The Effect of Water Glass Content on the Morphology and Thermal Properties of Anorthite-Based Ceramic Foam Filter for Aluminum Alloy Casting

The fabrication of anorthite-based ceramic foam filters with the function of filtering molten aluminum has been done using the replica method.To obtain the anorthite phase, kaolin and limestone were used as raw materials.Water glass acts as a deflocculant during the making of the slurry to lower the viscosity and improve the homogeneity of the suspension, with various weight percentages of 0.1%, 0.2%, and 0.3%.Samples were fired up to 1200 o C to obtain the anorthite phase.Characterization was conducted using SEM, EDS, XRD, and analysis of average pore area was performed using ImageJ software.Several tests were also carried out, including viscosity testing of the slurries, permanent linear change (PLC), and thermal expansion tests.An average pore area of 0.22 mm 2 to 0.28 mm 2 was obtained.Anorthite has been proven to be successfully obtained by firing up to 1200 o C. The water glass content does not affect the pore size and morphology but has a significant impact on the viscosity, permanent linear change, and thermal expansion.The more water glass content added to the slurry, the lower the viscosity and the higher the permanent linear change and thermal expansion percentage.The sample with 0.3 wt% of water glass results in the lowest viscosity of 1.25 cP, highest permanent linear change, and thermal expansion percentages of -4.19% and 0.67%.