Green Silicon Carbide

Introduction to Green silicon Carbide

　　The production mode of green silicon carbide powder is basically the same as that of black silicon carbide, but the raw material requirements are different. Green silicon carbide is made of petroleum coke and high-quality silica as the main raw materials, adding salt as an additive, and smelting at high temperature in a resistance furnace. The crystal formed by smelting is of high purity and hardness, and its hardness is between corundum and diamond, and its mechanical strength is higher than that of corundum.

Application

　　Green silicon carbide, suitable for machining hard alloy, glass, ceramic and non-metallic materials, also used for semiconductor materials, high temperature silicon carbon rod heating element, far infrared source substrate, etc.

The production process

　　With black silicon carbide, green silicon carbide manufacturing methods but the purity of raw materials demand is higher, also in the resistance furnace under the high temperature of 2200 ° C to form, green, translucent shape, hexagonal shape, the Sic content is higher in black, physical properties similar to black silicon carbide, but the performance is slightly crispy in black, also has good thermal conductivity and electrical properties.

　　1.Hardness and toughness of green silicon carbide

　　The hardness of green silicon carbide is between corundum and diamond. The new mohs hardness is 13, and the weil hardness is 3100~3400kg/mm and above.

　　The hardness of green silicon carbide also decreases with the increase of temperature, But the hardness value at each temperature is still higher than that of corundum.

　　The toughness value of green silicon carbide abrasive reflects the degree of crushing difficulty of granular green silicon carbide under external force.

　　The mechanical strength of green silicon carbide is higher than that of corundum. The compressive strength of high-purity green silicon carbide particles with an average size of 0.1mm is 186kN/cm-, While that of ordinary corundum abrasive is 100kN/cm. The finer the green silicon carbide abrasive is, the higher its crushing strength is. The average crushing strength of green silicon carbide with particle size ranging from 90 to 2500 microns is 5800kPa/cm, and that of corundum abrasive in the same size range is 5300kPa/cm.

　　2. The color of green silicon carbide

　　Green silicon carbide powder is green and crystal structure

　　There are many different reasons for the color development of green silicon carbide. It is generally believed to be caused by the presence of foreign impurities. For example, when boron is introduced in the form of boron carbide, the crystal will appear black. Green when the crystal contains nitrogen.

　　The appearance color of green silicon carbide is not only related to the color of the crystal itself but also to the interference of natural light on the crystal surface. When the thickness of silicon oxide film on the surface of green silicon carbide crystal is different, or the reflection Angle of light is different, the color of the surface of green silicon carbide crystal is also different. Therefore, in natural light, green silicon carbide is often seen to have a brilliant color.

　　3. Thermal conductivity and linear expansion coefficient of green silicon carbide

　　As a kind of high quality refractory, green silicon carbide has superior thermal shock resistance. It has high thermal conductivity (thermal conductivity) and low linear expansion coefficient. Table 2-1-7 shows the thermal conductivity system values of green silicon carbide samples with a certain ratio of clay binder.

　　In general engineering calculation, the thermal conductivity of green silicon carbide is 6.28~9.63 W/m. This value is about 4 times the thermal conductivity of corundum

　　In the range of 25~1400℃, the average linear expansion coefficient of green silicon carbide is 4.4× 10-6k /m. The linear expansion coefficient of corundum is (7 ~ 8) × 10-6k /m.

　　4. Conductivity of green silicon carbide

　　Industrial green silicon carbide is a kind of semiconductor, the conductivity with the introduction of the amount and type of impurities in the crystal varies, resistivity between 10 Ω · ㎝. The impurities that have the greatest influence on the conductivity of green silicon carbide are aluminum, nitrogen and boron.

　　The conductivity of green silicon carbide increases rapidly with the increase of electric field intensity and has the characteristic of nonlinear change.

　　The resistivity of green silicon carbide varies with temperature, but in a certain temperature range it is opposite to the resistance temperature characteristic of metal.

Green Silicon Carbide(GC)

Green silicon carbide is suitable for processing hard alloy, metallic and non-metallic materials with hard and brittle features such as copper, brass, aluminum, magnesium, jewel, optical glass, ceramics, etc. Super powder of it is also a kind of ceramic material.

Type value of green silicon carbide physical chemical performance index

For vitrified wheels and belts: GC

For organic wheels :GC-B

For sheets : GC-P

Green silicon carbide chemical composition & magnetic contents of China GB/T 2480-1996