Synthesis of New Superhard Materials and Their Application to Cutting Tools.

摘要

The process of Activated Reactive Evaporation (ARE) is used to synthesize superhard materials like carbides, oxides, nitrides and ultrafine grain cermets. The deposits are characterized by hardness, microstructure, microprobe analyses for chemistry and lattice parameter measurements. The synthesis and characterization of TiC-Co cermets is given. Machining evaluation of coated high speed tool steel inserts of type M-42 high speed steel (1/2in. X 1/2in X 1/8in.) were prepared from bar stock and heat treated to a hardness of RC 64 prior to hard coating by the ARE process. Screening tests using a fixed set of machining conditions were carried out. The coating variables studied were surface preparation prior to coating, composition of the coating (TiC and TiC-10Ni) and biasing of the substrate; i.e., 0 volts or ARE process and -2000 volts or biased ARE process. In all cases, the cutting forces were markedly lower for the hard coated tools as compared to the uncoated tools. Examination of the coated samples in the scanning electron microscope revealed that the coated tools showed much less wear than the uncoated tools. Some experiments were also tried with TiC coatings on cemented carbide (WC-Co) tool inserts. Again, the coated inserts showed much less wear so it is to be concluded that the effect is consistent; hard coatings of the type investigated do exhibit improved machinability. (Author)