Tailoring the Functional Profile of Niobium Carbide(NbC)as Cutting Tool Materials and for Wear Protection
The binary phase diagram of NbC is unique,as in a large range of homogeneity 0.75≤x≤1.0,the properties of NbCx,like micro-hardness,hot hardness,sliding wear resistance,elastic modulus and toughness can be tailored by the C/Nb ratio,the addition of secondary carbides and the type of binder.With increasing temperature,the gap in hardness or thermal diffusivity of NbC in relation to WC is narrowed or disappeared.NbC and Nb2O5 have so far no REACH classifications related to human toxicology and are not listed as substances of very high concern contrary to WO3 and Co3O4.Niobium is today largely available.The initial NbC grade was substoichiometric,SPS sintered and cobalt bonded(NbC0.88-12Co SPS).The NiMo-bonded stoichiometric NbC1.0 grades enable the substitution of cobalt by nickel,SPS by conventional sintering and NbC0.88 by NbC1.0 in view of functional properties.Nickel bonded NbC grades have improved toughnesses versus cobalt bonded NbC grades,but lose hardness.NiMo and NiMo2C bonded NbC1.0 grades compensated the loss in hardness while keeping the toughness.The tool lifes of uncoated NiMo-and NiMo2C-bonded stoichiometric NbC1.0 grades under dry turning 42CrMo4 and C45E were between+30%to+100%higher and up compared to WC-6Co(fine grain).NbC grades displayed lower dry sliding friction over WC grades.The softer Ni-and NiMo-bonded NbC1.0 –grades with lower toughnesses have a higher dry abrasive wear resistance(ASTM G65),as the tougher WC-Co grades.
Niobium carbide Properties Wear Machining
Woydt Mathias Huang Shuigen Vleugels Jef Mohrbacher Hardy Cannizza Eduardo
Division 6.3 Tribology & Wear Protection,BAM Federal Institute for Materials Research and Testing,Un Department of Materials Engineering(MTM),K.U.Leuven,Kasteelpark Arenberg 44,B-3001 Heverlee,Belgium NiobelCon bvba,B-2970 Schilde,Belgium EHT-Engineering Consulting Ltd,S(a)o Paulo,Brazil
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2018-09-16（万方平台首次上网日期，不代表论文的发表时间）