Abstract: High purity silicon carbide parts for a heat treating apparatuses for semiconductors; composed mainly of .alpha.-type silicon carbide and silicon; characterized in that a particle sizes of the .alpha.-type silicon carbide crystals composing the high purity silicon carbide parts are not larger than 44 .mu.m; a weight mean particle size of the .alpha.-type silicon carbide crystals is in a range from 2 to 25 .mu.m; high purity silicon is filled up among the particles of the .alpha.-type silicon carbide crystals; and a content of iron as an impurity element contained in the high purity silicon carbide parts is not larger than 5 ppm.

Abstract: A fired ceramic having dense and low thermal expansion characteristics comprises 0.3 to 8 wt. % of at least one of rare earth oxides and has a thermal expansion coefficient of less than 0.3% and a porosity of less than 10%.The fired ceramic having dense and low thermal expansion characteristics comprises a main component of cordierite, lithium aluminosilicates or aluminum titanate.The rare earth oxide is preferably Y.sub.2 O.sub.3 and can be CeO.sub.2 or La.sub.2 O.sub.3.