JPH0653618B2 - Hammer member for crusher - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hammer member made of a novel material used for a powder contact portion of an impact crusher.

[Conventional technology]

Hammer mill type impact crushers are useful for fine pulverization of various powders, but especially when targeting substances that do not like metal contamination such as fine ceramics, the hammer member at the powder contact part has high hardness. It must be made of a material with excellent wear resistance.

Conventionally, WC has been widely used for the above purpose,
Since this material has a remarkably high specific gravity (15.6 g / cc), the load on the power and rotary disk parts is increased, and various costs such as running costs and maintenance costs increase.

As a material replacing WC, a partially stabilized ZrO ₂ or Al ₂ O ₃ sintered body has recently been put into practical use. These oxide-based ceramic materials have a specific gravity of 1/3 to 1/4 as compared with WC.
However, partially stabilized ZrO ₂ does not have sufficient hardness to provide sufficient wear resistance, and Al ₂ O
_Since No. ₃ has poor fracture toughness, it has a problem of being easily broken under severe impact conditions.

[Problems to be Solved by the Invention]

TiC has a low specific gravity (4.94 g / cc) and a hardness of WC.
More than 1.8 times the level of Al ₂ O ₃ , SiC, Si
It is also higher than ceramics such as ₃ N ₄ . It is expected that the low specific gravity and high hardness characteristics will be applied to hammer materials for pulverizers, but TiC has a material defect that its fracture toughness is low like other ceramic materials.

The wear resistance of a hammer for a crusher depends most on the hardness of the constituent materials, and secondly on the fracture toughness. Therefore, if the fracture toughness of TiC can be improved to a practically acceptable level, it is optimal as a hammer member for a crusher.

As a result of repeated research based on the above idea, the present invention shows that Ti
The sintered body obtained by compounding a certain amount of SiC whiskers in C was developed after confirming the fact that it effectively acts to increase the toughness.

[Means for Solving the Problems]

That is, the hammer member for a crusher according to the present invention has a composition in which TiC is used as a matrix, SiC whiskers having a volume content of 5 to 40% are used as a composite reinforcement, and Cr ₃ C ₂ and B are used as a sintering aid. It is composed of a body.

5-40 volume content of SiC whiskers as composite reinforcement
The reason for limiting the range to% is that if it is less than 5%, the toughening effect does not appear, while if it exceeds 40%, the denseness of the sintered structure is markedly impaired. In particular, in order to allow the sintered body to have a well-balanced property of strength, hardness and fracture toughness, it is desirable to set the volume content of SiC whiskers within the range of 20% to 30%.

TiC is a ceramic that is essentially difficult to sinter and has a propensity to obtain a dense sintered structure. However, when SiC whiskers are mixed, the sintering density tends to be further reduced. When powders of Cr ₃ C ₂ and B are used as a sintering aid, the above phenomenon of low density is effectively improved, and by applying hot pressure sintering, 25% by volume of SiC whiskers are mixed. However, it is possible to give a denseness of 99% or more in relative density. The mixing amount of these sintering aids is preferably 1 to 10% by weight with respect to TiC.

The sintered body having the composition of the present invention can be prepared as follows.

Using TiC powder with an average particle size of 1 μm or less as a matrix,
This, a predetermined amount of SiC whiskers, and a sintering aid are put in a ball mill together with an organic solvent such as ethanol and acetone, and mixed by rotation until the composition components are uniformly dispersed. Then, the organic solvent is removed and hot pressure sintering is performed using a hot press.

[Action]

The sintered body having the above-mentioned composition exhibits the improved characteristics that TiC has the low specific gravity and high hardness performance, and the fracture toughness is improved to a practical application area equivalent to that of partially stabilized ZrO ₂ .

Therefore, the lightweight and high hardness, strength, toughness, and wear resistance characteristics required for hammer members for crushers are well-balanced, so that they can be used stably for a long time at low cost compared to conventional members. You can

〔Example〕

 Hereinafter, the present invention will be described based on examples.

Example 1, Comparative Examples 1-2 TiC fine powder having an average particle size of 0.7 μm [Nippon Shin Metal Co., Ltd.]
Manufactured by Tokai Carbon Co., Ltd. with a diameter of 0.3-0.6 μm and a length of 5-15 μm
TWS-300] was mixed at a volume content of 25%, and Cr ₃ C ₂ powder and B powder were added as a sintering aid in an amount of 5% by weight with respect to TiC (Example 1). For comparison, 5% by weight of Cr ₃ C ₂ powder alone was added to TiC (Comparative Example 1) and 5% by weight of B powder alone was added (Comparative Example 2).

500 g of the raw material components having these compositions were put in a ball mill together with 1000 m of ethanol, and were mixed by rotation for 20 hours, and then heated to volatilize and remove ethanol. Then, the mixed powder is roughly crushed and filled in a hot press mold, and the temperature is set to 1800.
Sintering treatment was carried out by holding for 2 hours under the hot-pressing condition of ℃ and pressure of 400 kg / cm ² .

The properties of these sinters as hammer members for crushers were measured, and shown in Table 1 together with the characteristic values of TiC used as a matrix, conventional materials such as WC, Al ₂ O ₃ and partially stabilized ZrO ₂ . . From the results shown in Table 1, the sintered body of Example 1 has a higher relative density than the sintered bodies of Comparative Examples 1 and 2 and has a dense structure and is excellent in hardness, toughness, strength and the like. Turns out.

Next, when the sintered bodies of Example 1 and Comparative Examples 1 and 2 were processed into a hammer shape and set in a commercially available impact type crusher and a mounting test was performed, the sintered body of Example 1 showed that WC The service life has been extended by 200 hours compared to hammers made by the manufacturer, and the motor load has been reduced from 3300V, 6.5A to 3300V, 5A. On the other hand, the sintered bodies of Comparative Examples 1 and 2 each have a service life of 120
Time and 150 hours, and the motor load is 3300
V, 4.5A and 4.5A.

Examples 2-3, Comparative Examples 3-4 The volume content of SiC whiskers was 3%, 10%, 35%, 45.
A sintered body was prepared under the same conditions as in Example 1 except that the content was changed to%.

Various characteristics of each of the obtained sintered bodies were measured and shown in Table 2.

Compared to Examples 2 and 3, in Comparative Example 3 in which the volume content of SiC whiskers was less than 5%, no improvement in fracture toughness was observed, and in Comparative Example 4 in which it exceeded 40%, the denseness of the sintered structure deteriorated. , Showed a decrease in relative density.

〔The invention's effect〕

As described above, according to the present invention, since it has a high balance of hardness, strength, toughness, and wear resistance that satisfy the practical level with the light weight required for a hammer member for a crusher,
Compared with conventional materials, it is possible to guarantee stable use for a long time at low cost.

Claims (1)

[Claims] 1. TiC as a matrix, SiC whiskers with a volume content of 5-40% as a composite reinforcement, and Cr _{3 as a} sintering aid.
A hammer member for a crusher, which is composed of a sintered body having a composition using C ₂ and B.