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advenced ceramic book

The fundamental nature of the research was exemplified by ab-initio predictions of the friction coefficient of single crystal diamond sliding against its mating diamond plane, and molecular dynamics calculations on single crystal calcium fluoride and barium fluoride interface shear forces. The test equipment developed for completing the model experiments included an Auger/ESCA tribometer capable of unidirectional and oscillatory sliding at room temperature, a scanning electron microscope tribometer designed for oscillatory sliding to 1000 C in vacuum and in partial pressures of reactive gases, an 850 C + dual-rubshoe friction and wear tester employing a rolling contact fatigue rod as one of the sliding specimens, and 850 C + friction/traction apparatus capable of operating to extraordinarily high PV limits. The fundamental nature of the research notwithstanding, the main goals were directed towards finding potential solutions and applications useful to practicing tribologists and lubrication engineers.

The fundamental nature of the research was exemplified by ab-initio predictions of the friction coefficient of single crystal diamond sliding against its mating diamond plane, and molecular dynamics calculations on single crystal calcium fluoride and barium fluoride interface shear forces. The test equipment developed for completing the model experiments included an Auger/ESCA tribometer capable of unidirectional and oscillatory sliding at room temperature, a scanning electron microscope tribometer designed for oscillatory sliding to 1000 C in vacuum and in partial pressures of reactive gases, an 850 C + dual-rubshoe friction and wear tester employing a rolling contact fatigue rod as one of the sliding specimens, and 850 C + friction/traction apparatus capable of operating to extraordinarily high PV limits. The fundamental nature of the research notwithstanding, the main goals were directed towards finding potential solutions and applications useful to practicing tribologists and lubrication engineers.

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.

The goals, structure and highlights of a recently completed multiyear/multinational research program are described. The main driving force behind this effort was the aim to advance the technology base so engineers can design, build and operate solid lubricated ceramic tribocomponents in extreme environments. Specially designed friction and wear testers were employed to perform well-defined model experiments on single crystal and polycrystalline ceramics and solid lubricants. The research led to discoveries such as (1) a lubricious oxide with the shear strength of molybdenum disulfide in vacuum, (2) CVD diamond films with low friction and extraordinarily low wear, (3) intercalated graphites with high tribothermal resistance in vacuum and in air, and (4) a wear equation for silicon nitride ceramics.

The goals, structure and highlights of a recently completed multiyear/multinational research program are described. The main driving force behind this effort was the aim to advance the technology base so engineers can successfully and confidentially design, build and operate solid lubricated ceramic tribocomponents in extreme environments. Specially designed friction and wear testers were employed to perform well-defined model experiment on single crystal and polycrystalline ceramics and solid lubricants. The research led to discoveries such as (1) a lubricious oxide with the shear strength of molybdenum disulfides in vacuum, (2) CVD diamond films with low friction and extraordinarily low wear, (3) intercalated graphites with high tribothermal resistance in vacuum and in air, and (4) a wear equation for silicon nitride ceramics. The fundamental nature of the research was exemplified by ab-initio predictions of the friction coefficient of single crystal diamond sliding against its mating diamond plane, and molecular dynamics calculations on single crystal calcium fluorides and barium fluorides interface shear forces. The test equipment developed for completing the model experiments included an Auger/ESCA tribometer capable of unidirectional and oscillatory sliding at room temperature, a scanning electron microscope (SEM) tribometer designed for oscillatory sliding to 1000 C in vacuum and in partial pressures of reactive gases, an 850 C + dual-rubshoe friction and wear tester employing a rolling contact fatigue rod as one of the sliding specimens, and 850 C + friction/ traction apparatus capable of operating to extraordinary high PV limits.