Sydorenko T. Wetting and contact interaction between liquid metals and barium titanates and some other ceramic materials with perovskite structure.

The thesis is dedicate to complex investigations, including studies of wetting by liquid metals, of metal coatings deposition onto ceramic surface and of brazing process, which were carried out for two states of barium titanate (BaTiO3), namely, semiconducting and ferroelectric perovskite ceramics. Pure metals and Ti-containing alloys were investigated under high vacuum at the semiconducting barium titanate surface. Wettability degree correlates approximately with chemical affinity of liquid metal phase to substrate oxygen (it increases when the affinity to oxygen increases). Addition of Ti increases essentially capillary properties and adhesion of components of the system under investigation. Analysis of BaTiO3/liquid metal interface has shown that TiO accounted for wetting in studied system. The effect of oxygen partial pressure around metal drop on wetting behavior of perovskite ceramics in contact with liquid metals was investigated. For the first time, wetting of ferroelectric perovskite ceramics by Ag-Cu-O system under oxygen atmosphere was studied; values of contact angle, adhesion, and strength of BaTiO3 - metals interface were obtained. The theoretical justification of adhesive processes specifics were suggested. Method of brazing for bouth ferroelectric and semiconducting ceramic materials based on BaTiO3, and also deposition method of coatings with high adhesion are developed.