Optimization of Surface Treatment and Improvement of Corrosion Resistance of Ductile Cast Iron by Liquid Sintering with Ni-based Alloy Powders Using the Heat of Pouring

摘要

Ductile cast iron is used in various fields including piping materials. Recently, improved corrosion resistance of the material is desired for usage in more corrosive environments. In order to fabricate economical and corrosion-resistant material, a molten ductile cast iron was poured into a mold, which was pre-painted with polymer containing Ni and stainless steel powder mixed with lower-melting Ni base alloy powder. Liquid sintering and inter-diffusion between ductile cast iron and alloy powder due to the molten heat in casting resulted in formation of anti-corroded layer. The obtained coated layer showed good corrosion resistance in an aqueous salt spray test for 75 days. In addition, a numerical simulation of the solidification processes was successfully applied to estimate an optimum forming condition of coated layer.