JP2006137993A - Aluminum based member, method for producing the same and surface treatment method for aluminum based member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum based member provided with a coating layer having excellent adhesion with a base material, fatigue strength, seizure resistance, corrosion resistance and electric insulation properties, and to provide a method for producing an aluminum based member suitable for the production. <P>SOLUTION: The aluminum based member is composed of: an aluminum base material essentially consisting of aluminum (Al), and having an activated face; and a coating layer formed on the activated face and comprising molybdenum disulfide; wherein, the X-ray intensity ratios of molybdenum (Mo), sulfur (S), oxygen (O) and carbon (C) by X-ray analysis in the surface of the coating layer satisfy Mo:3 to 20k%, S:2 to 15k%, O:1 to 15k% and C:10 to 35k%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an aluminum-based member provided with a coating layer having excellent adhesion to a substrate, fatigue strength, seizure resistance, corrosion resistance, and electrical insulation, a method for producing the same, and a surface treatment method for the aluminum-based member.

  In recent years, lightweight aluminum alloy products are being adopted due to demands for weight reduction of various products. By reducing the weight, the performance of various devices and the like can be improved. Especially in automobiles, the environment can be improved by improving the fuel efficiency by reducing the weight.

Since aluminum is a soft metal with low hardness, it is inferior in wear resistance and seizure resistance. Therefore, depending on the use situation, a surface treatment such as curing the surface of aluminum or aluminum alloy or forming a film having a small friction coefficient on the surface is required. However, aluminum has a strong affinity for oxygen in the air and easily binds to oxygen. For this reason, a dense and stable alumina (Al ₂ O ₃ ) layer is formed on the surface of aluminum. Due to the presence of the alumina layer, it is difficult to form a film having good adhesion on the surface of the aluminum base.

For example, anodization, plating, etc. are performed as the surface treatment of an aluminum substrate. Further, an ion nitriding treatment for forming an aluminum nitride layer on the surface of an aluminum base material is known (for example, see Patent Document 1). Furthermore, there is also a chemical conversion treatment for forming a chemical conversion film on the surface of the aluminum substrate (see, for example, Patent Document 2).
JP-A-60-211061 JP 2004-169120 A

  However, an anodic oxide film formed by anodizing treatment is relatively hard, but has low fatigue strength and poor seizure resistance. Moreover, since it is porous, corrosion resistance is not sufficient. Plating is easy to peel off and inferior in corrosion resistance. Since the chemical conversion film is thin, corrosion resistance and wear resistance are not sufficient. In any of the above surface treatments, the adhesion between the aluminum substrate and the film to be formed is not sufficient. Thus, the present condition is that the effective surface treatment method in order to improve the fatigue strength of the aluminum-type member, seizure resistance, etc. has not yet been found.

  By the way, an aluminum-based member is often manufactured by a die casting method from the viewpoints of cost reduction, mass productivity, and the like. In this case, the fatigue strength of the casting tends to decrease due to defects such as porosity existing inside. Further, the contact with the mold increases the irregularities on the casting surface. Therefore, when manufacturing an aluminum-type member by the die-casting method, the surface treatment method which can improve fatigue strength and can form a film with high adhesive force is strongly desired.

  The present invention has been made in view of such a situation, and provides an aluminum-based member including a coating layer excellent in adhesion to a base material, fatigue strength, seizure resistance, corrosion resistance, and electrical insulation. This is the issue. Another object of the present invention is to provide a method for producing an aluminum-based member suitable for the production. Furthermore, it aims at providing the surface treatment method of the aluminum-type member which forms such a coating layer on the surface of an aluminum-type member.

(1) An aluminum-based member of the present invention contains aluminum (Al) as a main component, an aluminum base material having an activated active surface, and formed on the active surface, and includes molybdenum disulfide (MoS ₂ ). The X-ray intensity ratio of molybdenum (Mo), sulfur (S), oxygen (O), and carbon (C) by X-ray analysis on the surface of the coating layer is Mo: 3 to 20 k%, S : 2 to 15 k%, O: 1 to 15 k%, C: 10 to 35 k%.

Since the coating layer containing MoS ₂ has self-lubricating properties, it has excellent seizure resistance. It also plays a role in suppressing the progress of fatigue. By forming such a coating layer, the aluminum-based member of the present invention exhibits high fatigue strength and is excellent in seizure resistance, corrosion resistance, and electrical insulation.

In addition, the “active surface” in the present specification means a surface that can enhance the adhesion of the coating layer formed on the surface. As an active surface, for example, a mode in which the surface of the aluminum base material is roughened, a mode in which the oxide layer previously formed on the surface is removed and cleaned, and an adhesion force with the coating layer is increased on the surface. Various aspects such as an aspect in which a coating film is formed are included. In the aluminum-based member of the present invention, the coating layer containing MoS ₂ is formed on the active surface of the aluminum substrate. For this reason, the adhesive force of a coating layer and an aluminum base material is high.

  As described above, an aluminum-based member including a coating layer having excellent adhesion to an aluminum substrate, fatigue strength, seizure resistance, corrosion resistance, and electrical insulation can be used in many fields. For example, in the automobile field, pistons for engine members, swash plates and shoes for air conditioners, pump parts such as side plates and flow controllers, carburetors, gear sliders, pulley shafts, guides, mandrels, shafts, and the like.

(2) The aluminum-based member provided with the coating layer having such excellent characteristics can be manufactured, for example, by the following manufacturing method of the present invention. That is, in the method for producing an aluminum-based member of the present invention, an activation step of activating the surface of an aluminum base material containing Al as a main component, and MoS ₂ powder and a solvent dissolved on the activated active surface. A coating layer containing MoS ₂ on the active surface of the aluminum base material, comprising: an adhesion step for adhering a mixed solution containing a resin; and a heating step for heating at least the mixed solution adhering portion to which the mixed solution adheres It is characterized by forming.

In the method for producing an aluminum-based member of the present invention, first, the surface of the aluminum substrate is activated in the activation step. By previously activating the surface of the aluminum substrate that forms the coating layer, the adhesion of the coating layer to be formed can be increased. Then, in the next attaching step, a mixed solution containing MoS ₂ powder is attached on the activated active surface, and heated in the subsequent heating step to form a coating layer containing MoS ₂ . Thus, according to the manufacturing method of the present invention, the aluminum-based member of the present invention can be easily manufactured.

(3) The present invention can also be understood as a surface treatment method for aluminum-based members. That is, the above-described coating layer can be formed by performing a new surface treatment on an existing aluminum base material. Therefore, the present invention provides an activation process for activating the surface of an aluminum base material containing Al as a main component, and a mixed liquid containing MoS ₂ powder and a resin dissolved in a solvent on the activated active surface. An adhesion step of attaching, and a heating step of heating at least the mixed solution adhesion portion to which the mixed solution adheres, and forming a coating layer containing MoS ₂ on the active surface of the aluminum substrate. It may be a surface treatment method of an aluminum-based member.

  In the aluminum-based member of the present invention, the coating layer constituting the surface layer portion is firmly adhered to the aluminum base, and exhibits excellent fatigue strength, seizure resistance, corrosion resistance, and electrical insulation. For this reason, the aluminum-based member of the present invention can be used in many fields including the automobile field. Moreover, according to the manufacturing method and the surface treatment method of the present invention, such an aluminum-based member of the present invention can be easily obtained.

  Next, the present invention will be described in more detail with reference to embodiments. Below, although the aluminum-type member of this invention and its manufacturing method are demonstrated, the content is applicable also to the surface treatment method of the aluminum-type member of this invention suitably. The contents described below can be appropriately selected or combined and applied to the aluminum-based member of the present invention, its manufacturing method, and its surface treatment method.

<Aluminum-based member>
The aluminum-based member of the present invention comprises an aluminum base material having Al as a main component and having an activated active surface, and a coating layer formed on the active surface and containing MoS ₂ , and the surface of the coating layer The X-ray intensity ratio of Mo, S, O, and C by X-ray analysis of Mo is 3 to 20 k%, S is 2 to 15 k%, O is 1 to 15 k%, and C is 10 to 35 k%.

  The aluminum-type member of this invention should just be equipped with the aluminum base material in the part in which a coating layer is formed. As long as an aluminum base material is provided in the portion where the coating layer is formed, other portions such as the inside may be composed of a metal other than Al, a resin, or the like.

  The composition and shape of the aluminum base material is not particularly a problem as long as Al is the main component. For example, pure Al materials [1050 series, etc.], Al alloy materials [2014 series, 5052 series, 7075 series wrought materials, JIS: die casting materials such as ADC1, JIS: AC2B, AC8A, AC4C etc. casting materials (high pressure Casting materials, low pressure casting materials, gravity casting materials, thixomold materials)], sintered powders obtained by mixing various elements and alloy powder methods, Al-based composite materials reinforced with fibers, etc. Is mentioned.

  The aluminum substrate has an activated active surface. As described above, the active surface includes various modes. The method for forming the active surface is not particularly limited as long as the adhesion of the coating layer formed on the surface can be increased. For example, the surface of the aluminum base material may be formed by performing at least one of chemical conversion treatment, honing, and sputtering. The formation method of the active surface will be described in detail in “(1) Activation step” of the manufacturing method described later.

The coating layer formed on the active surface contains MoS ₂ . Moreover, when the X-ray analysis of the coating layer surface is performed, the X-ray intensity ratio of Mo, S, O, and C is as follows: Mo: 3 to 20 k%, S: 2 to 15 k%, O: 1 to 15 k%, C: 10 35k%. In this specification, a value obtained by analyzing the surface of the coating layer with an X-ray microanalyzer (EPMA) is adopted as the X-ray intensity ratio.

The formation method of a coating layer is not specifically limited. For example, a liquid mixture containing MoS ₂ powder and a resin dissolved in a solvent is deposited on the active surface and then heated to form. The method for forming the coating layer will be described in detail in “(2) Adhering step, (3) Heating step” of the manufacturing method described later.

  The thickness of the coating layer is preferably 1 μm or more in consideration of adhesion to the aluminum substrate, wear resistance, and the like. More preferably, it is 3 m or more. On the other hand, if it exceeds 30 μm, the processing time becomes long and is not practical. For this reason, it is desirable to set it as 20 micrometers or less, and when it is 15 micrometers or less, it is more suitable.

<Method for producing aluminum-based member>
The manufacturing method of the aluminum-type member of this invention comprises an activation process, an adhesion process, and a heating process. Hereinafter, each step will be described.

(1) Activation process This process is a process of activating the surface of an aluminum base material containing Al as a main component. As a method for activating the surface of the aluminum substrate, various known surface treatments can be used. Among these, it is effective to perform at least one of chemical conversion treatment, honing, and sputtering.

  For example, the chemical conversion treatment may be performed by bringing a treatment liquid containing zinc phosphate, sodium phosphate or the like into contact with the surface of the aluminum base material. Various chemical conversion coatings are formed on the surface of the aluminum substrate depending on the composition of the treatment liquid. The surface of the formed chemical conversion film becomes an active surface. By forming the chemical conversion film, the adhesion of the coating layer is improved.

Honing may be performed using, for example, Al ₂ O ₃ particles according to a normal method. The oxide layer such as Al ₂ O ₃ formed on the surface of the aluminum base can be removed by honing. In this case, the surface after honing becomes the active surface. By removing the oxide layer, the adhesion of the coating layer is improved.

Sputtering may be performed according to a normal method, for example, using argon gas or the like. By performing sputtering with argon gas, an oxide layer such as Al ₂ O ₃ formed on the surface of the aluminum substrate can be removed. In this case, the surface after sputtering becomes the active surface. By removing the oxide layer, the adhesion of the coating layer is improved. When honing or sputtering is performed, fine irregularities are formed on the surface of the aluminum substrate. For this reason, if it is performed for a long time, the surface state of the active surface may be deteriorated. Further, a film such as titanium nitride (TiN) may be formed by sputtering. In this case, the surface of the formed film such as TiN becomes an active surface. By forming a film such as TiN, the adhesion of the coating layer is improved.

(2) Adhesion step This step is a step of adhering a mixed solution containing MoS ₂ powder and a resin dissolved in a solvent onto the active surface formed in the previous activation step.

The particle diameter of the MoS ₂ powder to be used is preferably as small as possible from the viewpoint of improving the adhesion to the aluminum substrate and reducing the surface roughness of the coating layer. For example, a powder having a particle size of −100 # to −320 # (average particle size of 45 μm to 150 μm) may be used. In the coating layer to be formed, the resin serves as a binder that binds the powders and binds the powder and the aluminum substrate. As such a resin, for example, a polyamide resin, a polyamideimide resin, a polyimide resin, and the like are preferable. Examples of the solvent for dissolving the resin include N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide (DMF) and the like. By mixing the resin and MoS ₂ powder dissolved in these solvents suitably viscous paste, or a slurry mixture may be prepared.

Moreover, it is desirable to add a powder of metal or the like to the above mixed solution from the viewpoint of further improving the fatigue strength, wear resistance, etc. of the coating layer and improving the familiarity with the aluminum base material. Suitable powders include metal powder, metal compound powder, silicon (Si) powder, silica (SiO ₂ ) powder, silicon carbide (SiC) powder, boron nitride (BN) powder, graphite powder, and fluororesin powder. . Depending on the desired properties of the coating layer, one kind selected from these may be added alone, or two or more kinds may be mixed and added.

Examples of the metal include chromium (Cr), antimony (Sb), titanium (Ti), tin (Sn), Al, vanadium (V), niobium (Nb), tantalum (Ta), tungsten (W), iron ( Fe), cobalt (Co), zirconium (Zr), nickel (Ni), manganese (Mn) and the like are suitable. Examples of the metal compound include metal oxides (CrO ₃ , Cr ₂ O ₃ , SbO ₂ , TiO ₂ , MoO ₃ , WO ₃ , Fe ₂ O ₃ , MnO ₂ , CoO ₃ , ZrO ₂ , NiO _2, etc.) , Titanium tetraisopropoxide (Ti [OCH (CH ₃ ) ₂ ] ₄ ), zirconium butoxide (Zr (n-OBu) ₄ ) and the like are suitable. Moreover, as a fluororesin, polytetrafluoroethylene (PTFE) etc. are suitable.

Among them, it is selected from one or more metal powders selected from Cr, Sb, Ti, Sn, and Al, compound powders of the metal, Si powder, SiO ₂ powder, SiC powder, BN powder, graphite powder, and PTFE powder. It is preferable to use one or more. In this case, the coating layer is in an embodiment containing a total of 2 to 10 k% of one or more elements selected from Cr, Si, Sb, Ti, Sn, Al, B, and N in terms of the X-ray intensity ratio.

For example, when a powder containing relatively soft graphite, PTFE, Sn, Sb, Co, Ni and oxides thereof is added, the compatibility with the aluminum base material is improved, and the adhesion of the coating layer is further improved. Further, when a powder containing relatively hard BN, Si, SiO ₂ , SiC or the like is added, the fatigue strength, wear resistance, etc. of the coating layer are improved. Hereinafter, the powder added in addition to the MoS ₂ powder is appropriately referred to as “added powder”.

Here, the mixing ratio of the MoS ₂ powder or the MoS ₂ powder and the additive powder in the mixed solution is 1% by mass when the total mass of the mixed solution is 100% by mass in consideration of the formation speed of the coating layer. It is desirable to set it above. It is more preferable to set it to 5 mass% or more. Meanwhile, in order to uniformly form the coating layer, MoS ₂ powder or, it is desirable that the proportion of MoS ₂ powder and added powder and 60 mass% or less. It is more suitable when it is 50 mass% or less.

  This mixed solution is deposited on the active surface of the aluminum substrate. Adhesion of the liquid mixture onto the active surface is, for example, a dip method in which the active surface is immersed in the liquid mixture, a brush coating method in which the liquid mixture is brushed on the active surface, or a spray method in which the liquid mixture is sprayed onto the active surface. Or the like. According to the dip method, productivity can be improved, and according to the brush coating method, the mixed solution can be easily attached to details, and according to the spray method, the mixed solution can be uniformly attached. be able to. What is necessary is just to adjust the viscosity etc. of a liquid mixture suitably according to the method to employ | adopt.

(3) Heating step This step is a step of forming a coating layer by heating at least the mixed solution adhering portion to which the mixed solution has adhered. Heating may be performed in an air atmosphere or in a non-oxidizing atmosphere such as argon gas or nitrogen gas. When forming a coating layer on the entire surface or most of the surface of the aluminum-based member, it is efficient to use a furnace capable of heating the entire aluminum-based member. Moreover, when forming a coating layer only on the partial surface of an aluminum-type member, it is good to use a burner etc.

  The heating temperature is desirably 150 ° C. or higher. This is because if the temperature is lower than 150 ° C., the resin in the mixed solution is difficult to be decomposed. 200 degreeC or more is more suitable. On the other hand, the upper limit of the heating temperature is preferably 350 ° C. in consideration of softening of the aluminum base material.

  The heating time varies depending on the heating means employed, the size of the heating target, and the like, and thus cannot be determined uniformly, but can be set to, for example, about 1 to 3 hours. In order to suppress thermal distortion, structural transformation, and the like of the aluminum substrate, it is desirable to shorten the heating time. Moreover, the thickness of the coating layer can be increased by repeatedly performing the previous adhesion step and the main heating step. For example, both steps may be repeated about 2 to 5 times.

  Next, an Example is given and this invention is demonstrated more concretely.

<Example 1>
First, a plate-like test piece having a thickness of 1.0 mm, a width of 25 mm, and a length of 60 mm made of an aluminum alloy for extension (A5052, composition is shown in Table 1 below) was prepared. This test piece corresponds to the aluminum substrate in the present invention. Moreover, the liquid mixture for coating layer formation was prepared. The mixed liquid was MoS ₂ powder having a particle size of -250 #: 30 parts by weight, SbO ₂ powder having a particle size of -150 #: 10 parts by weight, graphite powder having a particle size of -420 #: 5 parts by weight, PTFE powder: 5 parts by weight, NMP Prepared by mixing 50 parts by weight of a polyamide resin dissolved in

Next, after degreasing one surface of the test piece with acetone, it was honed using Al ₂ O ₃ particles having a particle size of 80 # to obtain an active surface (activation step). This test piece was heated to 60 ° C. and immersed in a liquid mixture prepared in advance for 1 minute (attachment step). The test piece to which the mixed liquid adhered was placed in a box-type heat treatment furnace and heated in an air atmosphere at 250 ° C. for 60 minutes (heating step). Such an adhesion step and a heating step were repeated five times.

  The cross section of the test piece obtained after the heating step was observed with an optical microscope. FIG. 1 shows an optical micrograph of a cross section of the test piece (magnification 500 times). From the photograph in FIG. 1, it can be seen that a coating layer having a thickness of about 8 μm is formed on the surface of the aluminum substrate. Moreover, the photograph of the external appearance of a test piece is shown in FIG. As shown in the photograph of FIG. 2, the surface of the coating layer was black and in a smooth and healthy state. In addition, such a coating layer was not formed when only the adhesion process and the heating process were performed without performing the honing process, that is, without performing the activation process.

Further, the cross section of the formed coating layer was subjected to line analysis by EPMA. The result is shown in FIG. In FIG. 3, the horizontal axis represents the measurement distance (μm), and the vertical axis represents the element concentration (mass%, hereinafter simply referred to as “%”). As shown in FIG. 3, O and a large amount of C were detected in addition to a maximum of about 8% Mo, about 7% S, about 5% Sb in the coating layer of about 8 μm. Moreover, the surface of the coating layer was analyzed by EPMA. The results are shown in Table 2 below. As shown in Table 2, the X-ray intensity ratio of each element was Mo: 8 k%, S: 7 k%, O: 7 k%, C: 26 k%, Sb: 5 k%. From these results, it can be seen that the main element constituting the coating layer is C, and Mo, S, Sb, and O are present almost uniformly. The diffraction lines obtained by X-ray diffraction on the surface of the coating layer were in good agreement with the diffraction lines of MoS ₂ , SbO ₂ , and C. From the above, it is surmised that the coating layer is composed of MoS ₂ and SbO ₂ dispersed in the carbon film.

<Example 2>
First, a plate-shaped test piece having a thickness of 7.0 mm, a width of 8 mm, and a length of 35 mm made of an aluminum alloy for casting (JIS type B: AC2B, the composition is shown in Table 1 below) was prepared. This alloy was subjected to T6 treatment (500 ° C. × 2 h heat treatment → water cooling → 160 ° C. × 5 h artificial aging treatment) after gravity casting. This test piece corresponds to the aluminum substrate in the present invention. Moreover, the liquid mixture for coating layer formation was prepared. The mixed solution was composed of 20 parts by weight of MoS ₂ powder having a particle size of 320 #, 13 parts by weight of SbO ₂ powder having a particle size of 250 #, 5 parts by weight of graphite powder having a particle size of 320 #, 2 parts by weight of PTFE powder, and NMP. A polyamide resin dissolved in 60 parts by weight was prepared by mixing.

  Next, one surface of the test piece was degreased with acetone and then subjected to chemical conversion treatment with a zinc phosphate solution to make an active surface (activation step). This test piece was heated to 60 ° C. and immersed in a liquid mixture prepared in advance for 1 minute (attachment step). The test piece to which the mixed liquid adhered was put in a box-type heat treatment furnace and heated in an air atmosphere at 350 ° C. for 60 minutes (heating process). Such an adhesion process and a heating process were repeated 6 times.

When the cross section of the test piece obtained after the heating step was observed with an optical microscope, a coating layer having a thickness of about 10 μm was formed on the surface of the aluminum substrate. The formed coating layer had a black and smooth surface as shown in FIG. 2 of Example 1. Further, when the cross section of the coating layer was subjected to line analysis by EPMA, in the coating layer of about 10 μm, O and a large amount of C were found in addition to about 9% Mo, about 8% S, about 6% Sb at the maximum. was detected. Moreover, the surface of the coating layer was analyzed by EPMA. The results are shown in Table 2 below. As shown in Table 2, the X-ray intensity ratio of the main elements is Mo: 9.8 k%, S: 7.7 k%, O: 3.0 k%, C: 23 k%, Sb: 5.1 k% there were. From these results, it can be seen that the main element constituting the coating layer is C, and Mo, S, Sb, and O are present almost uniformly. The diffraction lines obtained by X-ray diffraction on the surface of the coating layer were in good agreement with the diffraction lines of MoS ₂ , SbO ₂ , and C. From the above, it is surmised that the coating layer is composed of MoS ₂ and SbO ₂ dispersed in the carbon film.

<Example 3>
The test piece which consists of the same aluminum alloy for casting as Example 2 was prepared. Moreover, the liquid mixture for coating layer formation was prepared. The mixed solution was prepared in the same manner as in Example 1 except that SiO ₂ powder was used instead of SbO ₂ powder. Then, after degreasing one surface of the test piece with acetone, sputtering with argon gas was performed to make an active surface (activation step). This test piece was heated to 60 ° C. and immersed in a liquid mixture prepared in advance for 1 minute (attachment step). The test piece to which the mixed liquid adhered was placed in a box-type heat treatment furnace and heated in an air atmosphere at 250 ° C. for 60 minutes (heating step). Such an adhesion step and a heating step were repeated five times.

When the cross section of the test piece obtained after the heating step was observed with an optical microscope, a coating layer having a thickness of about 8 μm was formed on the surface of the aluminum substrate. The formed coating layer had a black and smooth surface as shown in FIG. 2 of Example 1. In addition, when the cross section of the coating layer was subjected to line analysis by EPMA, in the coating layer of about 8 μm, O and a large amount of C in addition to about 10% Mo, about 7% S, about 4% Si at maximum. was detected. Moreover, the surface of the coating layer was analyzed by EPMA. The results are shown in Table 2 below. As shown in Table 2, the X-ray intensity ratio of each element was Mo: 10 k%, S: 7 k%, O: 3.0 k%, C: 24 k%, Si: 4 k%. From these results, it can be seen that the main element constituting the coating layer is C, and Mo, S, Si, and O are present almost uniformly. The diffraction lines obtained by X-ray diffraction on the surface of the coating layer were in good agreement with the diffraction lines of MoS ₂ , SiO ₂ , and C. From the above, it is surmised that the coating layer is composed of MoS ₂ and SiO ₂ dispersed in the carbon film.

<Example 4>
First, a plate-like test piece having a thickness of 10 mm, a width of 20 mm, and a length of 100 mm made of an aluminum alloy for casting (AC4C equivalent material, composition is shown in Table 1 below) was prepared. This alloy is subjected to T6 treatment (530 ° C. × 5.5 h heat treatment → water cooling → 140 ° C. × 3.5 h artificial aging treatment) after gravity casting. The porosity of this alloy was about 0.5 vol%. This test piece corresponds to the aluminum substrate in the present invention. Moreover, the liquid mixture for coating layer formation was prepared. The mixed solution is 30 parts by weight of MoS ₂ powder having a particle size of 320 #, 10 parts by weight of Sn powder having a particle size of 350 #, 2 parts by weight of graphite powder having a particle size of 320 #, 3 parts by weight of PTFE powder, and NMP. Prepared by mixing 55 parts by weight of dissolved polyamide resin.

  Next, one surface of the test piece was degreased with acetone and then subjected to chemical conversion treatment with a zinc phosphate solution to make an active surface (activation step). This test piece was heated to 60 ° C. and immersed in a liquid mixture prepared in advance for 1 minute (attachment step). The test piece to which the mixed solution was attached was placed in a box-type heat treatment furnace and heated in an air atmosphere at 200 ° C. for 60 minutes (heating step). Such an adhesion step and a heating step were repeated five times.

The cross section of the test piece obtained after the heating step was observed with an optical microscope. In FIG. 4, the optical microscope photograph of the cross section of a test piece is shown (500-times multiplication factor). From the photograph in FIG. 4, it can be seen that a coating layer having a thickness of about 8 μm is formed on the surface of the aluminum substrate. Further, the formed coating layer had a black and smooth surface, similar to that shown in FIG. Further, when the cross section of the coating layer was subjected to line analysis by EPMA, in the coating layer of about 8 μm, O and a large amount of C in addition to about 10% Mo, about 8% S, about 5% Sn at maximum. was detected. Moreover, the surface of the coating layer was analyzed by EPMA. The results are shown in Table 2 below. As shown in Table 2, the X-ray intensity ratio of the main elements is Mo: 10.2 k%, S: 7.9 k%, O: 3.0 k%, C: 24 k%, Sn: 6.1 k% there were. From these results, it can be seen that the main element constituting the coating layer is C, and Mo, S, Sn, and O are present almost uniformly. Further, the diffraction lines obtained by X-ray diffraction on the surface of the coating layer were in good agreement with the diffraction lines of MoS ₂ , Sn, and C. From the above, it is surmised that the coating layer is composed of MoS ₂ and Sn dispersed in the carbon film. Further, according to this example, it was confirmed that even an aluminum alloy having a defect (porosity) inside can form a coating layer having a smooth surface by forming an active surface.

<Example 5 and Example 6>
A plate-like test piece having a thickness of 1.0 mm, a width of 20 mm, and a length of 50 mm made of the same aluminum alloy for extension (A5052) as in Example 1 was prepared, and the same surface treatment as in Example 1 was applied to this test piece. (Activation step → attachment step → heating step) was performed to form a coating layer. The composition, appearance, etc., of the formed coating layer were the same as in Example 1. Let the test piece in which the coating layer was formed be a test piece of Example 5.

  A plate-like test piece having a thickness of 7.0 mm, a width of 10 mm, and a length of 25 mm made of the same aluminum alloy for casting as in Example 2 (JIS type B: AC2B) was prepared, and this test piece was the same as in Example 2. The surface treatment (activation process → attachment process → heating process) was performed to form a coating layer. The composition, appearance, and the like of the formed coating layer were the same as in Example 2. Let the test piece in which the coating layer was formed be the test piece of Example 6.

  A salt spray test was performed on each of the test pieces of Examples 5 and 6. The salt spray test was performed in accordance with JIS Z 2371 by spraying each test piece with a 5% aqueous sodium chloride solution (pH: 6.5 to 7.2) at 35 ° C. for 100 hours. In FIG. 5, the external appearance photograph of each test piece after a test is shown. For comparison, a similar salt spray test was also performed on test pieces of two types of aluminum alloys (A5052, AC2B) that were not subjected to surface treatment. In FIG. 5, the external appearance photograph of the test piece used as these comparative examples is also shown.

  As is apparent from the photographs in FIG. 5, the surface of the test piece that was not subjected to the surface treatment, in other words, the surface of the test piece on which the coating layer was not formed was greatly corroded. In contrast, the test pieces of Examples 5 and 6 on which the coating layer was formed were hardly corroded. FIG. 6 shows changes in the surface roughness of each test piece before and after the test. As shown in FIG. 6, in the aluminum alloy for extension (A5052), the surface roughness did not change much regardless of the presence or absence of the coating layer. On the other hand, in the aluminum alloy for casting (AC2B), the surface roughness of the test piece on which the coating layer was not formed significantly increased after the test. From the above result, it was confirmed that the test piece of an Example provided with a coating layer shows high corrosion resistance.

<Example 7>
A test piece for a fatigue test was prepared from an aluminum alloy for casting (AC4C equivalent material, T6 treatment performed) having a porosity of about 0.5 vol%, the same as in Example 4. FIG. 7 shows the shape of the produced test piece. As shown in FIG. 7, the test piece 1 has a saddle shape with a length of 56 mm, and has a shaft portion 2 with a length of 23.4 mm at the center. A coating layer (not shown) is formed on the surface of the shaft portion 2. The coating layer was formed by the same surface treatment as in Example 1 (activation step → attachment step → heating step). The composition, appearance, etc. of the formed coating layer are the same as in Example 1. This test piece was used as the test piece of Example 7.

  In order to investigate the fatigue strength of the test piece of Example 7, a tensile-compression fatigue test was performed on the test piece. The fatigue test was carried out with a 50 Hz sine wave load control using an electrohydraulic fatigue test apparatus (“Servo Pulser” manufactured by Shimadzu Corporation). There were two test conditions: (a) normal temperature, maximum stress amplitude 90 MPa, (b) 200 ° C., maximum stress amplitude 80 MPa. FIG. 8 shows the number of repetitions until the test piece breaks. For comparison, a similar fatigue test was performed on a test piece on which no coating layer was formed. FIG. 8 also shows the number of repetitions until the test piece of this comparative example breaks.

As shown in FIG. 8, at room temperature, the test piece of Example 7 broke about 12 × 10 ⁵ times, whereas the test piece of Comparative Example broke about 4 × 10 ⁵ times. That is, the test piece of Example 7 showed about three times the fatigue strength as compared with the test piece of the comparative example. At 200 ° C., the test piece of Example 7 broke after about 22 × 10 ⁵ times, whereas the test piece of Comparative Example broke after about 13 × 10 ⁵ times. That is, even under high temperature, the test piece of Example 7 exhibited about twice the fatigue strength as compared with the test piece of the comparative example. From the above result, it was confirmed that the test piece of an Example provided with a coating layer shows high fatigue strength.

<Electrical insulation, seizure resistance, adhesion to aluminum substrate>
For example, when the aluminum-based member of the present invention is applied to sliding parts, in addition to the corrosion resistance and fatigue strength, seizure resistance and electrical insulation are also problematic. When this inventor performed the electricity supply test with a tester, each said test piece provided with a coating layer did not supply electricity at all. Moreover, it was confirmed by an endurance test that each of the test pieces including the coating layer has excellent seizure resistance and good adhesion of the coating layer.

It is an optical microscope photograph of the cross section of the test piece which concerns on Example 1 (500-times multiplication factor). It is a photograph of the appearance of the test piece. It is a graph which shows the line analysis result by EPMA of the cross section of the test piece. It is an optical microscope photograph of the cross section of the test piece which concerns on Example 4 (500-times multiplication factor). It is an external appearance photograph of each test piece after a salt spray test. It is a graph which shows the change of the surface roughness of each test piece before and behind the salt spray test. It is the schematic which shows the shape of the test piece for fatigue tests. It is a graph which shows the repetition number until the fracture | rupture of each test piece in a fatigue test.

Explanation of symbols

  1: Test piece 2: Shaft

Claims (10)

An aluminum base material mainly composed of aluminum (Al) and having an activated active surface;
A coating layer formed on the active surface and containing molybdenum disulfide (MoS ₂ ),
The X-ray intensity ratio of molybdenum (Mo), sulfur (S), oxygen (O), and carbon (C) by X-ray analysis on the surface of the coating layer is as follows: Mo: 3 to 20 k%, S: 2 to 15 k%, O : 1-15k%, C: 10-35k%, The aluminum-type member characterized by the above-mentioned.   The coating layer further includes one or more elements selected from chromium (Cr), silicon (Si), antimony (Sb), titanium (Ti), tin (Sn), Al, boron (B), and nitrogen (N). The aluminum-based member according to claim 1, comprising a total of 2 to 10 k% in terms of the X-ray intensity ratio.   The aluminum-based member according to claim 1, wherein the coating layer has a thickness of 1 μm to 20 μm.   The aluminum-based member according to claim 1, wherein the active surface is formed by performing at least one of chemical conversion treatment, honing, and sputtering on the surface of the aluminum base material. _2. The aluminum-based member according to claim 1, wherein the coating layer is formed by heating a mixed liquid containing MoS ₂ powder and a resin dissolved in a solvent on the active surface. The mixed liquid further includes one or more metal powders selected from Cr, Sb, Ti, Sn, and Al, compound powders of the metal, Si powder, silica (SiO ₂ ) powder, silicon carbide (SiC) powder, and boron nitride. The aluminum-based member according to claim 5, comprising at least one of (BN) powder, graphite powder, and fluororesin powder. An activation step of activating the surface of the aluminum base material mainly composed of Al;
An adhering step of adhering a mixed solution containing MoS ₂ powder and a resin dissolved in a solvent on the activated active surface;
A heating step of heating at least the mixed liquid adhering portion to which the mixed liquid has adhered,
Method for producing aluminum-based member and forming a coating layer containing MoS ₂ on the active surface of the aluminum substrate.   The method for producing an aluminum-based member according to claim 7, wherein the activation step is a step of performing at least one of chemical conversion treatment, honing, and sputtering on the surface of the aluminum base material. The mixed liquid further includes at least one metal powder selected from Cr, Sb, Ti, Sn, and Al, a compound powder of the metal, Si powder, SiO ₂ powder, SiC powder, BN powder, graphite powder, and fluororesin The manufacturing method of the aluminum-type member of Claim 7 containing at least 1 or more types of powder. An activation step of activating the surface of the aluminum base material mainly composed of Al;
An adhering step of adhering a mixed solution containing MoS ₂ powder and a resin dissolved in a solvent on the activated active surface;
A heating step of heating at least the mixed liquid adhering portion to which the mixed liquid has adhered,
A method for treating the surface of an aluminum-based member, comprising forming a coating layer containing MoS ₂ on the active surface of the aluminum substrate.

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