JPS6311559A - Manufacture of self-lubricating composite material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a method for manufacturing a composite material having self-lubricating properties, and in particular to a method for manufacturing a composite material having self-lubricating properties, and in particular, a composite material having a certain hardness, density, etc. The present invention relates to a method of advantageously producing self-lubricating composite materials with improved performance.

(Prior art and its problems) In recent years, due to the diversification of physical properties required of materials, various composite materials have been studied in the field of ceramics. For example, AlzOx -ZrQ□ system, 5lxNa
Composite materials such as SiC whisker-based materials have been reported.

The general manufacturing method for such ceramic composites (materials) is to uniformly disperse and mix the raw materials that will become the matrix phase and the raw materials that will become the dispersed phase, and then cold-forming them and then molding them under normal pressure. A pressureless sintering method in which sintering is performed and a pressure sintering method in which sintering is performed using a real press are known.

However, in the case of the above pressureless sintering method,
It is generally known that the sintered density of the composite does not increase and is often impractical. Furthermore, if the other pressure sintering method is used, the sintered density of the composite increases compared to the pressureless sintering method, and although the physical properties are satisfactory, the equipment for hot pressing becomes expensive. , and is not suitable for mass production C<, therefore, it has inherent problems of being impractical in terms of cost, and also has inherent constraints and problems such as the shape to be molded being limited to simple shaped products. ``On the other hand, regarding composite materials with self-lubricating properties that are useful as sliding members, those in which the matrix is made of resin or metal are currently in practical use, but recently ceramics are being used as a matrix. Various examples have been reported, such as st, N4 BN series, heβ20.-BN series, and ANzOz-graphite series (for example, U.S. Patent No. 2745763; Ceramics Association, 1988).
(See Proceedings of the Annual Meeting, pp. 651-652, etc.).

By the way, in such self-lubricating composite materials,
If a solid lubricant is selected as the dispersed phase and ceramics are selected as the matrix, a general method that belongs to the above-mentioned pressureless sintering method, from cold forming to sintering, is performed using matrix phase forming powder and solid lubricant. Conventional method (1) in which the mixture is directly mixed with powder, granulated, classified, then molded and sintered.
Also known is a conventional method (II) in which only matrix phase forming powder is granulated in advance, classified, and then mixed with solid lubricant powder, followed by molding and sintering.

However, such conventional method (I) and conventional method (II)
) to produce the desired self-lubricating composite material, the solid lubricant serving as the dispersed phase is added in an amount of several percent by volume in order to impart lubricating properties to the resulting composite.
Generally, the solid lubricant is mixed at about ~30%, but the solid lubricant blended in this ratio acts as a sintering inhibitor for matrix formation, inhibits the sintering of the composite, and thereby increases the hardness. This causes problems such as deterioration of properties such as heat and density.

It has been recognized that such problems are particularly serious when the solid lubricant is a fine powder on the order of several micrometers. Additionally, if the solid lubricant mixed into the matrixed ceramic has particles larger than the critical radius, it may cause cranking in the matrix during shaping and sintering, leading to deterioration of the strength of the composite. In many cases, sintering itself becomes impossible, and it is extremely difficult to obtain a practical level composite using the above-mentioned conventional methods.

(Solution Means) Here, the present invention solves the above-mentioned problems of the conventional method and makes it possible to easily and advantageously produce a ceramic composite material having self-lubricating properties. The feature is that the ceramic powder for matrix phase formation is granulated to form No. 1 granules of a predetermined particle size, while the solid lubricant powder is granulated to form No. 2 granules of a predetermined particle size. The granules are made into granules, then the two types of granules are uniformly blended, molded into a desired shape, and the resulting molded product is sintered.

(Function/Effect) As described above, the present invention differs from the conventional method described above in that the solid lubricant powder is granulated together with auxiliary agents and other additives that may be blended as necessary, and a separately prepared The reason is that a uniformly dispersed mixture of matrix phase forming powder (granules) is used as a molding powder, and as a result, the shape and size of the lubricating phase in the composite material can be controlled arbitrarily. This made it possible to easily produce ceramic composites with self-lubricating properties suitable for different uses.

The method of the present invention has the following features.

(a) The binding force of the granulation binder added during granulation of the solid lubricant prevents the fine powder of the solid lubricant from being incorporated into the IJ mass phase when uniformly dispersed and mixed with the matrix forming powder. Therefore, sintering of matrix formation proceeds without being hindered.

(b) The granulated solid lubricant powder can absorb and alleviate the compressive stress generated during molding and sintering through easy deformation of the granulated powder, thereby preventing the occurrence of matrix formation cranks. , does not cause deterioration in the strength of the matrix of the composite material (sintered body).

(c) When granulating solid lubricants, additives can be added that take into account compatibility with matrix formation, and the addition of such additives increases the compatibility between the lubricant phase and matrix formation, and improves lubrication. It is possible to strengthen the retention force of the drug phase,
Therefore, when the obtained composite material is used as a sliding member, it is possible to effectively prevent or suppress shedding of matrix particles near the boundary layer and macroscopic shedding of the lubricant phase.

(Specific Structure of the Invention) In the present invention, the ceramic powder used to form the matrix phase of the composite material having the desired self-lubricating property may include, depending on the use of the composite material, It is appropriately selected from among various known ceramic powders based on the characteristics required as a matrix phase. For example, S! iNn, Si
Non-oxides such as C 1,6. Oxides such as N, 03, and PSZ (partially stabilized zirconia) will be used.

The ceramic powder for matrix phase formation is then mixed with a binder and appropriate sintering aids and forming aids in the same manner as before, and granulated using conventional methods such as spray drying and pulverization. The granules are classified into No. 1 granules having a predetermined particle size. The particle size of this No. 1 granule is appropriately selected depending on the type and size of the ceramic powder, the size of the solid lubricant granule to be blended, molding conditions, sintering conditions, etc. That will happen.

On the other hand, as the solid lubricant powder used to form the lubricant phase which is the dispersed phase of the composite material having self-lubricating properties, various known solid lubricant powders are appropriately selected, such as graphite, BN, There are MoS2, WS2, etc.

Then, such solid lubricant powder is subjected to a granulation operation separately from the above-mentioned matrix phase forming ceramic powder, and is made into a No. 20 granulated product having a predetermined particle size. The granulation operation of this solid lubricant powder is carried out in the same way as the granulation operation of the ceramic powder described above, by blending an appropriate binder, as well as necessary molding aids and sintering aids, and uniformly distributing the solid lubricant powder in a mixed medium. Mix, disperse, and spray.
It is carried out by drying or drying/pulverizing granulation methods, and then, by taking out particles of a predetermined size through a classification operation, a second granule of the desired particle size is prepared. be.

Note that the particle size of the second granules obtained in this way also depends on the type and size of the solid lubricant powder, as in the first granules made of the matrix phase-forming ceramic powder. The size of the No. 1 granules to be blended is appropriately determined according to the molding conditions, sintering conditions, etc., for example, from 12 to 16 mesh size to 120 to 25 mesh size.
It will be used in various particle sizes, including those with a size of 0 mesh.

The two types of granules obtained in this way are then uniformly mixed at a predetermined blending ratio, and then molded into the desired composite material using a conventional molding method such as press molding. The ceramic powder is molded into a corresponding shape and sintered using known sintering techniques of ceramic powder forming a matrix phase, thereby forming the desired self-lubricating ceramic composite material. be.

The thus obtained self-lubricating ceramic composite material has significantly improved density, has a matrix phase with no deterioration in hardness, strength, etc., and has a lubricating material, shape, and size suitable for the intended use. This material has a lubricant phase uniformly dispersed therein, and thus a useful composite material with self-lubricating properties has been realized.

(Examples) Examples of the present invention will be shown below to clarify the present invention more specifically, but the present invention should not be construed in any way as limited by the description of these Examples. It goes without saying that. In addition to the following examples, the present invention also includes the specific embodiments described above.
It should also be understood that various changes, modifications, improvements, etc. may be made to the present invention without departing from the spirit of the present invention.

In order to produce a composite material in which the matrix phase is 5iC and the lubricant phase is graphite, commercially available β-3iC powder (particle size: 0.5 μm) was first used as the SiC raw material.
00 parts by weight, phenol resin: 4 parts by weight, B4
C:o, 13 parts by weight was blended, wet mixed in a ball mill in the presence of an appropriate amount of ethanol, dried, and the dried product was crushed and further classified to obtain a particle size of 120 mesh and under. SiC granulated powder was prepared.

On the other hand, graphite powder with primary particles of 5 to 8 μm was used as a solid lubricant, and 210 parts by weight of phenol resin and 0.6 parts by weight of B4C were blended with 100 parts by weight of the graphite powder, and an appropriate amount of ethanol was further blended. Then, the mixture was wet mixed in a ball mill, and after drying, the mixture was crushed and classified to obtain graphite granulated powder with a predetermined particle size.

Then, using the two types of granulated powder obtained in this way,
Under the conditions shown in Tables 1 and 2 below, various graphite blending ratios (volume basis) were uniformly blended to prepare various molding powders, and then 250 kg / After preforming at a pressure of 2 ton/cm" using a cold isostatic press machine
Main molding was carried out at a pressure of Next, these various molded bodies were sintered under conditions of 2180° C. for 45 minutes in an inert gas atmosphere (normal pressure) to obtain various test pieces (sintered bodies).

Table 1 Table 2 In addition, the conventional method (1) in Tables 1 and 2
As mentioned above, matrix phase forming powder and solid lubricant powder are directly mixed, then granulated, molded, and sintered to make a composite material. Similarly, a solid lubricant powder is mixed with a granulated matrix phase-forming powder, which is then molded and sintered to form a composite material.

Of the test pieces thus produced, the density and matrix phase hardness of those shown in Table 1 were measured, and the results are shown in Table 3 below. The density was calculated from the outer diameter and weight, and the hardness was determined using a micro-Vickers meter at a load of 300 g and a holding time of 20 seconds.

Table 3 Furthermore, the results of determining the relative densities of the test pieces of samples G-L shown in Table 2 are shown in Figure 1, and micrographs showing the structures of test pieces A, C, D, and E (
x50) are shown as FIGS. 2(a) to (d), respectively.

As is clear from these Table 3 and FIGS. 1 and 2 (a) to (d), 10% by volume obtained according to the method of the present invention
The composite material (sintered body) containing graphite has a relative density of over 90%, and as is clear from the micrograph in FIG. 2, the matrix phase has been sintered. The hardness also shows a value close to that of the sintered body (C) made only of SiC. Furthermore, compared to conventional methods, it is possible to reduce the decrease in relative density due to an increase in the amount of graphite added, which raises the upper limit of the amount of graphite added and expands the practical range of composites. .

In addition, in test piece B using graphite powder with a large particle size, which was cited as a comparative example, significant cracking occurred during sintering, and it was recognized that it could not be used in practice.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between graphite content and relative density in test pieces obtained in Examples, and FIGS. 2(a) to (d) are graphs obtained from tests obtained in Examples. It is a micrograph of the structure|tissue of pieces A, C, D, and E. Applicant: Brother Industries, Ltd. Figure 1 Braffite amount (vol 0 to) JI Figure 2 Procedure manual (method) % formula % 2. Name of the invention Method for manufacturing a composite material with self-lubricating properties 3. Person making the amendment Relationship to the case Patent applicant name (526) Brother Industries, Ltd. 4, Agent Hago 7, Statement of Contents of Amendment, page 18, line 7, ``Microphotograph of microstructure'' was replaced with ``Microphotograph of metallographic structure'' ” is corrected. Proceeding Authorization (Spontaneous) December 15, 1985 1. Indication of the case 1988 Patent Application No. 153630 2. Name of the invention Process for manufacturing a composite material with self-lubricating properties 3. Amendments made Patent applicant name (526) Brother Industries, Ltd. 4, Agent (11) Column for detailed explanation of the invention in the specification (2) Column for a brief explanation of the drawings in the specification (3) Drawings /Partner, 6. Contents of the amendment (1) On page 17 of the specification, line 4, "The micrograph (x50)" is corrected to "The sketch of the micrograph (x50)". (2) The specification Page 17, lines 9-10 “From micrographs”
is corrected to "From a sketch of a microscopic photograph." (3) Page 18 of the specification, lines 5 to 7 “Figure 2 (a) to ・
...'' (including the parts amended in the procedural amendment submitted on October 29, 1986)
) to (d) are sketches of microscopic photographs of the structures of test pieces A, C, D, and E obtained in Examples, respectively. ” is corrected. (4) Replace Figures 2 (a) to (d) of the drawings with those on separate sheets. Figure 2 above

Claims (1)

[Claims] Granulating the matrix phase forming ceramic powder to form a first granulated product having a predetermined particle size, and granulating a solid lubricant powder to form a second granulated product having a predetermined particle size; A method for producing a composite material having self-lubricating properties, characterized in that the two types of granules are then uniformly blended, molded into a desired shape, and the resulting molded body is sintered.