Study Of Effects On The Properties Of Phosphate No-bake Sand

The property of the phosphate no-bake sand was mainly impacted on the binder and the curing agent and the environment. By studying the modified binder and the composite curing agent, expatiated their effect to the property of the phosphate no-bake sand. The experiment studied the transformations of the phosphate no-bake sand under different temperature and relative humidity. Through the SEM, the microcosmic pattern of the phosphate no-bake sand was observed, and analyzed the mechanism.By studying the citric acid modified binder, it can be found that when the addition quantity of the binder and the curing agent was 4% and 10%, the tensile strength of the phosphate no-bake sand was 0.775 MPa, it has improved 35% than the non modified no-bake sand. United the citric acid and PVP in the binder, the taken off time of the phosphate no-bake sand was decrease most, from 55 minute to 25 minute. United the citric and the silicic acid in the binder, the store stability of the phosphate no-bake sand was improved, the undulation of the tensile strength was less than 14% during seven days.By studying the composite curing agent, it can be found that when the addition quantity of the rare earth in the curing agent was 10%, the highest tensile strength of the no-bake sand was reached 0.97 MPa, improved 60%, and the undulation was less than 17% during seven days. When the addition quantity of the iron oxide in the curing agent was 20%, the tensile strength of the no-bake sand was 0.775 MPa, improved 30%, when the addition quantity of the iron oxide in the curing agent was 30%, the undulation of the tensile strength was less than 5% during seven days. By using the iron oxide composite curing agent and magnesium compound modified binder together, the tensile strength of the no-bake sand can reach to 1.18 MPa, but the store stability was bad, the tensile strength had fallen down 47%.By studying the environmental factors, it can be found that under the low relative humidity, the harden time of the no-bake sand was 35 minute, the store stability was good, the undulation of tensile strength was less than 10% during seven days. If under the high relative humidity, the harden time of the no-bake sand was more than 95 minute, the store stability was badly, the tensile strength had fallen down more than 80% during seven days. Under the low temperature, the using time of the no-bake sand was longer than under the high temperature, the tensile strength was decreased 20% when the temperature getting higher.Through observing the microcosmic pattern of the no-bake sand, it can be found that the film adhesive and the cohesive bridge of the better property ones was smooth.