Refractory compound material
Such as carbides (silicon carbide, titanium carbide, tantalum carbide, etc.), nitrides (boron nitride, silicon nitride, etc.), borides (zirconium boride, titanium boride, hafnium boride, etc.), silicides (two molybdenum silicide, etc.) and sulfides (thorium sulfide, cerium sulfide, etc.). Their melting point is 2000~3887 degrees, the most difficult to melt is carbides.