Influence Of Mold Material Properties On Casting Quality Of Titanium Alloy And Optimization Of Formula

In recent years,titanium and titanium alloys have been widely used in aerospace materials due to their excellent corrosion resistance,specific strength,fatigue strength and high temperature oxidation resistance.The integrity and complexity of structural parts put forward higher requirements,and precision casting,a forming technology,has the advantages of low cost,high efficiency and near-net shape in the integrated forming of complex parts.This process includes wax pressing,wax trimming,tree forming,sizing,dewaxing,casting and post-processing,etc.The process flow is complicated,which ma kes the precision control of parts more difficult.Faced with the development requirements of structural and functional integration,large-scale complex thin-walled,and high-quality for titanium and titanium alloy components in the aerospace field,titani um alloy investment casting technology urgently needs to be improved,especially in the first link of the production process.Conduct related research on investment materials.In this paper,relying on the national key research and development project "pre cision casting technology for large and complex thin-walled structural parts of titanium alloys",the research on the influence of investment material components for precision casting on performance is carried out.First,the comparison of photosensitive r esin,polystyrene(PS)and wax The casting characteristics of the three most widely used investment mold materials at present,focusing on the analysis of the components of four kinds of wax mold materials that have been mass-produced,and designing and preparing binary,ternary,and quaternary waxes with different composition ratios The properties of the three types of investment molding materials were tested,and the effects of component content,distribution state and microstructure on the wax casting ch aracteristics were investigated.The main research results are as follows:(1)Among the three types of investment molding materials,in terms of roughness,the surface roughness of the investment mold corresponding to the photosensitive resin is the smallest,followed by the wax type investment mold,and the PS powder mold is the largest;in terms of deformation,the photosensitive resin molding investment mold has the smallest size change and the largest stab ility,followed by medium temperature wax mold,but it can also reach more than 80% of the area size error within ± 0.2mm,which meets the casting tolerance standard;in terms of coat ing ability,the water-based paint wets the surface of the PS powder mold with greater roughness,the wax mold is the second,and the photosensitive resin mold is the worst.Considering the price difference of the three types of mold materials,the wax mold material is still the most advantageous investment molding material among the three;(2)The infrared characterization results of the four kinds of wax materials commonly used in workshops show that the main components of the wax materials used for titanium alloy investment casting are all alkane compounds.In addition,the addition of aliphatic components can increase the temperature resistance,smoothness and fluidity of the wax,and at the same time,the softening temperature of the wax can be controlled within a reasonable range;the addition of rosin or alkane compounds containing halogenated groups can Increase wax strength and hardness;polyethylene and its derivatives can be used as wax blending agents to improve wax toughness and plasticity;the addition of epoxy compounds can effectively control wax shrinkage.The addition of these different types of compounds containing acyl halide,ether,hydroxyl,carboxyl,aldehyde and halogenated groups has different effects on the fluidity,softening temperature range and flexural strength of the wax;(3)Through the homogeneity,melting point and flexural strength of binary,ternary and quaternary wax materials,Penetration,shrinkage and microstructure comparison,and finally,it is determined that the wax material with rosin and polyethylene content of 5%,paraffin wax and stearic acid of 90% and the ratio of the two is 55:45 has the best comprehensive performance.The fusion homogeneity is the best,the bending strength can reach 6.52 MPa,and the minimum penetration is 1.06 m m.