Al/TiO2 bilayer coatings for space applications: Mechanical and thermoradiation properties

Spatial stabilization of long-length structures under the space conditions is connected with a need for minimization of changes of their temperature fields during the non-stationary heating by solar radiation. One of the most effective ways of the solution to this problem is the use of the method of passive thermoregulation due to deposited special coatings on the construction surfaces. In case of deployable structures these coatings should possess a complex of properties, including a definite combination of an absorption coefficient of solar radiation and an emission coefficient, high adhesion to the construction surface in case of its technological and service deforming, as well as a sufficient erosion resistance in contact with other materials. Taking into account the above-mentioned requirements the present work deals with a feasibility of use of two-layer thin coatings, consisting of an inner layer of aluminum and outer layer of titanium dioxide TiO2, which were produced by the method of electron beam deposition. Mechanical and thermal radiation properties of two-layer coatings (Al/TiO2) on the surface of stainless steel were investigated in this work. It is shown that these coatings possess high adhesion strength and are characterized by an optimal combination of coefficients of radiation and absorption of solar radiation that will provide thermal stabilization of deployable steel structures under conditions of their non-stationary irradiation.