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Green Silicon Carbide for Surface Treatment

Green Silicon Carbide for Surface Treatment

Green silicon carbide for surface treatment is made of petroleum coke and high quality silica as the main raw material, adding salt as an additive, and smelted at high temperature in a resistance furnace. It is green crystalline, brittle and sharp, and has certain thermal and electrical conductivity. The microscopic shape is hexagonal crystal, the Mohs hardness of silicon carbide is 9.4, microdensity hardness is 2940-3300kg/mm2, Nuptial hardness 2670-2815kg/mm2, higher than corundum in abrasives and second only to diamond, cubic boron nitride and boron carbide. The density is generally considered to be 3.20-3.25g/cm3. The natural bulk density of silicon carbide abrasive is between 1.2–1.6g/cm3, and the specific gravity is 3.20~3.25g/cm3.

Green silicon carbide micro powder is selected from high quality large crystalline silicon carbide block by crushing, vertical ball mill particle shaping, acid washing moisture, hydraulic precision classification, natural settlement after high temperature drying, stable quality, good crystallization, high surface cleanliness, no large particles, less fines content, concentrated particle size distribution, high grinding efficiency, suitable for a variety of precision grinding processing, processing of the workpiece surface uniformity, no scratches.

Green Silicon Carbide Macro Grits are the products of secondary shaping by Raymond mill, with less angular particles, good hydrophilicity, high grinding efficiency and long working life, etc.

Performance characteristics of green silicon carbide for surface treatment

Silicon carbide has high oxidation resistance

When heated to 1000 degrees Celsius in air, silicon carbide oxidizes only on the surface, forming a silicon dioxide film, which protects the silicon carbide material from oxidation.
When heated to 1300 degrees Celsius, the silicon dioxide film layer begins to precipitate square quartz, and the crystalline transformation causes the film layer to crack and the oxidation rate increases slightly.

When heated to 1500-1600 degrees Celsius, the silica film layer thickens and becomes more protective against oxidation, which results in the silicon carbide remaining stable at high temperatures. It is only when heated above 1627 degrees Celsius that the antioxidant capacity of silicon carbide decreases rapidly.

Silicon carbide is more chemically stable.

The chemical stability of silicon carbide is also produced by its ability to resist oxidation.

The hardness of silicon carbide

The hardness of silicon carbide is between corundum and diamond, black silicon carbide Moh’s hardness is 9.2-9.3, green silicon carbide Moh’s hardness is 9.4-9.5, Vickers hardness is 3100-3400kg/mm2. silicon carbide hardness also decreases with the increase of temperature, in the high temperature state of 1200 degrees, silicon carbide hardness can reach two times of corundum.

Toughness of silicon carbide

The toughness of silicon carbide abrasives refers to the degree of difficulty in breaking under the action of external forces, for example, 46 mesh, the toughness of the static pressure method test is about 68-78%.

The mechanical strength of silicon carbide is higher than that of corundum, for example, the compressive strength of silicon carbide is 186KN/cm2 and that of corundum abrasive is 100KN/cm2 at 120 mesh size.

Color of silicon carbide

Silicon carbide is divided into black silicon carbide and green silicon carbide. Its color is caused by the content and type of impurities present in the crystal. Black silicon carbide is light blue-black, and the purity of first-class black silicon carbide is 98%; green silicon carbide is green, and the purity of first-class green silicon carbide is 99%.

Thermal conductivity and linear expansion coefficient of silicon carbide

Thermal expansion coefficient of silicon carbide at different temperatures (x10-6/°C):

100-500 100-900 15-1000 25-1700 20-1000 20-1525 20-1000 20-1470
4.1 4.47 4.35 4.3 5.2 4.9 4.3 4.5

This shows that the average coefficient of thermal expansion of silicon carbide is 4.4×10-6/°C at 25-1400 degrees Celsius, while that of corundum is 7-8×10-6/°C.

Electrical conductivity of silicon carbide

Due to the introduction of impurities , silicon carbide has the properties of a semiconductor. The electrical conductivity of silicon carbide increases rapidly with the increase in electric field strength and has a non-linear character. In addition, the electrical conductivity of silicon carbide varies with temperature.

Chemical composition

SiC 99.05%
SiO2 0.20%
F,Si 0.03%
Fe2O3 0.10%
F.C 0.04%

Physical Properties

Mohs Hardness 9.4
Specific Gravity 3.2g/cm3
Bulk density 1.2-1.6 g/cm3
Color Green
Particle shape Ordinary: angular, irregular
Spherical: rounded particles
Melting point 2600 ℃ Free
Maximum operating temperature 1900℃

Application scenarios

1. Precision polishing of camera lens and other hard optical glass.
2. Sandblasting and open edge treatment of hard metal CNB tools such as titanium alloy and carbide.
3. Polishing and grinding quartz glass.
4. Grinding hard stone, marble, granite, etc.
5. Polishing PZT/piezoelectric ceramics.
6. Sandblasting copper and copper alloy.
7. Surface treatment of diamond tools.
9. Polishing diamond, cinnabar and other jewelry.
10. Grinding other thin and brittle material precision parts.
11. Fireproof new nano aerogel.
12. Sintered ceramics and other fireproof insulating materials.
13. Teflon coating (teflon non-stick coating added), fluorocarbon powder coating. To wear-resistant, corrosion-resistant, high-temperature-resistant role.
15. Aviation aircraft brakes and other high-quality brake additives.
16. Silicon carbide ceramic filler.
17. Polishing tools such as diamond water abrasive pads, PVC abrasive pads, etc.
18. Wear resistant, corrosion resistant and high temperature resistant coating.

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