JP2537276B2 - Abrasion resistant aluminum material and its manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an abrasion resistant material having a tungsten carbide layer of W ₃ C composition and a method for producing the same.

[Prior Art] Aluminum has hitherto been used because of its lightness, strength, corrosion resistance, workability, etc.
It is used in a wide range of applications such as air conditioners, refrigerators, automobile parts, computer parts, copiers, printers, facsimiles, building materials for homes, exterior products, buildings, civil engineering products, sports and leisure products, etc.
On the other hand, aluminum has excellent physical properties, but on the other hand, its surface hardness is not sufficient and its abrasion resistance is extremely low.
Therefore, a method of improving wear resistance by forming a hard film (alumite treatment) on the surface of aluminum and its alloy by anodization is used. More recently, a method has been proposed in which a nickel-based plating is formed on the surface of aluminum and its alloy by electroless plating, and then a tungsten carbide layer having better wear resistance than the hard film is formed by a chemical vapor deposition method. (JP-A-62-205275, JP-A-62-218567, JP-A-62-290871). However, since aluminum has a significantly negative electrode potential than most metals, there is a problem that it is difficult to obtain good plating.
Also, a plating step must be provided before chemical vapor deposition, which is complicated in any case.

[Specific Means for Solving Problems] The inventors of the present invention have made earnest studies in view of the problems of the above-mentioned conventional methods, and as a result, on the aluminum surface having an extremely high aluminum content, a tungsten carbide film was directly formed on the aluminum surface by a chemical vapor deposition method. The present invention has been completed by finding that the bite adheres well. That is, the present invention is a wear-resistant aluminum material in which a tungsten carbide layer having a W ₃ C composition is directly deposited on the surface of aluminum having a purity of 98% by weight or more, and the manufacturing method thereof is tungsten hexafluoride. A mixed gas of aromatic hydrocarbon and hydrogen, in which the atomic ratio of carbon to tungsten is 2 to 10 and the atomic ratio of hydrogen to carbon is 3 or more, the reaction temperature is 250 to 5
It is a method of chemical vapor deposition on aluminum having a purity of 98% by weight or more in the range of 00 ° C.

In the present invention, the aluminum as the base material needs to have a purity of 98% by weight or more, and when an aluminum material having a purity less than this range is used, a film having good adhesion cannot be obtained. It is a thing. As an aluminum-based material, a purity of 99, which is marketed as pure aluminum
Various aluminum alloys mainly containing copper, magnesium, zinc, or silicon are known in addition to materials with a weight percentage of not less than 90%.
It is in the range of about% by weight.

In the present invention, when such an aluminum alloy is used, the reason why a film having good adhesiveness cannot be obtained is not clear, but various metals present in the alloy are raw material gas components.
By the fluorine atmosphere derived from tungsten fluoride,
It is considered that the tungsten carbide is deposited while being modified and existing on the surface of the alloy, so that a film having good adhesion cannot be obtained.

In the present invention, a tungsten carbide layer having a W ₃ C composition is coated on the surface of aluminum with a purity of 98% by weight or more by a chemical vapor deposition method, and benzene or toluene is used as an aromatic hydrocarbon as a carbon source. , And various aromatic hydrocarbons such as xylene, but benzene is most preferable because of its high vapor pressure and easy supply. The amount of these aromatic hydrocarbons used is selected so that the ratio (C / W; atomic ratio) of carbon in the molecule to tungsten of the raw material tungsten hexafluoride is in the range of 2 to 10. If the amount of the aromatic hydrocarbon is less than this range, W ₃ C single film difficult to obtain, obtained as a mixed film of tungsten (W), as compared to W ₃ C single film It is not preferable because the physical properties such as gloss and abrasion resistance are inferior. Also,
Although there is no particular inconvenience when the amount is larger than this range, since the aromatic hydrocarbon as a raw material is wasteful, the range below this range is preferable.

In the present invention, the amount of hydrogen is also limited. That is, the ratio of hydrogen to carbon (H / C; atomic ratio)
Is required to be 3 or more, and when it is smaller than this, a mixed film of W and W ₃ C is obtained, which is not preferable.

In the present invention, in addition to these raw material gases, an inert gas such as argon may be further added to carry out the reaction.

The reaction temperature of the present invention is preferably in the range of 250 to 500 ° C., 25
If the temperature is lower than 0 ° C, a tungsten carbide layer having a good W ₃ C composition cannot be obtained. Further, aluminum is a material having relatively low heat resistance, and if it exceeds 500 ° C., various adverse effects are exerted on aluminum as a base material, which is not preferable.
More preferably 400 ° C from the standpoint of avoiding warpage of the base material.
Up to the range.

According to the chemical vapor deposition method using the source gas composition of the present invention, a tungsten carbide layer having a W ₃ C composition, which is more excellent in wear resistance, can be formed at a constant temperature, and thus is most suitable for coating aluminum.

In the present invention, the reaction pressure is not particularly limited, but it is a great feature that the reaction can be sufficiently performed even at atmospheric pressure. In applications where there is no particular requirement for appearance, the reaction under atmospheric pressure, which has a high film deposition rate, is suitable. In this case, it is not necessary to employ a special reactor as well, and the operation is simple. Further, for applications where the appearance is strictly required, it is possible to form a very good film under reduced pressure conditions, and it is possible to obtain a homogeneous film having excellent surface gloss.

Further, the thickness of the tungsten carbide layer of the W ₃ C composition of the present invention is not particularly limited, but in order to eliminate the influence of the base material and make a surface of sufficient hardness, the aluminum base material is soft. It is preferable that the film thickness is about 20 μm or more. In addition, there is no particular upper limit, but if it is too thick, it may cause inconvenience such as warpage due to the difference in coefficient of thermal expansion between aluminum and tungsten carbide of the base material, and from the viewpoint of surface modification of aluminum, It is preferable to set the film thickness to about 60 μm or less, because the film thickness not exceeding a certain level is not particularly required and it naturally takes time to form the film.

The material of the present invention is excellent not only in abrasion resistance due to surface hardness but also in corrosion resistance, and if it is desired to utilize such characteristics in particular, a film thickness of about 20 μm is not always necessary and about 10 μm is sufficient. .

 Hereinafter, the present invention will be specifically described with reference to examples.

Example 1 A horizontal flow type CVD apparatus equipped with a reactor having an inner diameter of 40 cm, a total length of 100 cm, and a uniform temperature region length of 60 cm was used. A raw material gas was introduced from one nozzle at one end of the reactor, and the width was 1 cm and the length was 5 cm.
A substrate sample having a thickness of cm and a thickness of 3 mm was placed in the center of the uniform temperature region to carry out the reaction. The reaction was carried out in the same manner in all of the following examples and comparative examples.

A mixed gas in which the molar ratio of tungsten hexafluoride, benzene and hydrogen was 2.2: 1: 33 (C / W atomic ratio = 2.7, H / C atomic ratio = 11) was 400 at a total flow rate of 7.8 / min under atmospheric pressure. An aluminum piece introduced into a reactor kept at ℃ and placed in this reactor (JIS nominal 1100 purity 99 wt% or more, 3 mm thickness, 1 x 5 cm)
Was coated for 1 hour. About 40 on a piece of aluminum
A film with a gloss of μm was obtained. From the X-ray diffraction pattern, W ₃
It was confirmed that the film was a C single film. The film adhered well to the substrate, and the film did not peel off when the sample piece was bent.

Example 2 A mixed gas having a molar ratio of tungsten hexafluoride, benzene and hydrogen of 1.4: 1: 10 (C / W atomic ratio = 4.3, H / C atomic ratio = 3.3) under atmospheric pressure and a total flow rate of 2.1 / It was introduced into a reactor kept at 300 ° C. for min and the aluminum pieces (same as in Example 1) placed in this reactor were coated for 2 hours. A film having a gloss of about 25 μm was obtained on the aluminum piece, and it was confirmed from the X-ray diffraction pattern that the film was a W ₃ C single film. This film also had a good adhesion state as in Example 1,
No peeling of the film was observed even after bending.

Example 3 A mixed gas in which the molar ratio of tungsten hexafluoride, benzene and hydrogen is 2.7: 1: 42 (C / W atomic ratio = 2.2, H / C atomic ratio = 7.0) is under atmospheric pressure and the total flow rate is 7.6 /. It was introduced into a reactor kept at 250 ° C. for min and the aluminum pieces (same as in Example 1) placed in this reactor were coated for 3 hours. A film having a gloss of about 22 μm was obtained on the aluminum piece, and it was confirmed from the X-ray diffraction pattern that the film was a W ₃ C single film. The adhesion state of the film was the same as in Example 1.

Example 4 A mixed gas in which the molar ratio of tungsten hexafluoride, benzene and hydrogen was 16: 1: 233 (C / W atomic ratio = 0.38, H / C atomic ratio = 78) was added under atmospheric pressure at a total flow rate of 7.5 /. It was introduced into a reactor kept at 400 ° C. for min and the aluminum pieces placed in this reactor (same as Example 1) were coated for 30 minutes. A 21 μm slightly dull film was obtained on the aluminum strip. It was confirmed from the X-ray diffraction pattern that this film was a mixed film of W and W ₃ C. The adhesion state of this film was the same as in Example 1.

Example 5 A mixed gas in which the molar ratio of tungsten hexafluoride, benzene and hydrogen is 2.9: 1: 8.1 (C / W atomic ratio = 2,8, H / C atomic ratio = 2.7) is set under atmospheric pressure at a total flow rate. It was introduced into a reactor kept at 400 ° C. at 1.0 / min, and an aluminum piece placed in the reactor (the same as in Example 1) was coated for 1 hour. A 30 μm glossy but slightly bluish film was obtained on the aluminum strip. This film shows that the W
And it was confirmed that the mixed film of W ₃ C. The adhesion state of this film was the same as in Example 1.

Example 6 A mixed gas in which the molar ratio of tungsten hexafluoride, benzene and hydrogen was 1.7: 1: 31 (C / W atomic ratio = 3.5, H / C atomic ratio = 10) was used at a total pressure of 90 Torr and a total flow rate of 2.4. It was introduced into a reactor kept at 400 ° C./min and the aluminum piece (same as that in Example 1) placed in the reactor was coated for 2 hours.
A 20 μm glossy film was obtained on the aluminum piece, and it was confirmed from the X-ray diffraction pattern that the film was a W ₃ C single film. In addition, the obtained film was a more uniform, smooth and glossy film as compared with the films obtained in Example 1, Example 2 and Example 3, and the adhesion state was the same as in Example 1. there were.

Example 7 A film was formed in the same manner as in Example 6 except that the reaction temperature was 300 ° C. and the coating time was 3 hours.
A W ₃ C single film having a film thickness of 15 μm was obtained. The appearance of this film was almost the same as that of the film obtained in Example 6, and the contact state was not different.

Comparative Example 1 The base material is an Al-Cu alloy (JIS2017, aluminum purity 94
Chemical vapor deposition was performed in the same manner as in Example 1 except that the content was changed to wt%. After the reaction was completed, the tungsten carbide layer was peeled from the substrate when taken out from the CVD device.

Comparative Example 2 The base material was an Al-Mg alloy (JIS5083, aluminum purity 93
Chemical vapor deposition was carried out in the same manner as in Example 1 except that the content was 38% by weight, and a W ₃ C single film having a film thickness of 38 μm was obtained. When this covering material was bent, the tungsten carbide film was easily peeled off from the base material.

Comparative Example 3 Substrate Al-Mg-Si alloy (JIS6061, aluminum purity of 97 wt%) except that the can in the same manner as Example 1 carried out chemical vapor deposition, W ₃ C single film having a thickness of 42μm is obtained Was given. When this covering material was bent, the tungsten carbide film was partially peeled from the base material.

[Advantages of the Invention] According to the present invention, it is possible to improve the low surface hardness, which is a drawback of aluminum, by using a material that is light and has excellent corrosion resistance, workability, conductivity, etc. to have a even better W ₃ tungsten carbide of C composition can be improved depositing the adhesion, household electric appliances, electronic components, heat exchangers, air conditioners, refrigerators, automobile parts, parts for computers, copying Machines, printers, facsimiles, building materials for homes, exterior products, buildings, civil engineering products, sports and leisure products, etc.
It is extremely useful in the field where surface abrasion resistance is required.

Claims (2)

(57) [Claims] 1. A wear-resistant aluminum material in which a tungsten carbide layer made of only W ₃ C is directly deposited on the surface of aluminum having a purity of 98% by weight or more. 2. Tungsten hexafluoride, aromatic hydrocarbon,
And the mixing ratio of hydrogen is 2 to 10 in terms of atomic ratio of carbon to tungsten, and 3 in terms of atomic ratio of hydrogen to carbon.
A process for producing an abrasion-resistant aluminum material, which comprises chemically vapor-depositing the mixed gas as described above on aluminum having a purity of 98% by weight or more in a reaction temperature range of 250 to 500 ° C.