Role of process control agent on synthesis and consolidation behavior of nano-crystalline copper produced by mechano-chemical route

Nano-crystal line copper was synthesized by mechano-chemical reduction of Cu2O with carbon. Influence of stearic acid addition as a process control agent (PCA) on characteristics of synthesized and consolidated copper samples was investigated. The structural evolution and morphology of powders were evaluated using XRD and SEM, respectively. It was found that the nano-crystalline Cu formed after 35 h of milling and addition of stearic acid prolonged the process. On the other hand, the use of stearic acid in final stages of the process prevented excessive cold welding of ultra fine Cu particles during milling. In fact, it successfully inhibited the formation of coarse Cu particles and eventually decreased the crystallite size of the product to 19 nm. The hardness of sintered Cu sample increased due to the reduction of mean crystallite size. (C) 2007 Elsevier B.V. All rights reserved.