A novel experimental approach to the evaluation of thermal expansion parameters of solid materials

Abstract

In this work a micromagnetic emission – aided experimental approach is presented by which the coefficients of thermal expansion (CTE) and related thermoplastics Young's as well as respective plastic moduli of various solids can optimally be evaluated. For this scope, certain well- established characteristics of stress (strain) – correlated ferromicromagnetic properties of Ni (nickel) material were used as basic- reference measuring parameters. In this context a well- determined Ni- based layer was produced by vapor deposition on the surface of tested substrate material. This layer in turn was utilized as a suitable sensor for its micromagnetic emission – response to stresses (strains) developed during simultaneous thermal cooling of Ni – layer and respective substrate. The substrate form of metallic oxides were prepared by suitable thermal oxidation treatment of the respective metal, where the desired quality and thickness of obtained oxide scale could be achieved with acceptable tolerance. As such, the reliability, versatility and conveniency of the proposed measuring technique was tested on the basis of titanium and nickel as well as three types of metallic oxides, i.e. MgO (magnesia) TiO₂ ( rutile) and Mn₃O₄ (Hausmannite). This was possible by subjection of these materials to controlled thermal cooling procedure within given temperature ranges. In this way one can demonstrate that the obtained experimental data concerning the overall- average as well as instantaneous CTE of these materials are in reasonable agreement with those found in the related literature. It was also found that the order of magnitude of the evaluated thermoelastic and plastic moduli were also in reasonably agreement with data in the respective literature. It should, however, be mentioned that owing to the scarcity of detailed data on these parameters, a more systematic and reliable assessment of the obtained values could not be made.