SBIR-STTR Award

Chromium is used in the hottest part of a jet engine as an alloying element is superalloys. None metallic impurities generally cause performance degradation and they have to be controlled. The existing chromiums used in supperalloys have C+S+O+ N+H>900 ppm according to specification. We are proposing to develop methods of refining that produce C+S+O+ N+H<100 ppm. Current methods rely on C+1/2 O2=CO and S+Sn=SnS(g) these reaction are carried out under vaccum at >1400 C. Another method is using hydrogen at high temperature about 1400 C. This process uses many times the stoichiometric amount of hydrogen and furnace maintenance is high. Two of our methods are designed to use hydrogen in an innovative ways at higher temperatures while avoiding furnace problem. The third method described does not use hydrogen or carbon. Our aim is to produce high purity at a reasonable cost.

This is a proposal to investigate further the results of the phase I project. In phase one our method of purifying chromium to reduce O, N, C, S, H was successful with one of the two methods. In this phase we will continue improving successful process and investigate a new method. In phase one we were able to reduce the oxygen from 4,200 ppm to 1,100 ppm. And we have not explored at least 2 variables. Our goal is to produce a high purity chromium in which O+N+S+C+H is less than 100 ppm. Our process is not conventional. The conventional process reacts the oxygen in chromium with carbon under about 1400 °C under good vacuum. We do not use vacuum and our temperature is lower.