Effect of Wood Sawdust Addition on the Morphology, Mechanical Properties, and Thermal Properties of Mullite-Based Porous Ceramic Filter Candidates for Aluminum Casting Process

Porous ceramic is a heat-resistant porous material with extensive applications, especially for filtering inclusions in aluminum casting industry. To meet local need for these filters, ceramic foam is fabricated by mixing raw materials including kaolin and chamotte as base material, wood sawdust (WSD) as pore-forming agent (PFA), and carboxymethyl cellulose (CMC) with water as binder. WSD content variable: 0%, 5%, 10%, and 15% was used for this research. The mixture was then formed with dry-press method and sintered at 1200°C to form mullite-based local filters. Characterization of samples morphology, composition, and phase were done using SEM-EDS, XRD, and XRF, while its mechanical and thermal properties were characterized by conducting STA, porosity, coefficient thermal expansion (CTE), permanent linear change (PLC), and flexural strength testing. Results showed an increase of WSD addition on the local filter increased the formation number of open-type pores in fiber form on the ceramic microstructure, no significant heat exchanges from decomposition were detected, increased CTE value from 0,0071 to 0,0371%, PLC from 0,0025 to 0,0345%, apparent porosity from 33,29 to 47,95%, and water infiltration from 18,27 to 33,05%, as well as decreased flexural strength from 13,48 to 6,33 MPa and density from 1.82 to 1.43 g/cm3.