Effect of the size distribution and morphology of refractory particle on self-curing time of water-based self-curing casting coatings

The self-curing mechanism of water-base self-curing sand-casting coating is described. The relationship between the moisture content and the self-curing time of the coating is analyzed on the basis of the principle of non-isometric ball stacking and verified experimentally. The influence law and cause of the size-distribution and morphology of refractory-aggregate particle on self-curing time of coating is studied based on experiments. The results show that: the moisture content of the coating has an approximate linear relationship with the self-curing time of the coating, the particle-size distribution of refractory-aggregate has a significant effect on the self-curing time, while the particle size has little effect. The particle size of refractory aggregate should be normally distributed with an average particle size of 200 mesh to 325 mesh. The particle morphology of the refractory aggregate also significantly affects self-curing time of the coating, the coating prepared by the powder quartz whose grain shape is similar to the spherical shape has a low moisture content and the coating can cure quickly. The coating with a thickness of 0.5mm can achieve self-curing within 100 minutes under an environmental condition of a relative humidity of 80%±2%, which is expected to meet the production requirements of resin sand casting under high humidity climate conditions in South China.