TWI779180B - Surface-treated aluminum alloy material and method for producing the same - Google Patents

Abstract

The present invention is a surface-treated aluminum alloy material and its production method. The object of the present invention is to provide an oxide film layer provided on the surface of a base material made of an aluminum alloy containing Si, which can reliably improve the adhesion to the resin layer. And surface-treated aluminum alloy materials with adhesive composition. The solution is to have: a substrate (2) containing Si, and an oxide film layer (3) formed on a part or the entire surface of the substrate (2) by alternating-current electrolytic treatment in an alkaline liquid. alloy material (1). The oxide film layer (3) has: a porous aluminum oxide film layer (31) with a thickness of 20 to 1000 nm formed on the surface side, and a barrier aluminum oxide film layer with a thickness of 3 to 50 nm formed on the substrate (2) side (32). For the porous aluminum oxide film layer (31) there are many small pores (4) with a diameter of 3-50nm, and the circle equivalent of the crystallization (5) formed by the intermetallic compound containing Si or Si alone The average diameter is 15 μm or less, and the area ratio of the crystallized product (5) is 15% or less.

Description

Surface-treated aluminum alloy material and manufacturing method thereof

The invention relates to a surface-treated aluminum alloy material and a manufacturing method thereof.

Aluminum is lightweight and has moderate mechanical properties, and is widely used in various structural components. By applying surface treatment to a part or the whole of these aluminum materials, properties such as corrosion resistance, adhesion, insulation, antibacterial properties, wear resistance, etc. are given, or these properties are improved and used for many users. . Aluminum alloy materials made of Al-Si alloys are widely used as casting molds such as die casting in the past. The characteristic of this point is that it is often used as a solder material for heat exchanger materials. In addition, in recent years, the low thermal expansion rate or heat resistance of the aluminum alloy material made of Al-Si alloy has been reviewed, and the color development (alloy color development) during anodic oxidation treatment has been reviewed, and it is suitable for structural members of the plate. . Structural components using such aluminum materials are especially suitable for transportation materials such as automobiles and aircraft, or electronic components such as electronic substrates and IT equipment. In order to reduce weight and improve functionality, they are also combined with resin materials. And be used.

For example, as disclosed in Patent Document 1, an Al—Si alloy plate is used as a substrate of a printed wiring board. In this printed wiring board, an anodized film is formed on the surface of an Al-Si alloy plate as a substrate, an insulating adhesive layer is formed as a resin layer on the anodized film, and a Cu foil is arranged on the top. constitute.

In such a printed wiring board, the adhesiveness or adhesion between the substrate and the resin layer is important, but this characteristic is controlled by the characteristics of the oxide film on the surface of the substrate. In general, since Si contained in the Al-Si alloy system inhibits the formation of anodic oxide film, the formation of the oxide film becomes uneven, and in many cases, desired performance cannot be obtained.

On the other hand, the patent document 2 series proposes that as a method of forming an oxide film on the surface of the Al-Si alloy, instead of using the anodic oxidation method with a direct current in a sulfuric acid bath as in patent document 1, anodic oxidation in an alkaline solution is used. The method of alternating current electrolytic treatment. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 6-41667 [Patent Document 2] Japanese Unexamined Patent Publication No. 2015-67844

[Problem to be solved by the invention]

The AC electrolytic treatment method of Patent Document 2 is particularly shown as a composition corresponding to an Al-Si alloy with a Si content of 1.7% by mass or less, and it is an obstacle when the amount of Si exceeds 1.7% by mass and increases. Uniform oxide film formation. In addition, when the amount of Si is 1.7% by mass or less, it is considered that a uniform oxide film is not completely formed.

However, it cannot be said that it is absolutely necessary to form a uniform oxide film when the target is superior in adhesion and adhesion to the resin layer. Therefore, it is important to clarify which requirements are satisfied for the composition of an oxide film layer excellent in adhesion and adhesion to the resin layer.

The present invention is constituted in view of the relevant background, and as an oxide film layer provided on the surface of a base material made of an aluminum alloy containing Si, it is intended to provide an oxide film layer capable of reliably improving the adhesion with the resin layer and Surface-treated aluminum alloy materials with improved adhesive properties. [Means to solve the problem]

In an aspect of the present invention, a surface-treated aluminum alloy material has: a substrate made of an aluminum alloy containing Si, and a part or all of the surface of the substrate formed by alternating current electrolytic treatment in an alkaline liquid A surface-treated aluminum alloy material with an oxide film layer, characterized by The aforementioned oxide film layer system has: a porous aluminum oxide film layer with a thickness of 20 to 1000 nm formed on the surface side, and a barrier aluminum oxide film layer with a thickness of 3 to 50 nm formed on the substrate side, For the above-mentioned porous aluminum oxide film layer, there are many small pores with a diameter of 3~50nm, and the equivalent circle diameter of the intermetallic compound containing Si or the crystallization of Si alone is less than 15 μm on average, and the Crystallization exists in the area ratio of 15% or less. [Invention effect]

For aluminum alloys containing Si, the oxide film layer formed by AC electrolytic treatment in alkaline liquid contains intermetallic compounds containing Si or crystallization of Si alone, and completely eliminates these The system is currently difficult. However, the surface-treated aluminum alloy material of this form is an intermetallic compound containing Si existing in the aforementioned porous aluminum oxide film layer or a crystallization product formed of Si alone, with an average equivalent circle diameter of 15 μm or less, and having other Crystallization is the condition that the area ratio of 15% or less exists. As a result of many examinations, the present inventors have found that as long as it has this structure, it can indeed improve the adhesion and adhesiveness with the resin layer.

As shown in Figure 1, the surface-treated aluminum alloy material 1 of the present application has: a substrate 2 made of an aluminum alloy containing Si, and a part of the substrate 2 formed by alternating-current electrolytic treatment in an alkaline liquid Or the surface-treated aluminum alloy material with the oxide film layer 3 on the entire surface. The oxide film layer 3 has: a porous aluminum oxide film layer 31 with a thickness of 20-1000 nm formed on the surface side, and a barrier-type aluminum oxide film layer 32 with a thickness of 3-50 nm formed on the substrate 2 side. For the porous aluminum oxide film layer 31, there are many small holes 4 with a diameter of 3-50nm, and the crystallization product formed by an intermetallic compound containing Si or a single Si has an average circle equivalent diameter of 15 μm or less. On the other hand, the crystallized product 5 exists at an area ratio of 15% or less. Below, it will be described in more detail.

＜Substrate＞ An aluminum alloy containing Si (Al—Si alloy) is used as the base material. The lower limit of the Si content is not particularly limited, but in Patent Document 2, when it exceeds 1.7% by mass which is not ideal, especially 2.0% by mass or more, it is effective to obtain the above-mentioned constitution. The more ideal system may be 3.0% by mass or more, the more ideal system may be 4.0% by mass, and the still more ideal system may be 5.0% by mass. On the other hand, the upper limit of the Si content is the range of a general Al-Si alloy and is not particularly limited. However, if the Si content is too high, the Si-containing intermetallic compound or Si alone Since the control of the crystallization part becomes difficult, it is ideally 20% by mass or less, more preferably 12% by mass or less.

Elements other than Si can be appropriately added in accordance with the required characteristics of the application of the above-mentioned surface-treated aluminum alloy material. For example, for substrates used in printed wiring boards, for example, Si: 5-20% by mass, Fe: 0.5-2.0% by mass, Cu: 0.1-0.5% by mass, and the remaining part is Al and unavoidable. The chemical composition of impurities.

＜Oxide film layer＞ The oxide film layer is composed of: a porous aluminum oxide film layer with a thickness of 20-1000nm formed on the surface side, and a barrier-type aluminum oxide film layer with a thickness of 3-50nm formed on the substrate side. In addition, the oxide film layer may be provided only on a part of the surface of the substrate, or may be provided on the entire surface of the substrate. In addition, when the base material is flat, the oxide film layer may be provided on only one surface, or the oxide film layer may be provided on both surfaces.

＜Porous aluminum oxide film layer＞ The thickness of the porous aluminum oxide film layer is 20~1000nm, preferably 50~500nm. When the thickness of the porous aluminum oxide film layer is less than 20nm, the thickness is not sufficient, and the formation of the pore structure described later is likely to be insufficient, and the adhesion or adhesion with the resin layer is reduced. Therefore, it is more preferable to set it as 50 nm or more. On the other hand, when the thickness of the porous aluminum oxide film layer exceeds 1000 nm, the porous aluminum oxide film layer itself is prone to coagulation failure, and the adhesion or adhesion with the resin layer is reduced. Therefore, it is more desirable to set it as 500 nm or less.

As an example, the measurement of the thickness of the porous aluminum oxide film layer can use a cross-sectional observer through a transmission electron microscope (TEM). Specifically, the porous aluminum oxide film layer is partially processed into a thin slice by an ultra-thin slicer or the like, and measured by TEM observation. However, the thickness of the porous aluminum oxide film layer is based on the arithmetic mean value of the measured values at multiple places in one observation field of view.

As shown in FIG. 1 , the porous aluminum oxide film layer 31 has a porous structure including pores 4 extending from the surface toward the depth direction. The diameter of the small hole 4 is 3~50nm, preferably 5~30nm. This small hole 4 is to increase the contact area between the resin layer or the adhesive layer and the aluminum oxide film layer 3 (31), and to exert the effect of increasing its adhesion or adhesion. When the diameter of the small hole 4 is less than 3 nm, there is a possibility that sufficient adhesive force or adhesion force cannot be obtained because the contact area is insufficient. On the other hand, when the diameter of the pores 4 exceeds 50 nm, the entire porous aluminum oxide film layer becomes brittle and undergoes coagulation failure, which may lower the adhesion or adhesion.

The ratio of the small pores to the total pore area of the surface area of the porous aluminum oxide film layer is not particularly limited, but it is used as the apparent surface area of the porous aluminum oxide film layer (without considering the small unevenness of the surface, In terms of the area expressed by the multiplication of the length and width) to the ratio of the total hole area of the small hole, 25~75% is ideal. When this ratio is less than 25%, the contact area may be insufficient and sufficient adhesion or adhesion may not be obtained. On the other hand, when this ratio exceeds 75%, the entire porous aluminum oxide film layer becomes brittle, coagulation failure occurs, and adhesive force or adhesion force may decrease.

For the measurement of the diameter and area occupancy of the small pores in the above-mentioned porous structure, as an example, surface observation through an electric field emission electron microscope (FE-SEM) and image analysis software Axiangjun (Asahi Kasei Engineering Co., Ltd.) can be used. Particle analyzer for ver. 2.50). Specifically, through an electric field emission electron microscope (FE-SEM), the secondary electron image taken at multiple places at an accelerating voltage of 2 kV and an observation field of view of 1 μm×0.7 μm was imported into the image analysis software, and the porous aluminum The small hole portion observed on the surface of the oxide film layer is regarded as the particle analyzer of each particle.

<Intermetallic compound or Si alone containing Si in the porous aluminum oxide film layer> For the porous aluminum oxide film layer, the crystallization formed by an intermetallic compound containing Si or Si alone has an equivalent circle diameter of 15 μm or less on average, and the crystallization can exist at an area ratio of 15% or less . The Si-containing intermetallic compound or simple Si crystallization in the porous aluminum oxide film layer (hereinafter, referred to as Si-based particles as appropriate) is the Si-containing intermetallic compound or simple Si present in the base material. The resulting crystallization remains in the porous aluminum oxide film layer after AC electrolytic treatment.

The portion where the Si-based particles remained in the porous aluminum oxide film layer is due to the formation of the above-mentioned small pores, and hardly contributes to the improvement of the adhesion and adhesiveness with the resin layer. Therefore, it is important to reduce the size of the Si-based particles, and the average equivalent circle diameter must be 15 μm or less, ideally 12 μm or less, more ideally 10 μm or less. The lower limit of the circle-equivalent diameter of Si-based particles is preferably as small as possible, but in practice, it is easy to be 2 μm or more, and sometimes 5 μm or more, but there is no problem if the above upper limit is maintained.

In addition, the aforementioned Si-based particles in the porous aluminum oxide film layer must be present in an area ratio of 15% or less. When the area ratio of Si-based particles exceeds 15%, the area of the portion having small holes participating in bonding decreases, and a sufficient contact area cannot be obtained for the resin layer, resulting in reduced adhesion or adhesion. The smaller the area ratio of the aforementioned Si-based particles in the porous aluminum oxide film layer, the better, but it is practically difficult to make it less than 1%.

The measurement of the area ratio of the intermetallic compound containing Si or the crystallization product (Si-based particles) of simple Si is, as an example, using surface observation with a field-emission scanning electron microscope (FE-SEM). Specifically, by FE-SEM (SU8200 manufactured by Hitachi High-Technologies Co., Ltd.), 5-field photography was performed at an accelerating voltage of 1 kV and an observation field of view of 126 μm×85 μm (about 1000 times), and Si-containing particles with an equivalent circle diameter of 0.01 μm or more were obtained. The surface area and number of intermetallic compounds or single Si particles are calculated from the total surface area of Si-containing intermetallic compounds or single Si particles present in the observation field. Divide the total area of the field of view by the calculated total surface area of intermetallic compounds containing Si or Si particles alone, and then calculate the area ratio for aluminum alloys containing intermetallic compounds or Si particles alone.

＜Barrier aluminum oxide film layer＞ The thickness of the barrier aluminum oxide film layer is 3~50nm, and ideally 5~30nm. When the thickness is less than 5nm, as an intervening layer between the porous aluminum oxide film layer and the aluminum texture, it is impossible to impart sufficient bonding force to the combination of the two, especially in severe environments such as high temperature and humidity. becomes insufficient. On the other hand, when the thickness exceeds 50nm, the barrier-type aluminum oxide film layer is prone to coagulation failure due to its compactness, and on the contrary, the adhesive force or adhesion force is reduced. As for the measurement of the thickness of the barrier aluminum oxide film layer, a cross-sectional observer through a transmission electron microscope (TEM) can be used as in the case of the porous aluminum oxide film layer. Specifically, the barrier-type aluminum oxide film layer is partially processed into thin slices with an ultra-thin slicer, and measured through TEM observation. However, the thickness of the barrier-type aluminum oxide film layer is based on the arithmetic mean of the measured values at multiple places in one observation field of view.

＜Manufacturing method of base material＞ The base material can be manufactured by casting to produce a plate with the desired chemical composition, and at least applying hot rolling to the plate. Cold rolling can be added if necessary.

Here, in the above-mentioned casting, casting is performed with a cooling rate of 0.5°C/sec or more at a portion of 100 mm from the surface of the sheet, and the final pass reduction rate when rolling the sheet by hot rolling is, It is effective if it is carried out within the range of 20%~70%. By satisfying these two requirements, first, it becomes possible to control the state of existence of the intermetallic compound containing Si contained in the base material or the crystallized product (Si-based particles) formed by Si alone. rangers.

When the size and quantity of the crystallization of the intermetallic compound containing Si contained in the base material or the crystallization of the single Si are set as the optimal range, the resulting AC electrolytic treatment can be obtained The state of the intermetallic compound containing Si or the crystallized product of simple Si existing in the porous aluminum oxide film layer is controlled within the above-mentioned specific range.

The best state of existence of intermetallic compounds containing Si contained in the base material or crystallization of Si alone is in the surface observation before AC electrolytic treatment, the average circle equivalent diameter of the crystallization is less than 15 μm Then, it is in a state where the area ratio is 15% or less.

The cooling rate at a portion 100 mm from the surface of the sheet material at the time of casting is 0.5° C./sec or more as described above. The ideal system should be above 1°C/sec. However, the upper limit of the cooling rate is not particularly limited, but it is usually difficult due to the limitation of the manufacturing equipment in the case of substantially 20° C./sec or more. When the cooling rate is less than 0.5° C./sec, the particle size of Si-containing intermetallic compounds or simple Si particles may become too large.

The cooling rate at the time of casting at 100 mm from the surface of the plate was calculated by measuring the dendrite arm spacing (Dendrite Arm Spacing: hereinafter, simply described as DAS). There is the following relationship between the cooling rate Cα (°C/sec) of the aluminum alloy and DAS and dr (μm) measured by the common line method. The relationship between cooling rate and DAS: dr=41Cα ^-0.32

DAS can be obtained by observing the section of the plate after casting. That is, after cutting a 100mm part of the plate casted under the same conditions from the surface along the casting direction, and cutting the central part of the plate along the thickness direction, the section grinding is performed on the total section and the cross section of the cut. After that, observe the metal structure of the central section of the plate through an optical microscope at a magnification of 500 times, and obtain the DAS by the intersection method. However, the relational expression and measurement method of DAS are based on the "Measurement Method of Dendrite Spacing and Cooling Rate of Aluminum", Report No. 20 (1988) of the Society for Light Metal Research, pp. 46-52.

In addition, as mentioned above, the rolling reduction in the final pass of hot rolling is 20 to 70%, preferably 30 to 60%. When the rolling reduction in the final pass of hot rolling is less than 20%, there is a possibility that large-sized particles may remain as an intermetallic compound containing Si contained in the base material or a crystallized product of Si alone. . On the other hand, when the rolling reduction in the final pass of hot rolling exceeds 70%, cracks are likely to occur during rolling, making it difficult to manufacture the base material.

<Alternating Current Electrolytic Treatment> The oxide film layer on the surface of the base material is formed by applying alternating current electrolytic treatment to the base material in alkaline liquid. As a specific method, while preparing the substrate as one electrode, and facing the counter electrode, use an alkaline aqueous solution at 35-80°C as the electrolytic solution with a pH of 9-13, and use a frequency of 20-100 Hz and a current density The conditions of 4~50A/dm ² and electrolysis time of 5~600 seconds are carried out by passing AC current between the two electrodes.

The shapes of the electrode and the counter electrode made of the base material are not particularly limited, but it is preferable to use a plate-shaped configuration for stable processing by making the distance between the two electrodes uniform. Specifically, as shown in FIG. 2 , an electrode 61 made of a substrate 2 and two counter electrodes 62 and 63 are prepared, and these are connected to an AC power source 71 as shown in the figure. Between the AC power source 71 and one counter electrode 63, a connection switch 72 for turning on and off the energized state is provided.

Each electrode is placed in an electrolytic cell filled with an electrolytic solution 8 of an alkaline aqueous solution, and an electrode 61 formed by clamping a base material 2 is arranged between a pair of counter electrodes 62 and 63 arranged oppositely. These 3 The electrodes 61 to 63 of the sheet are arranged at equal intervals in a substantially parallel manner. The counter electrodes 62, 63 are preferably those having the same or larger size as the electrode 61 formed on the base material 2, and it is preferable to perform the electrolysis operation with all the electrodes in a static state. However, in the case of treating only one surface of the substrate 2, by turning off the connection switch 72, only the surface on the counter electrode 62 side facing the electrode 61 formed on the substrate 2 can be processed.

The counter electrodes 62 and 63 used in the alternating current electrolytic treatment are, for example, known electrodes such as graphite, aluminum, titanium electrodes, etc., but must be used without deteriorating the alkali composition or temperature of the electrolytic solution and for the conductivity. Superior, moreover, the material itself does not cause electrochemical reactions. From such a point of view, it is preferable to use a graphite electrode as the counter electrode system. This is due to the chemical stability of the graphite electrode and the fact that it is easy to obtain at a low price. Through the action of many pores in the graphite electrode, in the AC electrolysis project, the electric force line is moderately diffused, and the porous aluminum oxide film layer and the barrier type aluminum oxide film layer are easy to become uniform at the same time.

The alkaline aqueous solution used as the electrolytic solution 8 can use alkali metal hydroxides such as sodium hydroxide and potassium hydroxide: phosphates such as sodium phosphate, sodium hydrogenphosphate, sodium pyrophosphate, potassium pyrophosphate, and sodium hypophosphite. : Sodium carbonate, sodium bicarbonate, potassium carbonate, etc. carbonates : Ammonium hydroxide : Or an aqueous solution containing these mixtures. As will be described later, since it is necessary to keep the pH of the electrolytic solution within a specific range, it is preferable to use an alkaline aqueous solution containing a phosphate substance whose buffering effect can be expected. The concentration of the alkali component contained in such an alkali aqueous solution is to adjust the pH of the electrolytic solution appropriately so that it becomes a desired value, but usually, it is 1×10 ^-4 ~1 mol/liter, and ideally it is 1×10 ^-3 ~0.8 moles/liter. However, it is also possible to add a surfactant or the like to these alkaline aqueous solutions in order to improve the cleanliness of the surface of the aluminum alloy material.

The pH of the alkaline aqueous solution as the electrolytic solution 8 is 9-13, and ideally 9.5-12.5. When the pH is less than 9, the alkaline etching power of the electrolytic solution is insufficient, and as a result, the growth rate of the porous structure of the porous aluminum oxide film layer becomes slower, the thickness of the porous aluminum oxide film layer becomes thinner, and the adhesion durability decreases. reduce. On the other hand, when the pH exceeds 13, the alkali etching force becomes excessive, and the porous structure of the porous aluminum oxide film layer dissolves, so that desired adhesion cannot be obtained.

The temperature of the electrolytic solution of the electrolytic solution 8 is 35-80°C, and ideally 40-75°C. When the temperature of the electrolytic solution is lower than 35°C, the alkali etching force is insufficient, and the formation of the porous aluminum oxide film layer becomes amorphous, and the adhesion durability decreases. On the other hand, when the temperature of the electrolytic solution exceeds 80°C, the alkali etching force becomes excessive, and the density of pores in the porous aluminum oxide film layer becomes small, making it difficult to obtain adhesion to resins, etc. The necessary alignment effect will reduce the adhesion durability.

The electrolysis time is 2 to 600 seconds, ideally 5 to 300 seconds, and more ideally 10 to 60 seconds. When the electrolysis time is less than 2 seconds, the porous structure of the porous aluminum oxide film layer is insufficient, and the adhesion with resin etc. is reduced. On the other hand, when the electrolysis time exceeds 600 seconds, the porous structure of the porous aluminum oxide film layer is redissolved, and productivity is also reduced.

The AC frequency number is 10~100Hz, and the ideal is 20~80Hz. When the frequency of alternating current is less than 20 Hz, the formation of the porous structure of the porous aluminum oxide film layer does not proceed as a result of the increase in the factor of direct current in electrical decomposition, and the adhesion to resin or the like decreases. On the other hand, when the AC frequency exceeds 100Hz, the reversal of the anode and the cathode is too fast, and the formation of the entire aluminum oxide film is extremely slow. For the specific porous structure of the porous aluminum oxide film layer It takes an extremely long time for the thickness system to become. However, the electrolysis waveform in alternating current electrolysis is not particularly limited, and waveforms such as sine wave, rectangular wave, trapezoidal wave, and triangular wave can be used.

The current density is 4~50A/dm ² , and ideally 5~40A/dm ² . When the current density is less than 4A/dm ² , among the aluminum oxide films, the growth rate of the porous aluminum oxide film layer is slow, and only a barrier type aluminum oxide film layer can be obtained. On the other hand, when the current density exceeds 50A/dm ² , the current becomes too large, and it becomes difficult to control the thickness of the porous aluminum oxide film layer and the barrier aluminum oxide film layer, which tends to cause uneven treatment. As a result, the porous aluminum oxide film layer may fall off from the aluminum base in an extremely thick portion.

The concentration of dissolved aluminum contained in the electrolytic solution is preferably 5 to 1000 ppm. The case where the dissolved aluminum concentration is less than 5ppm is due to the rapid formation reaction of the aluminum oxide film in the early stage of the electrolytic reaction, and the unevenness of the treatment process (contamination of the surface of the Al-Si alloy base material or the contamination state of the Al-Si alloy substrate) substrate installation status, etc.). As a result, a locally thick aluminum oxide film may be formed. On the other hand, when the dissolved aluminum concentration exceeds 1000ppm, the viscosity of the electrolytic solution increases and in the electrolysis process, while hindering the uniform convection near the electrode surface of the Al-Si alloy substrate, the dissolved aluminum acts on Suppresses the direction of aluminum oxide film formation. As a result, a locally thin aluminum oxide film may be formed. Thus, when the dissolved aluminum concentration deviates from the above-mentioned range, the thickness of the aluminum oxide film becomes thicker locally, and the formation of the aluminum oxide film is suppressed, which may cause a decrease in the adhesion and adhesion of the obtained aluminum oxide film.

＜Resin layer＞ When the treated surface of the aforementioned surface-treated aluminum alloy material is coated with a resin layer to form a resin-coated surface-treated aluminum alloy material, it can be used in more applications. Here, either thermosetting resin or thermoplastic resin can be used as the resin layer system, and various effects can be imparted by combining with the aluminum oxide film of the above-mentioned specific structure.

Usually, the bonding system of aluminum material and resin layer is compared with aluminum material, and the thermal expansion rate of resin is large, and the interface between aluminum material and resin layer is prone to damage such as peeling, fracture, cutting, etc. However, in the above-mentioned surface-treated aluminum alloy materials, the base material made of Al-Si alloy is used. This Al-Si alloy system has: Compared with other aluminum alloy materials, the thermal expansion rate is low, it is not easy to expand with the coated resin layer, and it is not easy to produce in the interface between the surface treated aluminum alloy material and the resin layer. Has the characteristics of the aforementioned damage. Therefore, the linear expansion coefficient of the resin layer laminated on the aforementioned surface-treated aluminum alloy material is preferably 80×10 ^-5 K ^-1 or less, and more preferably 50×10 ^-5 K ^-1 or less.

In particular, the resin-coated surface-treated aluminum alloy material that uses thermoplastic resin for the resin layer is used as a composite material for lightweight, high-rigidity transportation equipment, and specifically, it is optimally used in the fields of aviation and space, automobiles, and ships. , Structural components of railway vehicles, etc., and it is also best used in electronic equipment that must be highly designed or highly insulated. The coating method of the resin layer is generally a method of hot-pressing a thermoplastic resin member. When manufacturing a thermoplastic resin member by injection molding, inserting a surface-treated aluminum alloy material into a metal mold for injection molding and bonding it Wait. In addition, when the surface-treated aluminum alloy material is in the form of a plate, a thermoplastic resin film may be laminated.

As thermoplastic resins, polyolefins such as polyethylene and polypropylene can be used; polyvinyl chloride; polyethylene terephthalate, polyester such as polybutylene terephthalate; polyamide; polyphenylene Sulfide; aromatic polyetherketone such as polyetheretherketone and polyetherketone; polystyrene; fluorine resin such as polytetrafluoroethylene and polychlorotrifluoroethylene; acrylic resin such as polymethyl methacrylate; ABS Resin; polycarbonate; thermoplastic polyimide, etc.

The resin-coated surface-treated aluminum alloy material that uses a thermosetting resin for the resin layer is best used for design-coated panels, insulation coating applications for electronic materials, and the like. As a coating method of the resin layer, a method of using a thermosetting resin in a fluid state, making it contact and permeate the porous aluminum oxide film layer, and then heating and curing the thermosetting resin is used. As thermosetting resins, phenol resins; epoxy resins such as bisphenol A and novolak; melamine resins; urea resins; unsaturated polyester resins; alkyd resins; polyurethane resins; thermosetting polyamides Amines, etc.;

However, each of the aforementioned thermoplastic resins and thermosetting resins may be used singly, or may be used as a polymer mixture in which plural types of thermoplastic resins or plural types of thermosetting resins are mixed. In addition, when various fillers are added to the above-mentioned thermoplastic resin and thermosetting resin, physical properties such as strength and thermal expansion rate of the resin can be improved. As such a filler, various fibers such as glass fiber, carbon fiber, and amide fiber; inorganic substances such as calcium carbonate, magnesium carbonate, silicon dioxide, talc, and glass; clay; and other known substances can be used. [Example]

Hereinafter, the best embodiment of the present invention will be described in detail based on examples and comparative examples.

As the Al-Si-based aluminum alloy used for the base material 2, the composition having the Si content shown in Table 1 and Table 2 was melted and cast, and after hot rolling, it was subjected to cold rolling to obtain a final thickness of 1.0mm. The rolling plate. At this time, the conditions shown in Table 1 and Table 2 were used as the production conditions such as the cooling rate during casting and the rolling reduction at the final pass during hot rolling, and other known normal conditions were used. And, the board|substrate which cut and processed into length 600mm x width 50mm x plate thickness 1.0mm was produced.

As shown in FIG. 2, the obtained substrate was used for one electrode 61, and two flat graphite electrodes of length 150 mm x width 100 mm x thickness 2.0 mm were used as counter electrodes 62 and 63, and were connected as shown in the figure. As the electrolytic solution 8, an alkaline aqueous solution having sodium pyrophosphate as a main component having pH and temperature shown in Table 1 and Table 2 was used. The pH is properly adjusted with 1 mol/liter NaOH aqueous solution. The electrolyte concentration was made 0.1 mol/liter. In addition, AC electrolysis treatment was performed under the conditions of frequency, current density, and electrolysis time shown in Tables 1 to 3. Here, in Comparative Examples 5 and 6, the pH was adjusted to 8.5 and 3, respectively, with a 1 mol/liter sulfuric acid aqueous solution. However, the longitudinal direction of the electrode 61 of the aluminum alloy plate and the graphite counter electrodes 62, 63 is aligned with the depth direction of the electrolytic cell. In addition, in Comparative Example 15, for the purpose of comparison, a direct current was flowed using an electrode made of a base material as an anode.

The following measurements and evaluations were performed on the samples of the surface-treated aluminum alloy materials produced as above.

First of all, as an evaluation of the oxide film layer, the [structure] of the oxide film layer regards the case of "porous aluminum oxide film layer and barrier aluminum oxide film layer" as "two layers", and the case of either one as "one layer". ".

In addition, for the porous aluminum oxide film layer in the oxide film layer, the "thickness (nm) of the porous aluminum oxide film layer" and "Si-based particles (metal containing Si) contained in the porous aluminum oxide film layer were measured. The average circle-equivalent diameter (μm) and area ratio (%) of an inter-compound or a crystallized product of Si alone), "the diameter of pores existing in the porous aluminum oxide film layer (nm)".

In addition, among the oxide film layers, the "thickness (nm) of the barrier type aluminum oxide film layer" was measured for the barrier type aluminum oxide film layer.

In addition, the "average circle-equivalent diameter (μm) and area ratio (%) of Si-based particles (intermetallic compound containing Si or crystallized product of Si alone) contained in the substrate" was measured for the substrate.

The specific measuring method is as follows.

[Thickness of porous aluminum oxide film layer and barrier aluminum oxide film layer] For the sample of the surface-treated aluminum alloy material, cross-sectional observation along the longitudinal direction of the aluminum oxide film was performed through TEM. Specifically, the respective thicknesses of the porous aluminum oxide film layer and the barrier aluminum oxide film layer were measured. In order to measure the thickness of these oxide film layers, the thin-section sample for cross-sectional observation was produced from a sample using an ultramicrotome. Next, arbitrary 100 places in the observation field of view (1 μm×1 μm) were selected in this sheet sample, and the thickness of each oxide film layer was measured through TEM cross-sectional observation. The results are shown in Tables 4-6. However, the arithmetic mean value of the measurement results at 100 places was made about the thickness of these oxide film layers. According to the results of the measurement, the structure of the oxide film layer is also judged.

[Measurement of Particle Size of Si-based Particles Built in Porous Aluminum Oxide Film Layer] For the sample of the surface-treated aluminum alloy material, the particle size of the Si-based particles was measured through surface observation by FE-SEM (observation field of view: 10 locations of 126 μm×85 μm). As for the particle diameter, the arithmetic mean value of the measured values at 10 positions in the observation field of view was made.

[Area ratio of Si-based particles embedded in the porous aluminum oxide film layer] For the sample of the surface-treated aluminum alloy material, the area of the Si-based particles was calculated through surface observation by FE-SEM (observation field of view: 10 places of 126 μm×85 μm). The area ratio of Si-based particles (Si/Al) was calculated by dividing the area of the observed field of view by the calculated value. The area ratio of the Si-based particles was calculated as the arithmetic mean value of the measured values at 10 positions in the observation field of view.

[Measurement of Pore Diameter of Porous Aluminum Oxide Film Layer] For the sample of the surface-treated aluminum alloy material, the diameter of the pores of the porous aluminum oxide film layer was measured through surface observation by FE-SEM (observation field of view: 10 locations of 0.7 μm×1 μm). The diameter of the small hole is calculated as the arithmetic mean value of the measured values at 10 positions in the observation field of view.

In addition, in each Example and a comparative example, electrolytic treatment was performed with respect to 3 base materials under the same conditions, and the arithmetic mean value of these 3 was made into the value for evaluation. The evaluation results of the above-mentioned oxide film layer and base material are shown in Tables 3-5.

In addition, as a representative of the oxide film layer of the surface-treated aluminum alloy material, a photograph of Example 1 observed from the surface is shown in FIG. 4 . In the photo of the same figure, many particles A are observed, and these are Si-based particles (intermetallic compounds containing Si or crystallized products of Si alone) existing in the porous aluminum oxide film layer 31. .

Next, a resin layer was placed on the oxide film layer of the surface-treated aluminum alloy materials of the above-mentioned examples and comparative examples to produce a resin-coated surface-treated aluminum alloy material. First, 20 samples of the surface-treated aluminum alloy plate prepared above were prepared, and cut into test material 12 of 45 mm in length and 18 mm in width. A glass fiber-containing PPS resin (manufactured by DIC Corporation) was used as the resin layer 6, and 20 sets of test pieces bonded to the test material 12 of the surface-treated aluminum alloy plate were produced by insert molding. Specifically, a resin layer formed by inserting the test material 12 of the surface-treated aluminum plate into an injection molding metal mold (not shown), closing the metal mold and heating to 160°C, and injecting PPS resin at an injection temperature of 320°C 6. For bonding, the bonding test piece S shown in FIG. 3 was obtained. The joint test piece is in accordance with the shape of the form B of ISO19095-2. As shown in the drawing, the bonding test piece S has a structure having bonding portions 16 that are overlapped and bonded. The joint part 16 is a portion of 10 mm in length and 5 mm in width at the end of the sample of the surface-treated aluminum plate.

As above, in Examples 1 to 37 and Comparative Examples 1, 2, 4 to 14, the above-mentioned joint test piece S which was a joint body of a surface-treated aluminum alloy plate and a resin layer was obtained. However, in Comparative Example 15, the resin layer could not be bonded, and a bonded body could not be obtained.

[Joint Evaluation of Thermoplastic Resin] Bonding evaluation is based on 5.2.1.2 Specimen retainer of ISO19095-3, with a tensile testing machine at a speed of 5mm/min., 10 groups of bonded test pieces S made as above are stretched in the shearing direction and measured The coagulation failure rate of the thermoplastic resin at the junction was evaluated according to the following criteria. ◎: The coagulation breaking rate is more than 95% ○: The coagulation failure rate is more than 85% and less than 95% △: The coagulation failure rate is more than 75% and less than 85% ×: Composition with a coagulation failure rate of less than 75% The results are shown in Tables 3-5. For the number of the above-mentioned ◎, ○, △, and X among the 10 groups of joint samples shown in the same table, if all the cases are ◎ or ○, it is judged as acceptable, otherwise, it is judged as unfavorable qualified.

[Adhesion durability evaluation] Take 10 groups of jointed body samples prepared as above, plus the neutral salt spray test described in the salt spray test method (JIS Z 2371), take them out after 1000 hours, and use the tensile testing machine at 5mm/min . The velocity is stretched in the shearing direction, and the coagulation failure rate of the thermoplastic resin at the junction is measured, and evaluated according to the following criteria. ◎: The coagulation breaking rate is more than 80% ○: The coagulation failure rate is more than 65% and less than 80% △: The coagulation failure rate is more than 50% and less than 65% ×: Composition with a coagulation failure rate of less than 50% The results are shown in Tables 3-5. For the number of the above-mentioned ◎, ○, △, and X among the 10 groups of joint samples shown in the same table, if all the cases are ◎ or ○, it is judged as acceptable, otherwise, it is judged as unfavorable qualified.

[Total evaluation] If both of the evaluation of the adhesion of the thermoplastic resin of the aluminum oxide film and the evaluation of the adhesion durability are passed, the total evaluation is passed, and if at least one of these evaluations is unsatisfactory, the total evaluation is regarded as unsatisfactory. qualified.

As shown in Tables 3 to 5, in Examples 1 to 37, the oxide film layer has a dual structure of "porous aluminum oxide film layer and barrier aluminum oxide film layer, and the porous aluminum oxide film layer The thickness is in the range of 20~1000nm, the thickness of the barrier aluminum oxide film layer is in the range of 3~50nm, and, for the porous aluminum oxide film layer, there are mostly small holes with a diameter of 3~50nm, The circle-equivalent diameter of the crystallized product formed by the intermetallic compound containing Si or Si alone is less than 15 μm on average, and the crystallized product exists in an area ratio of 15% or less. The adhesion is excellent, and the adhesion durability is also good, and the overall evaluation is qualified.

In contrast, in Comparative Examples 1 to 15, at least the production method did not meet the desired conditions, and the oxide film layer of the above-mentioned desired form could not be obtained. Therefore, in the bonding with the resin layer, the bonding strength and adhesion durability At least one of them is unqualified, and the overall assessment is unqualified.

Specifically, in Comparative Example 1, since the cooling rate during casting was too slow, the particle diameters of intermetallic compounds containing Si crystallized in the base material and Si particles became large. Therefore, although the thickness of the porous aluminum oxide film layer is within the desired range through the AC electrolytic treatment, the circle-equivalent diameter of the Si-based particles contained in the porous aluminum oxide film layer becomes too large, and the bond with the resin layer The performance and adhesion durability evaluations are simultaneously unsatisfactory, and the overall evaluation is unsatisfactory.

In Comparative Example 2, since the rolling reduction during hot rolling was too low, the Si-based particles in the substrate did not become smaller, but large particles remained. Therefore, although the thickness of the porous aluminum oxide film layer is within the desired range through the AC electrolytic treatment, the circle-equivalent diameter of the Si-based particles contained in the porous aluminum oxide film layer becomes too large, and the bond with the resin layer The performance and adhesion durability evaluations are simultaneously unsatisfactory, and the overall evaluation is unsatisfactory.

In Comparative Example 3, since the rolling reduction during the hot rolling was too high, the sheet was likely to be broken and could not be produced by itself. Therefore, joint performance and adhesion durability were regarded as unassessable, and the overall evaluation was unacceptable.

In Comparative Example 4, since the pH of the electrolytic solution was too high, the diameter of the pores in the porous aluminum oxide film layer became too large, and the contact area between the thermoplastic resin layer and the aluminum oxide film layer decreased. As a result, the adhesion durability was unacceptable, and the overall evaluation was unacceptable.

In Comparative Example 5, since the pH of the electrolytic solution was around neutral, the film growth of the porous aluminum oxide film was slow, forming a thin porous oxide film, and the joint surface between the thermoplastic resin layer and the aluminum oxide film was reduced. As a result, adhesion and adhesion durability were unacceptable, and the overall evaluation was unacceptable.

In Comparative Example 6, because the pH of the electrolytic solution was too low, a thin porous aluminum oxide film was formed, the diameter of the pores was extremely large, and the thermoplastic resin could hardly flow into the aluminum oxide film. As a result, adhesion and adhesion durability were unacceptable, and the overall evaluation was unacceptable.

In Comparative Example 7, because the temperature of the electrolytic solution was too low, the diameter of the pores in the porous aluminum oxide film layer became extremely small, the area ratio of Al/Si became 0%, and the thermoplastic resin hardly flowed into the film. middle. As a result, adhesion and adhesion durability were unacceptable, and the overall evaluation was unacceptable.

In Comparative Example 8, because the temperature of the electrolytic solution was too high, the porous aluminum oxide film became thinner, the diameter of the pores became larger, and the area ratio of Al/Si became smaller than the specified value. The thermoplastic resin The bonding surface between the layer and the aluminum oxide film is reduced. As a result, adhesion and adhesion durability were unacceptable, and the overall evaluation was unacceptable.

In Comparative Example 9, the diameter of the pores in the porous aluminum oxide film layer was extremely large because the frequency of alkaline alternating current electrolysis was too low. As a result, the contact area with the thermoplastic resin layer became small, the adhesiveness and adhesion durability were unacceptable, and the overall evaluation was unacceptable.

In Comparative Example 10, because the frequency of alkaline alternating current electrolysis was too high, the diameter of the pores in the porous aluminum oxide film layer became extremely small, and the bonding surface between the thermoplastic resin layer and the aluminum oxide film decreased. As a result, adhesion and adhesion durability were unacceptable, and the overall evaluation was unacceptable.

In Comparative Example 11, the size of the pores in the porous aluminum oxide film layer was extremely small because the current density of the alkaline alternating current electrolysis was too small. Therefore, the thermoplastic resin hardly flows into the pores. As a result, adhesion and adhesion durability were unacceptable, and the overall evaluation was unacceptable.

In Comparative Example 12, because the current density of the alkaline alternating current electrolysis was too high, the size of the small pores became extremely large. Therefore, the bonding area between the thermoplastic resin layer and the aluminum oxide film decreases. As a result, the adhesion durability was unacceptable, and the overall evaluation was unacceptable.

In Comparative Example 13, because the electrolysis time of the alkaline AC electrolysis was too short, the barrier aluminum oxide film layer became thinner, and the bonding surface between the thermoplastic resin layer and the aluminum oxide film decreased. As a result, adhesion and adhesion durability were unacceptable, and the overall evaluation was unacceptable.

In Comparative Example 14, the porous aluminum oxide film layer and the barrier aluminum oxide film layer became thicker because the electrolysis time of the alkaline alternating current electrolysis was too long, and the inflow into the film of the thermoplastic resin was small. As a result, adhesion and adhesion durability were unacceptable, and the overall evaluation was unacceptable.

In Comparative Example 15, direct current electrolysis was used instead of alkaline alternating current electrolysis. In direct current electrolysis, only the barrier type aluminum oxide film layer is formed, and the porous aluminum oxide film layer and its pores are not formed. The thermoplastic resin layer cannot be joined. As a result, adhesiveness and adhesion durability could not be evaluated.

In Comparative Example 16, since the Si content was large, many Si-based particles in the base material existed, and accordingly, the area ratio of the crystallized product became larger than the predetermined value. The bonding surface with the thermoplastic resin layer is reduced by the presence of Si-based particles. As a result, adhesion and adhesion durability were unacceptable, and the overall evaluation was unacceptable.

1‧‧‧Surface treatment aluminum alloy 2‧‧‧Substrate 3‧‧‧Oxide film layer 31‧‧‧Porous aluminum oxide film layer 32‧‧‧Barrier aluminum oxide film layer 4‧‧‧small hole 5‧‧‧Si-based particles (containing Si intermetallic compounds or crystallized products of Si alone) 61‧‧‧electrodes 62‧‧‧counter electrode 71‧‧‧AC power supply 72‧‧‧Power switch 8‧‧‧Electrolytic solution 9‧‧‧Resin layer (thermoplastic resin sheet)

Fig. 1 is an explanatory diagram showing a cross-sectional structure of a surface-treated aluminum alloy material formed with an aluminum oxide film in an example. Fig. 2 is a diagram illustrating the configuration of an AC electrolysis device in an embodiment. Fig. 3 is a cross-sectional view of a test piece in which a surface-treated aluminum alloy material and a thermoplastic resin piece are joined in an example. FIG. 4 is a drawing-substitution photograph of the surface of a surface-treated aluminum alloy material observed with a scanning electron microscope (SEM) in Examples.

1‧‧‧Surface treatment aluminum alloy

2‧‧‧Substrate

3‧‧‧Oxide film layer

4‧‧‧small hole

5‧‧‧Si-based particles (containing Si intermetallic compounds or crystallized products of Si alone)

31‧‧‧Porous aluminum oxide film layer

32‧‧‧Barrier aluminum oxide film layer

Claims (2)

A surface-treated aluminum alloy material, comprising: a substrate made of an Al-Si alloy containing 5 to 20% by mass of Si, and part or all of the substrate formed by alternating-current electrolytic treatment in an alkaline liquid The oxide film layer on the surface; the surface-treated aluminum alloy material used as the substrate of the printed wiring board covered with the resin layer on the above-mentioned oxide film layer is characterized in that the above-mentioned oxide film layer has: the thickness formed on the surface side 20~1000nm porous aluminum oxide film layer, and a barrier type aluminum oxide film layer with a thickness of 3~50nm formed on the substrate side, there are many small pores with a diameter of 3~50nm in the aforementioned porous aluminum oxide film layer At the same time, the circle-equivalent diameter of the crystallization formed by the intermetallic compound containing Si or Si alone is less than 15 μm on average, and the crystallization exists in an area ratio of 15% or less. A method of manufacturing a surface-treated aluminum alloy material, which is a method of manufacturing a surface-treated aluminum alloy material as described in item 1 of the scope of the patent application, which is characterized in that a plate with the chemical composition of the aforementioned base material is produced by casting, and the plate is at least When the base material is produced by hot rolling, and then the base material is subjected to AC electrolytic treatment to obtain the surface-treated aluminum alloy material having the aforementioned oxide film, the casting system is carried out at a distance from the surface of the plate material to 100 mm. The cooling rate of the position is 0.5°C/sec or more. The above-mentioned hot rolling system is carried out in a plurality of rolling passes, and the reduction ratio of the final pass is carried out within the range of 20%~70%. The above-mentioned alternating current electrolytic treatment The electrode and the counter electrode made of the above-mentioned substrates are used, and the alkaline aqueous solution with a liquid temperature of 35-80°C is used as the electrolyte at a pH of 9-13, and the frequency is 10-100Hz, the current density is 4-50A/dm ² and The electrolysis time is between 2 and 600 seconds.

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