The sintering method of pressureless sintered silicon carbide seal rings/faces is that silicon carbide powder with a certain amount of B and C is sintered in a vacumme furnace in a high temperature where B is dissolved into sic to lower the cristal boundary energy and C can remove SO2 to improve the surface energy.Compared to reaction bonded silicon carbide seal faces/rings, they are better in the resistance to corrosion in the extremely strong acids and alkali.