Effect of coating on Sand Bonded sintering quality of cylinder block sand castings

The mold and core used to produce sand castings are bonded by sand particles with binder, so there are many pores. In the process of pouring and solidification, the liquid metal has static pressure and dynamic pressure, which tends to promote the liquid metal to immerse into the pores between sand particles, so as to form a metal layer that is difficult to clean on the surface of sand castings, resulting in sand sticking defects of sand castings.

The coating is applied or sprayed on the surface of the mold and core, the pores between the sand particles are closed due to the infiltration of the coating, the liquid metal cannot penetrate into the pores of the mold and core, the liquid metal is difficult to enter the pores between the sand particles, and the possibility of Mechanical sand adhesion of sand castings is reduced.

At present, graphite, corundum and zirconium powder coatings are commonly used in sand mold casting. In order to evaluate the effect of the three coatings on preventing sand sticking. The pouring experiment was carried out with three kinds of coatings under the conditions of FS powder 0, pouring temperature 1440 ℃ – 1460 ℃ and raw sand 50 / 100. The sand sticking prevention effect of the three coatings is equivalent, and the sand sticking grade is grade III. Considering that as a common graphite coating and zirconium powder coating for gray iron castings, the anti sticking sand effect of corundum coating is equivalent to that of graphite and zirconium powder coating, and has no obvious advantages, the influence of graphite and zirconium powder coating on anti sticking sand effect is mainly investigated.