테입 캐스팅 공정을 이용한 초경재료 박판재의 소결거동

Abstract

Tape casting process was applied to the fabrication of cemented carbide thin plate with thickness below 1 mm, which is expected to reduce the production cost and to enable the mass production of thin plates. Using the tape casting process, thin plates of cemented carbide were fabricated in the various forms such as monolithic and laminated, perforated and non-perforated thin plate forms. The debinding and sintering behavior were investigated to define the related problems and the solutions were suggested. Through sequential application of sheet forming by tape casting, lamination, debinding and vacuum sintering, the flat cemented carbide thin plates of lateral dimension, the sintered thickness and its deviation of 45~75 mm, minimum 500 μm and 50 μm, respectively, could be fabricated. Cemented carbide thin plates of perforated forms as well as the laminated forms could also be fabricated with a similar specification. Abnormal grain growth was observed in the microstructure, which was attributed to the incorporation of the impurities during the tape casting process. It was found to be readily preventable. Sintering behavior was investigated for the laminated composite thin plates of TiC-Ni/WC-Ni, in the performance diversification perspectives. When the grain growth kinetics were different for the two layers, an asymmetric capillary force was generated to induce a different shrinkages of the layers. This induced a severe warping of the plates. When the grain growth kinetics of the two layers were made identical by addition of grain growth inhibitor, the shrinkage difference was prevented, which enabled warp-free, dense laminated plate.