The analysis of strength and fracture morphology of Al-Si compound made from moulding sand formulation with bentonite binding material and Portland cement

Abstract

Purpose: This research aimed to analyse the casting result of Al-Si compound used formulation of moulding sand with bentonite binding material and Portland cement. Design/methodology/approach: Bentonite binding material’s type consisted of swelling (Na-bentonite) and non-swelling (Ca-bentonite). Optimum formulation of the moulding sand was 4% of swelling bentonite and 6% of Portland cement, 6% of non-swelling bentonite and 4% of Portland cement. The optimum formulation result of molding sand with bentonite binding material and Portland cement was used in Al-Si compound casting. The result of Al-Si compound casting strength was examined which in terms of its tensile strength, toughness, and hardness. Besides the three tests, the result was also supported by the fracture shape morphology of tensile test and impact toughness test result. Based on the Al-Si compound tensile test result, it was found that the best value was obtained when using 105.52 MPa of swelling bentonite. Findings: The impact toughness test result presented that the use of non-swelling bentonite produced better toughness value which was 0.00592 J/hour while the mickroVickers hardness test result showed that Al-Si compound result using non-swelling bentonite produced 111.04 HV hardness. Based on the fracture morphology test result using SEM of Al-Si compound casting result using swelling and non-swelling bentonite after being tested its tensile strength and impact toughness showed that the same fracture which was brittle fracture tended to appear. Research limitations/implications: In this casting process, combination which is being used is bentonite (swelling and non-swelling) and Portland cement as mould sand binding material. Practical implications: The combination can be used to find the bentonite type that can produce binding material formula with high binding level which can minimize defects on the resulted casting products. Originality/value: In this study swelling and non-swelling bentonite mixed with certain level of Portland cement combination are used.