JPH01278475A - Complex sliding member of silicon carbide - Google Patents

Abstract

PURPOSE:To obtain a sliding member showing excellent sliding characteristics even under dry or boundary friction condition or high-load condition by blending silicon carbide with a specific amount of specific coke, specific amount of B- based substance and specific amount of carbon or specific organic material and sintering. CONSTITUTION:The complex sliding material of silicon carbide is obtained by sintering mixture powder consisting of 25-45wt.% coke having <=4wt.% residual volatile content, 0.5-5wt.% boron or boron compound, 2-4wt.% carbon or 6-10wt.% organic material to be carbonized, having 2-4wt.% carbon content after carbonization and the rest of silicon carbide. The sliding material shows excellent sliding characteristics under dry or boundary friction condition or high-load condition not to mention under liquid friction condition and high mechanical strength and has excellent abrasive properties, so the material is suitable as a bearing material under a liquid useful in water, chemical solution, etc.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention relates to a silicon carbide composite sliding member, particularly a silicon carbide composite sliding member that exhibits good performance when used as a submerged bearing used in a fluid pump or the like. It is related to.

[Prior Art] Conventionally, carbon materials have been used for submerged bearings used, for example, in fluid pumps and various flowmeters.
Since this type of material has the disadvantage of causing abnormal wear due to the contamination of the sliding surface with foreign matter such as dirt and slurry, silicon carbide sintered bodies have recently begun to be used. Silicon carbide sintered bodies used as submerged bearings exhibit excellent sliding properties under low load conditions, but under cart conditions the friction coefficient increases and the number of worn needles increases. is usually
The desired shape is machined using a grinder, but if the depth of cut (m) is too large during machining, chattering will occur and it will be difficult to obtain a good finished surface, so the depth of cut must be reduced during machining. There are problems with workability, such as poor yield.

Furthermore, the submerged bearings of fluid pumps are dry or borderline 1!, where the liquid that acts as a lubricant is not sufficiently distributed to the sliding movement due to idle running, such as when the pump is started or due to operational errors. ! It was sometimes used under m conditions.

The bearing made of the above-mentioned silicon carbide sintered body is rated at 11! under dry or boundary rubbing conditions. As the coefficient of friction increases and the amount of wear increases, a complete liquid lubricant film is formed on the moving surface of the wall.
It has the disadvantage that it can only be used under so-called liquid lubrication conditions.

In order to solve the above-mentioned drawbacks of bearings made of silicon carbide sintered bodies, for example, Japanese Patent Application Laid-open No. 141676/1982 (hereinafter referred to as "prior art I") and Japanese Patent Publication No. 46508/1982 (hereinafter referred to as "prior art II") are proposed. ) has been proposed.

This prior art (2) consists of 1 to 48 weight percent graphite elemental carbon, an effective amount of sintering aid, and the remaining amount of silicon carbide, by adding 1 to 48 weight percent graphite elemental carbon. , dry or border r! ! It can be used under rubbing conditions. Furthermore, prior art (1) relates to a coke-silicon carbide composite sintered body, and is intended to improve the oxidation resistance of the sintered body.

[Problems to be Solved by the Invention] However, although the silicon carbide composite sintered body made of the above-mentioned prior art exhibits excellent activity characteristics under dry or boundary friction conditions, it has low mechanical strength and has only a slight There are handling problems such as cracking of the sintered body due to the impact.

In addition, when the coke-silicon carbide composite sintered body made from conventional technology (2) is applied to sliding members, it is particularly inferior to abrasion resistant bamboo, and cannot be used as bearings for submersible pumps that are forced to allow the inflow of earth and sand. It has the disadvantage of wanting to

The present invention solves the above-mentioned problems, and provides excellent I/O even under dry or boundary friction conditions when starting the pump or under high load conditions.
The object of the present invention is to obtain a silicon carbide composite sliding member that exhibits II 11 characteristics and high mechanical strength, and is particularly suitable for application to submerged bearings.

[Means for Solving the Problems] In order to achieve the above object, the present inventors conducted various studies and found that coke having a residual volatile content of 4% by weight or more and 25 to 45% by weight, boron or a boron compound of 0.5 to 5% weight%,
Silicon carbide composite sintered by sintering a mixed powder consisting of 2 to 4% by weight of carbon or 6 to 10% by weight of a carbonizable organic material whose carbon content after carbonization is 2 to 4% by weight, and the balance silicon carbide. Of course, under liquid lubrication conditions,
Excellent lFl even under dry or borderline n1f) conditions and under high load conditions! exhibits JIl characteristics,
It was also discovered that the material exhibits high mechanical strength, and based on this knowledge, the present invention was accomplished.

The silicon carbide powder which is the main component in the present invention can be used in either the α type or the β type, and the powder with an average particle size of 5 microns or less is used.

The coke used in the present invention is so-called raw coke that has a volatile content, and may be petroleum-based, coal-based, or resin-based, but in order to obtain particularly high-strength products, residual volatile content of 4% by weight or more is required. It is preferable to include.

The mixing ratio of coke is 25 to 4 to the total amount of mixed powder.
5% by weight, preferably 25-40% by weight.

If it is less than 25% by weight, it is difficult to obtain good sliding properties under high load conditions even under dry or boundary friction conditions or liquid lubrication conditions, and if it is more than 45% by weight is not preferable because it reduces the mechanical strength of the sintered body.

Boron or boron compounds such as boron carbide or boron nitride have been known since ancient times to play the role of a sintering aid for mixed powder and the role of promoting graphitization during sintering of coke as mentioned above. 0.5-5 based on the total amount of powder
Weight%.

Carbon, like the boron or boron compound described above, serves as a sintering aid for the mixed powder, and examples include carbon black. Furthermore, in the present invention, a carbonizable organic material can be used in place of the carbon described above. Examples of the carbonizable organic material include phenol resin and coal tar pitch, and phenol resin is particularly preferably used. The mixing ratio is 2 to 4% by weight when carbon is used, and 6 to 10% by weight when carbonizable organic material is used, based on the total amount of mixed powder. The amount of carbon is 2 relative to the total amount of mixed powder
~4% by weight.

In some cases, it is also effective to add a temporary binder, such as polyvinyl alcohol, to the mixed powder having the above-mentioned component composition. At this time, the amount of the temporary binder added is preferably about 3 parts by volume per 100 parts of the mixed powder.

Next, the manufacturing method of the present invention will be described.

First, coke powder and boron or a boron compound are added to silicon carbide powder, and then carbon or carbonizable organic material J3 and a temporary binder as necessary are added and mixed to obtain a mixture, and then the mixture is dried. and grind it into powder. The powder was loaded into a mold and heated to 1000 to 200
A molded body is obtained by pressure molding at a pressure of 01 (9/J).The molded body is then subjected to pressure molding at a pressure of 1900 to 2100 [(
1) 1[! [-0, between 5 and 21] to obtain a sintered body.

Hereinafter, the present invention will be explained in detail with reference to Examples.

[Examples 1-3. Comparative Examples 1 to 6] α-type silicon carbide powder (trade name: DU-A-1, manufactured by Showa Denko ■) with an average particle size of 0.5 microns in the proportions shown in Table 1,
After mixing coke powder with a residual volatile content of 11%, boron powder, phenol resin, and 50 cc of acetone using a ball mill for 10 hours, the mixture was dried and pulverized to 10 cc of residual volatile content.
A powder classified to 0 mesh under was obtained.

The mixed powder was loaded into a mold and press-molded at a pressure of 20001 (9/J) to obtain a molded body.

This molded body was placed in a heating furnace heated to a temperature of 2050 degrees (
The mixture was fired in an argon gas atmosphere for 1 hour to obtain a sintered body.

This sintered body is machined to a length of 3711111° and a width of 4I.
A bending strength test piece with a thickness of 3M and a thrust test piece with a length and width of 32m and a thickness of 7m were obtained.

[Comparative Example 7] α-type silicon carbide powder (trade name: DU-A-1, manufactured by Showa Denko ■) with an average particle size of 0°5 microns in the proportions shown in Table 1,
Carbon black powder, boron powder.

After mixing the phenol resin, 50 cc of acetone, and 3 parts by weight of polyvinyl alcohol using a ball mill for 10 hours, the mixture was dried and pulverized to obtain a powder classified into 100 mesh particles.

The mixed powder was loaded into a mold and press-molded at a pressure of 2,000 to 5/lJ to obtain a molded body.

This molded body was placed in a heating furnace heated to a temperature of 2050 degrees (
The mixture was fired in an argon gas atmosphere for 1 hour to obtain a sintered body.

The sintered body was machined to have a length of 37 m, a width of 4 gates, and a thickness of 3 #.
A bending test piece of I and a thrust test piece of 32 rttms in length and width and 7 m+ in thickness were obtained.

Comparative Example 8] α-type silicon carbide powder (trade name: DU-A-1, manufactured by Showa Denko) with an average particle size of 0.5 microns in the proportions shown in Table 1,
Graphite powder, boron powder, phenolic resin, and 50 cc of acetone were mixed for 10 hours using a ball mill.
The mixture was dried and ground to obtain a powder classified into 100 mesh particles.

The mixed powder was loaded into a mold and press-molded at a pressure of 2000 kg/ci to obtain a compact.

This molded body was placed in a heating furnace heated to a temperature of 2050 degrees (
The mixture was fired in an argon gas atmosphere for 1 hour to obtain a sintered body.

The sintered body was machined to produce a bending test piece with a length of 37M1 width of 4rIWi and a thickness of 3mm, and a bending test piece with 32 lines in the vertical and horizontal directions and a thickness of 7mm.
A thrust test piece of M was obtained.

[Comparative Example 9] α-type silicon carbide powder with an average particle size of 0.5 microns 38.9
51.2% by weight of coke powder with a residual volatile content of 11% and 9.9% by weight of boron carbide powder were ground and mixed in a mill for 5 hours. The thus obtained mixed powder was loaded into a mold and pressed at a pressure of 2000 KW/d to obtain a compact, which was then placed in a heating furnace heated to 2000 degrees (in an argon gas atmosphere). It was fired for 1 hour to obtain a sintered body. This sintered body was machined to produce a bending test piece with a length of 37 #l, a width of 4NR, and a thickness of 3.
A thrust test piece of 111+l was obtained.

The above Examples 1 to 3 and Comparative Examples 1 to 9 were JIS R1601
A three-point bending strength test was conducted in accordance with the "Fine Ceramic Bending Strength Test" and an underwater load-bearing thrust test was conducted under the following conditions. The results are shown in Table 1. Note that the "-" in the table indicates that the test was stopped midway due to an increase in the friction coefficient.

Speed: 5m/e+in Load: Accumulates 12.5Kg/J every 0.5hr and ends at 250kg/d Compatible material: 5iC (φ12×φ25X l 17) From the test results, Examples 1 to 3 The sintered body exhibited stable sliding properties throughout the entire test period. On the other hand, as the load increases, the sintered bodies of Comparative Examples 1 to 5 become r! 4r! The test was discontinued because the A coefficient increased and the blood pressure increased to 150 kg/ei.A rapid increase in the friction coefficient was observed.

Next, a more severe underwater thrust test was conducted on the sintered bodies of Example 3 and Comparative Example 9, which had shown good sliding characteristics in the above-mentioned test. The test conditions are as shown below.

Menu: 1501! Ff/! Speed:
5TrL/1n Time: 50hr Water: Distilled water 0.1wt% Kanto loam type 7 (JIS28
901) Addition partner 14:5iC (φ12×φ25X l 17) Table 2
shows the above test results.

Table 2 1”””””’”””””””’t’WJ”’: f,;
'i:! r'"1tls!'i'[:'lff1;"'
J:fff"'/cJ)"""('m/'m:"n)h
From the r''1 test results, the sintered body of Comparative Example 9 has many worn needles, has poor abrasive resistance, and cannot be applied to bearings such as submersible pumps that are forced to be penetrated by earth and sand.

[Effects of the Invention] The silicon carbide composite layered dynamic member of the present invention has low Iυ under liquid friction conditions, dry or boundary friction conditions, or high Iυ. It exhibits good sliding properties even under quadruple conditions, high mechanical strength, and excellent abrasion resistance, making it suitable as a material for submerged bearings used in water, chemical solutions, etc.

Claims (1)

[Claims] (1) Coke 25 with residual volatile content of 4% by weight or more
~45% by weight, boron or boron compound 0.5-5
% by weight, 2-4% by weight of carbon or 6-10% by weight of carbonizable organic material with a carbon content of 2-4% by weight after carbonization
and a silicon carbide composite sliding member made by sintering a mixed powder consisting of silicon carbide.