Improvement of mechanical properties of precision cast ceramic shell focused on the number of layers,drying time and chemical composition

Precision casting method, which is one of the sub-branches of casting and one of the important manufacturing methods, is a multi-process production technique. In investment casting, a specially designed model made of paraffin material, metallic- based molds and ceramic-based shells are used. Each stage of investment casting, which consists of wax injection mold making, wax model formation, model tree formation, ceramic shell formation, wax removal, sintering, casting, shell breaking, product cleaning/sanding, has an effect on the final product. In this study, it is aimed to optimize the drying time-number of layers parameters in the ceramic shell production stage, which is one of the most important steps in investment casting, and to obtain more mechanically useful shells and reduce the wastage rate by adding to the chemical composition after optimum conditions are achieved. In the study, the effect of drying time between coats and the number of coats was examined. Drying times were taken into account in increments of 30, 45, 60 minutes, and it was determined that as the drying time increased, the fracture modulus value measured by the three-point bending test increased. For the number of layers, samples with 5, 6 and 7 layers were evaluated and it was observed that the acceptance strength value increased as the number of layers increased. When the surface roughness values were examined, it was seen that the drying time and the number of layers did not have a significant effect on the surface roughness. Additionally, within the scope of the study, the relationship between disinfectant addition and fracture modulus was examined, considering that the bacterial status in the sludge affected the mechanical properties. A decrease in the number of bacteria was observed in the sludge with disinfectant added, but it was determined that the addition of disinfectant had no effect on the mechanical properties