Sintered Titanium Sponge Using Stop-Controlled SPS Technology

The need for porous materials is rapidly increasing in different applications like electrolysis, direct vaporization, and fluid transport by capillary lift. Additional to a certain porosity between 30 and 60 vol.%, the surface quality, mechanical stability and easy machinability come more and more into focus. Further requirements are raw materials that are low cost and available for mass production and the possibility to select from different materials like titanium, nickel, iron and their alloys for the chosen manufacturing route. In this work, the authors show a powder metallurgical approach on sintered titanium sponge to create a porous structure that meets the above-mentioned requirements. The sintering combines a fast hot pressing by Spark Plasma Sintering with a stop-controlled densification. With this setup it is possible to sinter a titanium sponge to sheets or discs. The sintered titanium sponge was densified to a porosity of 25 and 53 vol.% without any addition of organic or other sintering agents and creating a material that is close as possible to the purity of the initial sponge powder. The shape of the top and bottom of the sintered titanium sponge adapts the surface of the used punches during sintering and can be flat or structured. The plates or sheets can be easily machined to the desired shape using water jet cutting, wire erosion or drilling or milling. Preliminary tests were carried out on porous structures for capillary lift and direct heating elements for vaporisation.