AVS 49th International Symposium
    Surface Engineering Tuesday Sessions
       Session SE+TF-TuA

Paper SE+TF-TuA6
The Adhesion Behavior of Alumina-based Ceramic Nanocoatings and Nanostructures

Tuesday, November 5, 2002, 3:40 pm, Room C-111B

Session: Systems Design of Functional Coatings
Presenter: M. Istomin, Institute of Machine Reliability, NAS, Belarus
Authors: M.V. Kireitseu, Institute of Machine Reliability, NAS, Belarus
I.A. Nemerenco, Institute of Machine Reliability, NAS, Belarus
L.V. Yerakhavets, Institute of Machine Reliability, NAS, Belarus
M. Istomin, Institute of Machine Reliability, NAS, Belarus
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The adhesion behavior of alumina-based ceramic coatings and alumina-based nanostructures involved CrC nanoparticles in contact with themselves, metals and polymer surfaces is strongly dependent upon the chemistry of the ceramic surface and that of the solids with which contact is made. With clean alumina-based ceramic coating surfaces in contact crystallographic orientation influences adhesion as determined by friction force measurements. Friction force measurements are especially effective in gaining quantitative information on interfacial bond strengths. Ceramics, just as has been observed with metals, exhibit the smallest adhesive bond forces and accordingly the lowest friction for the high atomic density low surface energy crystallographic planes. This has been observed with oxide ceramics such as aluminum oxide and nanocomposites based on alumina matrix and chrome carbide nanoparticles. For metals contacting alumina-based ceramic coatings again the chemical activity of the metal is important to adhesive behavior. With noble metals silver and gold interfacial adhesive bonds were sufficiently weak so as not to result in separation of damage to the surfaces of the contacting solids. With other metals that form stable oxides, the interfacial adhesive bonds were sufficiently strong so as to result in fracture of single crystal sapphire when cleavage planes were parallel to the contact interface. Metals undergo shear when the alumina-based ceramic coatings is poly-crystalline aluminum oxide matrix of alpha and gamma phases and attempts are made to, by tangential motion, to fracture the adhered interface. Adsorbates reduce singificantly adhesion and friction forces.