Preparation And Properties Of Water-Soluble Salt-Core Used For MIM Process

Metal injection molding is a kind of manufacturing high quality precision components of near net shape technology,but this process requires the injection molding mold for mass production of parts with complex cavity structure,causing many shortcomings such as the manufacturing of mold and forming is difficulty,the costing of processing is high,the method of manufacturing processing is complicated,and even some parts can't use the mold injection molding.Use water-soluble salt-core can realize complex inner cavity structure forming parts,and water-soluble salt-core can be removed by using clean water was dissolved at room temperature,and removal time is short.The purpose of this article is study the high strength water-soluble salt-core used to metal injection molding.The water-soluble salt-core adopts metal mold casting process for casting,the bending strength of NaCl-NaNO₃,NaCl-CaCl₂,NaCl-Na₂SO₄ and NaCl-Na₂SO₄ with Al₂O₃ ceramic particles binary salt-cores were studied,and research the forming characteristics of the salt-core at the same time.Main conclusions are as follows:?1?The surface roughness of binary salt-core is lower than that of the unary salt-core.By controlling the pouring temperature can reduce shrinkage tendency of salt-core in solidification.Al₂O₃ ceramic particles added can improve the shrinkage characteristics of salt-core during solidification.?2?Binary system salt-core than unary salt-core has better bending strength,and the highest strength in the eutectic composition or eutectic composition area.When the component of Na₂SO₄ is 30%,NaCl-NaSO4 binary salt-core has the highest bending strength is 17.2MPa,when the component of binary salt-core near eutectic composition,the binary salt-core will crack or break.When the component of CaCl₂ is 40%,NaCl-CaCl₂ salt-core with the highest bending strength is 19.6MPa.The bending strength of NaCl-NaNO₃ is lowest than that of others,the highest bending strength is 9.8MPa when the components of NaNO₃ is 60 %.?3?Adding Al₂O₃ ceramic particles can improve the bending strength of NaCl-Na₂SO₄ binary salt-core.The addition of particles can be refined salt-core isometric area of grain,and improve the bending strength of salt-core.When the component of Al₂O₃ ceramic particles is 30%,binary salt-core can obtain the highest bending strength is 30.2MPa,further improve the component of Al₂O₃ ceramic particles,the bending strength decrease.