SiC sintered body having crystallized intergranular films and sintering method thereof

摘要

PURPOSE: Provided is a sintered SiC having resistance against oxidation, creep and impact at high temperature, and strength at room temperature by adding Al2O3-Y2O3-X(X: elements of group IIA) to SiC and crystallizing grain boundary through cooling after sintering without special thermal treatment. CONSTITUTION: The sintering method of SiC comprises the steps of: mixing 75.01-97.99wt.% of alpha or beta-SiC(0.2-5micrometer) containing 0.01-1.5wt.% of O2 and 0.01-3wt.% of surplus carbon for preventing amorphous SiO2 from being interposed in the liquid phase, 2-19.99wt.% of Al2O3-Y2O3 having a Al2O3/Y2O3 ratio between 1 and 9, and 0.01-5wt.% of compounds(carbides, carbonates or oxides) or powder offering group IIA elements such as Mg, Ca, Sr, MgCO3, CaCO3, SrCO3, MgO, CaO or SrO and forming; sintering at 1800-2000deg.C for 0.1-20hrs under pressure of 0.01-30MPa in vacuum, N2 or Ar atmosphere; and cooling at a rate of 0.01-50deg.C/min. The sintered SiC has a crystallized grain boundary(120) of 1nm thickness between SiC particles(100, 110), wherein Al, Y, Ca, Si, O, C, etc. are segregated in the grain boundary.