JPH0483820A - Production of mechanism element - Google Patents

Abstract

PURPOSE:To produce a mechanism element excellent in mechanical properties, such as toughness and hardness, by forming an aluminum oxide film on the surface of an alloy by subjecting an aluminum-containing alloy formed into the prescribed element shape to heating in an oxidizing atmosphere. CONSTITUTION:An alloy having a composition consisting of, by weight, 20-40% Cr, 5-25% Ni, 3-8% Al, 0-0.5% Ti, 0.05-1.0% of one or >=2 elements among Zr, Y, Hf, Ce, La, Nd, and Gd, and the balance Fe is formed into the prescribed element shape. The alloy formed into the desired shape is heated in an oxidizing atmosphere up to 800-1300 deg.C. Since an aluminum oxide film 1 is deposited on the surface of the alloy 2 with a specific composition as if it takes root 3 in the alloy 2 as a substrate, extremely superior adhesive strength to the substrate can be provided. In the mechanism element obtained by the manufacturing method of this invention, the alumina film 1 having high adhesive strength and high hardness is formed on the high hardness alloy 2 and high wear resistance is provided.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing mechanical parts such as chucks, rotating shafts, gears, cams, etc. of electric tools, and is concerned with a method of manufacturing mechanical parts such as chucks, rotating shafts, gears, cams, etc. of electric tools. The present invention relates to a method for manufacturing a highly hard and highly wear-resistant mechanical component made of a base material and covered with uniform aluminum oxide (hereinafter referred to as "alumina") with a dense and highly adhesive surface.

[Conventional technology]

In the case of mechanical parts such as chucks, rotating shafts, gears, cams, etc. of power tools, the wear resistance and corrosion resistance can be improved by coating the surfaces with high hardness materials such as oxides, nitrides, and carbides. Are known. The coating is
This is done by methods such as ion blating method and sputtering method.

Furthermore, the entire mechanical component has also been formed of a ceramic sintered body.

[Problem to be solved by the invention]

However, in the case of the above-mentioned ion blasting method, sputtering method, etc., it is difficult to make the coating thick enough. Further, in the case of a complicated shape, it is difficult to uniformly coat the entire surface, and on the other hand, in the case of a highly planar shape, there is a problem that the adhesion of the film is not good. In order to improve adhesion, troublesome treatments such as surface roughening and undercoat layer formation must be carried out.In the case of mechanical parts using bulk ceramic sintered bodies, dimensional accuracy is low and toughness is low. There is a problem that there is not enough water and it is easy to break.

In view of the above circumstances, this invention has been devised to provide a method for obtaining mechanical parts that are sufficiently covered with an alumina film with good adhesion, regardless of the shape of the part, and that have excellent mechanical properties such as toughness and hardness. The challenge is to provide the following.

[Means to solve the problem]

In order to solve the above problems, the method for manufacturing mechanical parts of the present invention involves heating an aluminum-containing alloy formed into a desired part shape in an oxidizing atmosphere at a temperature of 800°C or higher and 1200°C or lower. In depositing aluminum oxide on the surface of the alloy to form an aluminum oxide film, as the alloy, Cr: 20 to 40% by weight.
, Ni: 5-25% by weight, A! ! :3 to 8% by weight, Ti
:0 to 0.5% by weight, Zr, Y, Hf, Ce, La, N
Any one or more of d and Gd: 0
．． 05 to 1.0% by weight, Fe: balance.

The alloy with the above composition is molded into the desired part shape, but the molding requires a special method (it can be done by a commonly used method. For example, an alloy obtained by vacuum melting) After hot forging the ingot, it can be shaped by rolling and cutting.

There is no particular restriction on the shape of the part, and various shapes can be taken depending on, for example, a chuck, a rotating shaft, a gear, a cam, etc. of a power tool.

The alloy formed into the desired shape is heat treated in an oxidizing atmosphere. As the oxidizing atmosphere, a gas containing oxygen (including not only OX, but also compounds formed with other elements), such as air, is used. The heating temperature is
800°C or higher (preferably 1000°C or higher), 120
The temperature needs to be in a range of 0° C. or lower, and may be set within this range depending on the desired thickness of the oxide film, for example.

If it is below 800°C, there is a problem that the rate of formation of an aluminum oxide film (hereinafter referred to as an alumina film as appropriate) is extremely slow, and it takes a long time to obtain a film of 11 or more.
When the temperature exceeds 1200°C, there is a problem that not only the base alloy becomes softened, deformed, and further brittle, but also that the resulting film is likely to crack or peel. The heating time is not particularly limited, but is preferably 0.5 hours or more, and may be set within this range depending on the desired thickness of the oxide film. If the heating time is shorter than 0.5 hours, a uniform aluminum oxide film may not be formed over the entire surface.

Before heating, as shown in FIG. 1(a), the surface of alloy 2 with no aluminum film formed was coated with the heat treatment shown in FIG. 1(a).
'b), in the thus obtained product in which the alumina film 1 is formed, the aluminum oxide film 1 is formed on the surface of the alloy 2 having the specific composition, and the aluminum oxide film 1 is used as the base alloy. Since roots 3 are deposited on 2, so to speak, the adhesion to the substrate is extremely excellent. With this method, even if the shape is complex, it is possible to easily form a coating on the entire surface down to the smallest detail.
The thickness t of the alumina film 1 formed to look like roots 3 (as shown in Fig. 1, this thickness t is the minimum thickness excluding the so-called root part) also depends on the heat treatment temperature and/or Alternatively, it is possible to obtain a desired thickness by appropriately adjusting the heat treatment time. Furthermore, when comparing this method with the ion blasting method and sputtering method, the adhesion is far superior because, as mentioned above, the oxide is precipitated from within the alloy as if it were rooted in the alloy. . In the case of ion blating method or sputtering method,
As shown in FIG. 2, the alumina film 1' on the surface of the alloy 2' has no roots and is flat. Furthermore, there are no problems (for example, low dimensional accuracy or cracking) that occur when the entire mechanical component is formed from a ceramic sintered body. In the matrix of Alloy 2, finely and uniformly dispersed NiA1 (indicated by 4 in Fig. 1 (bl)) exists, which suppresses the coarsening of crystal grains.For this reason, Alloy 2 There is almost no deterioration in the mechanical properties of the matrix due to high-temperature heat treatment, resulting in high toughness.Furthermore, the base alloy has the above composition, so it has high hardness.Thus, this invention Mechanical parts obtained by the manufacturing method have a highly adhesive and highly hard alumina film formed on a highly hard base material, and have high wear resistance.

Note that there is no particular restriction on the thickness of the film to be formed.

The alloy used in this invention is C, which is a ferrite-forming element.
It is a Fe-based alloy containing large amounts of r, Al, and Ni, an austenite-forming element, and the amounts of each element are selected so that the alloy is mainly composed of a ferrite phase. Ferrite phase alloys tend to form a thick alumina film on the surface that is dense and has good adhesion to the substrate through oxidation heat treatment, but austenite phase alloys do not form an alumina film uniformly and may peel off. . When making the alloy into a ferrite phase, increasing the amount of Ni results in (Cr + A
It is also necessary to increase the amount of drop. Note that even if a small amount of austenite phase is mixed, the properties of the ferrite alloy of the present invention are not impaired.

In the alloy of this invention, Cr is 20 to 40% by weight of the total
occupies In the Fe-Cr-Aj2 alloy, Cr is necessary to form a dense and uniform alumina film on the alloy surface, but since the alloy of this invention contains a large amount of Ni, it makes the alloy a ferrite phase. For this purpose, Ni
Even when Aj2 is the lower limit and Aj2 is the upper limit, 20% by weight or more of Cr is required. In an alloy in which the Ni content is at the lower limit, the Al content is near the upper limit, and the Cr content is 20% by weight, the formation of the alumina film is incomplete. Therefore, the lower limit of Cr is 20% by weight. Furthermore, as the Cr content in the alloy increases, the tendency for embrittlement becomes stronger, so the upper limit for Cr is 40% by weight.
It is.

In the alloy used in this invention, Ni accounts for 5 to 25% by weight of the total. By precipitating fine NiAI into the alloy, the mechanical properties are improved, but in the coexistence with jl, N1A7! Ni is an essential element for precipitation. In order to be sufficiently effective in improving mechanical properties, approximately 5% by weight or more of Ni is required, so Ni
The lower limit of is 5% by weight. If the amount of Ni increases, N1A
j? However, since the alloy of this invention must be composed of a ferrite phase, an increase in the amount of Ni, which is an austenite-forming element, is advantageous for the precipitation of Cr, Al, and mechanical properties.
Requires an increase in quantity. However, if the amount of Ni exceeds 25% by weight, the amount of Cr must be increased, which tends to cause embrittlement, so the upper limit for Ni is 25% by weight.

In the alloy of this invention, Al occupies 3 to 8% by weight of the total. AI is an essential element for precipitating NiAl in the alloy and for forming an alumina film on the alloy surface by high-temperature oxidation treatment. In particular, in order to form a dense and uniform film, it is necessary to contain 3% by weight or more of jl. Increasing the Al content is advantageous for the precipitation of NiA# and the formation of an alumina film, but if it exceeds 8% by weight, the workability of the alloy decreases, so the upper limit for Al is 8% by weight.

In the alloy of this invention, Z r 1Y % Hf , , C
e 1Titanium group elements and rare earth elements such as La, Ncl, and Gd are mixed into the alumina film to improve the brittleness of the film, and are also dispersed as internal oxide particles in the alloy directly under the film, improving the adhesion of the film. significantly improve. In order for these effects to be exhibited, one or more of Zr, Y, Hf, Ce, La, Nd, and Gd must be at least 0.
05% by weight is required. On the other hand, if the content exceeds 1.0% by weight, the workability of the alloy will decrease rapidly, so the upper limit is 1.0% by weight.
．． It is 0% by weight.

When Ti is contained in the alloy at about 0.5% by weight,
Appropriate heat treatment forms fine intermetallic compounds that help strengthen the alloy. Although the alloy of the present invention may not contain Ti, for these reasons, it may not contain Ti.
May contain.

However, if the Ti content exceeds 0.5% by weight, the adhesion and denseness of the alumina film may be impaired.
The content is preferably 5% by weight or less.

In the alloy of this invention, the balance other than the above components is Fe. However, the present invention is not limited to the case where the remainder is entirely Fe, and includes, for example, the case where the remainder also contains unavoidably present impurities other than Fe. In addition, among the impurities, the three elements Si and C1N are
It is preferable to keep it within the following range.

Since Si becomes SiO□ during high-temperature oxidation treatment and may mix into the alumina film and impair the denseness of the film, it is desirable that the content be 0.3% by weight or less. It may be 0% by weight.

C reacts with Cr at high temperatures to form Cr carbides and embrittle the alloy. Also, CO is CO! It becomes a gas and destroys the alumina film. Furthermore, it easily reacts with rare earth elements and reduces the effect of rare earth elements on improving the adhesion of the film. For these reasons, C is desirably 0.01% by weight or less. It may be 0% by weight.

N reduces the toughness of the alloy, and also reacts with Cr during high-temperature heating to form Cr-based nitrides, which can cause embrittlement of the alloy. Therefore, the content is preferably 0.015% by weight or less. 0
It may be expressed in percent by weight.

〔Example〕

Specific examples and comparative examples of the present invention are shown below, but the present invention is not limited to the following examples.

Examples 1 to 8 and Comparative Examples 1 to 7 Alloys having the compositions shown in the columns of Examples 1 to 8, Comparative Examples 1 to 7, and Conventional Example 1 in Table 1 were melted in a high-frequency induction heating vacuum melting furnace. It was then hot rolled into a 2 mm plate shape. That is, in a high vacuum of 5 X 10-'Torr or more, electrolytic iron, electrolytic chromium, and Ni pellets are placed in an aluminum crucible and melted, and in the melt, aluminum-iron alloy, FeZ
r alloy, FeTi alloy, and Hf and rare earth element pieces were added. The alloy was then cast into an iron or copper mold in a furnace in the same vacuum to obtain an alloy ingot. The obtained ingot was heated to 1000-1150°C,
It was forged with a hammer and then cut into a chuck shape for power tools. This was carried out in the atmosphere at 1150℃ for 10
An alumina film having a thickness of 101 mm was deposited on the surface by heat treatment for several hours, and the chuck was completed.

For Examples and Comparative Examples, mechanical properties (hardness, tensile strength, and elongation: all measured at room temperature) were measured, and
The state of the oxide film was evaluated as ○ (no peeling), partial peeling (△), and peeling over the entire surface (x). The results are shown in Table 2.

In the case of the example, compared to the comparative example, the hardness and tensile strength are superior, and the 0.2% yield strength is also the same or higher, which indicates that the base material has excellent mechanical properties and has an excellent oxide film. can be formed.

In the case of the example, the film was an aluminum oxide film, but in the case of the comparative example, it was a mixed oxide film of Fes Crs Ni and Al.

Conventional Example 1 - A TiN film with a thickness of 0.3 nm was formed on the surface of the chuck-shaped alloy (no aluminum oxide film formed) obtained in Example 1 by the spunter method under the following conditions to obtain a chuck for a power tool. .

Conditions for sputtering method Using RF sputtering equipment, 10"" to 10-"T.

Applied voltage 2 kV, current 2 in rr (Ar + Ng) gas
Spunter was applied at 00 mA for 3 hours each from two directions perpendicular to the axis.

For Char-7 of Example 1 and Conventional Example 1, the adhesion of the film was evaluated by a vertical tensile strength test (measuring the tensile force when pulling the coated surface in a vertical direction and peeling it off).

In the case of the example, it was about 10 kg/cnl, and in the case of the conventional example, it was about 4 kg/cot. Further, in the example, the film was formed uniformly down to the details, whereas in the conventional example, the film in the details was thin.

Conventional Example 2 A chuck having the same shape as in Example 1 using die steel was obtained.

The chuck of Example and the chuck of Conventional Example 2 were pressed against rotating #80 emery paper with a constant load of 20 kg, and the amount of wear after sliding for 500 m was compared. About 10 g/n in Examples 1 to 8 (about 40 g/n in Conventional Example 2)
/ m, and it can be seen that the examples have excellent abrasion resistance.

In this way, in the case of the example, the base metal alloy is an alloy that has both high temperature oxidation resistance and mechanical strength, and it is possible to achieve good adhesion by heat treatment in the atmosphere without impairing the mechanical properties of the base metal. It can be sufficiently covered with an alumina film.

〔Effect of the invention〕

According to the method for manufacturing mechanical parts of the present invention, as described above, the mechanical parts are sufficiently covered with an alumina film with good adhesion regardless of the shape, and have excellent mechanical properties such as toughness and hardness. can be obtained.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing the appearance of an alloy before and after forming an alumina film in an example of the method for manufacturing mechanical parts of the present invention, and Figure 2 is a cross-sectional view showing the appearance of an alloy with a film formed by a conventional method. Figure 1 (a) 1... Aluminum oxide film 2... Alloy agent Patent attorney Takehiko Matsumoto Procedural amendment (voluntary November 1990? Patent application No. 2-200741 2, Invention Name of the manufacturing method for mechanical parts 3, Relationship with the case of the person making the amendment Patent applicant address 1048 Oaza Kadoma, Kadoma City, Osaka Name (583) Matsushita Electric Works Co., Ltd. 4, No attorney date 6, Subject of amendment Description 7, Contents of amendment ■ The entire text of the claims column of the description is corrected as follows. In the method for manufacturing a mechanical component, the alloy is heated in an atmosphere to precipitate aluminum oxide on the surface of the alloy to form an aluminum oxide film, wherein the alloy has Cr: 20 to 4.
0% by weight, Ni: 5-25% by weight, Aj! :3 to 8% by weight, Ti: 0 to 0.5% by weight, Zr, Y, Hf, (,e
, l=a, one or more of Nd and Gd? 0.05 to 1.0% by weight, Fe: balance. ” ■ Page 3 of the specification, lines 16-17, “800°C or higher, 1200°C
Correct the phrase ``below 1800℃'' to read ``below 1800℃''. ■ On page 4, line 19 of the specification, it says "r1200℃ or less".
I am corrected. ■ On page 5, line 5 of the specification, it says "r1200℃".
1300℃”.

Claims (1)

[Claims] 1. By heating an aluminum-containing alloy formed into a desired part shape in an oxidizing atmosphere at a temperature of 800°C or higher and 1200°C or lower, aluminum oxide is precipitated on the surface of the alloy to form an aluminum oxide film. In the method for manufacturing a mechanical component, the alloy comprises:
Cr: 20-40% by weight, Ni: 5-25% by weight, Al
:3 to 8% by weight, Ti: 0 to 0.5% by weight, Zr, Y,
Any one of Hf, Ce, La, Nd and Gd
A method for producing a mechanical component, characterized in that the content is 0.05 to 1.0% by weight of one or more species, and the balance is Fe.