Key Engineering Materials Vol. 1009

Abstract: Titanium-based materials are attractive candidates to make low-weight armor parts. However, a broad use of titanium is limited by its high cost, especially when traditional cast and wrought technology is in place. This issue requires more economical production and improved protective properties of titanium-based materials. Powder metallurgy is a valid alternative to make products less expensive, especially when low-cost hydrogenated titanium is used instead of high-quality titanium powder. For effective protection, titanium-based armor should exhibit a substantially improved combination of hardness, strength and ductility, which can be achieved by using laminate (layered) structures. In this study, laminates based on Ti-6Al-4V (wt.%) alloy and its composites reinforced with light and hard particles of TiC and TiB were made using blended elemental powder metallurgy of hydrogenated titanium. Simplest press-and-sinter option as well as additional hot isostatic pressing were tested to achieve high set of characteristics of individual layers and laminates as a whole. It has been shown that the used reinforcement presents an exceptional opportunity for hardening of Ti-based composites without compromising their low specific weight and capable of hardness increase by more than 40% compared to the base alloy. Fabricated structures were ballistic tested and compared with open data on commercial armor made of titanium.

Abstract: 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.