Research On Alcohol-Based Coating For Titanium Alloy Sand Casting

The chemical properties of titanium alloy is very lively,molten titanium liquid can easily react with mold material with extremmely chemical reaction.As a result,the phenomenon of pores and oxide wrinkled skin on the casting titanium alloy which seriously influence of the casting surface quality and performance.This paper developed a suitable silicon sol coating and zirconium acetate coating for titanium alloy casting,tested the performance of coating,such as the suspension,gas permeability,thixotropy and high temperature strength so on and verified the effect of the paint by using the pouring experiment.According to the silicon sol coating in this paper, with the increase of the silicon sol and the polyvinyl butyral,the viscosity,suspension and thixotropy of the coating get large improvement. Silicon sol as binder can effectively enhance the strength of the coating,but when the content of it is more than 25%,the high temperature anti-cracking and permeability is much lower bacause of the contraction of membrane layer. The influence of PVB content to the high temperature strength and the anti-cracking of the coating is not very big bacause it began to volatiled and decomposited at 250℃. The grading of the refractory aggregate can obviously improve the rheological properties of coating as well as the comprehensive performance is best when the content of the fine power is 40%.Finally by optimizing the test of mixing ratio of colloidal silica coating we optimized the content of the raw materials, zirconium oxide (325 mesh) 60% ,zirconia (1000 mesh) 40%, silicon sol 25%, PVB 4%, alcohol 110%.According to the acetic acid zirconium coating in this paper the contents of the binder and suspension formulation can obviously effect the viscosity, thixotropy ,suspended sex and paint temperature strength of coatings. When the content of acetic acid zirconium exceeds 20%, the coating liquidity , permeability and drying anti-cracking also becomes poor. Big gap-short time mixing can get good smearing coating and small gap-long time get high strength coating. According to the comprehensive advantages we get the coating mixied process is: gap 40μm, time 30min. Finally by the test of mixing ratio of acetic acid zirconium coating we optimized the content of the raw materials, zirconium oxide (325 mesh) 100% , acetic acid zirconium 20%, PVB 2%, alcohol 120%.