Development of investment casting molds based on Terengganu silica sand for aluminum and copper alloys

Abstract

The research reported in this thesis has four main objectives. These include to investigate the chemical composition and structural properties of Terengganu local silica sand for foundry use, to develop a suitable investment casting mold formulations, to investigate the thermal and mechanical properties of the developed mold and to recommend a suitable formulation and casting procedures for both of aluminium and copper alloy. The study was conducted in two main phases, where the first phase emphasized on the development of Terengganu silica sand as a mold material while the second phase focused on the application of the developed mold in investment casting process. With the silica content more than 97% and Grain Fineness Number (GFN) of 57 and 49, Kuala Abang and Jambu Bongkok silica were found the most appropriate silica as they can be used directly without the need to grind first. Then, using these silica as a refractory material and plaster of paris (POP) as a binder, several formulations were developed. The compositions used were 75% silica, 25% POP and 31 - 37% water. Silica percentage was also varied from 60 - 85% with POP content changing from 15 - 40%.