Preparation And Properties Of Unfired Silicon Carbide Refractories

The production and process of electrolytic aluminum tank usually uses phenol formaldehyde resin as a low temperature binding agent, but there are some weak points such as high pore ratio, low intensity and high cost of production.This article is mainly based on the original basis to modify low temperature binding agent of SiC refractory, reducing the porosity of electrolytic aluminum tank, improving its flexural strength, its corrosion resistance and low cost of production.The different grain sizes of silicon carbide were used as raw materials, organic silicon resin as binder,350MPa bi-directional compressor was used in shaping and the sample was sintered at960℃(simulated using ambient temperature). The materials properties investigated included material density, flexural strength, oxidation resistance, thermal shock resistance, anti-corrosion properties. XRD, SEM. were used to research the material of phase composition and microstructure. The results showed that:(1) with methyl phenyl silicone resin as binder, with the best silicon carbide grain size distribution, after shaping by350MPa bi-directional compressor and sintering at960℃, the flexural strength of sample first increases then decreases along with increasing mass percentage content of binder. When using binder of9%, the sample density was maximum at2.67g-cm-3, its porosity was minimum at14.98%and flexural strength of the material was maximum at26.49MPa.(2) The main phases of the material after sintering are SiC, SiO2, SixOyCz. Microstructure of material is homogeneous and the combination between big silicon carbide particles and binder is good. With the increase of the binder content, the fracture mode of the material was gradually transformed by the intergranular and transgranular mixed fracture.(3) Constant temperature oxidation resistance of the sample was increased with time and the decrease of oxidation weight increase was slow. In the oxidation of2-10hrs, with the extension of oxidation time, the strength of the material first increased then tends to be stable, the best strength’s silicone resin content is9%,the biggest strength after10hours oxidation is 29.56MPa.(4) For thermal shock resistance of the sample, after5times’thermal test, the samples which contain9%silicone resin will get the bset strength,and the residu al strength is10.11MPa.(5) When the mole ratio of2.2in electrolyte, under the condition of temperature of960℃, after3hrs,6hrs and12hrs anti-corrosion molten cryolite, sample with binding agent of9%had the best anti-corrosion property, corrosion temperature effect was obvious to the corrosion resistance of material.Thesis results for extending the service life of the electrolytic aluminum groove as well as production and application have certain guiding significance and practical value.