Study On New Water-soluble Binder And Its Effect On Core Performance

The advantages of magnesium, aluminum alloy are high specific strength,low density, excellent heat dissipation and other characteristics, so they arewidely used in the automotive industry and other fields. However, there is a coreshakeout difficult problem when castings with high precision size and complexshape are cast. Taking polyacrylonitrile fiber(PAN) as the main object of study,this paper discusses the effect of different hydrolysis process and corepreparation technology on the performance of water-soluble cores that are usedin magnesium, aluminum alloy.This paper studies the hydrolysis process of polyacrylonitrile fiber. In thealkaline hydrolysis of PAN, along with the extending of reaction time, increasingthe amount of catalyst and water, the specific tensile strength of core increasesfirst and then decreases, the maximum specific tensile strength is5.68MPa whenthe reaction time is7h, the radio of PAN and NaOH is1:0.6, water is8times ofPAN. When pressure hydrolysis is used, the reaction temperature is190℃,the specific tensile strength of core increases first and then decreases with theraise of reaction time, the maximum specific tensile strength is4.43MPa whenthe reaction time is6h. The polydispersity of alkaline hydrolysis is around2,performance is relatively stable.The best alkaline hydrolysis process is applied to study the preparationtechnology of core. Along with the increase of hydrolyzate amount, the specifictensile strength increases first and then decreases, the film thickness betweensand increases gradually. When the content of hydrolysate is5%of the sand,specific tensile strength reaches maximum that film thickness is5.3μm. Theaddition of clay reduces the tensile strength of the core. With the increase ofdrying time, specific tensile strength is down after first rise, when the drying timeis1h, strength is5.68MPa. With the growth of air humidity, specific tensile strength declines little by little. When the humidity is80%，core is placed inthe air after24h, the maximum specific tensile strength is4.5MPa that can alsosatisfy the requirement when re-drying time is30min.Magnesium alloy casting test is conducted after preparation of core utilizingthe best alkaline hydrolysis process and core preparation process. The strength ofcore is high and sand shakeout is easy. The casting surface and internal qualitycan be used to meet the general requirements. All that illustrate polyacrylonitrilehydrolyzate can be used in magnesium, aluminum alloy casting as the water-soluble core binder.