Static and dynamic oxidation of Pt-clad Mo47Re alloy

Abstract

Molybdenum-based alloys have the potential for meeting the materials requirements of many applications requiring strength values as high as 140 MPa at temperatures as high as 1,300 C. The addition of Re to Mo provides greater ductility and a lower ductile-to-brittle transition temperature than for unalloyed Mo. The alloy Mo-47Re (wt %) is one alloy from the Mo-Re system that is a candidate for use in hydrogen-fueled engines of hypersonic vehicles. Potential applications for the alloy in engines include heat exchanger tubes at temperatures up to 1,260 C and combustion chamber linings at temperatures to 1,370 C and hydrogen pressures to 175 ATM. The projected service life at peak temperature in such an application is about 12 h. Because of the reactivity of molybdenum and rhenium with oxygen in air at high temperatures, some means of protecting the alloy must be devised. One approach to protecting the alloy is to clad it with a non-reactive impermeable barrier layer. Platinum is proposed as a candidate for use as a cladding because of its high melting point (1,790 C) and chemical stability at high temperature. This paper presents results from a study of the oxidation performance of Pt-clad Mo-47Re. Pt-clad samples weremore » tested under static and dynamic oxidation conditions at 1,260 C. A single unclad sample was tested under dynamic oxidation conditions at 595 C. The static oxidation tests were conducted in an ambient pressure furnace with laboratory air. The dynamic oxidation tests were conducted in an electric arc-heated wind tunnel. Weight change, metallography, and microscopy results are presented to show the effects of oxidation on the alloy and interaction between the cladding and the alloy.« less