JPH0288744A - Cr2o3-mo sintered body - Google Patents

Abstract

PURPOSE:To permit the thickening of the title sintered body as a wear-resistant material and to improve its seizure resistance by specifying the content of Cr2O3 and Mo in a sintered body. CONSTITUTION:In a composite material sintered body, as the compsn., by weight, 30 to 90% Cr2O3) and 10 to 70% Mo are regulated and the total of Cr2O3 and Mo is regulated to 70 to 100%. In addition to trace amounts of impurities included in the material, a sintering auxiliary and the elements to improve corrosion resistance, strength, etc., can be incorporated into the sintered body. The Cr2O3-Mo sintered body is a composite material contg. Mo of high m.p. metal and Cr2O3 of ceramics having high hardness. Thus, the material combines high toughness of Mo and heat resistance, high hardness and chemical stability of Cr2O3 to improve the wear resistance of the sintered body. The sintered body is furthermore applicable to a member having complicated shape.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a Cr2O3-Mo based sintered body, in particular Cr,
By combining , 03 and MO, we can maintain the extremely excellent wear resistance of Cr2O2 while increasing the toughness of Mo, providing a member with high lubricant retention properties and extremely excellent wear resistance. The present invention relates to a Cr2O3Mo-based sintered body.

[Prior Art] In addition to sufficient mechanical strength, the constituent materials of mechanical parts and various devices must have properties such as wear resistance and corrosion resistance depending on the purpose of use. Materials with high
It is not easy for one type of material to have two or more properties at the same time, such as low toughness in many cases.

Therefore, various surface treatment methods have been developed to coat the surface of parts with highly wear-resistant materials. For example, molybdenum (M
O) or Mo alloy and Cr2Oz are used as raw materials, and M is sprayed onto the surface of the member to form a specific blend.

Alternatively, a patent application has been filed for a method of forming a wear-resistant coating composed of Mo alloy and Cr2O3 (Japanese Patent Application No. 1986-
No. 157111. Hereinafter referred to as "prior application". ).

[Problem to be solved by the invention] Since the wear-resistant coating according to the prior application is a thermally sprayed coating,
There were the following problems.

■ Cannot be made thicker. The maximum thickness is about 0.5mm,
It is difficult to increase the thickness further.

■ Thermal spraying method has limitations on the shape of parts to which it can be applied, and depending on the shape of the part, it may not be possible to form a sprayed coating. For example, it is extremely difficult to form a thermal spray coating on the inner surface of a cylinder with a small diameter of 10 mm in inner diameter and 50 mm in length.

An object of the present invention is to solve these problems and provide a Cr2O2Mo-based sintered body as a wear-resistant material that can be made thick and can be sufficiently applied to members with complex shapes.

[Means for Solving the Problems] The Cr2o, -Mo-based sintered body of the present invention contains 30 to 90% by weight of Cr2O3 and 10 to 70% by weight of Mo, and the total of Cr2O3 and Mo is 70% by weight. ~100% by weight.

The present invention will be explained in detail below.

First, the method for producing a Cr2o2-Mo based sintered body of the present invention will be described with reference to FIG. 1, which is a system diagram showing a specific method.

In producing the Cr2Oz Mo-based sintered body of the present invention, first, raw material powder for sintering is produced.

Examples of the method for producing the raw material powder for sintering include the following method.

■ Mechanically mix Cr2O5, Mo (or Mo alloy), sintering aid, and other additives (Route A in Figure 1). This method has the advantage of being easy to operate and having low processing costs.

■ Mixing and melting Cr2O3 and Mo (or Mo alloy),
After pulverizing and classifying to produce composite powder, sintering aids,
Add other additives and mix mechanically (B in Figure 1).
root). This method has the advantage that Cr2O3 and MO can be finely dispersed, and the resulting sintered body is toughened.

In this method, the melting method is not particularly limited, but arc melting is preferred. When melting,
In order to prevent the raw material from changing in quality due to oxidation of MO during heating and melting, it is preferable to heat and melt in an inert gas atmosphere such as Ar gas. Others, 10””Tor
It is also possible to employ a heating melting method using an electron beam under a vacuum of r or less. Melting may be carried out at a temperature at which the mixed powder melts, and is usually carried out at a temperature equal to or higher than the melting temperature of Mo or Mo alloy.

In the present invention, the raw material powder for sintering obtained in this manner preferably has a particle size of about 1 to 5 μm. If the particle size exceeds 5 μm, it is difficult to obtain a high-density sintered body, and if the particle size is less than 1 μm, the composite material of Cr2O3 and Mo will be crushed excessively, and many particles will be separated into Cr2O3 and Mo again, resulting in a high-density sintered body. It is difficult to obtain a tough sintered body.

Next, the obtained raw material powder for sintering is sintered.

Examples of the sintering method include the following method.

■ Pressure sintering by hot press or HIP method (Route C in Figure 1). Specifically, a Mo container or the like is filled with raw material powder, the inside of the container is evacuated, the container is sealed, and the container is sintered under pressure using a hot isostatic press or the like. This method has the advantage that a sintered body with high density and high strength can be obtained.

■ The raw material powder for sintering is granulated, compacted, and then sintered under normal pressure in an inert gas (route D in Figure 1).This method does not require special and expensive sintering equipment. There are advantages.

The CrCr2Os-based sintered body of the present invention can be manufactured into a member having a desired shape by such sintering, or can be further cut into a member having a desired shape.

The Cr2OsMo-based sintered body of the present invention can be applied to almost all members regardless of their shape and size. For example, if the cylinder has an inner diameter of 10 mm and a length of 50 mm, to which it is difficult to apply the thermal spraying described above, the entire cylinder may be made of the Cr2O5-Mo-based sintered body of the present invention, or the cylinder may be coated with an appropriate wall thickness. By making the sleeve of the CrCr2Os-based sintered body of the present invention, it can be easily applied.

Next, the composition of the Cr2O3-Mo based sintered body of the present invention will be explained. In addition, in the following, "1%" is "weight%"
” is shown.

The Cr2OsMo-based sintered body of the present invention has Cr2OsMo-based sintered body.
When the content of o3 is X% and the content of MO is Y%, X 1,000 30-90 Y = 10-70 70≦x +Y≦100. That is, in the correlation diagram of the mixing ratio of Cr2O3 and MO shown in FIG. 2, x=30 x; 90 y=t.

This is the area surrounded by the line segments y=70 x+y=70 x+y=100, that is, the area surrounded by points a, b, c, and d.

When Cr2O3 is less than 30%, C has excellent wear resistance.
The characteristics of r2O3 cannot be fully exhibited, and the wear resistance of the sintered body deteriorates. Furthermore, if Cr2o3 exceeds 90%, even if the remainder is entirely Mo, the amount of MO will be relatively small, and the sufficient effect of the composite will not be obtained, resulting in a decrease in the toughness of the sintered body, etc. This will cause problems.

If the MO content is less than 10%, the Mo content is too small and a sufficient effect cannot be obtained by compounding. When Mo exceeds 70%, even if the remainder is all Cr2O3, Cr2O
3 is less than 30%, and the excellent wear resistance of Cr2O5 cannot be fully utilized.

The ratio of Cr2O3 and Mo depends on the use of the sintered body.
It is selected as appropriate within the above composition range, but Cr2O3 and MO
If the total amount of Cr2O5 and Mo is less than 70%, the effect of improving wear resistance etc. by combining Cr2O5 and Mo cannot be sufficiently obtained, so the total amount of both should be 70% or more.

In the present invention, % Cr2o3. The content of other components other than Mo is less than 30% from the definition of the preferred range. Examples of components other than Cr2O5 and MO (D) include the following (1) to (2).

■ Trace impurities contained in the raw material Cr2O3.

For example, SiO2, TiO2, Fe2O3, etc.

■ Trace impurities contained in the raw material Mo. For example, Fe,
Al1 etc.

■ Alloying elements and trace impurities when Mo alloy is used as a raw material. For example, Fe, All.

Ni, Cr, Co, C, etc.

■ In addition to Mo or Mo alloy or Cr2O2, in the manufacturing process, sintered bodies are densified, crystal grain coarsening is suppressed, etc.
Added separately to obtain the effect as a sintering aid.

For example, TiO2, MgO, SiO2゜Y2　o, etc.

(2) In addition to Mo or Mo alloy or Cr2O3, something added separately in the manufacturing process to improve the chemical properties such as corrosion resistance of the sintered body and/or to improve the mechanical properties of the strength-enhancing ring.

For example, Cr, Co, Ni, Ag, Ti.

Zr, Re, C, etc.

In addition, in the present invention, when using a Mo alloy as a raw material, the Mo alloy contains 50% or less Fe, AiLIO%
Hereinafter, it is preferable that the content is NilO% or less, Cr15% or less, Co10% or less, and Co3 or less.

Fe is cheap and can reduce the price of Mo alloy, but if it is present excessively, wear resistance will be impaired, so Fe is
It is preferably 0% or less, especially 20% or less.

AJZ can refine the metal structure and improve its corrosion resistance, but if the amount is too large, it impairs wear resistance, so it is preferably 10% or less, especially 7% or less.

Although Ni is effective in strengthening bases, excessive amounts of Ni tend to generate foreign tissue. Therefore, the Ni content is preferably 10% or less, especially 7% or less.

Although Cr improves the corrosion resistance of the matrix, it has a strong tendency to form carbides, and if its content is excessively high, the toughness of the metal structure tends to decrease. Therefore, Cr is 15% or less, especially 10%
The following is preferable.

CO has an effective effect on strengthening the base, but if it increases excessively, it lowers the melting point of the base, so it should not exceed 10%, especially 7%.
% or less.

C has the effect of increasing the seizure resistance and wear resistance of the base,
If it increases too much, the amount of carbide precipitation increases and the strength of the base itself decreases, so it is preferably 3% or less.

[Function] The Cr2O5-Mo-based sintered body of the present invention is a composite material containing MO, which is a high melting point metal, and Cr2O3, which is a high hardness ceramic. For this reason, the high toughness of Mo and Cr2
It is an extremely excellent sintered body that has both O2 heat resistance, high hardness, and chemical stability. In this way, having both high toughness and high hardness significantly improves the wear resistance of the sintered body.

The sintered body of the present invention has a structure in which the MO phase is dispersed in the Cr2O5 matrix, but when its surface slides with other members,
M has lower hardness than Cr2O3.

The phase portion is worn away, and the Cr2O3 phase portion is exposed to protrude from the coating surface, and many minute recesses are formed on the surface. This concave portion acts as a good lubricant reservoir, resulting in extremely high lubricant retention properties and extremely high wear resistance.

Since the Cr2Oa Mo-based sintered body of the present invention is a sintered crystal of a Cr2O3-Mo-based composite material having such excellent properties, it can be made into various shapes and sizes. In particular, since the thickness can be increased compared to a thermally sprayed coating, the wear allowance due to the above-mentioned sliding can be increased, and as a result, it is possible to extend the life of the member.

[Example] Examples and comparative examples will be described below.

Example 1 70% er2O3 with particle size 1-5 μm and particle size 1-3 μm
29% of Mo, and Ti with a particle size of 1 to 5 μm as a sintering aid.
After mechanically mixing O21%, it was filled into an MO container, and the Mo container was sealed while the inside of the Mo container was evacuated. Put this Mo container into a hot isostatic press machine, and
soot.

The material was heated and pressurized to tookg/crrl' and held for 1 hour to perform sintering. In this way, the diameter is 60 mm and the thickness is 1.
A 5 mm disk-shaped sintered body was created.

Two sintered bodies of the same shape were manufactured using the above method, and one was ground to a thickness of 13 mm and a diameter of 5 mm as shown in Figure 3.
A disk-shaped test piece 11 of 8 mm was prepared. Also, on the other hand,
A bottle 12a having a diameter of 5 mm and a height of 6 mm was formed by cutting and machining, and was fixed to a disk-shaped holder 12b to obtain a bottle-shaped test piece 12.

The obtained bottle-shaped test piece (rotating side) 12 and disc-shaped test piece (fixed side) 11 were set so that a rotational force R and a vertical load W were applied as shown in Fig. 5. A bottle-on-disc wear test was conducted using the equipment shown, and the amount of wear was measured. In addition, in FIG. 5, 13 is a belt, 1
4 is a clutch, 15 is a motor, 16 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 1.

The results are shown in Table 2.

Comparative Example 1.2 For comparison, a disk-shaped test piece made of Cr2O3 (pressure sintered body) and the same bottle-shaped test piece (Comparative Example 1), a disk-shaped test piece made of Mo (pressure sintered body) and the same bottle-type test piece were prepared. A pin-on-disc wear test was also conducted on the bottle-shaped test piece (Comparative Example 2) under the same conditions as in Example 1.

The results are shown in Table 2.

Example 2 A raw material having a composition of 84% Cr2O3 + 16% Mo was melted in a melting furnace 21 shown in FIG. For melting, first open the valve v1 and apply 1xl using the vacuum pump 23.
Vacuum was applied to O-' Torr. Next, valve V was closed and valve 2 was opened to introduce Ar gas with a purity of 99.99%, and the pressure in the melting chamber 22 was set to 760 Torr.

In this state, the tungsten electrode (-pole) inside the melting chamber 22
A voltage is applied between 24 and a water-cooled copper crucible (child) 25 (in the figure, 26 is the cooling water population, and 27 is the cooling water outlet), an arc is discharged, and the raw material 2O is melted by the arc heat. did.

Thereafter, the arc discharge was stopped and the melt was allowed to cool and solidify.

The obtained ingot was roughly pulverized with a hammer mill, finely pulverized with an alumina ball mill, and then classified to obtain a composite powder with a particle size of 1 to 5 μm. After mixing 99% of this composite powder and 31% of Y.2O with a particle size of 1 to 5 μm as a sintering aid, it was granulated using a spray dryer, and the resulting granulated powder was The powder was compacted by applying a pressure of 1,000 kg/crn.
The mixture was kept at 00° C. for 2 hours and sintered under normal pressure to produce a sintered body with a diameter of 60 mm and a thickness of 15 mm.

Using this sintering method, a bottle-on-disk test piece was prepared in the same manner as in Example 1, and the test was conducted in the same manner.

The results are shown in Table 2.

Table 2 From Table 2, it is clear that both the sintered bodies of the present invention of Example 1.2 have significantly better wear resistance than the sintered bodies of Comparative Example 1.2.

[Effect of the invention] As detailed above, Cr2Os-M of the present invention.

The system sintered body is a high-performance material in which Cr2Oa and Mo are finely dispersed, has good lubricant retention properties, has extremely excellent wear resistance and seizure resistance, and has excellent mechanical properties.

Moreover, the Cr2Oa-Mo based sintered body of the present invention can be applied to members of all shapes and sizes by sintering, and it is also possible to improve wear resistance by increasing the thickness.

According to the present invention, it is possible to significantly extend the durability of sliding members and the like that use lubricant.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing the method for producing a Cr2O3-M O-based sintered body of the present invention, and FIG.
A graph showing the preferred content ratio of Mo and Cr2Og in the o-based sintered body, FIG. 3 is a perspective view of the test pieces prepared in Examples and Comparative Examples, FIG. 4 is a front view of the same, and FIG. FIG. 6 is a cross-sectional view illustrating the test method of Examples and Comparative Examples, and FIG. 6 is a cross-sectional view showing the arc melting furnace used in Example 2. DESCRIPTION OF SYMBOLS 11... Disc-shaped test piece, 12... Pin-shaped test piece, 2O... Raw material, 21... Melting furnace, 24... Tungsten electrode, 25... Copper crucible.

Claims (1)

[Claims] (1) 30-90% by weight of Cr_2O_3 and 10-70% by weight
Cr containing % by weight of Mo, and the total of Cr_2O_3 and Mo is 70 to 100% by weight.
_2O_3-Mo-based sintered body.