of a peeling sensor typically.

  One or more components arbitrarily selected from the present specification can be added to the components of the present invention described above. The contents described in the present specification can be applied not only to the peeling sensor of the present invention but also to a peeling detecting system and a peeling detecting method using the same. Which embodiment is best depends on the target, required performance, and the like.

《Peeling sensor》
The peel sensor includes at least a metal specimen, a resin specimen, a separator, and an auxiliary electrode. In addition, since the detection of peeling is performed by measuring the electrical characteristics between the metal specimen and the auxiliary electrode, there is a means for electrically connecting the metal specimen and the auxiliary electrode to an external circuit (such as a measuring device). Good. For example, the peeling sensor may include a terminal, a wiring, and the like for that purpose.

(1) Metal Specimen and Resin Specimen The first metal constituting the metal specimen and the resin constituting the resin specimen are actually already joined or are selected from metals and resins which are assumed to be joined. Good.

  The peeling sensor may be one that uses at least one of a metal body and a resin body that constitute a member that is currently in practical use or a member that is expected to be in practical use (both are simply referred to as “real members”). For example, a separator and an auxiliary electrode provided for a sensor are arranged (laminated) on a metal body constituting a real member. Thereafter, they are encapsulated with a resin constituting a resin body. These may constitute a peeling sensor. The use of such a peeling sensor enables monitoring of peeling that may occur in an actual member for a long period of time, and is useful for specifying and predicting (estimating) the peeling time and the product life.

  When the metal specimen or the resin specimen is configured exclusively for the peel sensor, the form (shape, size, etc.) thereof can be arbitrarily selected. The metal specimen may be intact or may be surface-treated (plating, PVD, CVD, chemical conversion, oxidation, etc.) and covered with a coating. However, it is preferable that the portion in contact with the separator has conductivity. For example, if a resin specimen and a metal specimen covered with an insulating film are joined, the joining interface of the metal specimen is left as it is, and only the contact portion of the separator is peeled off from the insulating film in advance. Good.

  The resin specimen may be formed of a resin-based adhesive for bonding a metal body and another member, assuming a real member. Further, the resin test body may be made of a resin that is filled in a metal body or is integrally formed with the metal body (such as insert molding).

  The resin specimen encapsulates the separator and the auxiliary electrode disposed on the metal specimen in a liquid-tight manner. Here, “liquid-tight” means that the liquid (including vapor) in the outside does not enter the separator except when it enters from the peeled portion of the bonding interface. In short, a state in which the separator is electrochemically isolated from the outside by the resin specimen joined to the metal specimen is a “liquid tight” state.

(2) Separator The separator is made of an insulating material and has liquid permeability. As the insulating material, for example, various materials such as ceramics, resin, and paper can be used. Since the voltage generated between the metal test piece and the auxiliary electrode or the voltage to be applied is generally about several volts, the insulation withstand voltage of the separator may be, for example, about 10 volts.

  The liquid permeability means that a current (or ion conduction) is conducted between the metal test piece and the auxiliary electrode by the liquid (including vapor) penetrating the separator.

  The separator is, for example, a porous body having pores communicating from one surface side to the other surface side. As the porous body, for example, various filters can be used. The filter is thin and has excellent liquid retention. Further, the filter is usually easily available and easily processed into a desired shape. The material of the filter is preferably, for example, an insulating material such as paper and resin.

  The separator is interposed between the metal specimen and the auxiliary electrode. As long as the liquid that has penetrated into the separator can come into contact with the metal test piece and the auxiliary electrode, the separator itself does not necessarily need to be in direct contact with them. However, usually, both surfaces of the separator are in contact with the respective surfaces of the metal specimen and the auxiliary electrode. Thereby, the peeling sensor can be simplified and thinned.

  Note that the separator may include a solute (electrolyte) that dissolves in a liquid (solvent) penetrating from the peeled portion to form an electrolytic solution as long as the insulating property is ensured.

(3) Auxiliary electrode The auxiliary electrode is made of the second metal, and is provided on the separator. Various forms of the auxiliary electrode are arbitrarily selected as in the case of the separator.

  As with the first metal, the type of the second metal is not limited as long as conductivity (electric conductivity) is ensured. The second metal may be the same or different material from the first metal constituting the metal specimen. Strictly speaking, the first metal and the second metal may have the same or different standard electrode potentials with respect to the same reference electrode. The reference electrode used for specifying the standard electrode potential may be a silver-silver chloride electrode or a calomel electrode in addition to a general standard hydrogen electrode (SHE).

  When the standard electrode potential of the first metal and the standard electrode potential of the second metal are substantially the same (when substantially no battery reaction occurs), the electric resistance value (or change thereof) between the metal specimen and the auxiliary electrode is measured (monitored). Thereby, peeling of the bonding interface is detected.

  Note that the measurement of the electric resistance value (change) referred to in the present specification includes a case of measuring a current value (change) or a voltage value (change) when energized (supplied with a predetermined voltage or current). . In any case, they are common in that the degree of conduction between the metal test piece and the auxiliary electrode, which is generated when power is supplied (power is supplied) from the external circuit to the peeling sensor, is measured.

  When the standard electrode potential of the first metal is different from the standard electrode potential of the second metal, the liquid (vapor) penetrating into the separator from the peeled portion becomes an electrolytic solution, and an electrode reaction (battery reaction) may occur between the metal specimen and the auxiliary electrode. As a result, a potential difference (voltage) corresponding to the standard electrode potential of the first metal and the second metal and the type of liquid that has penetrated into the separator is generated between the metal specimen and the auxiliary electrode. By measuring (monitoring) a voltage (change) equal to or higher than the threshold value or a current (change) based on the voltage at this time, it is possible to detect peeling of the bonding interface.

  When the standard electrode potential of the first metal and the standard electrode potential of the second metal are different from each other, when peeling occurs at the joint interface between the metal specimen and the resin specimen, the peeling sensor itself can transmit an electric signal to an external circuit. . In this case, the separation of the bonding interface can be detected without constantly or periodically supplying power from an external circuit. Therefore, the difference (absolute value) between the standard electrode potential (vs. SHE) of the first metal and the second metal may be, for example, 0.1 to 2 V, and more preferably 0.5 to 1.5 V.

  In addition, the standard electrode potential referred to in the present specification is “substantially the same” when the standard electrode potential difference is less than 0.1 V or even 0.05 V or less. Metals having a standard electrode potential difference within such a range are referred to as “same materials”. The “same material” does not have to be a metal having the same chemical composition or main component element.

(4) Terminal The peel sensor detects the peeling of the bonding interface based on a quantitative or qualitative electrical characteristic (change) generated between the metal specimen and the auxiliary electrode. For this reason, the peeling sensor usually includes a terminal or a wiring (lead) for electrically connecting the metal test object and the auxiliary electrode to an external circuit (a measuring device or the like) (these are collectively referred to as a “terminal”). Good. There are various types of terminals. A terminal for connecting the auxiliary electrode to an external circuit is called an auxiliary terminal, and a terminal for connecting the metal test piece to the external circuit is called a main terminal.

  Auxiliary terminals (including wiring) connected to or extending from the auxiliary electrode that is liquid-tightly encapsulated by the resin specimen are provided through the resin specimen in a liquid-tight manner. It is good to be. This is to prevent liquid or vapor from entering from portions other than the separation portion.

《Peeling detection system》
The peeling detection system includes, in addition to the peeling sensor, measuring means for measuring an electrical property between the metal specimen and the auxiliary electrode. The measuring means is, for example, an ohmmeter, an ammeter, a voltmeter, or the like.

  If the standard electrode potential of the first metal of the metal specimen and the standard electrode potential of the second metal of the auxiliary electrode are substantially the same, the measuring means measures the electrical characteristics (resistance value, etc.) when the metal specimen and the auxiliary electrode are energized. Good to do. In this case, the measuring means may include not only a measuring device (detection device) such as a resistance meter, but also a power supply for supplying electricity (power supply) required for measurement between the metal specimen and the auxiliary electrode.

  If the standard electrode potential of the first metal of the metal specimen is different from the standard electrode potential of the second metal of the auxiliary electrode, the measuring means determines the electrical characteristics (current value, voltage value, etc.) generated between the metal specimen and the auxiliary electrode. It is good to measure. When peeling occurs at the bonding interface, a battery is formed between the metal specimen and the auxiliary electrode, using the liquid that has penetrated into the separator from the peeled portion as the electrolytic solution. In this case, it is preferable to measure a voltage or current between terminals (or a current flowing in an external circuit) generated between the metal test piece and the auxiliary electrode. As such a measuring means, there are, for example, a (no resistance) ammeter, a voltmeter and the like. A potentiostat or galvanostat may be used as the measuring means. The measuring means may be composed of a general-purpose product or a dedicated product (such as a circuit element developed for detecting peeling).

《Other》
The peeling sensor may be one in which a plurality of pairs of separators and auxiliary electrodes are provided on one metal specimen. By detecting the electrical characteristics generated at each auxiliary electrode, it is possible to detect the separation and to specify the position where the separation has occurred.

  The auxiliary terminal may be provided for each auxiliary electrode, or may be provided for each predetermined group. For example, when a pair of separators and auxiliary electrodes (hereinafter simply referred to as “detectors”) are arranged in m rows × n columns (m × n in total), each detector in the same row and each detector in the same column Are provided with auxiliary terminals. Then, by mutually evaluating the electrical characteristics measured for each row and each column, peeling can be detected at m × n positions with m + n (≦ m × n) auxiliary terminals.

  FIG. 1A schematically shows a vertical cross-sectional view of a peeling detection system S according to an embodiment of the present invention. FIG. 1B shows a plan view of the main part (peeling sensor 1). Both figures are simply referred to as “FIG. 1”.

《Peeling detection system》
(1) Outline The peel detection system S includes a peel sensor 1 and a measuring device 9 (measuring unit). The peel sensor 1 includes a metal test body 11, a separator 12, an auxiliary electrode 13, a resin test body 14, a main terminal 111, and an auxiliary terminal 131.

  The separator 12 and the auxiliary electrode 13 have substantially the same size. The auxiliary electrode 13 is provided on the upper surface (upper surface) of the metal specimen 11 with the separator 12 interposed therebetween. The separator 12 and the auxiliary electrode 13 are arranged closer to one side of the metal specimen 11 (closer to the left side in FIG. 1A). Conversely, the upper surface on the other side (the right side in FIG. 1A) of the metal specimen 11 is exposed.

  The resin specimen 14 adheres to the upper surface on one side of the metal specimen 11 while enclosing the separator 12 and the auxiliary electrode 13. Thus, the separator 12 and the auxiliary electrode 13 are shut off from the outside by the resin test body 14, and are in a liquid-tight state. Note that, on the upper surface of the metal specimen 11, the portion where the distance (d / see FIG. 1B) between the outer periphery of the resin separator 12 and the outer periphery of the resin specimen 14 is the shortest is the other side of the resin specimen 14 ( (Right side of the figure).

  The peeling sensor 1 is electrically connected to the measuring instrument 9 via a main terminal 111 and an auxiliary terminal 131 each having one side joined to the metal specimen 11 and the auxiliary electrode 13 by soldering or the like. The auxiliary terminal 131 penetrates the resin specimen 14 in a liquid-tight manner, and one end thereof is led out of the resin specimen 14.

(2) Detection principle of peeling The peeling detection system S detects peeling that may occur between the metal specimen 11 and the resin specimen 14 as follows. When the peeling sensor 1 is exposed to a peeling environment such as under a solution or a humid environment, as shown in FIG. 2, the bonding interface 11a of the metal test body 11 and the bonding of the resin test body 14 due to aged deterioration or corrosion. Peeling may occur between the interface 14a. Due to the separation, a gap is generated between the bonding interfaces 11a and 14a. From the gap, the liquid 1 (for example, water or an aqueous solution) or its vapor (for example, water vapor) existing in the outside world (peeling environment) enters the separator 12 side.

  For example, when the liquid 1 penetrates into the separator 12 having liquid permeability and the separator 12 is filled with the liquid 1, the liquid 1 comes into contact with the metal specimen 11 and the resin specimen 14. In this way, the electric resistance between the two is reduced, or a battery is formed between the two. In any case, a change occurs in the electrical characteristics between the metal specimen 11 and the resin specimen 14. By measuring this change with the measuring device 9, peeling occurring at the bonding interfaces 11a and 14a is detected.

《Experimental example》
(1) Configuration The fact that peeling is actually detected by the peeling detection system S is described below. First, substrates (50 mm × 19 mm × 3 mm) made of two types of Al alloys (first metals) were prepared as metal test pieces 11. Here, the peeling sensor 1 using a substrate made of a cast material (JIS, ADC12) is referred to as a sample 1, and the peeling sensor 1 using a substrate formed of a wrought material (JIS A6061) is referred to as a sample 2.

  As the separator 12, a filter (filter paper: ADVANTEC 5A / 3 mm × 7 mm × t 0.18 mm) which is a porous material was used. Copper foil (5 mm × 7 mm × t0.05 mm) was used for the auxiliary electrode 13. Since each Al alloy (first metal) of the metal test body 11 and copper (second metal) of the auxiliary electrode 13 are different metals having different standard electrode potentials (vs. SHE), the measurement device 9 has no resistance. An ammeter was used.

  As the resin test piece 14, a two-part, room-temperature-curable epoxy resin-based adhesive (Bond Quick 5 manufactured by Konishi Co., Ltd.) was used. After enclosing the separator 12 and the auxiliary electrode 13 laminated on the metal specimen 11 with this adhesive, the adhesive was cured in that state. In this way, the peel sensor 1 in which the resin test piece 14 that covers the separator 12 and the auxiliary electrode 13 in a liquid-tight manner was joined to the metal test piece 1 was obtained. The distance (d / see FIG. 1B) between the outer periphery of the auxiliary electrode 13 and the outer periphery of the cured adhesive (resin test body 14) was 2 mm.

(2) Peeling test The following composite cycle peeling test was performed on each peeling sensor 1 of the sample 1 or the sample 2. The combined cycle peeling test includes (a) a salt water spraying step in which salt water (5% NaCl) is sprayed on the peeling sensor 1 in the air (35 ° C.) for 2 hours, and (b) the peeling sensor 1 is heated in the air (60 ° C.). (X) 25% RH) for 4 hours, and (c) a wetting step for holding the peeling sensor 1 in a high humidity atmosphere (50 ° C x 95% RH) for 2 hours. . The current value between the metal test piece 11 and the auxiliary electrode 13 was measured by the measuring instrument 9 while repeatedly performing this composite cycle peeling test (one cycle: 8 hours). The results obtained in this way are shown in FIG.

(3) Evaluation As is clear from FIG. 3, in the case of the sample 1 made of the Al alloy (ADC 12) in which the metal test piece 11 is easily corroded, a sharp increase in the current was detected after a lapse of a predetermined time. At this time, it was confirmed that peeling occurred between the metal test piece 11 and the resin test piece 14.

  On the other hand, in the case where the metal specimen 11 was the specimen 2 made of a highly corrosion-resistant Al alloy (A6061), no sharp current was detected, and no peeling occurred between the metal specimen 11 and the resin specimen 14.

  From these results, it was confirmed that the peeling at the bonding interface between the metal and the resin can be detected by using the peeling sensor or the peeling detecting system of the present invention.

《Modification》
The peel sensor 1 may be a peel sensor 2 as shown in FIG. The peeling sensor 2 includes a metal specimen 21, a resin specimen 24, and nine electrode chips 25 (detectors) arranged in a grid.

  The metal specimen 21 is the same as the metal specimen 11. Each electrode tip 25 is formed by laminating a pair of separators and auxiliary electrodes similar to the separators 12 and the auxiliary electrodes 13. Similarly to the resin test body 14, the resin test body 24 is bonded (adhered) to the metal test body 21 in a state in which each electrode chip 25 is covered in a liquid-tight manner.

  In this case, when a current is detected at a specific electrode tip 25, it can be understood that peeling has occurred around the specific electrode tip 25. That is, when the peeling sensor 2 is used, not only the presence or absence of peeling but also the position (part, region, direction, etc.) can be detected.

DESCRIPTION OF SYMBOLS 1 Peeling sensor 11 Metal specimen 12 Separator 13 Auxiliary electrode 14 Resin specimen 9 Measuring instrument S Peeling detection system

Claims (8)

A metal specimen made of the first metal;
A separator disposed on the metal test body and made of an insulating material and having liquid permeability,
An auxiliary electrode made of a second metal disposed on the separator;
It is made of resin, and comprises a resin test piece joined to the metal test piece while enclosing the separator and the auxiliary electrode in a liquid-tight manner,
A peeling sensor capable of detecting peeling that may occur at a bonding interface between the metal specimen and the resin specimen.   The peeling sensor according to claim 1, further comprising an auxiliary terminal arranged to penetrate the resin test body in a liquid-tight manner and connecting the auxiliary electrode to an external circuit.   The peeling sensor according to claim 1, wherein a plurality of pairs of the separator and the auxiliary electrode are disposed on one metal specimen.   The peeling sensor according to claim 1, wherein the first metal and the second metal have different standard electrode potentials.   The peeling sensor according to claim 1, wherein the first metal and the second metal have substantially the same standard electrode potential. A peeling sensor according to any one of claims 1 to 5,
Measuring means for measuring the electrical characteristics between the metal test body and the auxiliary electrode,
A separation detection system comprising: The first metal of the metal specimen and the second metal of the auxiliary electrode have different standard electrode potentials,
The peeling detection system according to claim 6, wherein the measuring unit measures an electrical characteristic generated between the metal specimen and the auxiliary electrode. The first metal of the metal specimen and the second metal of the auxiliary electrode have substantially the same standard electrode potential,
The peeling detection system according to claim 6, wherein the measuring unit measures an electrical characteristic when a current is applied to the metal specimen and the auxiliary electrode.