Investigation of the influence of softening modifiers on the knockout of investment castings

The paper considers the problem of laboriousness of cleaning and knocking out investment casting castings from ceramic molds material. The influence of softening modifiers on the structure and residual strength of ceramic samples was analyzed. A magnesium sulfide and copper chloride were selected for the study because of their temperature of destruction, which is in the range of the calcination temperature of the ceramic shells and the temperature of pouring the mold with liquid metal. For comparative studies of particle size distribution after exposure to shock loading the samples were formed from ceramic suspension with introduction of 1.5 and 3 wt.% of softening modifiers. Fractures of ceramics were examined using a two-beam electron scanning microscope “Versa 3D”. It was shown that the use of copper chloride as a softening modifier in the composition of ceramics is facilitate the process of knockout the mold of investment casting.