Predicting oxidation‐limited lifetime of Ni‐Al‐Cr porous radiant burners made by combustion synthesis

Abstract

Ni-Al intermetallic alloys have superior high-temperature properties such as excellent oxidation resistance and high yield strength, making them particularly attractive as materials for the fabrication of porous components of energy conversion and combustion devices. In this study, the cyclic oxidation resistance of highly permeable Ni-Al-Cr alloys has been investigated. The porous alloys with a structure of irregular porous scaffold comprised of welded mm-sized spheroidal strut elements forming a net of mm-sized interconnected pore channels (porosity of 0.55–0.60, specific surface area below 10−3 m2/g) were manufactured by the combustion synthesis method using μm-sized Ni, Al, and Cr powders of commercial purity as starting reagents. The surface area of alloys exposed to oxidation was calculated with an accuracy of 6% using quantitative 2D stereology. The cyclic oxidation tests were conducted in dry artificial air at 1150 ℃ for 100 h. The Ni‐Al‐Cr alloys, compared to Ni‐Al alloys, exhibited a twofold increased oxidation resistance because of decreased scale spallation. The porous alloys were also tested in a combustion environment. The lifetime prediction showed that Ni‐Al‐Cr radiant burners could be used for > 10,000 h at a temperature of 1000 ℃, which makes them relevant for application in domestic combustion appliances such as water heating boilers.