Effect of Starch Content on Morphology, Mechanical Properties, and Thermal Properties of Mullite-Based Porous Ceramic as a Candidate Filter in Aluminum Casting

Abstract

Research on ceramic filters, needed in the aluminum casting industry because of their ability to filter inclusions, has been done. This study's primary material to make ceramic or local filters is kaolin. The manufacture of local filters in this study uses the dry press method. In this study, potato starch with a composition of 5%, 10%, and 15% acted as a pore-former in the local filter. The local filter burned to a temperature of about 1200°C to obtain the mullite phase. Local filter characterization used SEM, XRD, XRF, and DTA. Several tests were carried out in this study, including Permanent Linear Change (PLC) test, thermal expansion test, flexural strength test, and porosity test. The results obtained in this study show that pores on the local filter are not open, have a prolate shape, and have an average pore size of 10 to 55 m. Burning kaolin up to 1200°C proved successful in obtaining the mullite phase. Another result of this study, the more starch content added to the material, the greater the shrinkage and expansion of the material; the highest shrinkage value on the material is 0.17%, and the highest expansion value of the material is 0,29%, the 15% values owned by potato starch. It is different in the flexural strength value, which has the highest value with 0% potato starch at 14.14 MPa and the lowest value with 15% potato starch at 5.39 MPa.