Study On Alcohol-based High Alumina Coatings For Sand Casting

Sand casting is the most widely used casting method.Coating on the surface of sand mold(core)is an effective measure to reduce casting defects and improve the quality of castings.It is of great practical significance to use dust powder produced in the preparation of ceramic casting sand as refractory aggregate to prepare casting coating,which not only realizes the reuse of solid waste,reduces the discharge of solid waste,but also reduces the production cost.Therefore,the research work of preparing casting coating by using dust powder produced by ceramic casting sand as refractory aggregate was carried out.The rheological and thixotropic properties of ethanol suspension after mixing suspension,composite suspension and binder were studied by the method of combining experimental research with theoretical analysis.It was found that the ethanol suspension of organobentonites induced by xylene and 120 ?m solvent oil and the ethanol suspension with concentration of12.0%,13.0% and 14.0% showed the basic characteristics of plasticizing fluid,forming a small thixotropic ring.The shear stress of yield value and the same shear rate increases with the increase of initiator ratio.The ethanol suspension with 11.0%,11.5% and 12.0% concavity of attapulgite has the basic characteristics of pseudo plastic fluid with yield value.With the increase of attapulgite concentration,the yield value of suspension increases,the shear stress increases at the same shear rate,and the thixotropic ring is closed in the anti clockwise direction.The content of organic bentonite is fixed at 6%.In the suspension of mechanical bentonite and PVB ethanol,the PVB concentration is 0.1% ? 0.5%,and the PVB concentration is 1.0% ? 2.0%,and the pseudo plastic fluid is the characteristic.The mechanical bentonite and EC ethanol suspension are plastic fluid when EC concentration is 0.1% ? 2.0%.With the increase of PVB(or EC)concentration in the composite suspension,the yield value remained unchanged and the thixotropic ring area increased.The suspension agent of sand casting alcohol based high aluminum coating is organic bentonite and PVB,binder is phenolic resin,and its suitable addition is 2.5% of total refractory aggregate,3.0% of total refractory aggregate and 0.3% of total refractory aggregate.The rheological properties of alcohol based high aluminum coating and the rheological properties of suspension and ethanol suspension after the mixture of suspension and binder are related.The flow pattern of the coating is generally better than that of the same suspension or suspension or suspension and binder,and the thixotropy is improved.The developed sand casting alcohol based high aluminum coating has good suspension,wear resistance,fluidity,leveling,drying crack resistance and heat exposure,low gas emission and burning reduction,no sand sticking and smooth surface of casting,and has good sand prevention effect.