Abstract: A TiC-Fe cermet graded composite coating on a cast steel substrate was successfully fabricated by an SHS casting route. The effects of technological parameters, such as pouring temperature of liquid steel, composition of Ti-C-Fe preform and its relative green density, on the microstructure of the coating were emphatically studied. The results show that, under the condition of ensuring the preform to be ignited, properly increasing the pouring temperature of liquid steel and decreasing the green density of the preform are favorable to the formation of the graded composite coating. Furthermore, adding a kind of metal diluents with lower melting point into the preform not only can decrease the size of the synthesized TiC particles, but also is more advantageous for the formation of the graded composite coating. It is considered by analysis that the formation of the graded composite coating is related to the combined effects of the infiltration of the melt into the preform, the fusion of Fe powders and the diluents in the preform, and the converse diffusion of the synthesized TiC particles into the poured melt.
Effects of technological parameters on microstructure of TiC-Fe cermet graded composite coating on cast steel substrate by SHS- casting route
Abstract:
A TiC-Fe cermet graded composite coating on a cast s te el substrate was successfully fabricated by an SHS-casting route. The effects o f technological parameters, such as pouring temperature of liquid steel, composi tion of Ti-C-Fe preform and its relative green density, on the microstructure of the coating were emphatically studied. The results show that, under the condi tion of ensuring the preform to be ignited, properly increasing the pouring temp erature of liquid steel and decreasing the green density of the preform are favo rable to the formation of the graded composite coating. Furthermore, adding a ki nd of metal diluents with lower melting point into the preform not only can decr ease the size of the synthesized TiC particles, but also is more advantageous fo r the formation of the graded composite coating. It is considered by analysis th at the formation of the graded composite coating is related to the combined effe cts of the infiltration of the melt into the preform, the fusion of Fe powders a nd the diluents in the preform, and the converse diffusion of the synthesized Ti C particles into the poured melt.
Fig.3 Effect of pouring temperature of liquid steel on interfacial structure between synthesized coating and steel substrate (a)—1 550 ℃; (b)—1 650 ℃(no-etched specimens)
图4 预制块的密实度对表面复合材料界面结构的影响
Fig.4 Effect of relative green density of preform on interfacial structure between synthesized coating and substrate (a)—30%; (b)—70% (etched specimens)
Fig.5 Effect of adding amount of diluents in preform on interfacial structure of coating/substrate (a)—0; (b)—5% (etched specimens)
图6 涂层不同部位处的显微结构(SEM)
Fig.6 SEM photographs of synthesized coating at different distances from outside surfuce (a)—2 mm from outside surfuce; (b)—6 mm from outside surfuce; (c)—10 mm from outside surfuce