Abstract: The microstructure and the electronic conductivity of plasma sprayed boron carbidecoating were studied. The results show that B₄C phase in the coating exists in two major structuregrained and flaky structures. Metal Fe as the impurity phase in the coating is the key factorresulting in the abnormality of electronic conductivity of B₄C coating. Another impurity phase,which consists of B, C and Fe elements, will decrease the microhardness of B₄C coating.

Key words: boron carbide coating, microhardness, electronic conductivity, impurity phase