Effects of some parameters on formation and structure of infiltrated (surface) layer prepared by vacuum infiltration casting technique

Ni-based particles reinforced copper matrix surface infiltrated layer was fabricated on bronze substrate using vacuum infiltration casting technique. The vacuum degree, pouring temperature, preheating temperature, grain size of the Ni-based particles and the thickness of preform during infiltration casting played an important role on the process of forming the surface infiltrated layer. The results showed that three cases were obtained in the vacuum infiltration casting technique: no infiltration, partial infiltration and full infiltration. The reasons for no infiltration were that the vacuum degree was not enough so that the force acting on the liquid metal was lower than the resistance due to the surface tension and the pouring temperature was somewhat low. Partial infiltration was because of somewhat lower vacuum degree and pouring temperature. Full desired infiltration was on account of suitable infiltration casting conditions, such as vacuum degree, pouring temperature, grain size, preheating temperature and thickness of the preform. The most important factors affecting formation of surface infiltrated layer were the vacuum degree, then pouring temperature and particle size. Surface infiltrated layer up to 4.5 mm in thickness with compact microstructure could be fabricated via vacuum infiltration casting technique under the optimum experimental conditions: the vacuum degree of − 0.06 MPa, pouring temperature of 1220 °C, grain size of 0.15–0.20 mm, preheating temperature of 150 °C, and preform thickness of 4.0 mm.