The influence of MoS2 additions on the densification of water-atomized HSS powders

Molybdenum disulphide (MoS2) might be a useful addition in the production of composite self-lubricating high-speed steel parts, which are used in different anti-wear applications. MoS2 might also has a favourable influence on the synthesis of sintered high-speed steels (HSSs) improving the compressibility of the metal powder mixture during its cold compaction, as well as acting as a sinterability enhancer of powder compacts during their sintering. In view of this, the compressibility and the sinterability of M3/2 and M35 types of HSS powder mixtures with MoS2 additions were investigated. In this article, the influence of MoS2 additions on the densification during cold compaction and vacuum sintering of selected HSSs is presented. It has been established that the MoS2 promotes a consolidation of HSS powders during automatic die compaction, as well as final densification during sintering. Sintering of HSS-MoS2 powder mixtures proceeds by the combination of a reactive and supersolidus liquid-phase sintering process. The added MoS2 reacts with the steel matrix, enhancing densification. Fine dispersion of complex sulfides (Cr, V, Fe)S is formed, which improves the machinability and tribological properties of sintered steel.