The effects of organic template and thickening agent on structure and mechanical properties of titanium foam fabricated by replica impregnation method

Several organic components are involved in the fabrication of titanium foam using the replica impregnation method, for example polyurethane (PU) foam is used as sacrificial template and PVA as a thickening agent in titanium slurry. Such organic ingredients if not properly selected and subsequently efficiently removed during debinding can be detrimental to the mechanical properties of the titanium foam produced. In this study, polyester- and polyether-based PU foams, as well as degraded polyester-based PU foam, have been used to study the effects of template material on titanium foam quality. In addition, the effects of three different weight percentages of PVA in slurry formulation on coating uniformity have been investigated. The results showed that new (non-degraded) polyester-based PU foam is suitable as the template material for titanium foam production providing foam with a low level of contamination and acceptable compressibility behaviour. Although increasing PVA content increased the viscosity of titanium slurry and improved the coating coverage ability of slurry on the PU foam template, too high PVA content tended to cause pore blockage. The optimum PVA content was found to be 1.5 wt%.