Silicon nitride bonded silicon carbide bricks are the most widely used nitride boned SiC refractories. Nitride bonded SiC materials have many excellent high temperature performances such as high mechanical strength, good thermal conductivity, small linear expansion coefficient, good thermal shock resistance, alkali corrosion resistance, oxidization resistance, molten metal liquid( zinc, copper, aluminum, lead,etc) corrosion resistance, as well as high temperature abrasion resistance. Si3N4 bonded SiC bricks are composite refractory, main crystalline phase is SiC, secondary crystalline phase is α-Si3N4 and β-Si3N4.
Si3N4 Bonded SiC Bricks Characteristics
Low apparent porosity.
Excellent high temperature mechanical strength.
Good high temperature creep resistance, at 0.2 Mpa load condition, RUL beginning temperature is higher than 1800℃.
High modulus of rupture.
Good thermal conductivity.
Very high alkali corrosion resistance.
Excellent oxidization resistance.
Prominent thermal shock resistance.
Excellent slag corrosion resistance.
Have strong cryolite corrosion resistance , ZnO corrosion resistance and electrolyte permeation resistance.
Si3N4 Bonded SiC Bricks Physiochemical Index
Item
Si3N4 bonded SiC brick
Sialon bonded SiC brick
Fine Si3N4 bonded SiC brick
SiC %
75.04
73.54
66~80
Si3N4 %
22.18
/
20~30
Al2O3 %
0.37
/
/
Fe2O3 %
0.27
0.32
/
Bulk density g/cm3
2.73
2.72
2.80
Apparent porosity %
13.3
14
≤11
Cold crushing strength Mpa
229
220
580
Modulus of rupture Mpa（1400℃）
65.2
56.7
180 (1200℃)
Linear expansion coefficient ℃-1 (20~1000℃)
4.5*10-6
4.7*10-6
4.4*10-6
Thermal conductivity w·（m·K）-1 1000℃
18.4
18.2
/
Si3N4 Bonded SiC Bricks Application
Si3N4 bonded SiC refractories are widely used in steel industry, nonferrous metals industry, ceramics industry and so on. Blast furnace refractory materials corrosion reasons include: alkali corrosion, CO, Zn, SiO and water vapor oxidization, abrasion, low thermal conductivity, thermal shock and slag corrosion. In light of this condition, Si3N4 bonded SiC bricks are the ideal products for blast furnace inner lining. The service life of silicon nitride bonded silicon carbide bricks inner lining can reach to 10~15 years. It is the first choice of large scale blast furnace inner lining refractory material.
SiN4 bonded SiC refractory is the best choice of new generation aluminum reduction cell inner lining. It can decrease horizontal electric current, increase side part heat diffusion, decline cell temperature, enhance electric current efficiency and save energy. Besides, the service life of aluminum reduction cell is greatly prolonged. SiN4 bonded SiC bricks have good thermal conductivity, cryolite corrosion resistance, oxidization resistance and scouring resistance. During using, SiN4 bonded SiC bricks inner lining can form a thick and stable protective layer, which in turn effectively prolongs the service life of aluminum electrolysis cell.
Si3N4 bonded SiC bricks are also used as kiln furniture of ceramic kilns.
