JP3377881B2 - Crusher components - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member for a pulverizer, and more particularly to a member such as a medium or a lining material in a dry or wet pulverizer. [0002] At present, various types of pulverizers such as a ball mill, a sand mill, an attritor, a vibration mill, a hammer mill, a jet mill, a rod mill, and a roller mill are widely used. These pulverizers use a pulverizing medium (media) such as a ball and a roll to perform pulverization mainly by friction and impact crushing force, and perform pulverization by moving the particles to be pulverized at high speed to perform the pulverization by the impact and crushing force. They are roughly divided into devices. [0003] Natural materials, porcelain, alumina, glass, natural materials, porcelain, alumina, glass, etc.
Rubber, plastic, steel, agate, etc. are used, but these materials are easily abraded and often wear powder is mixed in the crushed material, and it becomes difficult to separate the mixed wear powder. This is a major obstacle in terms of simplification and product purity. In addition, since the lining material of the apparatus is rapidly worn, continuous operation cannot be performed, and time and cost are required for maintenance. Therefore, ceramics having excellent wear resistance, mainly composed of zirconia, silicon carbide, silicon nitride, etc., in addition to alumina, have been used for pulverizer members (Japanese Patent Publication No. 2-20587). Gazette). However, among the above-mentioned ceramic pulverizer members, those made of alumina, zirconia and silicon nitride have a problem that they are easily worn due to their relatively low hardness. Was. Further, silicon carbide ceramics are generally obtained by solid-phase sintering containing boron (B) and carbon (C), and have high hardness and extremely high wear resistance. Since the value is relatively low, cracking and destruction are likely to occur due to impact or collision during pulverization, and the original wear resistance has not been utilized. Further, in a dry mill, a jet mill grinder crushes the particles to be crushed at a high speed against a member called a collision plate, which is generated when the collision plate is formed of insulating ceramics. It was easy to be charged without discharging static electricity. Therefore, for example, in the case of pulverizing toner or carbon, there is a risk of explosion if a spark is generated due to the static electricity. Therefore, ceramics cannot be used for crushing explosive objects such as toner and carbon which are prone to explosion, and when used, explosion-proof devices are required. Therefore, the present invention is characterized in that the pulverizer member is made of a silicon carbide ceramic having a fracture toughness (K _1C ) of not less than 5.0 MPa√m. That is, the silicon carbide ceramic has a high Vickers hardness of 1500 to 2500 kg / mm ² and a high wear resistance. If the fracture toughness value (K _1C ) is increased to 5.0 MPa√m or more by liquid phase sintering with a composition as described below, cracking and destruction due to impact or collision at the time of pulverization can be prevented. It is. Here, the fracture toughness value (K _1C ) is set to 5.0 MPa.
The reason for setting it to be not less than √m is that if it is less than 5.0 MPa√m, abnormal wear occurs due to grain boundary destruction in a blast wear test, and preferably not less than 5.5 MPa√m. The silicon carbide ceramic of the present invention contains 95% by weight or more of SiC as a main component, and 0.5 to 3% by weight of Al ₂ O ₃ and 0.5 to ₂ % by weight as a sintering aid.
Containing Y ₂ O ₃ . Al ₂ O ₃ and Y
₂ O ₃ as a sintering aid enhances the sinterability of silicon carbide ceramics, and forms a grain boundary phase (liquid phase) between silicon carbide crystal grains in the sintered body to prevent the development of cracks. ,
It has the effect of increasing the toughness of ceramics. And Al
The contents of ₂ O ₃ and Y ₂ O ₃ are set to the above ranges because the hardness and strength of the ceramics decrease when the content exceeds 3% by weight and 2% by weight, respectively. If the content is less than 0.5% by weight, the effect of increasing the toughness is poor. The reason why the amount of SiC is set to 95% by weight or more is that if the amount is less than 95% by weight, hardness, strength, and the like become low. Further, the silicon carbide-based ceramic of the present invention has a bulk specific gravity of 3.0 or more. This is because if the bulk specific gravity is less than 3.0, the hardness and strength are reduced. Further, the average crystal particle diameter is in the range of 3 to 50 μm. Further, the silicon carbide ceramics constituting the pulverizer member of the present invention has a volume resistivity of 10 ⁷ Ω · cm.
It is as follows. This is a resistance value required for discharging static electricity when used in the above-described jet mill pulverizer, and is preferably 10 ⁶ Ω · cm or less. The method of producing the silicon carbide ceramics constituting the pulverizer member of the present invention is as follows. First, α-S is adjusted so as to be in the above composition range.
The iC powder, Al ₂ O ₃ , and Y ₂ O ₃ powders are mixed and pulverized, a predetermined binder is added, and then formed into a predetermined shape by a known method such as press molding. The obtained molded body is fired at a temperature of 1800 to 2000 ° C. in a non-oxidizing atmosphere, and the obtained sintered body is subjected to grinding and polishing, if necessary, to obtain a pulverizer member. . Embodiments of the present invention will be described below. As schematically shown in FIG. 1, the jet mill pulverizer comprises a collision plate 1 and a nozzle 2 which are one embodiment of the pulverizer member of the present invention. Then, high-pressure air is supplied from the rear end of the nozzle 2 and injected from the front end, and the material 3 to be ground is supplied from the middle of the nozzle 2.
Is ejected from the tip of the nozzle 2, collides with the conical surface 1 a of the collision plate 1, and is crushed by the impact.
Is to be collected. The impact plate 1 is made of a high-toughness silicon carbide ceramic having a fracture toughness (K _1C ) of 5.0 MPaＭＰm or more as described above. Chipping and abrasion are extremely small, it can be used favorably for a long period of time, and mixing of abrasion powder into the crushed object 3 can be prevented. Moreover, since the silicon carbide-based ceramic has a volume resistivity value of 10 ⁷ Ω · cm or less, it is possible to discharge static electricity generated by collision and to prevent generation of spark. Therefore, the collision plate 1 can be used for pulverizing the explosive material 3 such as toner or carbon, which does not require explosion-proof devices. In the above embodiment, the entire impact plate 1 is formed of high-toughness silicon carbide ceramics.
Only a can be formed into a high toughness silicon carbide ceramics. Further, in the above embodiment, the collision plate 1 is provided with the conical surface 1a, but this portion may be flat or have another shape. Although the jet mill crusher has been described above, the present invention can be applied to various other crushers.
For example, in various pulverizers such as a ball mill, a sand mill, an attritor, a vibration mill, a hammer mill, a jet mill, a rod mill, and a roller mill, a pulverizer member such as a pulverization medium (media) or a lining material is replaced with the high-toughness silicon carbide. When formed of porous ceramics, it exhibits excellent wear resistance, can have a long life, can prevent wear powder from being mixed into the material to be ground, and has a thermal conductivity of 60 W / m2 of silicon carbide ceramics. -Since it is as high as K or more, heat generated during pulverization can be rapidly released. EXPERIMENTAL EXAMPLE 1 As an example of the present invention, a raw material powder consisting of 98% by weight of SiC, 1.5% by weight of Al ₂ O ₃ and 0.5% by weight of Y ₂ O ₃ was mixed with a predetermined binder. Into a shape of the collision plate 1 shown in FIG. 1 at 1900 ° C. in a non-oxidizing atmosphere.
To obtain a collision plate 1 having a diameter of 100 mm and an outer peripheral thickness of 20 mm. As a comparative example, 99% by weight of SiC was used.
And solid-phase sintered silicon carbide ceramics comprising 0.5% by weight of boron (B) and 0.5% by weight of carbon (C);
A collision plate 1 having the same shape and dimensions was manufactured using alumina ceramics having an Al ₂ O ₃ content of 99% by weight. The specific gravity, Vickers hardness, and fracture toughness (K _1C ) were measured. In addition, the measurement of the fracture toughness value was performed by the indentation method. In addition, a use test was conducted in which each collision plate 1 was mounted on a jet mill pulverizer and the nozzle 2 was jetted with compressed air of 3 to 5 kg / cm ² using glass beads as the material 3 to be pulverized. The results are as shown in Table 1. From this result, the comparative example using alumina ceramics (No. 3) became unusable in one month because the center of the conical surface 1a was worn due to low hardness. Further, among the silicon carbide ceramics, solid-phase sintered one (No. 2) had a low toughness, so that the tip of the conical surface 1a was damaged and became unusable in two months. On the other hand, in the embodiment of the present invention (No. 1) made of the high-toughness silicon carbide ceramics sintered in the liquid phase, both the hardness and the toughness are high.
a was a little worn slightly smoothly, and maintained a usable state. As described above, the collision plate 1 according to the embodiment of the present invention includes:
The service life can be prolonged, and since the wear amount is small, it is possible to prevent wear powder from being mixed into the crushed object 3. [Table 1] Experimental Example 2 Next, as an example of the present invention, 50 × 5
A sample of 0 × 10 mm was prepared. On the other hand, as a comparative example, 9
Samples having the same shape and dimensions were made of 2% and 99% of alumina ceramics mainly containing Al ₂ O ₃ and silicon nitride ceramics mainly containing Si ₃ N ₄ . Further, as a comparative example, a sample having the same shape and dimensions was made of metal (SUS304). The samples were subjected to a blast abrasion test in which glass beads having a particle diameter of 74 μm were jetted with high-pressure air of 4.5 kg / cm ² from a distance of 30 mm in a direction perpendicular to the main plane. As shown in FIG. 2, the relationship between the test time and the amount of wear is as follows. The sample made of the high-toughness silicon carbide-based ceramics according to the present invention is about one-half the metal (SUS304) compared to the alumina sample. It can be seen that the amount of wear can be extremely reduced to about 1/27 as compared with. As described above, according to the present invention, the member for the pulverizer is constituted by a silicon carbide sintered body having a fracture toughness value (K _1C ) of 5.0 MPa√m or more. Since the abrasion resistance is extremely high and it is hard to break, the life can be prolonged, and it is possible to prevent the material from being mixed into the material to be ground. Further, by setting the volume resistivity of the silicon carbide-based ceramic to 10 ⁷ Ω · cm or less,
Even when used in a jet mill pulverizer, the electrostatic charge can be prevented, and the possibility of explosion can be eliminated even when pulverizing toner or carbon.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a jet mill pulverizer according to one embodiment of the present invention. FIG. 2 is a graph showing the results of a blast wear test for each type of material. [Description of Signs] 1: Collision plate 1a: Conical surface 2: Nozzle 3: Pulverized object

Claims (1)

(1) Claims 1. A member used in a jet mill pulverizer for pulverizing an explosive object such as toner or carbon which is liable to explode, comprising 95% by weight or more of SiC and 0.5% by weight. ~ 3% by weight of A
L ₂ O ₃ and 0.5 to 2% by weight of Y ₂ O ₃ , a fracture toughness (K _IC ) of 5.0 MPaＭＰm or more, a Vickers hardness of 1500 to 2500 kg / mm ² , and a volume resistivity value Made of a silicon carbide-based ceramic having a particle size of 10 ⁷ Ω · cm or less.