Research on TiAl Alloy Porous Metal Flow Restrictors

Abstract

For the restriction application, the uniformity of pore size and connectivity of pore channels are much more important for TiAl restrictor. TiAl porous materials have expansion phenomenon during reaction sintering for the Kirkendall Effect, and the pores were generated by its partial diffusion. In this paper, elemental powders blending and reaction sintering methods were adopted to prepare TiAl porous flow restrictor materials. The influence of particle size, the fraction of Ti and Al powder, pressing pressure, sintering temperature on the pore character of TiAl porous flow restrictor was studied. The results show that the maximum pore size and expansion coefficient increased with the increase of Al powder particle size, the porosity and permeability increased only when the Al powder particle size is larger than −400/+600 mesh. With the decrease of larger particle Al powder fraction, the porosity and permeability decreased, but the maximum pore size shows little change. With the increase of fraction of fine Al powder, the porosity and permeability increased to a certain value then decreased. With the increase of pressing pressure, maximum pore size, porosity and permeability decreased. When the sintering temperature is lower than 800°C, the porosity and permeability increased with the increase of sintering temperature. At above 800°C, the porosity and permeability decreased with the increase of sintering temperature.