JP2683268B2 - Ceramic sliding member and method of manufacturing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a ceramic sliding member having excellent mechanical strength, wear resistance and seizure resistance, and a method for manufacturing the same.

(Prior Art) Generally, ceramic materials expected as a sliding material include a silicon carbide sintered body and a silicon nitride sintered body, but the silicon carbide sintered body has excellent seizure resistance. ,
Since it has poor fracture toughness and strength, it has the drawback that chips and cracks easily occur during operation of parts, or during processing and assembly. On the other hand, the silicon nitride sintered body is excellent in heat resistance, thermal shock resistance, mechanical strength, corrosion resistance, etc.
It is considered to be applied to various mechanical parts that operate under severe conditions where metallic materials cannot be used, and the development of its applications is being actively pursued.

By the way, since sintering of the silicon nitride sintered body does not take a liquid phase of Si ₃ N ₄ itself, an auxiliary agent for strongly bonding the particles is required. In general, oxides have been widely used as this type of auxiliary agent because they themselves melt to form a liquid phase or form a low melting point compound with other components in the material. These auxiliaries are represented by Y ₂ O ₃ , Al ₂ O ₃ and BoO. That is, the characteristics of the silicon nitride sintered body largely depend on the characteristics of Si ₃ N ₄ and the characteristics of the auxiliary agent that constitutes the grain boundary. It is well known that the conventional silicon nitride sintered body is obtained by adding Y ₂ O ₃ , Al ₂ O _{3 and the} like to the main component Si ₃ N ₄ inside and outside by 10 wt% and sintering it in an inert gas atmosphere. However, some problems that cannot be avoided in the sintered body, such as lack of reliability represented by defects caused by foreign matters and pores, and absolute lack of strength, often occur.

From the above viewpoint, in order to obtain a high-density silicon nitride sintered body having excellent mechanical strength, a predetermined amount of Y ₂ O ₃ , MgO, and CeO ₂ is added to Si ₃ N _{4 as the} main component. In addition, a sintered body is disclosed in JP-A-61-68373.

(Problems to be Solved by the Invention) As in the above-mentioned known example, Y ₂ O ₃ , Mg as a sintering aid is used.
The silicon nitride sintered body using O and CeO ₂ has high strength and excellent impact resistance, but a sliding test using a Cr plating material as the mating material showed that It was found that the wear resistance and seizure resistance were poor. Therefore, the distribution of Si, Mg, and Y in the cross section of the test piece was examined before and after the sliding test by EPMA (electron probe microanalysis method). The results are as follows. First
In the figure, the vertical axis represents the relative content of each element, and the horizontal axis represents the depth from the surface in the cross section of the test piece.

From the results shown in FIG. 1, it can be seen that the amount of Mg near the surface of the test piece after the sliding test is extremely high. This is probably because the heat generated on the surface of the test piece during the sliding test elutes the internal Mg component and permeates the surface layer. Take
It can be inferred that the increase in the amount of Mg in the surface layer of the test piece due to the penetration of Mg into the surface layer is one of the causes of impairing the wear resistance and seizure resistance.

Therefore, the present inventors have decided to use Mg used as a sintering aid.
By adjusting the amount of O, it is possible to confirm the fact that extremely good wear resistance and seizure resistance can be secured by controlling the amount of Mg elution to the surface layer of the test piece after the sliding test. It has arrived.

The present invention has been made in view of the above points, by adjusting the amount of Mg in the silicon nitride sintered body, to obtain a ceramic sliding member having extremely high wear resistance and seizure resistance. It is intended.

(Means and Actions for Solving the Problems) According to the invention of claim 1, in a ceramic sliding member composed of a sintered body containing Si ₃ N ₄ as a main component and containing Y, Mg and Ce, Y is contained. The amount is ₂ to 20% by weight in terms of Y ₂ O ₃ , the content of Mg is 0.1 to 0.9% by weight in terms of MgO, the content of Ce is 1 to 10% by weight in terms of CeO ₂ , and the balance Says Si ₃ N ₄ .

By doing so, since the amount of Mg in the ceramic sliding member is suppressed to a small amount, the amount of Mg that elutes and permeates to the surface layer side due to the sliding heat can be suppressed to a small amount. In addition, 1% by weight of Mg converted to MgO
In the above cases, the seizure phenomenon was observed, and the seizure phenomenon increased as the amount of Mg increased.
If it is 0.1% by weight or less in terms of MgO, the deterioration in strength becomes remarkable and it becomes unusable for practical use, so the above range is preferable. Regarding Y and Ce, when the upper limit values (that is, Y: 20% by weight, Ce: 10% by weight) or more are promoted, the growth of the tissue is promoted, and the impact resistance is greatly deteriorated. If it is less than Y (2% by weight, Ce: 1% by weight) or less, sufficient sinterability cannot be ensured and a problem occurs in strength, so the above range is preferable. Also, in order to improve the sliding characteristics,
It is desirable to contain a small amount of carbides such as SiC and TiC. Furthermore, MgO is an oxide that is effective in forming a liquid phase at low temperatures, and although it is effective even in a small amount, when it becomes extremely small, other compounds (for example,
One or more oxides, nitrides, borides, and carbides of Group IIa, IIIa, IVa, and Va elements of the periodic table excluding Ce and Mg and, in some cases, lanthanide elements It is desirable to contain oxides, nitrides, borides, carbides and composite compounds thereof in an amount of 15% by weight or less,
It is desirable that the content of other unavoidable impurities does not exceed 0.5% by weight.

According to the invention of claim 2, a sintered body containing Si ₃ N ₄ as a main component and containing Y, Mg, Ce and the like, wherein the content of Y is ₂ to 20% by weight in terms of Y ₂ O ₃ , Mg content converted to MgO 0.1 ~
0.9% by weight, the content of Ce is 0.1 to 0.9% by weight in terms of CeO _2, and the content of one or more elements of the IIa, IIIa, IVa and Va groups of the periodic table excluding Ce and Mg Are oxides, nitrides, borides,
It is 15% by weight or less in terms of carbides and their composite compounds, and the balance is Si ₃ N ₄ .

By doing the above, since the amount of Mg in the ceramic sliding member is suppressed to a small amount, the amount of Mg eluted and permeated to the surface layer side by the sliding heat can be suppressed to a small amount. Although similar to the case of the invention, in the case of the present invention, Ce also, in view of causing elution at high temperature, by reducing its content, elution permeation into the surface layer will be suppressed. -ing Further, if the content of Mg and Ce is reduced as described above, the absolute amount as a sintering aid will be insufficient, so in the present invention, Ce, the periodic table IIa, III excluding Mg, III The content of at least one of the elements a, IVa, and Va is 15% by weight or less in terms of oxides, nitrides, borides, carbides, and composite compounds thereof. As a result, the sinterability can be improved and the strength of the obtained sintered body can be secured. In addition, the Periodic Table II excluding Ce and Mg
If the content of at least one of the elements a, IIIa, IVa, and Va is more than 15 hours when converted to oxides, nitrides, borides, carbides, and composite compounds thereof, the growth of the tissue is promoted. As a result, the impact resistance deteriorates significantly. Also in the case of the present invention, as in the case of the above-mentioned invention of claim 1, when MgO and CeO ₂ become extremely small, other compounds (for example, oxides, nitrides, borides of lanthanide elements) are formed. , Carbides and their complex compounds) in an amount of 15% by weight or less, and the content of other unavoidable impurities is preferably not more than 0.5% by weight.

In the invention of claim 3, the main components are Si ₃ N ₄ , ₂ to 20% by weight of Y ₂ O ₃ , and 0.1% of MgO having an average particle size of 1500Å or less.
To 0.9 wt% and a sintering aid containing 1 to 10 wt% CeO ₂ are mixed and pulverized to form a powder mixture, which is then fired at 1600 to 1850 ° C. in an inert gas atmosphere. I am trying.

In the ceramic sliding member obtained as described above, Mg
Since the content of is 0.1 to 0.9% by weight in terms of MgO, the amount of Mg eluted and permeated to the surface side by sliding heat can be suppressed to be small. Further, in the method of the present invention, the average particle size of MgO added as a sintering aid is set to 1500 Å or less, so that when Si ₃ N _{4 as the} main component and the sintering aid are mixed and pulverized, MgO The atomization is facilitated, and the dispersibility of MgO in the sintered body becomes extremely good. In particular, as in the method of the present invention, when the amount of MgO is limited to a small amount, the dispersibility thereof has a great effect on the homogeneity and strength of the obtained sintered body, which is more effective. By the way, when the average particle size of MgO added as a sintering aid was changed and the strength (four-point bending strength) of the obtained sintered body was examined,
It was obtained as shown in FIG. According to this, when the average particle size of MgO exceeds 1500 Å, the strength of the obtained sintered body is reduced. This means that as in the method of the present invention, the average particle size is small (for example, 1000
Å) The structure of the sintered body obtained by using MgO is homogeneous as shown in Fig. 3 (a), while the average grain size is large (for example, 2000Å) As shown in Fig. 3 (b), the structure of the obtained sintered body is inhomogeneous, and the MgO content is high (the shaded area) and the MgO content is low. It seems that the damage occurs from the boundary with the part (unpatterned part). The sintering in the method of the present invention is preferably performed by a hot pressing method or a hot isostatic pressing method, but an atmospheric pressure sintering method may be used. However, if the density of the sintered body is less than 95%, the mechanical properties will deteriorate and it will not be practically applicable. Further, as the inert gas used during sintering, nitrogen gas is desirable in order to suppress decomposition of Si ₃ N ₄ during sintering. Further, when the sintering temperature is 1600 ° C. or lower, the firing is insufficient and the structure does not become dense, and at 1850 ° C. or higher, the decomposition and evaporation of Si ₃ N ₄ is so intense that a dense sintered body cannot be obtained. Therefore, it is desirable to set the temperature to 1600 to 1850 ° C. In addition,
Once held at 1200 to 1500 ° C during temperature reduction after sintering, crystallization of the glass phase of the generated grain boundary occurs, which contributes to strength improvement. It is desirable to set it to the extent that

In the invention of claim 4, the silicon nitride raw material powder as the main component, Y ₂ O ₃ 2 to 20 wt%, the MgO 0.1 to 0.9 wt%, CeO
_The compounding powder obtained by mixing and pulverizing ₂ with 1 to 10% by weight of a sintering aid is molded, and then 16% in an inert gas atmosphere.
After firing at 00 to 1850 ° C and subjecting the obtained sintered body to predetermined machining, it is heat-treated at a temperature of 1100 to 1500 ° C for 1 to 5 hours.

In the ceramic sliding member obtained as described above, Mg
The content of Mg is 0.1 to 0.9% by weight in terms of MgO, so that the amount of Mg that elutes and permeates to the surface side due to sliding heat can be suppressed to a small level as in the case of the invention of claim 3. Although it is the same, the microcracks and residual stress generated by the machining process soften the vitreous material by applying a heat treatment at a temperature of 1100 to 1500 ° C for 1 to 5 hours after the machining process and before the finishing process. As a result, it is relaxed and the crystallization of grain boundaries is promoted. When the heat treatment temperature is 1100 ° C. or lower, the softening of the vitreous becomes insufficient, and when it is 1500 ° C. or higher, the crystallization of grain boundaries proceeds too much.

(Effect of the Invention) According to the invention of claim 1, Si ₃ N ₄ as a main component, Y, M
In a ceramic sliding member composed of a sintered body containing g and Ce, the Y content is ₂ to 20 in terms of Y ₂ O _3.
% By weight, content of Mg converted to MgO 0.1-0.9% by weight, C
The content of e is 1 to 10% by weight calculated as CeO ₂ , and the balance is Si ₃ N ₄
However, since the amount of Mg in the ceramic sliding member is kept small, the amount of Mg that elutes and permeates to the surface side due to sliding heat can be kept small, and the mechanical strength, etc. can be maintained without deterioration. There is an excellent effect that the wear resistance and the seizure resistance can be improved.

According to the invention of claim 2, Si ₃ N ₄ is the main component, and Y, M
A sintered body containing g, Ce, etc., in which the Y content is Y ₂ O ₃
2 to 20% by weight in terms of Mg content converted to MgO
0.1 to 0.9 wt%, the content of Ce is in terms of CeO ₂ 0.1 to 0.9
Periodic Table IIa, IIIa, IVa, Va excluding wt%, Ce, Mg
The content of at least one group element is 15% by weight or less in terms of oxides, nitrides, borides, carbides and their composite compounds, and the balance is Si ₃ N _4, and the content in the ceramic sliding member is Since the amounts of Mg and Ce are kept low, the amount of Mg and Ce that elute and penetrate to the surface side due to sliding heat
Since the amount is suppressed to be small, there is an excellent effect that the wear resistance and the seizure resistance can be further improved without lowering the mechanical strength and the like. Although there is a concern that the sinterability and strength may decrease due to the decrease in the content of Ce, the periodic table IIa, III excluding Ce and Mg
The content of at least one of the a, IV a, and V a group elements is set to 15% by weight or less in terms of oxide, nitride, boride, carbide, and composite compounds thereof. Concerns have been resolved.

According to the invention of claim 3, Si ₃ N ₄ which is the main component and Y ₂ O.
₃ to 2 to 20% by weight, MgO having an average particle size of 1500 Å or less
Mix powder with 0.1 to 0.9 wt% and sintering aid containing 1 to 10 wt% of CeO ₂ and pulverize it to form mixed powder, and then burn at 1600 to 1850 ℃ in inert gas atmosphere. Therefore, in the obtained ceramic sliding member, the content of Mg is Mg
From 0.1 to 0.9% by weight in terms of O, the amount of Mg that elutes and permeates to the surface side due to sliding heat is suppressed to a small amount, and abrasion resistance and seizure resistance are sufficiently secured, and By setting the average particle size of MgO added as a sintering aid to 1500 Å or less, the main component Si ₃ N ₄
When mixing and crushing and the sintering aid, MgO will be easily atomized, the dispersibility of MgO in the sintered body will be extremely good, and a high-strength ceramic sliding member will be obtained. It has an excellent effect.

According to the invention of claim 4, Si ₃ N ₄ which is a main component and Y ₂ O.
₃ to 2 to 20 wt%, MgO to 0.1 to 0.9 wt%, CeO ₂ to 1 to 10
Molded powder obtained by mixing and pulverizing with a sintering aid containing 1 wt%, then in an inert gas atmosphere at 1600 ~ 1850 ℃
Since the obtained sintered body is fired at a temperature of 1100-1500 ° C. for 1-5 hours after being subjected to predetermined machining, the obtained ceramic sliding member is Since the content of Mg is 0.1 to 0.9 wt% when converted to MgO, the amount of Mg that elutes and permeates to the surface side due to sliding heat is suppressed to a small amount, and wear resistance and seizure resistance are sufficiently secured. 1100 ~ after being machined
By heat treatment at a temperature of 1500 ° C for 1 to 5 hours, microcracks and residual stress generated by machining are alleviated with the softening of the glass and the crystallization of grain boundaries is promoted. Therefore, there is an excellent effect that the reliability of strength is significantly improved.

(Examples) Hereinafter, some examples of the present invention will be described.

Example 1 Si ₃ N _{4 having} an average particle size of 0.7 μm, Y ₂ O _{3 having} an average particle size of 0.4 μm,
Raw material powders of CeO _{2 having} an average particle diameter of 0.4 μm, MgO having an average particle diameter of 0.1 μm, and other additives were mixed in the proportions shown in Table 1, and mixed and pulverized using a vibration mill. The raw material thus obtained is dried to prepare a compound powder, and the compound powder is sintered using a hot pressing device or a hot isostatic pressing device under the temperature conditions and nitrogen gas atmospheres shown in Table 1,
Then, predetermined machining and finishing were performed to obtain ceramic sliding members NO1-18 according to the present invention. Also,
Separately, a ceramic sliding member NO18-26 of a comparative example was prepared under the same conditions as above, except that the composition was out of the compositional range.
As a result of the chemical analysis of these ceramic sliding members, the composition of Y, Ce and Mg in the ceramic sliding members NO1 to 26 is
It almost agreed with the composition. Table 1 shows the strength (kgf / mm ² ), impact value (kgfm), wear amount (g) and evaluation of sliding characteristics of these ceramic sliding members. Among the products of the present invention shown in Table 1, only No12 was sintered by the hot isostatic pressing apparatus, and the others were sintered by the hot pressing apparatus. Further, the present invention product No. 10, 14,
16 and Comparative Example No. 20 are 1300 ° C when the temperature is lowered after sintering.
It was once held in. Further, the present invention No. 12,16,
17 and Comparative Example NO25 are examples containing a carbide (TiC in this example), and the products of the present invention NO9, 10, 11 are the IIa, IIIa, IVa of the periodic table excluding Ce and Mg. , Group V a oxides, nitrides, borides, carbides and their composites 1
An example containing more than one kind, the product NO15 of the present invention is an example containing one or more kinds of oxides, nitrides, borides, carbides of lanthanide elements and composite compounds thereof.

According to Table 1, it can be seen that all of the products of the present invention show extremely good sliding characteristics, whereas the comparative examples do not have good sliding characteristics. For example, Comparative Example NO
In 18,22, the amount of wear was large, and particularly in NO18, measurement became impossible, and in Comparative Examples NO19, 20, 24, seizure was observed.
At 21,23,25, opponent aggression was seen.

By the way, the results of a sliding test using the product NO1 of the present invention and the comparative example NO19 as examples are shown in FIGS. 4 (a) and 4 (b). According to this, in the product NO1 of the present invention, a sharp increase in the friction coefficient was not observed, whereas in the comparative example NO19, a local sharp increase in the friction coefficient was observed. This indicates that the seizure phenomenon occurred during the sliding test.

Example 2 A compounded powder having the same composition as that of the product NO1 of the present invention was placed in a rubber mold, rubber-pressed at a pressure of 3 Ton / cmm ² , and then sintered in a nitrogen atmosphere (8 atm) at 1800 ° C. for 3 hours. The relative density of the obtained sintered body was 96%. When a sliding test similar to the above was conducted using a test piece prepared from the sintered body, the self-abrasion property was slightly increased, but good sliding property was exhibited.

Example 3 Si ₃ N ₄ : 90.5 wt%, Y ₂ O ₃ : 7 wt%, Ce with 90% alpha conversion, Ce
Each material was compounded so as to have a composition of O ₂ : 2 wt% and MgO: 0.5 wt%. At this time, the average particle size of each is Si ₃ N ₄ : 0.1μ
m, Y ₂ O ₃ : 0.4 μm and CeO ₂ : 0.4 μm. In addition, MgO
About 500Å, 1000Å, 1500Å, 2000Å, 4000Å
The above five kinds of materials were mixed and pulverized for 25 hours in a solvent to which a dispersant was appropriately added using a vibration mill. The obtained slurry was dried with a spray dryer to obtain Samples 1 to 5. These samples 1 to 5 were preliminarily pressed with a die and then sintered in a nitrogen atmosphere at 1750 ° C. for 2 hours using a hot press machine. When each of the obtained sintered bodies was processed into a test piece and the mechanical properties were investigated, the results shown in FIG. 2 were obtained.

According to this, it can be seen that the strength of MgO particles with an average particle size of 2000 Å or more is reduced by nearly 20% as compared with those without MgO particles. A similar tendency was observed in the variation in strength. Observation of the test piece of sample 4 obtained by adding MgO having an average particle size of 2000Å showed spot-like unevenness as shown by the shaded area in Fig. 3 (b), which was confirmed in the strength test. It fractured along the boundary. In other words, when MgO with a large average particle size is added, the dispersibility of MgO decreases and a non-homogeneous sintered body is obtained.
There is a difference in strength between a portion with a high gO content (hatched portion) and a portion with a low gO content (non-patterned portion), and when fractured, it is dominated by the weaker portion.
On the other hand, the sample 2 obtained by using MgO having an average particle size of 1500 Å or less (for example, 1000 Å) is shown in FIG.
As shown in the figure, it is homogeneous and breaks at the limit of its mechanical strength.

However, at this time, if the average particle size of MgO is too small, the particles remain aggregated due to factors such as intermolecular force, resulting in poor dispersibility. Also, as for the mixing time, a short time is not sufficient, and it is desirable to mix for 15 hours or more.

Example 4 93.5% by weight of Si ₃ N ₄ having an average particle size of 0.7 μm and an average particle size of 0.4
4% by weight of Y ₂ O ₃ having a particle diameter of 0.5 μm, 0.5% by weight of MgO having an average particle diameter of 0.1 μm, and 2% by weight of CeO ₂ having an average particle diameter of 0.4 μm were mixed and pulverized to form a mixed powder, Was fired in a nitrogen gas atmosphere at 1700 ° C. for 1 hour, the obtained sintered body was subjected to predetermined machining, and then heat-treated at a temperature of 1100 to 1500 ° C. for 1 to 5 hours before finishing. . In the ceramic sliding member thus obtained, microcracks and residual stress generated by machining are alleviated with the softening of the glassy material during the heat treatment, and crystallization of grain boundaries is promoted. When the heat treatment temperature is 1100 ° C. or lower, the softening of the vitreous becomes insufficient, and when it is 1500 ° C. or higher, the crystallization of grain boundaries proceeds too much.

Example 5 Si ₃ N ₄ : 91.5% by weight having an α conversion of 91% and an average particle size of 0.4 μm,
Y ₂ O _{3 with} an average particle size of 0.4 μm: 6% by weight, CeO _{2 with the} same average particle size:
2% by weight, MgO with an average particle size of 0.1 μm: 0.5% by weight, SiC
10% by weight of whiskers (0.1 μm diameter, 35 μm length)
In addition, ultrasonic waves were used for mixing and stirring in a predetermined solvent, and then mixed and pulverized using a resin pot and Si ₃ N ₄ balls. Mixing times were 1 hour, 5 hours, 10 hours, 30 hours, 75 hours, and 150 hours, respectively, and 6 types of adjusted powder samples were prepared. Each of the obtained samples was dried using a spray dryer and then sintered (1800 ° C. × 1 Hr) in an inert gas atmosphere with a hot press machine. And
The adjusted powder samples were observed with an electron microscope, and the sintered samples were processed into test pieces and subjected to a strength test and a sliding test. The respective results are shown in FIGS.
Shown in Figures and 7. Here, in FIG.
The change in the average length of the SiC whiskers in the prepared powder sample with respect to the mixing time of the raw material powder is shown. Fig. 6 shows the four points of the sintered sample with respect to the average length of the SiC whiskers in the sintered sample. The change in bending strength is shown in FIG. 7. The change in the friction coefficient with respect to the sliding test time is shown in FIG.
A comparison is made with the one without C whiskers (that is, the comparative example).

The above results show that high strength can be obtained when the average length of the SiC whiskers contained in the sintered sample is 5 μm or less, and SiC whiskers having such an average length are produced in the sintered body. To do so, it is desirable that the mixing time of the raw material powder is at least 75 hours or longer. As a result of a sliding test, it was confirmed that the sintered body containing the SiC whiskers exhibited better sliding characteristics than the sintered body containing no SiC whiskers.

Example 6 Using the same raw material powder as in Example 2, Y ₂
O ₃ : 5% by weight, CeO ₂ : 2% by weight, MgO: 0.5% by weight, ZrO ₂ : 1% by weight are mixed, and further 10% by weight of SiC whiskers are added,
After mixing and pulverizing for an hour, it was dried and sintered. When the thus obtained sintered body was observed and tested in the same manner as in Example 5, the same result as that of Example 2 was obtained.

Example 7 Si ₃ N _{4 having} an average particle size of 0.1 μm, Y ₂ O _{3 having} an average particle size of 0.4 μm,
Raw material powders of CeO _{2 having} an average particle diameter of 0.4 μm, MgO having an average particle diameter of 0.2 μm and other compounds were mixed at the ratios shown in Table 2, and mixed and ground for about 25 hours using a vibration mill. The raw material thus obtained is dried to prepare a mixed powder, and the prepared powder is sintered using a hot pressing device or a hot isostatic pressing device under the temperature conditions and the nitrogen gas atmosphere described in the second indication, and then predetermined. The ceramic sliding members NO1 to NO11 according to the present invention were obtained by performing the mechanical processing and the finishing processing. Separately from this, a ceramic sliding member NO12 of a comparative example was prepared under the same conditions except that the composition limit range of the present invention was
I got 19. As a result of chemical analysis of these ceramic sliding members, Y, Ce, Mg and oxides of Group IIa, IIIa, IVa, Va of the periodic table excluding Ce, Mg in the ceramic sliding members NO1 to 19, Compositions of one or more of nitrides, borides, carbides, and composite compounds thereof were almost in agreement with the formulation composition. In addition, the strength of these ceramic sliding members (kgf / mm
² ), impact value (Kgfm), wear amount (g) and evaluation of sliding characteristics are shown in Table 2. The products Nos. 3 to 9 of the present invention and the comparative examples Nos. 12 to 17 shown in Table 2 were sintered by a hot isostatic pressing device, and the others were sintered by a hot pressing device. Inventive products Nos. 6 and 11 were once held at 1300 ° C. after temperature reduction after sintering, and Comparative Example NO17 was once held at 1300 ° C. during temperature reduction after sintering. The products NO8 and 10 of the present invention are examples in which one or more kinds of oxides, nitrides, borides, carbides of lanthanide elements and composite compounds thereof are contained.

According to this Table 2, it can be seen that all of the products of the present invention show extremely good sliding characteristics, whereas the comparative examples do not have good sliding characteristics. For example, Comparative Example NO
In 16,17,19, the wear amount was large, in Comparative Example NO13, seizure was large and measurement was impossible, and in Comparative Example NO14,18, the opponent's aggression was observed, and in Comparative Example NO12,13, the strength was insufficient, N
A chip occurred at O11.

[Brief description of the drawings]

Fig. 1 (a) and (b) are characteristic diagrams showing the results of EPMA analysis of the Si, Mg and Y component distributions before and after the sliding test of the silicon nitride sintered body. Fig. 2 shows the sintering aid. The characteristic diagram showing the change of strength of the obtained sintered body with respect to the average particle size of MgO used, Fig. 3 (a) and (b), use MgO with an average particle size of 1000Å and 2000Å as a sintering aid. Fig. 4 (a) and Fig. 4 (b) showing a cross section and a fractured state of the obtained sintered body, respectively, show the friction coefficient in the sliding test between the product NO1 of the present invention in Example 1 and the comparative example NO19. FIG. 5 is a characteristic diagram showing changes, FIG. 5 is a characteristic diagram showing changes in the average length of the SiC whiskers in the obtained adjusted powder sample with respect to the mixing time of the material powder in Example 5, and FIG. 6 is the baking in Example 5. Characteristics of changes in four-point bending strength of sintered samples with respect to the average length of SiC whiskers in sintered samples , FIG. 7 is a variation of the friction coefficient with respect to the sliding test time in Example 5,
FIG. 4 is a characteristic diagram showing a comparison between a device containing SiC whiskers (that is, that of the present embodiment) and a device not containing SiC whiskers (that is, a comparative example).

Claims (4)

(57) [Claims] 1. A sintered body containing Si ₃ N ₄ as a main component and containing Y, Mg and Ce, wherein the content of Y is ₂ to 20 in terms of Y ₂ O _3.
% By weight, content of Mg converted to MgO 0.1-0.9% by weight, C
The content of e is 1 to 10% by weight calculated as CeO ₂ , and the balance is Si ₃ N ₄
The ceramic sliding member is characterized by: 2. A sintered body containing Si ₃ N ₄ as a main component and containing Y, Mg, Ce, etc., wherein the content of Y is _{2 to 3} in terms of Y ₂ O _3.
20% by weight, the content of Mg is 0.1 to 0.9% by weight in terms of MgO, the content of Ce is 0.1 to 0.9% by weight in terms of CeO ₂ , Ce,
1 of Group IIa, IIIa, IVa, Va elements of the Periodic Table excluding Mg
A ceramic sliding member having a content of at least 15% by weight in terms of oxides, nitrides, borides, carbides and composite compounds thereof, with the balance being Si ₃ N ₄ . 3. Si ₂ N ₄ which is the main component, ₂ to 20% by weight of Y ₂ O ₃ , 0.1 to 0.9% by weight of MgO having an average particle size of 1500Å or less, and 1 to 10% by weight of CeO _2. A method for producing a ceramic sliding member, comprising: mixing and pulverizing a sintering aid containing a mixture to obtain a powder mixture, and then firing the mixture at 1600 to 1850 ° C. in an inert gas atmosphere. 4. A sintering aid containing Si ₃ N _{4 as} a main component and ₂ to 20% by weight of Y ₂ O ₃ , 0.1 to 0.9% by weight of MgO and 1 to 10% by weight of CeO _2. Mold the mixed powder obtained by mixing and crushing,
Next, after firing at 1600 to 1850 ° C in an inert gas atmosphere, and subjecting the obtained sintered body to predetermined machining, 1100
A method for manufacturing a ceramic sliding member, which comprises heat-treating at a temperature of -1500 ° C for 1-5 hours.