JPH05301775A - Member for pulverizer composed of silicon nitride-based sintered compact - Google Patents

Abstract

PURPOSE:To provide a material composition of a member for a pulverizer such as a lining material, a container or media, hardly worn not as the member for the pulverizer without being restricted by pulverizing conditions, etc. CONSTITUTION:The objective member is completed by finding a silicon nitride- based sintered compact to satisfy the requirements. This sintered compact has three conditions of firstly including an oxide such as Al2O3 or Y2O3 as a sintering assistant and substantially >=80wt.% sialon, secondly >=0 and <3.5 Z value of sialon and thirdly >=2.8g/cm<3> bulk density of the sintered compact as essential requirements. Thereby, the objective sintered compact for the member such as container of fine pulverizer, a lining material or media, excellent in strength and abrasion resistance and further toughness with hardly any abrasion wear is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crusher member such as a fine crusher container, a lining material, and a crushing medium used for finely crushing particles in a dry or wet manner.

[0002]

2. Description of the Related Art Conventionally, a ball mill, a sand mill, an attritor, a vibration mill, a hammer mill, a jet mill, a rod mill, a roller mill, a combination of a mortar and a pestle, etc. have been widely used as a fine pulverizer. These pulverizers use fine pulverizing media (media) such as balls and rollers, and mainly pulverize by friction and impact crushing force, and a device that performs high speed movement of particles to pulverize by the impact force. It is roughly divided into. Natural stones, porcelain, alumina, glass, plastics, steel and agate are used as crushing members such as lining materials and media for crushing, depending on the type of object to be crushed.

However, these materials are easily worn, wear powder is easily mixed in the object to be crushed, and it is difficult to separate the mixed wear powder from the finely pulverized product, which is a major obstacle in terms of product purity. Is becoming

Therefore, for example, when steel is used as a member for a crusher, a deironing step is added to the crushing step, or a hard alumina material is used in order to reduce mixed wear powder, Means such as the use of a member made of a material such as rubber or plastic that has little influence on the purity of the obtained fine powder and therefore allows a slight amount of abrasion powder to be mixed is adopted.

However, in recent ceramics, electronic materials, coating materials, and powder media, even small amounts of components in the object to be crushed mixed in the fine crushing process have a great influence, and as a member for such a crusher, the amount of wear is mixed. There has been a demand for a material that is absolutely small and has little influence on the physical properties of the fine powder.

From this sense, Japanese Patent Publication No. 2-20587 discloses that zirconia ceramics is used as a member for a crusher.

[0007]

However, zirconia ceramics are thermally deteriorated at 100 to 300 ° C. in water, the tetragonal structure on the surface is transformed into monoclinic crystals, and the wear resistance peculiar to tetragonal crystals is maintained. There is a problem that becomes difficult.
Further, the thermal conductivity of zirconia is lower than that of conventionally used alumina or steel. Therefore, when zirconia is used in the container of the medium agitation mill for ultra-fine pulverization and dispersion, the water cooling effect is significantly inferior to the conventional material, and the slurry temperature including the object to be pulverized is raised, which causes restrictions on the pulverization conditions. There is a drawback that the performance of the crusher cannot be fully utilized.

An object of the present invention is to provide a member for a crusher such as a lining material, a container, a medium, etc., which is not easily worn and is not restricted by crushing conditions and the like.

[0009]

The present invention has been completed with the finding that a silicon nitride sintered body satisfies the requirements, and is a member for a crusher having the following three conditions as essential conditions. ..

The first condition is that Al is used as a sintering aid.
_It is intended to contain oxides such as ₂ O ₃ and Y ₂ O ₃ and to contain substantially 80% by weight or more of sialon.

Since silicon nitride and sialon are covalently bonded substances, they are superior in mechanical properties such as strength and wear resistance to other ceramics such as alumina.
Therefore, if the content of sialon in the silicon nitride-based sintered body used as the crusher member is less than 80% by weight,
The strength and wear resistance of the sintered body itself are inferior.

As the second condition, the Z value of sialon is
0 or more, 3. It must be less than 5. Z value is
When it is 3.5 or more, the strength, toughness, and wear resistance of the silicon nitride sintered body cannot be satisfactory.

The third condition is that the bulk density of the sintered body is 2.8 g / cm ³ or more. When the bulk density is less than 2.8 g / cm ³ , many pores are present in the sintered body to form a porous structure, and the strength, toughness, and wear resistance are significantly reduced. Further, if it has a porous structure, the thermal conductivity is lowered, and the advantage of silicon nitride described above cannot be utilized depending on the pulverizer.

The member for a crusher according to the present invention is the above first member.
-When the third condition is satisfied, impurities such as Fe usually contained in silicon nitride may be contained up to about 1% by weight.

The crusher member of the present invention can be manufactured as follows.

Al ₂ O ₃ , Y in the silicon nitride powder
_A total of 20% by weight or less of ₂ O ₃ , AlN or the like is added as a sintering aid, and the mixture is prepared in a pot mill with a mixing-grinding device such as a ball mill or an attritor containing water or a solvent. At this time, a dispersant for the slurry, a binder for dry molding, and the like are added to obtain a molding slurry. The resulting slurry is dried and then isostatically press-molded, or is cast into a predetermined shape by a known molding method for ceramic products, and is processed if necessary. The molded body is subjected to a degreasing treatment in the next step or is directly degreased and fired in the sintering step. The firing temperature is 1400 to 1900 ° C. in a choking atmosphere. In this case, if the temperature is less than 1400 ° C, the density does not reach the predetermined value,
If the temperature exceeds 0 ° C, decomposition of silicon nitride occurs. In that case, the pressure inside the furnace is atmospheric pressure or under pressure, and the bulk density is 2.8 g / cm.
Obtain ³ or more sintered bodies. When the sintered body is a medium, the surface is finished smooth if necessary. In the case of a lining material, it is attached or fitted with an adhesive to the inner surface of the crusher with which the object to be crushed should come into contact.

[0017]

The mechanical properties such as strength and abrasion resistance due to the inclusion of 80% by weight or more of the covalent silicon nitride or sialon containing the sintering aid, which is the first condition, and the second condition Z value of sialon which is the condition of 0 or more, 3
． The strength, toughness, and wear resistance of the silicon nitride sintered body are improved by setting the ratio to be less than 5, and the compactness due to the bulk density of the sintered body being the third condition being 2.8 g / cm ³ or more. As a result, there is little wear as a member for a crusher, and even if a very small amount is mixed, the characteristics of the fine powder are not adversely affected.

[0018]

【Example】

Example 1 A composition having the composition shown in Table 1 was subjected to dispersion pulverization treatment by a wet method, 3% by weight of PVA was added as a molding aid, and pressure molding was performed at lton / cm ² with an isostatic press. The compact was sintered in nitrogen at 1750 ° C. for 2 hours under normal pressure to obtain a crushed media having a diameter of 10 mm. Further, a sintered body having a shape of 50 mm × 50 mm × 5 mm was prepared by the same method, processed into 4 mm × 3 mm × 40 mm, and then subjected to a bending test according to JIS standard. Sample No. 1-4 are
Sample No. 1 is a medium according to an embodiment of the present invention. 5-
8 is a comparative example. After measuring the bulk density of the obtained medium by the Archimedes method, the medium was put into a 2 liter pot mill, 800 cc of water and 1800 g of the medium were added, and a shearing test was performed at a rotation speed of 100 rpm. After operating for 48 hours, the media was taken out, washed and dried, and then the weight was measured to calculate the damage rate (%). The results are shown in Table 1. As shown in the wear rate of physical properties in the table, it is understood that the examples of the present invention are significantly superior to the comparative examples.

[0019]

[Table 1] Example 2 Silicon nitride powder having an average particle size of 0.3 μm and Al having an average particle size of 1 μm or less
₂ O ₃ 3%, Y ₂ O ₃ 5%, AlN21 Polytype 2
% Was wet-dispersed and pulverized, and then dried to obtain a molding powder. This powder was granulated into a ball body having a diameter of 1.2 mm by a tumbling method and fired in a nitrogen atmosphere at 1750 ° C. for 2 hours to give a bulk density of 3.23 g / cm ³ , 1 mm.
Diameter Sialon media was obtained. A shear wear test was conducted on the obtained media under the test conditions shown in Table 2 for 400 hours. As a comparative example, commercially available zirconia,
Alumina media was also tested. It can be seen that the sialon media according to the present invention is significantly superior to zirconia and alumina.

[0020]

[Table 2] Example 3 A cap of an end-sealed tube having a sintered body equivalent to that of Sialon of Example 2 and having upper and lower end diameters of 25 mm and 10 mm and a length of 40 mm was manufactured as a trial, and a cover for a stirring arm of a sand grinder mill was manufactured. Installed as.

28 kg of zirconia media having a diameter of 3 mm was put into a 10 liter crusher, and the rotation speed was 700 rp.
After 1,000 hours of running in water, the weight reduction rate of the cap sintered body was examined. As a comparative example, commercially available 3 mol% Y ₂
O ₃ -ZrO ₂ sintered body (density 6.02 g / cm ³ ) and 9
A 5% Al ₂ O ₃ sintered body (density, 3.70 g / cm ³ ) was also tested under the same conditions. The results are shown in Table 3. There are 26 caps attached to the crusher, and the weight reduction rate of each cap is ± 0.05 for Sialon.
The variation range is within%, and Y ₂ O ₃ —ZnO ₂ is
It was within ± 1%. The values in Table 3 are shown as the average value of 26 caps.

[0022]

[Table 3] Example 4 Sintered body equivalent to Sialon of Example 2 and 3 mol% Y ₂
A tube shape of O ₃ —ZnO ₂ sintered body 210 mm outer diameter × 195 mm inner diameter × 470 mm length was experimentally manufactured. Each tube was set as a lining material for a sand grinder mill, and a 325 mesh alumina powder uncrushed test was conducted. Table 4 shows the grinding conditions and the results.

From the results shown in Table 4, it can be seen that when Sialon is used as the lining material, an increase in the slurry temperature can be prevented as compared with zirconia, and the pulverization characteristics are good.

[0024]

[Table 4]

[0025]

The present invention has the following effects.

(1) The resistance to abrasion is extremely high, and even when it is used for a crusher member such as a container, an inner lining, and a crushing media, the amount of wear is extremely small, and it is extremely little mixed with the fine powder. Does not reduce the purity.

(2) It can be manufactured relatively easily according to the conventional sintering method, does not affect the basic structure of the crushing at all, and can be directly applied to the conventional fine crusher.

Claims (1)

[Claims] 1. An oxide as a sintering aid, silicon nitride, or a Z value of 0 or more, 3. Substantially 80 wt% or more of less than 5 sialon, and the bulk density of the sintered body is 2.8 g.
A member for a crusher, which is made of a silicon nitride-based sintered body having a density of not less than / cm ³ .