The effect of adding SBR latex to backup slurries on the properties of ceramic molds in investment casting

Investment casting is an effective way to produce very thin and most complex components with very high-dimensional accuracy and surface finish. One of the steps in the production of components by investment casting is the production of ceramic molds, which are often made of colloidal silica adhesive due to the strength of the molds fired molds. However, this type of adhesive has low strength in green molds, which sometimes causes the molds to fail; hence additives such as fiber or polymer are used to avoid mold failure. Turbine blades are also produced by investment casting due to their sensitivity and high dimensional accuracy. The present study aims to achieve the desired properties in ceramic molds by adding SBR latex to the slurry. For this purpose, layers of slurry with the following two compositions are applied to the wax patterns: a) refractory powder and colloidal silica, b) refractory powder, colloidal silica and latex SBR. Based on this, two ceramic molds from the blade model were layered with the two mentioned compositions and different thicknesses. According to the results, the addition of SBR latex increased Sag Resistance and flexural strength of the molds in the green state and at high temperatures. Examination of the 3D scan results showed that the dimensional accuracy of the cast blades improved at 1400 ° C.