Oxygen in Atomized MCrAlY Powder and Its Effect on HVOF Coatings

Since its commercial introduction in the early 1980s, it has been known that HVOF spraying can produce layers with low oxide levels, high toughness, and excellent adhesion strength. Unlike low-pressure and vacuum plasma spraying, the HVOF process does not require a controlled atmosphere. As a result, the oxygen content of the wettable powder plays a significant role in layer quality. In this paper, the oxygen content of normal MCrAlY powder is varied and its influence on coating quality is examined. It is shown that, by limiting the initial oxygen content in spray powder, higher density HVOF layers with lower oxide proportions can be achieved. Paper includes a German-language abstract.