JPH06128032A - Sintered zirconia for sliding part and it s production - Google Patents

Abstract

PURPOSE:To provide a sintered zirconia suitable for various sliding parts giving remarkably low abrasion on the counter metallic part and to provide a process for producing the sintered zirconia. CONSTITUTION:The sintered zirconia for sliding part is a sintered material composed mainly of zirconia and having an alumina content of <=1.5wt.%. The sintered zirconia for sliding part is produced by using a crushing member having an alumina content of <=3wt.% for the crushing of the zirconia raw material and other raw materials. As an alternative, the alumina content of the sintered zirconia for sliding part is decreased to <=1.5wt.% by adjusting the time for crushing the zirconia raw material and other raw materials and the alumina content of the crushing member to be used for the crushing of the raw materials.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zirconia sintered body for sliding parts and a method for producing the same, and more specifically, it has a significantly small amount of wear of a mating metal member and can be suitably used for various sliding parts. The present invention relates to a zirconia sintered body for moving parts and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, it has been attempted to use various ceramic materials such as oxide-based, carbide-based, and nitride-based ceramic materials as constituent materials of mechanical parts required to have heat resistance and wear resistance.

Among them, the zirconia sintered body is particularly high in strength and toughness, and is also excellent in heat insulation. Therefore, as disclosed in JP-A-57-191274, mechanical parts such as engine parts are disclosed. The application to is being actively studied. By the way, there are many sliding parts that move when the mating metal member is in contact with the mechanical parts that have been attempted to use this zirconia sintered body, such as engine tappets, cams, rocker arms, and cylinder liners. Is being considered for use.

[0004]

However, when a zirconia sintered body is used as the sliding part, the zirconia sintered body itself does not wear, but the amount of wear of the mating metal member increases remarkably. There is a problem that it cannot be used suitably.

The present invention has been made to solve the above problems, and the amount of wear of the mating metal member is extremely small, and the zirconia sintered body for sliding parts which can be suitably used for various sliding parts and the manufacturing method thereof are provided. The purpose is to provide.

[0006]

The invention according to claim 1 for attaining this object is a sintered body containing zirconia as a main component, wherein the content of alumina is 1.5% by weight or less. The gist is a zirconia sintered body for sliding parts, which is characterized by

The invention of claim 2 is the same as claim 1
The method for producing a zirconia sintered body for sliding parts according to the item 1, wherein a crushing member having an alumina content of 3% by weight or less is used as a crushing member for crushing a zirconia raw material and another raw material. The gist is the method for producing a zirconia sintered body for sliding parts.

Further, the invention of claim 3 is the same as claim 1
In the method for producing a zirconia sintered body for sliding parts according to the paragraph, based on the pulverizing time for pulverizing the zirconia raw material and the other raw material, and the content of alumina in the pulverizing member used for the pulverization, The gist of the method for producing a zirconia sintered body for sliding parts is that the alumina content of the zirconia sintered body for sliding is set to 1.5% by weight or less.

The zirconia sintered body for sliding parts is made of, for example, Y ₂ O ₃ , CeO ₂ , Yb ₂ O ₃ , CaO or MgO in order to achieve high strength and high toughness. Stabilizing additives may be added. Among these stabilizing additives, Y ₂ O ₃ is preferably used from the viewpoint of improving strength, and the addition amount thereof is preferably 2.5 to 8.0% by weight.

Further, impurities such as SiO ₂ and TiO ₂ in the zirconia sintered body for sliding parts or oxides such as Cr, Mn, Fe, Co, Ni, Cu, Mo and Er as colorants are used. The content is preferably small in terms of strength characteristics, but when coloring is required in appearance, the coloring oxides may be added in the range of 1.5% by weight or less.

The surface state of the zirconia sintered body for sliding parts is preferably as smooth as possible because it is used as sliding parts. However, after burning, barrel polishing or diamond grindstone processing is performed or baking is performed. There is no particular limitation on the surface finishing method such as not performing processing after releasing.

The porosity of the zirconia sintered body for sliding parts is preferably 5% or less in order to maintain its strength, but it is preferable to use it by impregnating the zirconia sintered body with a lubricant. When the sliding characteristics are improved, a sintered body having a high porosity may be used. The sliding component is not particularly limited in its application as long as it is a component that slides in contact with metal. For example, a rocker arm used in an engine,
In addition to tappets, injector dowels, shims, etc., it can be used for various components such as ball bearings, roller bearings, and other bearing components.

As a method of using the sliding component,
The sliding part may be slid in a lubricant so that the temperature does not rise. Examples of the crushing member for crushing the zirconia raw material and the other raw material include a crushing container such as a pot mill and trommel, a lining material for the crushing container, and a ball stone used in the crushing container. The crushing member of the present invention includes not only crushing raw materials but also those used for the purpose of mixing.

[0014]

The present inventor has conducted earnest research on the phenomenon that the amount of wear of the mating metal member significantly increases due to the use of the conventional sliding parts made of the zirconia sintered body. We have found out that the cause of this is alumina.

FIG. 3A shows a zirconia sintered body containing alumina (ZrO ₂ : 92 wt%, Y ₂ O ₃ : 4 wt%, A
1 ₂ O ₃ : 4% by weight) is a photograph of a grain structure of a mirror-polished product by a secondary electron image, and FIG. 3 (b) is a grain structure of the same zirconia sintered body by a characteristic X-ray of an Al element. It is a photograph. As is clear from these photographs, alumina particles are segregated in the zirconia sintered body. That is, among these segregated alumina particles, those exposed on the sliding surface in contact with the mating metal member mechanically scrape off the surface of the mating metal member.

Further, it has been found that the above-mentioned alumina is mixed in during the manufacturing process of the zirconia sintered body. That is, the mixing of alumina into the zirconia sintered body, the step of pulverizing and mixing the zirconia raw material and another raw material (for example, the step of pulverizing and mixing the stabilizing additive such as zirconia and yttria) It has been found to occur by using crushing members such as spheres and trommel.

Also, when the mixed raw material is produced by the coprecipitation method (for example, when the zirconia-yttria type powder is produced by the coprecipitation method), the secondary particles aggregated by the calcination after the coprecipitation are loosened. Since alumina spherulites and alumina trommel are used, it has been found that alumina is mixed.

Therefore, in the zirconia sintered body for sliding parts according to the first aspect of the present invention, by setting the content of alumina to 1.5% by weight or less, the mating metal member is mechanically increased in quantity by the alumina particles. It is not scraped off, and the amount of wear of the mating metal member is significantly reduced.

In the method for producing a zirconia sintered body for sliding parts according to the second aspect of the present invention, by using an alumina content of 3% by weight or less in the crushing member, alumina is mixed in the production process. The amount can be kept low, and the alumina content in the zirconia sintered body can be 1.5% by weight or less.

Further, in the method for producing a zirconia sintered body for sliding parts according to the third aspect of the present invention, the pulverizing time for pulverizing the zirconia raw material and the other raw material, and the content of alumina in the pulverizing member used for the pulverization. Based on the amount, the amount of alumina mixed in the manufacturing process can be suppressed low. That is, for example, even when the content of alumina in the crushing member is large, the amount of alumina mixed can be suppressed to be low by appropriately shortening the crushing time, and the alumina content of the sliding zirconia sintered body can be 1. It can be 5% by weight or less.

[0021]

EXAMPLES In order to further clarify the operation of the present invention described above, preferred examples of the present invention will be described below. [Example 1] First, six types of zirconia sintered bodies having different alumina contents were manufactured as follows.

Raw materials of ZrO ₂ , Y ₂ O ₃ and Al ₂ O ₃ (each having a purity of 99.9%) were prepared in four ratios shown in Table 1 (sample Nos. 1 to 4 of the examples). Each of them was mixed with sphere and trommel for 2 hours to prepare four kinds of mixed raw materials. The composition of spheres and trommel is ZrO 2.
_{Two ninety-three} wt%, Y ₂ O _3: 4 wt%, Al ₂ O _3: was used in 3% by weight.

Then, the water content in the mixed raw material is adjusted to 40%.
The mixture was made to be wt%, an appropriate amount of a binder was added, and the mixture was further mixed, and then granulated by a spray dryer at 170 ° C. Then, after die press molding at a pressure of 100 MPa, this molded product was fired at 1550 ° C. for 1 hour to obtain a zirconia sintered body. The component composition of this zirconia sintered body (measured by fluorescent X-ray analysis) was as shown in Table 1.

Here, as is clear from the comparison of the composition value of the sintered body of Al ₂ O ₃ and the value of the raw material mixing ratio in Table 1, in Example 1, Al ₂ was used for pulverizing and mixing the raw materials. Since spheres and trommel with a low O ₃ content (Al ₂ O ₃ : 3% by weight) are used, the amount of alumina mixed in the zirconia sintered body is 0 to 0.2% by weight. Turned out to be few.

Next, a sliding test using this zirconia sintered body as a sliding component will be described. First, the zirconia sintered body obtained as described above was used as a plate-shaped test piece 1 having a curved upper surface as shown in FIG. 1 using a diamond grindstone.
(A = 20 mm, B = 10 mm, C = 3 mm, D = 5 m
m, the radius of curvature of the upper surface R = 50 mm). The maximum surface roughness of Specimen 1 was 2.0 μm.

Next, as shown in FIG. 2, the test piece 1 was brazed and attached to the cam contact portion 7 of the cast iron rocker arm 5 of the commercially available diesel engine 3. In this diesel engine 3, the central portion 2 of the test piece 1 has a valve spring 11
2, the cam 9 is constantly pressed against the cam 9, and when the diesel engine 3 is operated, the cam 9 rotates and the rocker arm 5 swings up and down to move the valve 13 up and down. It is a moving mechanism. Here, the test conditions such as the material of the cam 9 are shown below.

Cam material: JIS-S50C Lubricating oil temperature: 80 ° C. Valve spring load: 100 kg (cam clearance and test piece are always in contact with valve clearance -0.3 mm) Then, test piece 1 is attached as described above. After that, the diesel engine was operated for 100 hours and the cam was set to 400 rpm.
Then, the sliding test was performed by rotating the sample No. 1 and the maximum wear amount of the cam nose 15 and the central portion 2 of the sample 1 was measured as the surface roughness using a surface roughness meter. The results are shown in Table 1.

As is apparent from the results shown in Table 1, the wear amount of the test piece 1 is the same as that of the sample No. 1 to 4 all less than 2.0 μm,
It was good. Further, regarding the cam nose wear amount, it was found that the wear amount was smaller as the alumina content in the sintered body was smaller. Then, the sample No. 1 of Example 1 having an alumina content of 1.5% by weight or less. In Nos. 1 to 4, the cam nose wear amount was remarkably small at 3.3 μm or less, and it was found to be suitable as a sliding component. Comparative Example 1 Next, Comparative Example 1 will be described.

In the same manner as in Example 1, ZrO ₂ , Y ₂
O ₃ and Al ₂ O ₃ raw materials were mixed at two different ratios shown in Table 1 (Sample Nos. 5 and 6 of Comparative Examples), and raw material powders were prepared using the same spheres and trommel as in Example 1, respectively. A zirconia sintered body was prepared in the same manner as in Example 1. Component composition of this zirconia sintered body (measured by fluorescent X-ray analysis)
Was as shown in Table 1.

Then, a sliding test was conducted in the same manner as in Example 1 to measure the maximum amount of wear of the central portion 2 of the test piece 1 and the cam nose 15. The results are shown in Table 1. As is clear from the results in Table 1, the wear amount of the test piece 1 is as shown in the sample No. Both 5 and 6 2.
It was less than 0 μm, but regarding the wear amount of the cam nose,
It was 17.5 μm or more, which was not preferable as a sliding part.

As a comparative example, a sliding test was also conducted on a chill cast iron sample (Sample No. 7). As is clear from the results in Table 1, the amounts of wear of the sample and the cam nose were 65 and 115 μm, both of which are sample No. It was a value larger than 1 to 6.

[0032]

[Table 1]

[Example 2] ZrO ₂ and Y ₂ O ₃ raw materials (each having a purity of 99.9%) were prepared at a ratio of ZrO ₂ : 95.0% by weight and Y ₂ O ₃ : 5.0% by weight. Formulated and mixed with spheres and trommel as in Example 1.
Here, in Example 2, two kinds of mixed raw materials (Sample No. 3) in which the mixing time was changed as shown in Table 2 were used using spherulites and trommel having an Al ₂ O ₃ content of 92% by weight.
8, 9) was prepared.

Subsequently, this mixed raw material was granulated, molded and fired in the same manner as in Example 1 to obtain a zirconia sintered body. The component composition (measured by fluorescent X-ray analysis) of the obtained sintered body was as shown in Table 2. The “others” in the composition of the sintered body in Table 2 indicate other components such as SiO ₂ .

Then, the same sliding test as in Example 1 was conducted to measure the wear amounts of the test piece 1 and the cam nose 15. The results are shown in Table 2. As is clear from the values of Al ₂ O _{3 in} the composition of the sintered body in Table 2, in the case of using the boulder containing 92% by weight of Al ₂ O ₃ and the trommel (Example 2), ₃ of Al ₂ O ₃ was used. When using boulders and trommel containing wt% (Example 1)
The amount of Al ₂ O ₃ mixed in the sintered body is larger than that of the above, and this amount of mixing increases as the mixing time increases. However, as in this Example 2, A in spheres and trommel
Even when the content of l ₂ O ₃ is as high as 92% by weight, the amount of Al ₂ O ₃ mixed in the sintered body can be suppressed to 1.4% by weight or less if the pulverization time is within 8 hours.

That is, as described above, in the sample of Example 2 (No. 8 and 9) in which the mixing time was within 8 hours and the Al ₂ O ₃ content was 1.4 wt% or less, the cam nose The amount of wear is 2.9 μm or less, which is extremely small, and is suitable as a sliding component. In addition, as is clear from the results in Table 2, test piece 1
The wear amount of the sample No. Both 8 and 9 were less than 2.0 μm, which was good. Comparative Example 2 Next, Comparative Example 2 will be described.

[0037] formulated with ZrO ₂ and Y ₂ O ₃ raw material in the same proportions as in Example 2, which in the same manner as in Example 2 Al
By using spheres and trommel having a ₂ O ₃ content of 92% by weight, three types of comparative raw materials (Sample Nos. 10 to 12) having different mixing times as shown in Table 2 were prepared. A zirconia sintered body was obtained. The component composition of this zirconia sintered body was as shown in Table 3.

Then, a sliding test was conducted in the same manner as in Example 2 to measure the maximum wear amount of the central portion 2 of the test piece 1 and the cam nose 15. The results are shown in Table 2. As is clear from the results in Table 2, the wear amount of the test piece 1 is the same as that of the sample No. 1 of Comparative Example 2. 10
.About.12 were all less than 2.0 .mu.m, but the cam nose wear amount was as large as 15.0 .mu.m or more, which was not preferable as a sliding part.

[0039]

[Table 2]

[Example 3] First, a ZrO ₂ -Y ₂ O ₃ based powder, which is a raw material for a zirconia sintered body, was manufactured by a well-known coprecipitation method. Here, in Example 3, in the process of loosening and crushing the secondary agglomerated particles obtained by the calcination after coprecipitation, the composition was ZrO ₂ : 93 wt%, Y ₂ O ₃ :
4% by weight, Al ₂ O ₃ : 3% by weight of boulder and trommel (crushing member A) were used. The crushing process was performed for 20 hours.

The ZrO ₂ --Y ₂ obtained as described above is then used.
A binder was added to O ₃ -based powder (Sample No. 13) in the same manner as in Examples 1 and 2, and the mixture was granulated, molded, and fired to obtain a zirconia sintered body. In addition, the sample No. The mixing member A was used for both 13 and 14.

The component composition (measured by fluorescent X-ray analysis) of the sintered body obtained as described above is shown in Table 3. In addition, "other" of the sintered body composition in Table 3 means SiO ₂
Other components such as Then, the obtained zirconia sintered body was processed into a test piece 1 and a sliding test similar to that in Examples 1 and 2 was performed to measure the wear amounts of the test piece 1 and the cam nose 15. The results are shown in Table 3.

As is clear from the value of Al ₂ O _{3 in} the sintered body composition shown in Table 3, the crushing member A (Al ₂
Sample No. 3 of Example 3 using spheres and trommel having an O ₃ content of 3% by weight. In No. 13, Al ₂ O ₃ was hardly mixed. Then, the content of Al ₂ O ₃ is 1.
The sample No. 3 of Example 3 containing 5% by weight or less. The wear amount of the cam nose No. 13 was 1.8 μm, which is extremely small, and is suitable as a sliding component. [Comparative Example 3] In Comparative Example 3, in the step of loosening and pulverizing the secondary agglomerated particles obtained by coprecipitation in Example 3, spheres and trommel containing 92% by weight of Al ₂ O ₃ (pulverizing member B) was used. Other conditions are the same as in the third embodiment.

Table 3 shows the component composition of the sintered body and the wear amounts of the test piece 1 and the cam nose 15. As is clear from the results in Table 3, the sample No. 3 of Comparative Example 3 using the crushed member B (the boulder and the trommel having the Al ₂ O ₃ content of 92% by weight) was used. 2.3% by weight, that is, 1.5% by weight or more of Al ₂ O ₃ is mixed in No. 14.

The wear amount of the test piece 1 was less than 2.0 μm, but the wear amount of the cam nose was as large as 7.8 μm, which was not preferable as a sliding part.

[0046]

[Table 3]

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and may be implemented in various modes without departing from the scope of the present invention. Of course.

[0048]

As described in detail above, in the zirconia sintered body for sliding parts of the present invention, the amount of wear of the mating metal member is extremely small. Therefore, the life of the sliding component is extended, and the number of maintenance operations is reduced.

According to the method for manufacturing a zirconia sintered body for sliding parts of the present invention, the amount of alumina mixed in the manufacturing process can be suppressed to a low level, and the alumina content in the zirconia sintered body is 1. It becomes possible to obtain the zirconia sintered body for sliding parts of the present invention when the content is 5% by weight or less.

[Brief description of drawings]

FIG. 1 is a perspective view of a zirconia sintered body test piece used in a sliding test of first to third examples.

FIG. 2 is an explanatory diagram showing a sliding test of first to third examples.

FIG. 3 is a photograph showing a particle structure of a zirconia sintered body containing alumina.

[Explanation of symbols]

 1 ... Specimen 3 ... Diesel engine 5 ... Rocker arm

Claims (3)

[Claims] 1. A zirconia sintered body for sliding parts, which is a sintered body containing zirconia as a main component, wherein the content of alumina is 1.5% by weight or less. 2. The method for producing a zirconia sintered body for sliding parts according to claim 1, wherein the zirconia raw material and the other raw material are pulverized members having an alumina content of 3% by weight or less. The method for producing a zirconia sintered body for sliding parts, characterized in that 3. A method of manufacturing a zirconia sintered body for sliding parts according to claim 1, wherein a pulverizing time for pulverizing a zirconia raw material and another raw material, and a pulverizing member used for the pulverizing A method for producing a zirconia sintered body for sliding parts, wherein the alumina content of the sliding zirconia sintered body is 1.5% by weight or less based on the alumina content of 1.