A new in situ process in precision casting for mold fabrication

A new in situ process for mold fabrication in precision casting has been developed to decrease processing time and production costs, and produce an environmentally friendly mold, compared with the conventional process. In the new process, the starting powder is fastened by an inorganic binder, whereas the mold in the conventional process takes its form by using an organic binder. The fixing of powders by the inorganic binder is caused by a sol–gel reaction of precursor materials. Therefore, the new mold process is more environmentally friendly and simpler than the conventional process. The inorganic binder system for the in situ process was prepared from a mixture of tetraethyl orthosilicate and poly(dimethyl siloxane) as SiO2 precursor, and sodium methoxide as Na2O precursor. The prepared samples show a fracture strength of about 5 MPa, indicating that the in situ process can be applied to the fabrication of molds having high mechanical properties.