Preparation Of TiC-Fe Based Composite Coating By Lost Foam Casting And Self-propagating High-temperature Synthesis

TiC-Fe-based composite coatings were successfully prepared in situ by self-propagating high-temperature synthesis combined with vacuum expendable pattern casting process in this work.The effects of the casting temperature,Fe content and the ratio of titanium to carbon on the composition and microstructure of the composite coating,the adhesion between the coating and the matrix and coating enhancement were investigated in detail.The experimental results showed that the band-like TiC phase embedded in the continuous Fe phase in the composite coating.The increasing casting temperature and the decreasing Fe content in the block would increase the temperature in the coating area.The change of the Ti/C ratio would also affect the self propagating temperature.When the coating zone temperature was low,the mesophase of Fe2 Ti formed in the composite coatingphase.The higher the temperature in coating area was,the more opportunity for the direct synthesis of TiC phase by self propagating was.With the increase of temperature in coating area,the agglomeration of TiC particles in the reaction region was more serious,and the diffusion of Ti from the coating zone to the substrate was also more serious.The content and distribution of TiC enhanced particles had an obviouse effect on the micro hardness and macro hardness of the composite coating.The hardness of the coatings increased first and then decreased with increasing casting temperature,and reached the highest value when the casting temperature was 1550 °C.When the casting temperature was 1550 °C and the content of Fe was 25-48 %,the micro hardness of the coatings increased first and then decreased and then increased with increasing the content of Fe,and reached the highest value when the content of Fe was 35 %.When the casting temperature was 1550 °C and the content of Fe was 42 % and the Ti/C ratio was higher than 16:1,the coating could not be combined with the matrix.When the Ti/C ratio was lower than 16:1,the micro hardness of the coatings increased with increasing Ti/C ratio,and reached the highest value when the Ti/C ratio was 16:1.