The history of the technological progress of hardmetals

Abstract The impressive history of hardmetals starts with the search for a proper and cheaper material for drawing dies for the drawing of non-sag tungsten (NS-W) after the First World War. The OSRAM R&D group tried to reduce the brittleness of pure WC by adding nickel at first and soon thereafter cobalt, which was utterly successful. Hence, a project aimed to find the solution to a specific problem can unexpectedly lead to a much more important application: The classical hardmetal was born at the OSRAM Studiengesellschaft in Berlin. The famous respective Schroter patent was issued in 1923. Since nobody at OSRAM was realizing the significance of this invention, the patent was offered to the Krupp Company where the development of a production technology for the manufacture of hardmetals was started. Especially in the prewar and war-years (1935–1945) the hardmetal production at KRUPP increased exponentially from ca. 30 t/year to 500 t/year. The further development of hardmetals is characterized by other carbide and binder combinations. TiC-based hardmetals are a great step forward in the machining of steels and so are fine-grained hardmetals for a wide spectrum of applications. Coating technologies have greatly increased the wear resistance of hardmetals. With the rising tendency of automation in metal cutting, indexable inserts with quite complex geometries were developed for the application in lathes and milling centers working with computer numerical control (CNC). Coating technologies by chemical vapor deposition (CVD) and physical vapor deposition (PVD) have greatly increased the wear resistance of hard metals. Coating with aluminum oxide multilayers and with diamond was devised as well as compact nonmetallic hard materials such as cubic boron nitride, oxide and nitride ceramics and mixed ceramics. Cermets are only briefly discussed here. Hence, after a period of almost 90 years, cemented carbides have evolved from a temporary solution in industry (as a substitute for diamond in W-wire-drawing in the lighting industry) to a very successful and almost irreplaceable material for the manufacturing industry. It is also one of the best characterized materials and makes for 36% of global PM-production. The authors of this presentation consider it remarkable that from the very beginning of hardmetals, the optimal combination of WC and Co was chosen. Even today, 90 years later, there is no better combination of hard carbide and metallic binder in sight. Finally, a short survey of the literature of hardmetals and hard materials is given.