Ertuan Zhao

Interfacial reactions between Ti-1100 alloy and ceramic mould during investment casting

Abstract The characteristics of the interfacial reaction between Ti-1100 melt and different primary coating materials was investigate. The effect of refractory materials and mould temperature on the reaction was analyzed by comparing the thickness, distribution of elements and microhardness of α-case layer. The α-case layer thickness of Ti-1100 casting with ZrO 2 primary coating is approximately 38 μm, which is higher than that with Y 2 O 3 primary coating (18 μm). Ti-1100 casting using ZrO 2 primary coating shows higher surface microhardness than that using Y 2 O 3 primary coating. The higher mold temperature results in more severe interfacial reaction. With the same primary coating material and mould temperature, Ti6Al4V alloy presents better stability than Ti-1100 alloy.

Effect of different primary coating materials and mold temperatures on fluidity of high-temperature titanium alloy

In this study, the fluidity of near-α high-temperature titanium alloy with different primary coating materials (Y2O3, ZrO2 and Al2O3) and mold temperatures were investigated. The fluidity as an index of castability was evaluated by a fluidity spiral pattern. The Y2O3 primary coating presents the best fluidity and weakest interfacial reaction compared with the ZrO2 and Al2O3 primary coating. The effect of interfacial reaction resulting from different mold materials on fluidity is determined by the stability of mold materials. The interfacial reaction becomes more and more severe with increasing mold preheating temperature. The fluidity does not increase with increasing mold preheating temperature owing to the effect of interfacial reaction. The fluidity is greatly improved at 900 °C, while decreases at 600 °C, indicating the fluidity, depends on the interaction between the interfacial reaction and chilling effect of the mold.

Fabrication of Thin-Walled High-Temperature Titanium Alloy Component by Investment Casting

In order to fabricate a thin-walled high-temperature titanium alloy component, the mold filling capacity of 600°C high-temperature titanium alloy was investigated by a mesh pattern. The results indicate that 600°C high-temperature titanium alloys present poorer mold filling capacity than Ti6Al4V alloy. The effect of different primary coating materials (Y2O3, ZrO2, and Al2O3) and mold preheating temperature on mold filling capacity were also evaluated. It is found that the Y2O3 primary coating presents the best mold filling capacity. The mold filling capacity does not continuously increase with increasing mold preheating temperature due to the influence of interfacial reaction. The proper mold temperature for 600°C high-temperature titanium alloy investment casting is about 300°C. A thin-walled high-temperature titanium alloy component was fabricated successfully.