JPH0258345B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a wear-resistant coating and a method for forming the same, and more particularly to a coating with high oil retention and extremely excellent wear resistance, and a method for forming the same. [Prior Art] The constituent materials of mechanical parts and various devices must not only have sufficient mechanical strength but also have characteristics such as wear resistance and corrosion resistance depending on the purpose of use. However, materials with high wear resistance often have low toughness, and it is not easy for one type of material to have two or more properties at the same time. Therefore, various surface treatment methods have been developed in which the surfaces of components are coated with highly wear-resistant materials. Various methods of surface treatment are known, such as plating, enameling, vapor deposition, thermal spraying, and overlay welding. Among these, according to the thermal spray method,
Since a film is formed on the surface of the member by molten metal or ceramics and collides with the substrate at high speed, it is possible to form a film of various metals, ceramics, or a cermet composite of these. For example, by thermally spraying a metal, properties such as corrosion resistance, heat resistance, and electrical conductivity can be imparted. [Problems to be Solved by the Invention] When the surface of a member is thermally sprayed with, for example, a hard metal, the wear resistance is increased accordingly, but when the member is a sliding member that slides on other members, ,
As sliding wear occurs, the surface becomes excessively smooth and there is a risk of seizure. In other words, if the surface of a type that supplies lubricating oil to the sliding surface is excessively smooth, the oil retention property (oil retention) of the sliding surface will be low, causing oil depletion and seizure. Become. Additionally, when ceramic is thermally sprayed, wear resistance can be improved due to the hardness of the coating, but similarly, when the member is a sliding member,
Since the coating surface has a high roughness, the sliding properties are inevitably poor. Furthermore, the highly hard ceramic coating may damage the mating material. [Means for solving the problems] The wear-resistant coating of the present invention is made of molybdenum (Mo).
Alternatively, it is composed of 5 to 85 parts by weight of Mo alloy and 95 to 15 parts by weight of Cr ₂ O ₃ . Furthermore, in the method for forming a wear-resistant coating of the present invention, such a coating is formed by thermal spraying onto the surface of a member using Mo or a Mo alloy and Cr ₂ O ₃ as raw materials. In addition, in the present invention, Mo alloy refers to Fe30%
Below, Al10% or less, Ni10% or less, Cr15% or less,
It contains 10% or less of Co, 3% or less of C, and the remainder is essentially Mo. In addition, % is weight %. Below, the addition ratio of these alloying elements will be explained. Fe is cheap and can reduce the price of Mo alloys, but if it is in a moderate amount, it lowers the wear resistance and melting point of Mo alloys, so it is recommended that Fe be added in an amount of 30% or less, especially 20% or less. preferable. Al can refine the metal structure and improve its corrosion resistance, but if it is used in a moderate amount,
Since it lowers the corrosion resistance and melting point of the alloy, it is preferably added in an amount of 10% or less, especially 7% or less. Although Ni is effective in strengthening bases, excessive amounts tend to generate foreign tissue. Therefore,
The amount of Ni added is preferably 10% or less, especially 7% or less. Cr improves the corrosion resistance of the matrix, but has a strong tendency to form carbides, and if its content is excessively high, the toughness of the metal structure tends to decrease. So, Cr is 15%
It is particularly preferable that the amount added be 10% or less. Although Co has an effective effect on strengthening the base, if it increases excessively, it lowers the melting point of the base, so the amount added is preferably 10% or less, especially 7% or less. C has the effect of increasing the seizure resistance and abrasion resistance of the base, but if it increases excessively, the amount of carbide precipitation increases and the strength of the base itself decreases.
The amount added is preferably 3% or less. In addition, the raw material powder suitable for the method of forming a wear-resistant coating of the present invention is one in which some or all of these additive elements are replaced with Mo, or some of them are added instead of the Mo alloy.
It may be used in combination with the Mo alloy, or it may be made into the desired shape by some method after melting these elements. When using powder as a raw material for thermal spraying, the preferred particle size of Mo or Mo alloy is 5 to 63 μm.
In particular, it is between 10 and 40 μm. Further, the preferred particle size of Cr ₂ O ₃ is 5 to 63 μm, particularly 10 to 44 μm.
Furthermore, when the powder is made into a powder after being dissolved, it is preferable to have a particle size of 5 to 63 μm. In the present invention, Mo or Mo of the wear-resistant coating
The mixing ratio of alloy and Cr ₂ O ₃ is Mo or Mo alloy 5~
85 parts by weight, and 95-15 parts by weight _{of Cr2O3} . When the Cr ₂ O ₃ content exceeds this range, the amount of metal in the coating becomes relatively small, and the toughness of the coating tends to decrease. Furthermore, when the content range of Cr ₂ O ₃ is less than the above range, the wear resistance of the coating decreases. The raw material used to form the wear-resistant coating of the present invention is produced, for example, by mixing a predetermined amount of Mo or Mo alloy and Cr ₂ O ₃ and then sintering or melting the mixture as necessary. . In the method of the present invention, Mo or Mo alloy
After thermally spraying Cr ₂ O ₃ onto the surface of the member, the surface of the coating may be further irradiated with a laser beam to promote melting of the coating. Such laser irradiation is suitable for use when the raw material is insufficiently melted, but even when sufficiently melted powder is sprayed, it has the effect of increasing the density of the sprayed film. Furthermore, by melting the bonding interface between the film and the substrate, it also has the effect of increasing the bonding strength and making it possible to form it on any substrate. The method of the present invention can form a film on the surface of almost any material, regardless of the material of the member. Moreover, the thickness of the coating to be formed can be arbitrarily adjusted by changing spraying conditions such as spraying time. [Function] The wear-resistant coating of the present invention is a high melting point metal.
Mo or Mo alloy and high hardness ceramics
It is a cermet coating consisting of Cr ₂ O ₃ . For this reason, the high toughness of Mo or Mo alloy and the heat resistance of Cr ₂ O ₃ ,
It has both high hardness and chemical stability. Such a wear-resistant coating of the present invention is extremely advantageously formed by the method of the present invention. In addition, in the method of the present invention, in the coating immediately after thermal spraying or after thermal spraying and subjected to laser melting treatment, for example, when the content of Cr ₂ O ₃ is 95 to 60 parts by weight, as shown in FIG. Coating 1 is Mo
The structure remains that the phase or Mo alloy phase particles are dispersed in the Cr ₂ O ₃ matrix, but when the coating surface 1a slides against other members, the Cr 2 O 3 becomes more concentrated than the Cr ₂ O ₃ as shown in The layer 2 of Mo phase or Mo alloy phase with low hardness is worn away,
The Cr ₂ O ₃ phase 3 is exposed so as to protrude from the coating surface, and a large number of minute recesses 5 are formed on the coating surface. This concave portion 5 acts as a good oil reservoir, and the lubricating oil retention property is significantly increased, and the wear resistance of the member surface is significantly improved. [Example] Examples 1 to 9, Comparative Examples 1 to 3 Mo powder and Cr ₂ O ₃ powder were mixed on the surface of a steel substrate so as to have the raw material powder composition shown in Table 1 (however, In Comparative Example 1 and Comparative Example 3, Mo or
Either one of Cr ₂ O ₃ powder was used. ) A test piece whose surface was coated with a film was produced by plasma spraying to form a film, and this was processed to produce a pin-shaped test piece and a disk-shaped test piece. The particle sizes of the Mo powder and Cr ₂ O ₃ powder used and the thermal spraying conditions are as shown below. Particle size Mo powder: 10 to 53 μm Cr ₂ O ₃ powder: 10 to 44 μm Spraying conditions Thermal spraying equipment: Plasma spraying equipment Powder supply amount: 1.5 Kg/hr Obtained pin-shaped test piece (rotating side) 12 and disc-shaped test piece (Fixed side) 11 was set in the device shown in Fig. 4 so that rotational force R and vertical load W were applied, and a pin-on-disk wear test was carried out.
The amount of wear was measured. In addition, in Figure 4, 13
is the belt, 14 is the clutch, 15 is the motor, 1
6 is a cooling oil flow pipe, 17 is a lubricant, and 18 is an air cylinder. The experimental conditions at this time are as shown in Table 2. In addition, a test piece for a bending test was cut out from each test piece, and a bending test was conducted while observing the state of breakage of the film using AE (acoustic emission) to examine the breakage strain value. The results are shown in Table 1. Further, the relationship between the amount of wear and the load in Example 3 is shown in FIG.

【table】

【table】

[Table] From Table 1, it is clear that the wear-resistant coating according to the present invention has not only excellent wear resistance but also high strength. Comparative Example 4 A pin-type test piece and a disk-type test piece were manufactured from flaky graphite cast iron, and a wear test was conducted in the same manner as in Example 1. The relationship between the amount of wear and the load is shown in FIG. It is clear from FIG. 3 that the coating formed according to the method of the present invention has an order of magnitude less wear than cast iron. Example 10 A film made of Mo alloy and Cr ₂ O ₃ was formed on the surface of the substrate in the same manner as in Example 1 except that Mo alloy was used instead of Mo and the mixing ratio of Cr ₂ O ₃ was 95% by weight. It was formed and subjected to an abrasion test. The composition of the Mo alloy is as shown below. Mo: 70% Fe: 15% Co: 5% Ni: 5% Al: 5% C: 2% As a result, the coating made of Cr ₂ O ₃ -Mo alloy also has extremely excellent wear resistance as in Example 1. It has been found. Example 11 The same operations as in Example 10 were carried out except that the mixing ratio of Mo alloy and Cr ₂ O ₃ was 85:15 and that the laser beam was further irradiated after the thermal spray coating was formed. A coating was then formed on the surface of the substrate, and an abrasion test was conducted. Note that the laser irradiation conditions are as follows. Model of laser device: CO ₂ laser output: 3.5kw Scanning speed: 0.4m/sec As a result, the coating formed in this example also had excellent wear resistance, similar to the coating formed in Example 1. It turned out that [Effects] As detailed above, the wear-resistant coating of the present invention has the following effects:
It has good oil retention, excellent wear resistance and scuff resistance, and high mechanical strength. Thus, such a coating can be formed very easily on the surface of a substrate made of any material by the method of the present invention. According to the present invention, it is possible to significantly extend the durability of sliding members and the like that use lubricating oil.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic cross-sectional views showing the structure of a coating formed by the method of the present invention.
FIG. 3 is a graph showing the results of the wear test of Example 1 and Comparative Example 4. FIG. 4 is a sectional view showing the wear test device. 1... Film, 2... Mo phase or Mo alloy phase, 3
... Cr ₂ O ₃ phase, 4 ... substrate, 5 ... recess.

Claims (1)

[Claims] 1 Fe 30% or less, Al 10% or less, Ni 10% or less,
A molybdenum alloy consisting of 15% or less Cr, 10% or less Co, 3% or less C, and the remainder substantially Mo, or consisting of 5 to 85 parts by weight of molybdenum and 95 to 15 parts by weight of Cr ₂ O ₃ Abrasion-resistant coating. 2 Molybdenum alloy or molybdenum and Cr ₂ O ₃ are used as raw materials and thermally sprayed onto the surface of the material, and the surface of the weld material is coated with Fe30% or less, Al10% or less, Ni10% or less,
Forms a molybdenum alloy consisting of 15% or less Cr, 10% or less Co, 3% or less C, and the remainder substantially Mo, or a film composed of 5 to 85 parts by weight of molybdenum and 95 to 15 parts by weight of Cr ₂ O ₃ 1. A method for forming a wear-resistant film, comprising the step of: