Vacuum sintering of water-atomised HSS powders with MoS2 additions

Molybdenum disulphide (MoS2) is a well-known and widely used solid lubricant. As such, it might also 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 have a favourable influence on the synthesis of sintered HSS. 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 paper, the influence of MoS2 on the densification during vacuum sintering of selected HSSs is presented. It has been established that the densification of HSS-MoS2 powder mixture proceeds by a combination of a reactive and super-solidus liquid-phase sintering process. The added MoS2 reacts with the steel matrix, enhancing densification. Complex sulphides (Cr, V, Fe)S are formed, whilst the Mo enriches the steel matrix and forms complex carbides with other alloying elements. (C) 2001 Elsevier Science Ltd. All rights reserved.