Sintering of ferrous metallic compacts: Chemical reactions that involve interstitial elements. Issue 2 (19th September 2018) - Gierl‐Mayer, Christian
Abstract: For sintering of ferrous metallic compacts, the chemical reactions with the atmosphere are of special interest. This is due to the very large specific surface of the compacts that makes them highly reactive with the atmosphere, much more than cast and wrought metals. Within this paper, the interactions of interstitial elements with the metallic matrix and the surrounding atmosphere are described. The main reaction partners are interstitial elements that may emerge from the starting powders or from the surrounding atmosphere. The oxidation/reduction and decarburization phenomena have been studied by thermoanalytical techniques both for mixed and prealloyed systems. The reaction mechanisms are discussed as well as their impacts on the sintering processes and the resulting properties. Oxygen transfer reactions ("Internal gettering") and formation of methane are observed for systems with widely varying oxygen affinity of the components. The results presented show that controlling the interactions of the interstitial elements with the metallic components is crucial for successful sintering of advanced PM alloy steels.