SHS production, processing and evaluation of advanced materials for wear-resistant cutting tools

Self-propagating high temperature synthesis (SHS) has demonstrated in the past decade to be a cost-effective process for the manufacturing of advanced multi-phase materials difficult to produce through conventional routes. Due to its intrinsic flexibility, the SHS process perfectly suits to the production of ceramic materials characterized by high hardness at room and high temperature, chemical inertia and refractoriness, being thus ideal candidates as hard phase for wear-resistant and cutting tools applications. The aim of this work was the synthesis of multiphase powder systems with sub-micrometric level degree of homogenisation. The SHS reactions have been set up and optimised in order to obtain composite powders with different compositions starting from inexpensive raw materials. The stoichiometry of the reactions investigated was tuned to obtain sufficient exothermicity to allow the self-propagation to completion, investigating several powder systems with tailored mixed carbides, borides and oxides compositions. The densification. of the SHS-produced compositions for the manufacturing of dense ceramic materials was investigated. The hot pressed materials turned out to be valid candidates for wear-resistant applications due to the high hardness and toughness properties demonstrated. This was verified through the production of cutting tools prototypes with the optimised compositions. PVD coating was set up for the prototype tools. The evaluation of the on-work performance of both coated and uncoated cutting tools showed good results in terms of wear resistance. As a final remark, the application of the developed materials in wear-resistant components introduces a real improvement in cutting and machining processes because of the intrinsic eco-compatibility of the SHS process towards competitor synthesis routes.