Synthesis of Powder Molybdates for Micro-Alloying of ADI Castings

摘要

Cast austempered ductile irons, currently known as ADI, is a unique family of heat-treated iron-based materials having excellent mechanical properties such as toughness, strength, wear behavior and low production cost. The effect of alloying elements such as Cu, Ni and Mo in ADI influences both the heat treatment cycle and the austempering transformation, increasing the hardenability of the alloy. This paper deals with the fabrication of Cu, Ni and Fe molybdates powders for direct alloying into the melt. The studied compounds were obtained by precipitation following reactions of aqueous solutions of ammonium heptamolybdate and the metal cations in sulfate solutions. Very fine particle-size powders of 1 micron in average diameter were obtained and characterized by means of the usual techniques. Alloying with these products as powder or tablets resulted in Cu, Ni and Mo elements entering the melt with yields up to 100 %.