JP2000279833A - Crusher - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crusher equipped with a lightweight and inexpensive container excellent in abrasion resistance and high in heat conductivity. SOLUTION: At least the inner wall of a container 2 is based on Al2O3 and contains 0.2-2 wt.% of Ti in terms of TiO2, 0-2 wt.% of Mg in terms of MgO, 0-2 wt.% of at least one element selected from the group consisting of rare earth elements, Zr, hf and Si in total in terms of oxide and inevitable impurities the total amt. of which is 1.5 wt.% or less in terms of oxide. This inner wall is produced from an oxide sintered body with fracture toughness of 4.0 MPam1/2 or more and heat conductivity of 25 W/mK or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an abrasion-resistant material,
The present invention relates to a highly durable pulverizer provided with a container having high thermal conductivity.

[0002]

2. Description of the Related Art In general, powder milling methods include ball milling, sand milling, as well as hand milling using a mortar and pestle.
Various types of pulverization are carried out using containers such as attritor mills, disk mills, vibratory mills, hammer mills, jet mills, and roller mills. The method is widely used.

Conventionally, containers of the above-mentioned pulverizers include natural stone, porcelain made of Al ₂ O ₃ ceramics, glass,
Plastics, steels, agates and the like are used, but these materials are liable to be worn away, have a short life, and have a serious problem that abrasion powder is mixed into the material to be ground.

Therefore, as a high-hardness and high-toughness porcelain material having high abrasion resistance, Al ₂ O ₃ -based crystals can be refined,
A technique of adding SiC or ZrO ₂ to l ₂ O ₃ to form a composite (Japanese Patent Application Laid-Open Nos. 61-122164 and
No. 3,139,044), or partially stabilized ZrO ₂ ceramics having high abrasion resistance have been developed and used.

[0005]

[SUMMARY OF THE INVENTION However, among the ceramic materials described above, only the crystal grain-refining of Al ₂ O ₃ is hardness low toughness and abrasion resistance of the improvement to what is improved, also, Al ₂ When ZrO ₂ is added to O ₃ and combined, the hardness is reduced, so that the improvement in wear resistance is small. Further, when SiC is added to Al ₂ O ₃ , the production cost is greatly increased. There was a problem.

[0006] Further, the partially stabilized ZrO ₂ ceramics have low thermal conductivity, so that the temperature of the wear surface of the container rises extremely due to the impact or friction of the material to be ground on the container during the grinding. And toughness etc. deteriorate, abrasion resistance decreases, and in some cases cracks etc. occur on the inner surface of the container,
Abnormal wear could occur.

[0007] When grinding a slurry containing an organic solvent in particular, a water cooling pipe for cooling is arranged on the outer periphery of the container in order to avoid a rise in the temperature of the slurry and an increase in the pressure inside the container. If the thermal conductivity of the container is low,
There is a problem that the temperature rise of the slurry cannot be suppressed, and further, a temperature difference between the inner surface and the outer surface of the container becomes large, and a stress due to a difference in thermal expansion occurs, which may lead to damage of the container.

Accordingly, an object of the present invention is to form a container of a pulverizer at a low cost by using a material having high hardness, high toughness, high abrasion resistance and high thermal conductivity at a low cost. And a low-cost pulverizer.

[0009]

Means for Solving the Problems As a result of repeated studies on the material constituting the container, the present inventors have found that an oxide sintered body having a high hardness, a high toughness and a thermal conductivity of a specific value or more is used. This led to the discovery that the above-mentioned problems could be solved, leading to the present invention.

That is, the pulverizer of the present invention stores and grinds an object to be pulverized in a container, wherein at least the inner wall of the container has Al ₂ O ₃ as a main component and Ti has a Ti content.
0.2 to 2% by weight in terms of O ₂ , and 0% of Mg in terms of MgO.
And 2% by weight and a total amount of at least one oxide selected from the group consisting of rare earth elements, Zr, Hf and Si in terms of oxide.
To 2% by weight, and the total amount of unavoidable impurities is 1.
5% by weight or less, and fracture toughness of 4.0 MPam ^1/2
As described above, it is characterized by comprising an oxide sintered body having a thermal conductivity of 25 W / mK or more.

Here, in order to improve the wear resistance,
The oxide sintered body is composed of Al ₂ O ₃ quality crystal and the Al ₂ O ₃
And oxide fine particles containing Ti and / or Mg dispersed in the porous crystal grains, and the Vickers hardness of the oxide sintered body is preferably 18.5 GPa or more.

Further, 30% by volume of the Al ₂ O ₃ crystalline
When the above has anisotropy with an aspect ratio of 4 or more, crack propagation resistance is significantly increased, fracture toughness is improved, and wear resistance and reliability are improved.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A crusher of the present invention will be described with reference to FIG. 1 which is a schematic sectional view of one example. FIG.
Is a continuous rotating disk mill type pulverizer, and pulverizer 1
Is composed of a container (cylindrical sleeve) 2 and a disk member 3. In the container 2, a medium 4 such as a ball and a powdery or slurry-like material to be crushed are introduced, and the disk member 3 rotates. By doing so, the medium 4 and the object to be crushed rotate, and the medium 4 and the object to be crushed can be crushed by collision.

Further, the container 2 is provided with a crushed material injection 5 and a crushed material discharge port 6 for introducing or discharging the crushed material into or from the container. A water cooling pipe 7 for cooling the inside of the tube 2 is provided.

Here, at least the inner wall of the container 2 is made of Al
_The main component is ₂ O ₃ , and Ti is 0.2 to _{2 in} terms of TiO _2.
% Of Mg, 0 to 2% by weight of Mg in terms of MgO, and at least one selected from the group consisting of rare earth elements, Zr, Hf, and Si.
It is made of an oxide sintered body containing 0 to 2% by weight in total as oxides and 1.5% by weight or less in total of inevitable impurities as oxides.

According to such a sintered body, the strength and toughness can be remarkably increased with a small number of sub-components other than alumina, and since the sintered body has a high thermal conductivity, the temperature in the container increases due to heat generation during pulverization. Or the temperature of the inner and outer surfaces of the container becomes uneven and stress can be prevented from occurring,
In particular, cracks and the like generated on the inner surface of the container can be prevented.

Of the above components, Ti is a component that forms a solid solution or precipitates in the alumina crystal grains, and thereby induces strain and the like in the alumina crystal grains, thereby increasing the hardness and strength of the grains. . That is, T of Ti
When iO ₂ equivalent amount is less than 0.2 wt%, high hardness of the particles, a high strength is insufficient, the terms of TiO ₂ amount is larger than 2 wt%, Al ₂ in the grain boundary of the sintered body TiO _{5 and the} like may precipitate and the thermal conductivity of the sintered body may decrease, and the abrasion resistance may decrease. Desired range of Ti is 0.5 to 2% by weight in terms of TiO ₂ weight.

Further, according to the present invention, as an additional component, T
By adding Mg, a rare earth element, Zr, Hf, Si or the like in addition to i, it is possible to increase the hardness and strength of the sintered body.
Of these, Mg can form a solid solution or precipitate in the alumina-based crystal particles to increase the hardness and strength of the sintered body. However, when the added amount of MgO exceeds 2% by weight, Al ₂ MgO _{4 and the} like precipitate at the grain boundaries, and the thermal conductivity decreases. The desirable range of Mg is 0.5-1.5% by weight.

The rare earth elements, Zr, Hf, and Si are mainly present at the grain boundaries, and the difference in thermal expansion coefficient can increase the hardness of the sintered body, and induces cracks at the grain boundaries. Can be inhibited, and the toughness can be improved.

If these components are added in too large an amount, the strength or the thermal conductivity may be reduced. Therefore, at least one selected from the group consisting of rare earth elements, Zr, Hf, and Si is preferred. The total amount is 0-2% by weight, especially 0.5-
It is important that it be 1.5% by weight.

When the content of the additive is less than the predetermined range, the effect of improving the toughness with respect to alumina is small. On the other hand, when the content is large, the thermal conductivity is reduced, and in some cases, coarse crystal grains of alumina are reduced. The formation may cause a decrease in wear resistance.

The rare earth element is defined as the third element in the periodic table.
It refers to the element of the a group, but among them, from the effect of improving toughness,
Y, La, Ce, Pr, Nd, Sm are preferably used,
Further, Y, La, Ce, and Pr are preferable.

The unavoidable impurities are components that are mixed in the raw material or at the time of production. Specifically, K, Na,
Ca, Fe, and the like, but these unavoidable impurities reduce the wear resistance and thermal conductivity of the sintered body.
The total amount of unavoidable impurities is 1.5% by weight or less in terms of oxide,
In particular, it must be 1.0% by weight or less.

Further, according to the present invention, A
Oxide fine particles containing Ti and / or Mg are precipitated and dispersed in the l ₂ O ₃ crystal grains, and the hardness of the sintered body can be improved.

That is, the extraneous crystal particles are precipitated and present in the alumina crystal, thereby generating a residual stress in the crystal and increasing the hardness. In addition, the fine particles function as pinning, so that the fine particles function as cracks in the crack particles. And the strength and toughness of the porcelain can be increased.

Specific examples of the fine particles include Ti
It is composed of O ₂ , Al ₂ MgO ₄ , and Al ₂ TiO ₅ , and its size is set to 0.1 from the viewpoint of increasing hardness and wear resistance.
It is preferably 3 μm or less, particularly preferably 0.2 μm or less.

Further, the fine particles enhance the wear resistance of the porcelain, prevent the occurrence of cracks due to thermal stress, and
In order to maintain high thermal conductivity, it is desirable that a large amount be present near the surface of the porcelain.

According to the present invention, it is desirable that 30% by volume or more, particularly 50% by volume or more of the Al ₂ O ₃ crystalline particles are plate-like crystals having an anisotropy of an aspect ratio of 4 or more. Thereby, crack deflection and cross-linking effects are enhanced, and high toughness can be achieved.

The sintered body obtained under the above conditions has a fracture toughness of 4.0 MPam ^1/2 or more, particularly 5.0 MPam ^1/2.
As described above, excellent properties such as a hardness of 18.5 GPa or more, particularly 19 GPa or more, and a thermal conductivity of 25 W / mK or more, particularly 28 W / mK or more are obtained.

The disk member 3 is made of Al ₂ O ₃ or S
It is formed of a ceramic having high hardness and high toughness such as i ₃ N ₄ , but a ceramic having the above-described composition can also be used.

Further, in addition to the above, the pulverizer of the present invention stores and grinds a material to be pulverized in a container such as a ball mill, a sand mill, an attritor, a vibration mill, a hammer mill, a jet mill, and a roller mill. It can be used for members requiring abrasion resistance, such as containers, media, and crushed members.

According to the pulverizer of the present invention, the conventional Z
Since the weight can be reduced as compared with the rO ₂ -based sintered body or the like, handling and the like are easy, and it can be manufactured at low cost.

Next, a method for producing the pulverizer of the present invention will be described. First, to make the container, 98% purity
As described above, TiO ₂ , MgO, rare earth oxide, ZrO ₂ , and Hf were used for Al ₂ O ₃ having an average particle size of 0.2 to 1.5 μm.
A predetermined amount of O ₂ and SiO ₂ raw materials is added and mixed. The raw material may be any of oxide powder, metal powder, organic salts, inorganic salts and a solution thereof.

The above mixture is formed into an arbitrary shape by known molding means, for example, a mold press, a cold isostatic press, injection molding, extrusion molding, casting molding, etc.
It can be manufactured by firing at 200 to 1700 ° C. and densifying.

In the above calcination, when MgO is not added, it is kept in a non-oxidizing atmosphere and Ti ₂ Al ₂ O
After forming a solid solution dissolved amount increased to to _3, by holding in an oxidizing atmosphere, a solid solution of Ti element for dissolution of the Al ₂ O ₃ of Ti is reduced as TiO ₂ Al It can be precipitated in ₂ O ₃ crystal grains.

That is, when Ti is heated in a reducing atmosphere, the ionic valence of Ti becomes 3+, the solubility in alumina crystals increases, and a solid solution is formed. Then, return to the ionic valence of the Ti by treating the solid solution in an oxidizing atmosphere 4+, results solubility in alumina crystal is lowered, be deposited on Al ₂ O ₃ crystal Ti as TiO ₂ crystallites Can be.

When Ti and MgO are added, Ti ⁴⁺ and Mg ²⁺ can be substituted with Al ^{3+ in an} equimolar manner to form a solid solution. By increasing the amount of Mg and Mg dissolved in Al ₂ O ₃ to form a solid solution and then maintaining the same in a reducing atmosphere, Ti ⁴⁺ changes its valence to Ti ³⁺ , resulting in Mg ²⁺ can is to alone can not dissolve the Al ₂ O ₃ crystal, in the form of microcrystals of Al ₂ MgO ₄ is deposited on Al ₂ O ₃ crystal.

When the molar ratio between Ti and Mg is different, the material properties are not affected even if a small amount of excess component is present mainly at the grain boundaries.

Regarding the above calcination conditions, if the temperature during the solid solution or precipitation treatment is low, the desired structure is not formed, and if the temperature is high, the alumina crystal particles and precipitated particles are coarsened. Further, in order to densify the sintered body, a pressure and heat treatment such as HIP may be performed after the heat treatment.

A pulverized member made of an Al ₂ O ₃ or Si ₃ N ₄ sintered body produced by a known molding and firing method or a sintered body produced by the same method as described above is incorporated into the obtained container. Thereby, the pulverizer of the present invention can be manufactured.

[0041]

EXAMPLES (Example) Purity 99.9% or 98.0
%, An Al ₂ O ₃ powder having an average particle size of 0.7 μm, a TiO ₂ powder having a purity of 99.9% or more, a Mg (OH) ₂ powder,
Rare earth oxide powder, ZrO ₂ powder, HfO ₂ powder and S
The iO ₂ powder was prepared so that the composition of the sintered body was as shown in Table 1, and mixed with a rotary mill to obtain a mixed powder. Then, the mixed powder was formed into a shape of φ60 mm × 6 mm at a pressure of 1 t / cm ² , and further subjected to cold isostatic pressing at a pressure of 3 t / cm ² to form a formed body. Then, a sintered body having a relative density of 98.5% or more was obtained.

With respect to each of the obtained sintered bodies, intragranular precipitated particles were identified by surface XRD measurement. The aspect ratio was 4 by SEM observation and computer image processing.
The fraction of the above plate crystals was measured. Further, the Vickers hardness was measured on the mirror surface of the sintered body as a mechanical property, the fracture toughness was calculated by the Vickers indentation method, and the wear rate was measured by the pin-on-disk method (load 1 kg, speed 5 m / sec, 5 minutes). . Further, the thermal conductivity of a sample having a thickness of 1 mm was measured by a laser flash method. Table 2 shows the results.

Further, according to the same composition and conditions as those of the above sample, the outer diameter is 100 mm, the inner diameter is 85 mm, and the height is 200 m.
m (cylindrical sleeve) and a disk having an outer diameter of 80 mm were prepared, and these were assembled to prepare a continuous rotation disk mill type pulverizer shown in FIG.

The pulverizer thus obtained was mixed with A having an average particle size of 710 μm.
The slurry containing l ₂ O ₃ powder was continuously charged and operated at a disk rotation speed of 160 rpm for 20 hours. At this time, the temperature of the slurry immediately after being discharged was measured. After the test, the container (cylindrical sleeve) was removed, and the weight change before and after the test was converted into a wear volume. Further, a part of the inner surface of the container (cylindrical sleeve) was subjected to SEM observation to confirm the state of the inner wall. The results are shown in Table 2.

(Comparative Example 1) Using the Al ₂ O ₃ powder of the example, molding was performed in the same manner as in the example, and sintering was performed under the conditions shown in Table 1 to produce a sintered body and a pulverizer. went. The results are shown in Tables 1 and 2 (Sample No. 24).

[0046] (Comparative Example 2) ZrO ₂ powder of Example Y ₂
O ₃ powder was added at the ratio shown in Table 1, mixed and molded in the same manner as in the examples, and then fired under the conditions shown in Table 1 to produce a sintered body and a crusher, which were evaluated. The results are shown in Tables 1 and 2 (Sample No. 25).

[0047]

[Table 1]

[0048]

[Table 2]

According to Tables 1 and ₂ , the content of TiO ₂ was 0.2
Sample No. less than% by weight. In 3, the wear resistance is poor,
Shattering was observed on the inner wall of the container. In addition, the sample No. having a TiO ₂ content of more than 2% by weight. 7. The content of MgO is 2
% Of the sample no. In Nos. 12 and 13, the temperature of the slurry was 40 because of poor abrasion resistance and low thermal conductivity.
° C or higher.

Sample No. 2 in which the total amount of rare earth elements, Zr, Hf, and Si in terms of oxide exceeds 2% by weight. 1
Sample No. 4 and the total amount of unavoidable impurities exceeded 1.5% by weight in terms of oxide. In No. 15, the temperature of the slurry exceeded 40 ° C. due to poor abrasion resistance and low thermal conductivity.

Further, in Sample No. to which TiO ₂ and MgO were not added. In No. 24, the abrasion resistance was poor, and the abrasion volume was 13.2 cm ^3, and a large amount of contamination was mixed in the slurry. In addition, Sample No. made of a material containing ZrO ₂ as a main component was used. In the case of No. 25, the thermal conductivity is low, the temperature of the container increases, the abrasion resistance decreases, and the inner wall of the container cracks,
Chipping was observed, and the temperature of the slurry increased to 88 ° C.

On the other hand, the sintered body obtained according to the present invention has a hardness of 17.5 GPa or more and a fracture toughness of 4.2 M
Pam ^1/2 or more, excellent thermal conductivity of 25 W / mK or more.
It was 10 ⁶ mm ³ / kg · m or less, and there was no abnormality in the inner surface state of the container, suggesting a longer service life. Furthermore, the rise in temperature of the slurry could be suppressed.

[0053]

As described above in detail, according to the pulverizer of the present invention, since the container is excellent in abrasion resistance containing Al ₂ O ₃ as a main component and has high thermal conductivity, A highly reliable pulverizer can be provided at a low cost and at a low cost.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a crusher of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crusher 2 Container 3 Disk member 4 Media 5 Injection port of crushed object 6 Outlet of crushed object 7 Water cooling tube

Claims (4)

[Claims] 1. A crusher for storing and crushing an object to be crushed in a container, wherein at least an inner wall of the container is made of Al ₂ O _3.
As a main component, and 0.2 to 2% by weight of Ti in terms of TiO ₂
And 0 to 2% by weight of Mg in terms of MgO, a rare earth element,
The total content of at least one oxide selected from the group consisting of Zr, Hf, and Si in terms of oxide is 0 to 2% by weight, and the total amount of inevitable impurities is 1.5% by weight or less in terms of oxide. 4.0MPam ^1/2 or more and thermal conductivity 25W /
A pulverizer comprising an oxide sintered body having a mK or more. Wherein said oxide sintered body, and Al ₂ O ₃ quality crystals, by containing the oxide fine particles containing Ti and / or Mg dispersed in the Al ₂ O ₃ quality crystal grains The crusher according to claim 1, characterized in that: 3. The oxide sintered body has a Vickers hardness of 1
The crusher according to claim 1 or 2, wherein the crusher is 8.5 GPa or more. 4. The pulverizer according to claim 1, wherein 30% by volume or more of said Al ₂ O ₃ crystalline has an anisotropy of an aspect ratio of 4 or more.