Dongguan Ming Rui Ceramic Technology Co., Ltd
Silicon carbide ceramic tube strength, high resistance to high temperature and high temperature environment, has been widely used in the field of national economy and people's livelihood, silicon carbide ceramic tube is a compound of covalent bond is very strong, the Si - C key ionic only around 12%, as a result, it also has excellent mechanical properties, excellent oxidation resistance, high abrasion resistance and low friction coefficient, etc.
The biggest characteristic of silicon carbide ceramic tubes is high strength at high temperature. The strength of ordinary ceramic materials will be significantly reduced at 1200 ~ 1400 ° c, while the bending strength of silicon carbide remains at 500 ~600MPa at 1400 ° c, so its working temperature can reach 1600 ~ 1700 ° c.
Silicon carbide ceramic tubes have excellent mechanical properties, excellent oxidation resistance, high abrasion resistance and low friction coefficient.
Silicon carbide has two main crystal structures, that is, cubic - SiC and hexagonal - SiC.
The basic structural units of SiC crystal are interpenetration tetrahedron of SiC and CSi.The tetrahedron coexists to form a plane layer and is connected with the next layer of tetrahedron by the vertex to form a three-dimensional structure.Because tetrahedral stacking order can form different structures, hundreds of variants have been found.Generally, the letter C(cubic), H(hexagonal) and R(rhomboid) meters are used to represent the lattice type, and the number of layers contained in the unit cell are used to distinguish them. For example, nH represents the hexagonal structure with n-layer repetition cycle along the C axis, while mR represents the rhombohedral structure with m-layer repetition cycle along the C axis.
Silicon carbide is synthesized at high temperature, so silicon carbide ceramic tubes are mostly prepared at high temperature or used at high temperature.
If only a rough calculation is made, the average thermal expansion coefficient of silicon carbide can be taken as 4.4×10-6/℃ within the range of 25~1400℃.The results show that the thermal expansion coefficient of silicon carbide is much smaller than that of other abrasives and high-temperature materials. For example, the thermal expansion coefficient of corundum can be as high as (7~8)×10-6/℃.The high thermal conductivity of SiC is another important characteristic of the physical properties of silicon carbide ceramic tubes.
Its thermal conductivity is much greater than that of other refractory and abrasive materials, about 4 times that of corundum.Therefore, silicon carbide has a low thermal expansion coefficient and high thermal conductivity, so silicon carbide ceramic tubes are subjected to less thermal stress in the process of heating and cooling, which is the reason why silicon carbide ceramic tubes have a particularly good thermal shock resistance.
Silicon carbide ceramic matrix composite material refers to the composite material with the introduction of silicon carbide fiber as reinforcing material into the silicon carbide ceramic matrix to form the composite material with the introduced silicon carbide reinforcing fiber as the dispersed phase and the silicon carbide ceramic matrix as the continuous phase.What are its performance characteristics?
The silicon carbide ceramic matrix composite retains the advantages of high temperature resistance, high strength, oxidation resistance, corrosion resistance and impact resistance of silicon carbide ceramics. At the same time, it also has the effect of reinforcing and toughening silicon carbide fibers, and overcomes the congenital defects of low fracture toughness of silicon carbide ceramics and poor resistance to external impact load.The material can be maintained at 1316°C without degradation of its physical and chemical properties.When the surface of silicon carbide is sprayed with thermal barrier coating, the maximum working temperature can be increased to 1480°C.
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