Ceramics-Silikáty

The poor surface metallurgical quality of machined graphite mould titanium alloy castings is one of the key issues limiting their application. A surface coating treatment was applied to the graphite mould, and its improvement effect was studied. Using small-batch titanium alloy nozzle shell castings as the subject, GSK fine-particle graphite was machined to prepare the mould, and an inert surface coating formulated from high-purity fused Y₂O₃ powder and zirconium acetate binder was applied. Comparative analysis experiments were conducted after casting. The focus was on exploring the coating’s effects on the surface appearance, fluorescent defects, X-ray defects, and surface α layer of the titanium alloy castings. After surface coating the graphite mould, the surface roughness of the titanium castings decreased from 3.473~14.560 μm to 2.116~6.153 μm; the number of fluorescent defects decreased by 73.2%, with linear defects reduced by 91.8%; there was no significant difference in the internal defects of the castings; and the thickness of the surface α layer decreased from 185 μm to 136 μm. The surface coating can effectively improve the poor metallurgical quality of machined graphite mould titanium alloy castings and has good potential for promotion in engineering applications.