Nitrides used in this experiment are BN, AIN and Si3N4. First, we studied wettability between nitrides and molten Au-Ag-Pd alloy (composition Au: 12 wt%, Ag: 45 wt%, Cu: 18 wt%, Pd: 20 wt%, Bal.: 5 wt%; melting point: 930°c).
Secondly, we studied feasibility of nitrides as coating materials for wax patterns, that is, Au-Ag-Pd alloy was cast after painting wax patterns with coating material of nitrides. The temperature of mold was 700°C, and an argon arc vacuum-pressure casting machine was used. Surfaces of casted material were investigated using a scanning electron microscope, X-ray diffractometer and surface roughness analyzer.
Results were summarized as follows;
1. The nitrides little wetted molten Au-Ag-Pd alloy.
2. The color of the cast surface coated BN was purple with a dash of red, and this was derived from Cu2O.
3. The dense coating layer of BN inhibited formation of CuO on the cast surface and reduced the surface roughness of the cast.
4. The cast surface coated the nitrides had less clinging than uncoated one, and this indicated that its cleansability was improved.
