Modification Of Investment Casting Wax Pattern

With the demand of national strategy,the precision forming technology of superalloy has been paid more and more attention in the fields of aerospace,ship and so on.It is used to prepare complex thinwalled castings such as Aeroengine Blades,turbine rear gearbox and so on.With the development of lightweight integrated manufacturing,the structure of precision casting is more and more complex,which leads to the structure of wax mold is more and more complex.The complexity of wax mold will increase the difficulty of slurry and sand spraying in investment casting process,which makes the preparation of ceramic shell more difficult.In order to avoid the problems of the uniformity of shell making and the low density of surface layer brought by the traditional technology of slurry and sand spraying,a new technology route is explored in this paper.The uniform and dense ceramic shell layer is prepared by electrophoretic deposition technology.The precondition of electrodeposition is to modify the non-conductive wax into electrode material with certain conductivity.In this paper,conductive carbon black was used as filler to modify wax for investment casting.The influence of carbon black mass fraction and other parameters on the conductivity and fluidity of wax was investigated systematically.The results show that when the content of BP2000 carbon black is 9%,the resistivity of modified wax is 19.853 ?·cm,and it keeps good fluidity.Finally,a kind of precision casting wax mold with high conductivity was prepared by using the modified wax.In order to prepare mold shell ceramic layer by electrophoretic deposition technology,a set of electrophoretic deposition device was specially designed,and the electrophoretic deposition experiment was carried out with ZrSiO4,a casting mold shell material.The effects of the main parameters,such as the iodine concentration of ZrSiO4 suspension,the voltage of DC power supply and the time of electrophoretic deposition,on the deposition thickness of ZrSiO4 ceramic layer were investigated.The results show that a relatively complete ZrSiO4 ceramic layer can be formed on the wax mold surface after 10 minutes of electrophoretic deposition,and the thickness of ZrSiO4 ceramic layer can reach 100?m after 60 minutes.The stability of ZrSiO4 ceramic layer was evaluated by the adhesion test of ZrSiO4 ceramic layer and wax mold surface.Finally,the best iodine concentration 1.0g/L of ZrSiO4 suspension and DC voltage220 V were determined through the comparative analysis of several test results.