Accession Number : ADA295170

Title :   Determination of the Tribological Fundamentals of Solid Lubricated Ceramics. Part 3: Molecular Engineering of Rutile (TiO2-x) as a Lubricious Oxide.

Descriptive Note : Final rept. 1 Aug 90-1 Jul 93,

Corporate Author : HUGHES AIRCRAFT CO EL SEGUNDO CA

Personal Author(s) : Gardos, M. N.

PDF Url : ADA295170

Report Date : OCT 1994

Pagination or Media Count : 195

Abstract : A study was conducted to (a) confirm a Hughes hypothesis correlating the oxygen stoichiometry of rutile Magneli phases (Ti sub n O sub 2n-1) with their tribological behavior, and (b) show feasibility of controlling the stoichiometry (and thus the tribological performance) by doping specifically with Cu2+/Cu1+ and other selected cations. Variable temperature (from R.T. to 1000 deg C) SEM tribometry completed on fully stoichiometric, single crystal and polycrystalline rutile samples and other polycrystalline specimens reduced into narrow stoichiometric ranges confirmed that the shear strength and the resultant friction are highly dependent on oxygen-content-controlled development of various crystallographic shear planes (the TinO2n-1 Magneli phases). However, the high sensitivity of these phases to structural changes induced by the variation of the sample temperature and the partial pressures of oxygen around the sample render the rutile polymorph of TiO2.00 a tribooxidatively unstable material. Polycrystalline rutile was subsequently doped with cations predicted to stabilize or fail to stabilize stoichiometry. X-ray diffraction combined with four-point electrical conductivity measurements of model rutile compositions doped with CuO indicated the predicted the feasibility of generating chemically induced crystallographic shear planes through the creation of a Ti-Cu bronze equivalent in behavior to a TiO18.9 Magneli phase. SEM tribhometry, combined with other high temperature tribotests performed with an engineering-type friction and wear bench tester, demonstrated the enhanced tribooxidative stability of the copper-doped, TiOi1.89-like doped lubricious oxide prototype.

Descriptors :   *SOLID LUBRICANTS, *TRIBOLOGY, *RUTILE, SHEAR PROPERTIES, CATIONS, ENVIRONMENTS, STRUCTURAL PROPERTIES, HIGH TEMPERATURE, X RAY DIFFRACTION, PROTOTYPES, SINGLE CRYSTALS, ELECTRICAL CONDUCTIVITY, OXYGEN, CERAMIC MATERIALS, ENGINEERING, SAMPLING, DOPING, BEHAVIOR, HYPOTHESES, FRICTION, PLANE WAVES, STOICHIOMETRY, ELECTRICAL MEASUREMENT, CRYSTALLOGRAPHY, POLYCRYSTALLINE, SHEAR STRENGTH, TITANIUM OXIDES, PARTIAL PRESSURE, HIGH SENSITIVITY.

Subject Categories : Lubricants and Hydraulic Fluids
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE