Study On The Adhensive Behavior And Sintering Performance Of Natural Yellow Loam Clay-bonded Sand

In sand casting process,generating a piece of strippable burn-on sand layer between sand mould and casting metals under pouring condition,is a effective way to prevent the burn-on defects and acquire castings with high surface finish quality and high dimension accuracy.The studies in this paper indicate,the applicable formula of molding sand for steel casting can be acquired by adjusting the ingredients of natural yellow loam clay-bonded sand(NYCS).In steel casting process,a piece of sinter layer can be generated between sand mould and casting metal while the NYCS is sintered moderately.At high temperature,the NYCS sinter layer,which sticks compactly to the surfaces of casting metals,shows excellent plasticity with certain strength to resist the penetrating of molten metal.The dimension accuracy of steel casts is assured by these two characteristics;at room temperature,the NYCS sinter layer shows certain brittleness.Steel casts with high surface finish quality can be produced while the sinter layer can be easily stripped from surfaces of steel casts.The application of NYCS in steel casting process is closely related to the sintering performance and adhering behavior of NYCS.The NYCS steel casting process shows great advantages,such as abundant raw material resources,environmental friendly,high production efficiency and low fuel cost.Thus,it is necessary to intensively study on the NYCS steel casting process.Based on the ingredients of iron casting yellow loam clay-bonded sand,components and silica sand size are changed to adjust the steel castings.A new yellow loam mineral resource is exploited.The sintering performance of different ingredients of NYCS is studied by a series of sintering experiments.The pouring experiment proved,the optimum formulas in sintering experiment are appropriate to steel cast production.The chemical constituent and mineral composition of NYCS and sinter layer are examined.The results indicate,the strippable burn-on sand layer might possibly contain vitreous objects,and possibly needs the participation of ferric oxide in the process of formation.The author names the strippable burn-on sand layer of steeling casting sinter layer,as the strippable burn-on sand layer shows comprehensive characteristics of oxidation type and sintering type.The sintering experiment of NYCS indicates,the participation of ferric oxide is needed in the formation of sinter layer.The refractoriness of molding sand can be changed with the variation of the sand formula,and the sintering performance can be controlled.The moderate sintered NYCS,which is formed during steel casting,contributes to the formation of sinter layer.The study of adhering behavior of NYCS indicates,the optimum water dose of NYCS is 6w%.The green compression strength of NYCS can be improved about 30%by adding inorganic clay strengthening agent.The study assures the appropriate green compression strength and permeability of NYCS in steel casting production.The study of mechanical performance of NCYS sinter layer at high temperatures and room temperatures indicates,the NYCS steel casing process can effectively prevent the burn-on defects of steel casts,and hot shake-out can be realized because of the mechanical performance of NCYS sinter layer.