Sub-stoichiometric oxides for wear resistance

• Published in: Wear Vol. 440-441; p. 203104
• Main Author: Woydt, M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-12-2019; Elsevier Science Ltd
• Subjects: Block structures; Carbide; Cemented carbides; Cermet; Cermets; Friction; Hardmetal; Homology; Magnéli; Molybdates; Monolithic materials; Nickel compounds; Niobium; Oxidation resistance; Planar defects; Sub-oxide; Titanium; Titanium oxides; Tribo-oxidation; Tribology; Wear; Wear resistance; Carbide; Tribo-oxidation; Block structures; Friction; Cermet; Wear; Hardmetal; Titanium; Magnéli; Sub-oxide; Niobium; Planar defects
• ISSN: 0043-1648; 1873-2577
• DOI: 10.1016/j.wear.2019.203104

Sub-stoichiometric oxides formed by tribo-oxidation were often analyzed in tribofilms, like γ-Ti3O5, Ti5O9 and Ti9O17 and Mo0,975Ti0,025O2 as well as double oxides, like β-NiMoO4 or NiTiO3. Thus, the contribution of sub-oxides with planar defects (TinO2n-1, Tin-2Cr2O2n-1) or as block-structures (Nb3n+1O8n-2) to the tribological profile of carbides by using monolithic oxides is of scientific interest and has model character.
The tribological profiles of these model oxides under dry unidirectional sliding have shown, that sub-oxides have a contribution to the tribological behavior of carbides and cermets, when they are tribo-oxidatively formed, because their tribological profiles as monolithic materials are homologuous in part or totally, or compete with hardmetals or cermets, depending from the operating conditions regarded.
•The paper summarizes the dry sliding behavior at 22°C and 400°C of 720 tests and more than 36 metallurgical systems.•Sub-oxides with planar defects (TinO2n-1, Tin-2Cr2O2n-1) or block-structures (Nb3n+1O8n-2) compete with carbidic hardmetals or cermets.•Monolithic sub-oxides have a contribution to the tribological behavior of carbidic hardmetals and cermets, when they are tribo-oxidatively formed.•Suboxides presented a broad spectrum in hardness (600-2,000 HV), elastic modulus (155-700 GPa), thermal conductivity (1-100 W/m×K).•The range of properties enabled no relations to the tribological profile (friction and wear coefficients)