Investigation on mm-wave sintering of metal powder compacts using in-situ dilatometry and electrical resistivity measurements

摘要

Sintering of metal powders is a well-established in-dustrial process for specific applications, which allow acheap series production of metal parts even with complexshape. The residual porosity, always present in sinteredpower compacts, limits their mechanical strength. On theother hand, for several products such porosity is needed.Products of that kind are for example: metal filters show-ing a porosity of about 50%, or self-lubricating plainbearings with a value between 5% and 30%, dependingon the technological working conditions. In the case ofself-lubricating plain bearings made of sintered iron orsintered brass, the open pores are filled with lubricants.Pore-free sinter metals are obtained by hot pressing orimpregnation with a low-melting metalThe use of microwave technology for metal powdersintering had been reported by many researchers, demon-strating improvements in the materials properties and/orin the overall process. Although microwave are not ableto penetrate into bull metals, significant penetration depthin metal power compacts has been reported by theoreticalas well as experimental investigations [1, 2].Here, the progress of microwave sintering of metalpower compacts with focus on copper powders was in-vestigated by systematic variation of process parameters.Those investigations were supported by both in-situ elec-trical resistivity and dilatometry measurements that giveimportant information about the sintering progress andmicrostructural changes.