Swelling of Precipitated Nickel Powder

Abstract

When nickel powders produced by precipitation are heated at elevated temperatures, cracks and voids form within the particles causing them to swell. This swelling has been correlated with the liberation of gases generated by trace impurities in the metal. Using gas volumetric, gas density balance, infrared, and microchemical analyses, carbon dioxide and nitrogen have been identified as the gases mainly responsible for the swelling when the powders are heated in nitrogen. On the other hand, hydrogen sulphide has the major influence when they are heated in hydrogen.