10

2020

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09

The difference between white corundum and emery and the cause of color change


Emery packaging and specifications: 25 or 50kg woven bags, commonly used particle sizes can be divided into: 80-120 mesh emery, 40-60 mesh emery, 0.5-1mm emery, 1-2mm emery, 2-4mm emery, 4-8mm emery, etc. (Depending on customer needs).

Using industrial alumina powder as raw material, it is made by cooling after melting at a high temperature above 2000 degrees in an arc. After crushing and shaping, magnetic separation to remove iron, and screening into various particle sizes, its quality white corundum is suitable for manufacturing ceramics, resin consolidated abrasive tools, grinding, polishing, sandblasting, precision casting (corundum for precision casting), etc., and can also be used for manufacturing refractory materials, code name "WA" is common standard, most of standard, there are also rationing within users.

Product size according to international standards and the standard production, can be processed according to user requirements granularity. The general particle size number is F4 ~ F320, and its chemical composition varies depending on the particle size. The prominent point is that the crystal size is small and impact resistant. If the self-grinding machine is used to process and break, the particles are mostly spherical particles, the surface is dry and clean, and it is easy to bond. Beijing emery, emery emery abrasive sandblasting emery, polished emery, wear-resistant floor emery, ceramic emery, Beijing Beike green emery specifications sell well, emery, also known as silicon carbide, can be divided into natural emery and artificial emery. Silicon carbide includes black silicon carbide and green silicon carbide, of which: black silicon carbide is made of quartz sand, petroleum coke and high-quality silica as the main raw materials, through high-temperature smelting in a resistance furnace. Its hardness is between corundum and diamond, mechanical strength is higher than corundum, brittle and sharp.

Emery use:

(1) As an abrasive, it can be used as abrasive tools, such as grinding wheels, oilstones, grinding heads, sand tiles, etc.

(2) As a metallurgical deoxidizer and high temperature resistant material.

(3) high purity single crystal, can be used in the manufacture of semiconductors, the manufacture of silicon carbide fibers.

Main purpose: used for 3-12 inch monocrystalline silicon, polycrystalline silicon, potassium arsenide, quartz crystal and other wire cutting. Solar photovoltaic industry, semiconductor industry, piezoelectric crystal industry engineering processing materials. Abrasives, silicon carbide mainly has four major applications, namely: functional ceramics, refractory materials, abrasives and metallurgical raw materials. At present, silicon carbide coarse material has been able to supply a large number of high-tech products, and the application of nano-silicon carbide powder with high technical content can not form economies of scale in a short time.

Mainly used in the production of grinding wheel, sandpaper, abrasive belt, oilstone, grinding block, grinding head, grinding paste and photovoltaic products in monocrystalline silicon, polycrystalline silicon and piezoelectric crystals in the electronics industry, such as grinding, polishing and so on.

The color of white corundum will appear white in red, red yellow, green gray tones, affecting the appearance of the product. And there is sodium oxide in the content, and a small amount of sodium oxide will eliminate a large amount of Al2O3 (18.10 times the mass of Na2O) to generate sodium aluminate. Therefore, in addition to the Al2O3 content, the content of Na2O is strictly limited in the chemical composition standard of white corundum. Due to the aluminum oxide powder in addition to Al2O3 and trace amounts of Na2O, other components are few. We made white corundum raw materials, firing atmosphere and other aspects, to explore the impact of white corundum color change factors, and put forward to prevent white corundum color change measures taken. Through theoretical analysis and a large number of experiments, we draw the following main conclusions:

The color change of white corundum abrasive is mainly determined by the amount of impurity content in the binder and the sintering atmosphere. If it is fired in an oxidizing atmosphere, when the content of (TiO2 + Fe2O3) in the binder is less than 0.55%, the white corundum will not appear red, red and yellow. With the increase of Fe2O3 and TiO2 content in the binder, white corundum abrasive white red, red and yellow tone gradually increased, therefore, if the binder (TiO2 + Fe2O3) content> 0.55, white corundum abrasive firing should not use oxidizing atmosphere, the use of neutral atmosphere or weak oxidizing atmosphere firing.

The addition of talcum powder, quartz powder and magnesium oxide powder to the ceramic binder white corundum grinding tool can eliminate the red color of white corundum, but it has an impact on the strength of the grinding tool.

However, the content of Fe2O3 is not specified in the chemical composition of corundum abrasives. The reason is that the content of iron oxide has a greater influence on the magnetic properties of white corundum than color. In the standard of magnetic content of abrasives, the content of magnetic materials is strictly specified, and the content of iron oxide is strictly limited. In fact, the content of iron oxide is indirectly more stringent regulations. This can solve the problem of white corundum color.


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