Disclosed are a cermet alloy having excellent wear resistance and strength at elevated temperatures, and a composite mechanical part containing a strong layer of any such cermet alloy formed on the outer or inner surface of an alloy base. The materials which are used for making rolls, dies, punches, etc. are required to have excellent toughness, impact resistance, high-temperature strength and wear resistances. The conventional ultrahard WC--Co alloys are, however, unsatisfactory in high-temperature strength, through they have a satisfactorily high level of wear resistance. The conventional cermet alloys are low in toughness and impact strength, though they have high oxidation resistance. There has not been availabe any alloy that satisfies all of the requirements as herein-above stated. An energetic study has been made of the effects which the components of a cermet alloy may have on those requirements, and it has been found that all of those requirements can be satisfied by a cermet alloy which comprises a hard phase comprising 20 to 50% by weight of at least one of the carbides, nitrides and carbonitrides of Group IVa, VA and VIa elements and further containing at least one of the carbide, nitride and carbonitride of titanium, and a binding phase containing appropriate amounts of nickel and chromium. This cermet can be used to form a layer bonded to a surface of an alloy base to make a composite mechanical part.
A cermet tool that has excellent thermal crack resistance, while maintaining plastic deformation resistance, wear resistance and a long service life even when it is used for intermittent cutting is disclosed. The cermet tool comprises Ni or Ni and Co in a total amount of 4-20 wt. %, Ti in an amount of 50-60 wt. %, V, Cr, Zr, Nb, Mo, Hf, Ta, and W in a total amount of 30-40 wt. %, C in an amount of 5-10 wt. %, and N in an amount of 3-8 wt. %. The carbonitride phase contains grains of a Ti carbonitride phase containing Ti in an amount of 90 wt. % or more with respect to all the metal components of the phase. When the cross-sectional microcrystalline structure of the cermet is observed, the ratio of "total area of grains of the Ti carbonitride phase having a ratio of D.sub.max /D.sub.min of 1.5 or more" to "total area of the hard phase" is 50% or more.
The present invention provides a process for preparing titanium nitride sintered masses having no residual pores and consisting of TiN solid solution particles and Ni solid solution matrix, in which a granulated powder of the following composition: wherein: p is 5 to 20 wt %; q is 0 to 1.5 wt %; r is 15 to 30 wt %; s is 0 to 5 wt %; MeC is one or more carbides selected from VC, WC, TaC and NbC; with the proviso that q and s are not 0 wt % simultaneously; is compacted and sintered. The process according to the present invention can provide sintered TiN cermets of high density and a small grain size.
Method of manufacturing a sintered carbonitride alloy comprising wet milling powders of forming binder phase containing Co, Ni and mixture thereof and powder forming hard constituents of nitrides and carbonitrides with Ti as the main component to a mixture with desired composition; compacting said mixture to form compact; heating the compact at 100-300 C. in oxygen or air and subjecting said compact in multiple heating steps to effect sintering.
A sintered titanium-based carbonitride alloy contains hard constituents based on, in addition to Ti, W and/or Mo, one or more of the metals Zr, Hf, V, Nb, Ta or Cr in 5-30% binder phase based on Cobalt and/or nickel. The content of tungsten and/or molybdenum, preferably molybdenum in the binder phase is >1.5 times higher than in the rim and >3.5 times higher than in the core of adjacent hard constituent grains. The alloy is produced by a particular method.
The present invention provides a vane material having an excellent scuffing resistance in a compressor employing an alternative Freon gas as a cooling medium and a process for the preparation thereof. In accordance with the present invention, a vane material is provided having a structure comprising a base material consisting essentially of 1.0 to 4.5% by weight of carbon, not more than 1.5% by weight of silicon, not more than 1.0% by weight of manganese, 3 to 6% by weight of chromium, not more than 30% of tungsten and/or not more than 20% by weight of molybdenum provided that (W+2Mo) is not more than 45% by weight, 2 to 10% by weight of vanadium and/or niobium, not more than 20% by weight of cobalt, and a balance of iron and inavoidable impurities with additive particles of a carbide and additive particles of a nitride and/or a carbonitride, sintered thereto in an amount of more than 0% to not more than 25% by weight and 2 to 25% by weight based on the total weight of the vane material, respectively. The vane material according to the present invention can be obtained by sintering the mixture of the base powder with the particulate carbide and nitride or carbonitride powders.
