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Recrystallized silicon carbide (Recrystallized Silicon Carbide, R-SiC) ceramic has a unique high temperature resistance, corrosion resistance, oxidation resistance, thermal conductivity, strength, regenerative small, the advantages of long life and low thermal expansion coefficient, which is widely used in aviation aerospace, metallurgy, electronics and information, chemicals, energy, environmental protection and other fields. However, in the harsh conditions of high temperature and thermal shock such that its performance is reduced, the life becomes short. Therefore, this paper aims to study the R-SiC ceramic high-temperature oxidation behavior and thermal shock behavior for the design of high-performance, long-life R-SiC ceramic to provide a theoretical basis. First, the use of silicon carbide powder Changle, Shandong Xinyuan Co., Ltd. production of SiC raw performance of R-SiC ceramics were successfully prepared. Raw material particle size distribution, the molding pressure, molding additives, the molding moisture and sintering temperature on the mechanical properties and microstructure of R-SiC ceramic. When GC100: GC07 = 65:35, a molding pressure of 100 MPa, forming a water content of 6wt%, the CMC content of 2 wt%, the firing temperature is 2400 ℃ obtained R-SiC bulk density of 2.54 g/cm3 , and the maximum bending strength of 64 MPa. Then the system studied R-SiC ceramics under different temperature oxidation behavior and study of its at 1500 ℃ after oxidation rupture strength and oxidation time of the relationship, through the thermal weight (TG), scanning electric microscopy (SEM),, X Are ray diffraction (XRD) were analyzed by means of oxidation mechanism, the oxidation kinetics and the oxidation of the breaking strength. The results show that: R-SiC in the the 1250-1350 ℃ oxidation kinetics curve was typical parabolic shape, the oxidation mechanism of O2 in the surface Si02 layer diffusion control and interface oxidation together; R-SiC after 1500 ° C high temperature oxidation bending strength showed a trend first and then decreased with increasing oxidation time, when the oxidation time of 21 h, the maximum flexural strength of 87MPa; R-SiC early in the oxidation of dense amorphous oxide film on the surface of the specimen defects and scratches play a passivation effect, leading to material fracture strength at room temperature increased; oxidation late due to the amorphous oxide film is crystallized generated cristobalite, and cyclic oxidation cristobalite occurs during cooling phase change to produce volume contraction, making the oxide film is too large tensile stress and cracking, which reduces the breaking strength of the R-SiC ceramics. The last study of SiC particle size of raw materials, the thickness of the sample of R-SiC ceramic thermal shock resistance. When the sample containing 50 wt% 60 # SiC, the critical thermal shock temperature difference of up to 395 ℃, showed good thermal shock resistance, Coarse SiC added to produce a large number of micro-cracks, rapidly absorbed stored in the material The elastic strain energy, thus improving performance of the thermal shock damage;, R-SiC ceramic thermal shock resistance decreases with the increase in the thickness of the sample.
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