JP3483056B2 - Silicon nitride sintered body for sliding members - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic material having excellent heat insulating properties and sliding properties. Specifically, it has improved heat insulation, improved seizure resistance and wear resistance, has a low coefficient of friction, has good retention of lubricating oil, and has improved toughness.
The present invention relates to a high-strength silicon nitride sintered body for sliding members.

[0002]

2. Description of the Related Art Silicon nitride sintered bodies have high temperature strength, high hardness, and high corrosion resistance as compared with metal materials, and are used as materials for sliding members at high temperatures, high loads and sliding speeds. It has been used for applications with high sliding conditions. For example, rolling elements and bearing rings of rolling bearings, sliding bearings, cylinder liners of internal combustion engines, piston rings, rocker arms, etc.
It is used for rolling rollers, metal cutting tools, molds, etc. In order to improve the heat insulating property of the silicon nitride sintered body in these applications, it is desirable that the structure of the silicon nitride sintered body for the sliding member has fine pores (pores). Conventionally, there are very few applications for improvement of a silicon nitride sintered body aimed at improvement of heat insulating property so that it can be used for a heat insulating ceramic engine or the like.

Japanese Unexamined Patent Publication No. 6-122555 and Japanese Unexamined Patent Publication No.
JP-A-183841 and JP-A-6-234564 describe a low-friction ceramic in which a non-oxide ceramic containing Si is used as a mother phase and at least one kind of a transition metal or a compound thereof is dispersed therein. It is disclosed.
By dispersing a metal compound in a mother phase, it is intended to improve the adsorptivity with oil and realize a ceramic having a low friction coefficient and high strength.

[0004]

At this time, however, sufficient consideration has not been made on measuring the area ratio of the pores and setting the area ratio of the pores to an appropriate value from the viewpoint of improving the heat insulating property. In addition, the size of pores, which is effective for improving heat insulation, and the distribution of the pores are not sufficiently studied. Rather, if pores (pores) remain in the silicon nitride sintered body for sliding members, the pores become the starting point of fracture, and the strength of the silicon nitride sintered body for sliding members decreases, so there should be almost no pores. Was said to be good. Thus, from the viewpoint of the strength of the silicon nitride sintered body for the sliding member, reducing the pores as much as possible increases the thermal conductivity of the sintered body.
It is not preferable for improving the heat insulating property of the sintered body.

The present invention has been made against the background of the above-mentioned prior art, and positively utilizes the pores to improve the heat insulating property, and the seizure resistance and wear resistance are improved. It is an object of the present invention to provide a high-strength silicon nitride sintered body for a sliding member, which has a good retaining property for lubricating oil and an improved toughness.

[0006]

In order to solve the above problems, a silicon nitride sintered body for a sliding member of the present invention is a mixed powder containing a sulfide of a transition metal, a silicon nitride based powder and a sintering aid. Is a silicon nitride sintered body obtained by sintering, and fine pores, fine acicular silicon nitride, and a transition metal silicide are uniformly dispersed on at least the surface of the silicon nitride sintered body. Here, the transition metal is preferably molybdenum or iron.

The ceramic powder constituting the present invention is required to have excellent properties in strength, toughness, and abrasion resistance for use as a structural member. Therefore, silicon nitride ceramics such as silicon nitride and sialon ( Si-Al-
ON-N) is preferred.

As the transition metal added in the form of sulfide, molybdenum, which forms a metal silicide having good wettability with a lubricating oil by a sintering reaction with a ceramic component of a mother phase,
Iron, nickel, cobalt, chromium, manganese, tungsten, tantalum, and the like are preferable, and molybdenum and iron are more preferable, but these are not always provided as long as they produce a lipophilic precipitate in the sintering process. It is not limited to the element. Two or more kinds of these metal element sulfides may be added at the same time. In particular, FeS and MoS ₂ are preferable because they increase the density of the sintered body.

Since the ceramic powder has poor sinterability, a sintering aid is usually required to sinter it into a structural member. As the sintering aid, yttrium oxide, aluminum oxide, magnesium oxide, and oxide are used. A material selected from cerium, neodymium oxide, lanthanum oxide, ytterbium oxide, strontium oxide, and titanium oxide is suitable. These sintering aids may be used alone or in combination of two or more. Particularly for silicon nitride, it is desirable to add aluminum oxide and yttrium oxide. The preferable total addition amount of the sintering aid is 1 to 12 wt%.

During the process of sintering the mixed powder containing the transition metal sulfide, the silicon nitride-based powder, and the sintering aid, the surface of the silicon nitride sintered body of the present invention is formed on the surface of the transition metal sulfide. The metal silicide formed by the reaction between the metal element and the Si atom due to the dissociation of silicon nitride is finely and uniformly dispersed, and in addition, there are innumerable ultrafine pores having a pore diameter of several μm order. In addition, fine acicular silicon nitride is uniformly dispersed. This acicular silicon nitride is normally produced only by sintering at a considerably high temperature, but in the present invention, it can be produced at a relatively low temperature by adding a sulfide of a transition metal.

As a method for molding the silicon nitride sintered body of the present invention, generally known injection molding, slip casting, press molding, and low temperature isostatic pressing (CIP) can be used. Hot pressing is preferable to obtain a high-density sintered body, but since the shape that can be molded is limited to a simple shape and the cost is high, it is usually desirable to perform CIP after press molding. However, the molding method is not necessarily limited to this.

[0012]

In the silicon nitride sintered body of the present invention, since the fine acicular crystals are uniformly dispersed in the bulk silicon nitride forming the matrix phase, the toughness of the sintered body is improved.

The silicon nitride sintered body of the present invention has improved seizure resistance and wear resistance and a low friction coefficient due to the improvement of wettability with the liquid lubricant by the metal silicide and the micropool effect by the ultrafine pores. Is achieved. In the silicon nitride sintered body of the present invention, metal silicide (hereinafter referred to as a precipitate) is finely precipitated in the ceramic of the mother phase during the sintering process, and these precipitates have good affinity with the liquid lubricant. Therefore, the wettability of the silicon nitride sintered body with the liquid lubricant is improved. Also, because the precipitates are extremely finely dispersed,
The liquid lubricant is evenly spread over the sliding parts and easily held.
In addition, innumerable ultrafine pores existing on the surface of the sintered body easily hold the liquid lubricant on the sliding portion due to the micropool effect. Therefore, when the silicon nitride sintered body of the present invention is used in an environment of fluid lubrication, the coefficient of friction is reduced, wear is reduced, and the seizure limit can be increased.

Further, in the silicon nitride sintered body of the present invention, the pores are controlled by the original sintering technique and the sintering aid system, and there are no extremely coarse pores. Pore tends to occur when sintered at high temperature and becomes coarse. The coarse pores reduce the strength, but the fine pores rarely reduce the strength. Innumerable ultrafine pores existing on the surface of the silicon nitride sintered body of the present invention reduce the thermal conductivity of the sintered body and improve the heat insulating property of the sintered body.

Since the silicon nitride sintered body of the present invention is obtained by adding a sulfide of a transition metal to silicon nitride-based powder for sintering, it forms a metal silicide and a mother phase which contribute to the improvement of sliding characteristics. The bond with the interface of the silicon nitride particles is strong, and the metal silicide does not easily fall off during use, and has excellent durability.
Therefore, generally, the decrease in strength that can occur when an additive (impurity) is added is extremely small.

[0016]

EXAMPLES The present invention will be specifically described below with reference to examples, but these examples do not limit the present invention.

Example 1 5 wt% of silicon nitride raw powder (9S: manufactured by Denki Kagaku Kogyo) was mixed with yttrium oxide (made by Japan Yttrium) as a sintering aid.
%, Aluminum oxide (Sumitomo Chemical Co., Ltd.) added 3 wt%,
As a sulfide of a transition metal, molybdenum disulfide (MoS ₂ ) powder (manufactured by Kojundo Chemical Co., Ltd.) was added. These powders were mixed and pulverized in ethanol using a ball mill. The resulting slurry was dried using a rotary evaporator and then press-molded with a 35 × 55 mm die (200 kg
/ Cm ² ) and CIP (pressure 3 t / cm ² ) was performed to obtain a molded body. Using silicon nitride and boron nitride powder as stuffing powder, this molded body was separately sintered at two temperatures of 1800 ° C. and 1950 ° C. for 4 hours in a nitrogen atmosphere at 9 atm. 3 x 4 x 40 mm JI
The S piece was cut out and lapped with diamond paste to produce a test piece having a surface roughness of 0.8S.

1 to 4 show the test piece of Example 1 in which the amount of 180 molybdenum disulfide (MoS ₂ ) was added.
It is an optical microscope photograph which shows the structure of the test piece sintered at the temperature of 0 degreeC. 1 to 4, the surface of the test piece was lapped with diamond paste. The magnification is 100 times. It can be seen that the addition of molybdenum disulfide (MoS ₂ ) increases the number of fine pores in the matrix ceramics. Further, it can be seen that molybdenum silicide (precipitate) appears in the ceramic of the matrix. In the case of Example 1, molybdenum disulfide (MoS ₂ )
It can be seen that, by the addition of Al, the fine pores and the fine molybdenum silicide (precipitates) are more dispersed in the matrix ceramics in almost proportion to the addition amount. The part that looks black is the pore, and the part that looks white is the precipitate.
It is considered that these precipitates contribute to the improvement of wettability.

FIGS. 7 to 10 show 18 samples for each addition amount of molybdenum disulfide (MoS ₂ ) in the test piece of Example 1.
It is a scanning electron micrograph which shows the internal structure of the test piece separately sintered at two temperature of 00 degreeC and 1950 degreeC.
The surface of the test piece was lapped with diamond paste. The magnification is 750 times. It can be seen that columnar crystals or acicular crystals of silicon nitride develop by the addition of molybdenum sulfide. The degree of development of the columnar crystals or acicular crystals is large due to the increase in the amount of molybdenum sulfide added. Generally, when the firing temperature is raised, for example, when firing at 1950 ° C. in this case, columnar crystals develop,
As shown in FIG. 10, there is a defect that the internal structure becomes coarse and the porosity increases. The increase in porosity, that is, the appearance of large pores causes the strength of the silicon nitride sintered body to decrease. In the present invention, the firing temperature is lowered to develop columnar crystals and improve the toughness of the silicon nitride sintered body.

1800 ° C. of the test piece of Example 1
The thermal conductivity of the test piece sintered at the temperature of was measured. In addition, regarding the above test piece, a structure photograph was taken with an optical microscope and image analysis was performed with a computer to measure the size distribution of the fine pores dispersed in the matrix ceramics and the total area ratio of the pores. did.

Table 1 shows the values of thermal conductivity and pore area ratio of the test pieces fired under various sintering conditions. Compared with the case without the addition of molybdenum disulfide (MoS _2), by adding molybdenum disulfide (MoS _2), it can be seen that the thermal conductivity is significantly decreased. If the sintering temperature is the same,
Depending on the amount of molybdenum disulfide (MoS ₂ ) added, the pore area ratio becomes larger and the thermal conductivity becomes smaller.

[0022]

[Table 1]

FIG. 11 is a graph showing the relationship between the added amount of molybdenum disulfide (MoS ₂ ) shown in Table 1 and the thermal conductivity. It can be seen that the thermal conductivity is governed by the amount of molybdenum disulfide added. Up to about 1 wt% of molybdenum disulfide, the effect of reducing the thermal conductivity is remarkable. 5 wt
If it exceeds%, the effect on the reduction of the thermal conductivity becomes small. Further, if it exceeds 8 wt%, the thermal conductivity becomes almost independent of the added amount. The decrease in the thermal conductivity due to the addition of molybdenum disulfide shows that the addition of molybdenum disulfide has the effect of improving the heat insulating property.

12 to 14 show molybdenum disulfide (M
The histogram of the equivalent circular diameter of the pore is shown for each addition amount of oS ₂ ). The equivalent circle diameter is the diameter of a circle having the same area as pores of various shapes. It is easy to see that the pores of the order of several μm in diameter increase depending on the amount of molybdenum disulfide (MoS ₂ ) added. As described above, the increase of pores having a diameter of several μm suppresses the reduction in strength and improves the heat insulating property of the sintered body.

Among the test pieces of Example 1, the test piece sintered without adding molybdenum disulfide (MoS ₂ ) at a temperature of 1950 ° C. and 5 wt% of molybdenum disulfide (MoS ₂ ) were added to the test piece of 1800 ° C. The thermal conductivity, the pore size distribution, the total area ratio of the pores, and the bending strength of the test piece sintered at the temperature were measured. The methods for measuring the thermal conductivity, the pore size distribution, and the total area ratio of the pores are the same as those in Table 1 and FIGS. 12 to 14 described above.

Table 2 shows the values of thermal conductivity, pore area ratio and bending strength of the test pieces fired under the above two sintering conditions. Two the disulfide compared with the case without the addition of molybdenum (MoS _2), by adding molybdenum disulfide (MoS _2), Tables 1 and likewise it can be seen that the thermal conductivity is significantly decreased. However, in the case of Table 2, the pore area ratio does not increase depending on the addition amount of molybdenum disulfide (MoS ₂ ). Rather, the pore area ratio is molybdenum disulfide (M
When oS ₂ ) is not added, it is larger than when it is added. This is considered to be due to the difference in sintering temperature.

[0027]

[Table 2]

FIG. 15 shows a histogram of equivalent circular diameters of pores of a test piece sintered at a temperature of 1950 ° C. without adding molybdenum disulfide (MoS ₂ ). Add 5 wt% of molybdenum disulfide (MoS ₂ ) shown in FIG.
Comparing the histogram of the equivalent circular diameter of the pores of the test piece sintered at a temperature of ℃ to the histogram of FIG. 15, the frequency of pores of the order of several μm in diameter is about 1/3 of that in FIG. Decreasing, on the contrary, diameter of 10 μm
The frequency of pores of the above order is increased by about 25% from FIG. This means that in FIG. 15, the frequency of pores on the order of 10 μm or more in diameter is several μm in FIG.
It shows that it is relatively large with respect to the frequency of order pores. That is, in FIG. 14, fine (diameter of several μm order)
In contrast to the large number of pores, there are slightly larger large pores (on the order of several tens of μm in diameter) in FIG. That is, FIG. 14 shows that many fine pores are dispersed, and FIG. 15 shows that there are a few large pores.

Here, looking at the bending strength in Table 2, the bending strength is higher when molybdenum disulfide (MoS ₂ ) is added by 5 wt% than when it is not added. The pore area ratio is 10 both with and without addition.
Since it is only a few percent and there is no significant difference, it cannot be said that the pore area ratio alone affects the bending strength. It is considered that the size and number of pores affect the bending strength. When added, quite a few fine pores (on the order of several μm in diameter) exist, but this does not have a large effect on bending strength, and when not added, it is large (10 μm in diameter).
Since there are slightly more pores (of the above order), this is considered to affect the bending strength. It can be seen that the bending strength decreases as the number of large pores (on the order of several 10 μm in diameter) increases. When added, there are many fine pores, but few large pores, so the bending strength is high.

Next, looking at the thermal conductivity in Table 2, the thermal conductivity is smaller when 5 wt% of molybdenum disulfide (MoS ₂ ) is added than when it is not added. Since the pore area ratios are 10 and 10% both when added and when not added, it cannot be said that the pore area ratio alone affects the thermal conductivity. It is considered that the size and number of pores affect the thermal conductivity. When added, a large number of fine pores (on the order of several μm in diameter) are present, and this is considered to affect the thermal conductivity. When not added, a large number of large pores (on the order of several 10 μm in diameter) are present, but this does not greatly affect the thermal conductivity. Fine (diameter several μ
It can be seen that the thermal conductivity decreases as the number of pores (m-order) increases. When added, there are many fine pores, so the thermal conductivity is high. In this way, the increase of pores of the order of several μm in diameter improves the heat insulating property of the sintered body.

The test piece of Example 1 was subjected to point contact seizure and wear test using a pin-on-disc type friction wear tester. Silicon nitride ceramics and molybdenum disulfide (M
oS ₂ ) Silicon nitride ceramics with 5 wt% addition was used. Bearing steel was used as the disc material in all tests. The test conditions are ascending load speed of 10 kg / min.
The load P and the friction coefficient μ at the time of seizing in the atmosphere were measured at 1 to 15 m / s. As the lubricating oil, Honda Ultra U10W-30 was used, and the lubricating condition was to apply oil on the disk before the test to cut off the supply in order to prevent the uneven contact in the initial stage. Therefore, it is considered that the phenomenon of oil film breakage that occurs in high surface pressure and high-speed sliding members can be artificially generated and the toughness against oil film breakage can be evaluated. Further, the test piece after the test was evaluated by calculating the wear amount by the calculation from the image processing of the optical micrograph.

Table 3 shows the seizure load and wear volume of the test piece when molybdenum disulfide (MoS ₂ ) was not added and when it was added at 5 wt%. Two the disulfide compared with the case without the addition of molybdenum (MoS _2), towards the case of adding molybdenum disulfide (MoS _2), large seizure load, it can be seen that the wear volume is small.

[0033]

[Table 3]

FIG. 16 is a graph showing how the relationship between the sliding speed and the seizure load changes when molybdenum disulfide (MoS ₂ ) shown in Table 3 is not added and when 5 wt% is added. In FIG. 16, the seizure load is larger in the silicon nitride ceramics added with 5 wt% of molybdenum disulfide (MoS ₂ ) than in the silicon nitride ceramics not added at any slip rate. This indicates that the addition of 5 wt% molybdenum disulfide (MoS ₂ ) improved the seizure resistance of the silicon nitride ceramics.

FIG. 17 is a graph showing how the relationship between the slip rate and the wear volume changes between the case where molybdenum disulfide (MoS ₂ ) shown in Table 3 is not added and the case where 5 wt% is added. In FIG. 17, the wear volume of silicon nitride ceramics containing 5 wt% of molybdenum disulfide (MoS ₂ ) is smaller than that of silicon nitride ceramics containing no addition at any slip rate. This means molybdenum disulfide (MoS ₂ )
It shows that the wear resistance of silicon nitride ceramics was improved by adding 5 wt%.

This is 5 wt% of molybdenum disulfide (MoS ₂ ).
%, Silicon nitride has a micropool effect due to innumerable ultrafine pores of the order of several μm in diameter generated on the sliding surface of silicon nitride ceramics and an improvement in lipophilicity due to finely deposited metal silicide on the sliding surface. It shows that the ceramics have remarkable seizure resistance and wear resistance. The effect of adding 5 wt% of molybdenum disulfide (MoS ₂ ) is remarkable in the low speed region and the high load region. When a low viscosity lubricant is used, the sliding characteristics of silicon nitride ceramics can be expected to be further improved.

Example 2 In the same manner as in Example 1, iron (II) sulfide (FeS) powder was added instead of molybdenum disulfide (MoS ₂ ) powder to prepare a test piece. FIG. 5 shows that in the test piece of Example 2, the amount of iron (II) sulfide (FeS) added was 5
It is an optical microscope photograph which shows the structure of the test piece sintered at the temperature of 1800 degreeC at wt%. In FIG. 5, the surface of the test piece was lapped with diamond paste. The magnification is 100 times. Example 1
As in the case of adding the molybdenum disulfide (MoS ₂ ) powder, the addition of iron (II) sulfide (FeS) increases the number of fine pores in the matrix ceramics. Further, it can be seen that iron silicide (precipitate) appears in the mother phase ceramics. The part that looks black is the pore, and the part that looks white is the precipitate. It is considered that these precipitates contribute to the improvement of wettability.

1800 ° C. of the test piece of Example 2
The thermal conductivity of the test piece sintered at the temperature was measured by the same method as in Example 1. With respect to the test piece of Example 2, a structure photograph was taken with an optical microscope in the same manner as in Example 1 and image analysis was performed by a computer, whereby the size distribution and pores of fine pores dispersed in the ceramic of the matrix phase were obtained. Was measured.

Table 4 shows the values of thermal conductivity and pore area ratio of the test pieces fired under various sintering conditions. Iron sulfide (II)
Compared to the case where (FeS) is not added, iron sulfide (II)
It can be seen that the thermal conductivity is remarkably reduced by adding (FeS). The thermal conductivity decreases as the pore area ratio increases.

[0040]

[Table 4]

Of the test pieces of Example 2, iron sulfide (I
I) (FeS) with 5 wt% added has a thermal conductivity of 2
It was 4.2 (W / (K · m)). The pore size distribution of the test piece of Example 2 was not measured, but it seems that the test piece of Example 2 exhibits a distribution similar to that of Example 1.

Example 3 In the same manner as in Example 1, powder of iron disulfide (FeS ₂ ) was added instead of powder of molybdenum disulfide (MoS ₂ ),
A test piece was produced. FIG. 6 is an optical micrograph showing the structure of the test piece of Example 3, which was sintered at a temperature of 1800 ° C. when the addition amount of iron disulfide (FeS ₂ ) was 5 wt%. In FIG. 6, the surface of the test piece was lapped with diamond paste. The magnification is 100 times. As in the case of adding the molybdenum disulfide (MoS ₂ ) powder of Example 1,
It can be seen that the addition of iron disulfide (FeS ₂ ) increases the number of fine pores in the ceramic of the matrix phase. Further, it can be seen that iron silicide (precipitate) appears in the mother phase ceramics. The part that looks black is the pore, and the part that looks white is the precipitate. It is considered that these precipitates contribute to the improvement of the wettability with the lubricant.

1800 ° C. of the test piece of Example 3
The thermal conductivity of the test piece sintered at the temperature was measured by the same method as in Example 1. With respect to the test piece of Example 3, a structure photograph was taken with an optical microscope in the same manner as in Example 1 and image analysis was performed by a computer, whereby the size distribution and pores of fine pores dispersed in the ceramic of the matrix phase were obtained. Was measured.

Table 5 shows the values of thermal conductivity and pore area ratio of the test pieces fired under various sintering conditions. Iron disulfide (F
Compared to the case where eS ₂ ) is not added, iron disulfide (Fe
It can be seen that the thermal conductivity is remarkably reduced by adding S ₂ ). The thermal conductivity decreases as the pore area ratio increases.

[0045]

[Table 5]

The thermal conductivity of the test piece of Example 3 containing 5 wt% of iron disulfide (FeS ₂ ) was 24.3.
(W / (K · m)). The pore size distribution of the test piece of Example 3 was not measured, but it seems that the test piece of Example 3 exhibits a distribution similar to that of Example 1.

[0047]

EFFECTS OF THE INVENTION In the silicon nitride sintered body of the present invention, since fine needle-like crystals are uniformly dispersed in the bulk silicon nitride forming the matrix phase, the toughness of the sintered body is improved.

In the silicon nitride sintered body of the present invention, metal silicide (hereinafter referred to as a precipitate) is finely precipitated in the ceramic of the mother phase during the sintering process, and these precipitates have an affinity with the liquid lubricant. The good wettability improves the wettability of the silicon nitride sintered body with the liquid lubricant. Further, since the precipitates are extremely finely dispersed, the liquid lubricant is evenly spread over the sliding portion and easily held. In addition, innumerable ultrafine pores existing on the surface of the sintered body easily hold the liquid lubricant on the sliding portion due to the micropool effect. Therefore, when the silicon nitride sintered body of the present invention is used under a fluid lubrication environment, the friction coefficient is reduced.

Further, the silicon nitride sintered body of the present invention has an affinity for the micropool effect due to the innumerable ultrafine pores generated on the sliding surface and the lubricant due to the metal silicide finely deposited on the sliding surface. Shows improved seizure resistance and wear resistance.

Further, in the silicon nitride sintered body of the present invention, the pores are controlled by the original sintering technique and the sintering aid system, and there are no extremely coarse pores. Pore tends to occur when sintered at high temperature and becomes coarse. The coarse pores reduce the strength of the sintered body, but since the pores dispersed on the surface of the silicon nitride sintered body of the present invention are fine pores,
Less likely to reduce strength.

The countless ultrafine pores present on the surface of the silicon nitride sintered body of the present invention reduce the thermal conductivity of the sintered body and improve the heat insulating property of the sintered body.

Since the silicon nitride sintered body of the present invention is sintered by adding a sulfide of a transition metal to silicon nitride-based powder, it forms a metal silicide and a mother phase which contribute to the improvement of sliding characteristics. The bond with the interface of the silicon nitride particles is strong, and the metal silicide does not easily fall off during use, and has excellent durability.
Therefore, generally, the decrease in strength that can occur when an additive (impurity) is added is extremely small.

[Brief description of drawings]

FIG. 1 is an optical micrograph showing the structure of a test piece of the test piece of Example 1, which was sintered at a temperature of 1800 ° C. when the amount of molybdenum disulfide (MoS ₂ ) added was 0 wt%.

FIG. 2 is an optical micrograph showing the structure of a test piece of the test piece of Example 1, which was sintered at a temperature of 1800 ° C. when the amount of molybdenum disulfide (MoS ₂ ) added was 1 wt%.

3 is an optical micrograph showing the structure of a test piece of the test piece of Example 1, which was sintered at a temperature of 1800 ° C. when the amount of molybdenum disulfide (MoS ₂ ) added was 5 wt%.

FIG. 4 is 1800 ° C. when the amount of molybdenum disulfide (MoS ₂ ) added in the test piece of Example 1 is 10 wt%.
Photomicrograph showing the structure of the test piece sintered at the temperature.

FIG. 5: Iron sulfide (II) among the test pieces of Example 2
The optical microscope photograph which shows the structure of the test piece sintered at the temperature of 1800 degreeC when the addition amount of (FeS) is 5 wt%.

FIG. 6 shows iron disulfide (F) among the test pieces of Example 3.
When the addition amount of eS ₂₎ is 5 wt%, an optical micrograph showing a test piece of tissue sintered at a temperature of 1800 ° C..

FIG. 7 is a scanning electron micrograph showing the structure of a test piece of the test piece of Example 1, which was sintered at a temperature of 1800 ° C. when the addition amount of molybdenum disulfide (MoS ₂ ) was 0 wt%.

8 is a scanning electron micrograph showing the structure of a test piece of the test piece of Example 1, which was sintered at a temperature of 1800 ° C. when the amount of molybdenum disulfide (MoS ₂ ) added was 1 wt%.

9 is a scanning electron micrograph showing the structure of a test piece of the test piece of Example 1, which was sintered at a temperature of 1800 ° C. when the amount of molybdenum disulfide (MoS ₂ ) added was 5 wt%.

10 is a test piece of Example 1, when the addition amount of molybdenum disulfide (MoS ₂ ) is 0 wt%, 1950 ° C.
Scanning electron micrograph showing the structure of the test piece sintered at the temperature.

FIG. 11: Of the test piece of Example 1, 1800 ° C.
3 is a graph showing the relationship between the added amount of molybdenum disulfide (MoS ₂ ) and the thermal conductivity in the test piece sintered at the temperature of.

FIG. 12 shows the molybdenum disulfide (Mo) in Example 1.
Histogram of equivalent circular diameters of pores of a test piece sintered at a temperature of 1800 ° C. when the addition amount of S ₂ ) is 0 wt%.

FIG. 13 shows the molybdenum disulfide (Mo) in Example 1.
Histogram of the equivalent circular diameter of the pores of the test piece sintered at a temperature of 1800 ° C. when the addition amount of S ₂ ) was 1 wt%.

FIG. 14 shows the molybdenum disulfide (Mo) in Example 1.
A histogram of equivalent circular diameters of pores of a test piece sintered at a temperature of 1800 ° C. when the addition amount of S ₂ ) is 5 wt%.

FIG. 15 shows the molybdenum disulfide (Mo) in Example 1.
Histogram of the equivalent circular diameter of the pores of the test piece sintered at a temperature of 1950 ° C. when the added amount of S ₂ ) was 0 wt%.

16] Of the test pieces of Example 1, 1800 ° C
A graph showing how the relationship between the sliding speed and the seizure load changes in the test piece sintered at the temperature of 5% with or without the addition of molybdenum disulfide (MoS ₂ ).

FIG. 17: Of the test piece of Example 1, 1800 ° C.
A graph showing how the relationship between the slip rate and the wear volume changes in the test piece sintered at the temperature of 5% with or without the addition of molybdenum disulfide (MoS ₂ ).

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasunobu Kawakami 1-4-1 Chuo, Wako-shi, Saitama, Ltd. Inside Honda R & D Co., Ltd. (56) Reference JP-A-6-183841 (JP, A) JP-A 7-277834 (JP, A) JP-A-8-91938 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/584

Claims (2)

(57) [Claims] 1. A silicon nitride sintered body obtained by sintering a mixed powder containing a sulfide of a transition metal, a silicon nitride-based powder, and a sintering aid, which is at least on the surface of the silicon nitride sintered body. A silicon nitride sintered body for a sliding member, characterized in that fine pores, fine needle-shaped silicon nitride and a silicide of a transition metal are uniformly dispersed. 2. The silicon nitride sintered body for a sliding member according to claim 1, wherein the transition metal is molybdenum or iron.