Study of wetting of SnO2—In2O3-ceramics with copper-silver melts

To improve the wetting of oxide ceramic with metals in addition to traditional dopands (Ti, Zr, Nb, etc.), which have a high chemical affinity to solid phase atoms, alternative active additions can also be used. In particular, it relates to non-metallic electronegative elements VIa—VIIa groups of the periodic system (O, S, Se, F, Cl, Br), which have a high affinity to electron. Such additives are able to reduce free surface energy at the liquid/gas and liquid/solid interfaces and in such a way improve the wetting. The SnO2—In2O3 system is the most optimal material for the layers of the so-called TCO (Transparent Conductive Oxide). Since the cost of metal indium and its compounds continues to grow and new technologies are actively developing, there is a need to find alternative TCO that would have less In2O3 content. That is why systems containing SnO2, doped by relatively small amounts of In2O3 were explored. Ag—Cu based fillers is often used to joint oxide materials. In this case, there is a significant effect of the additives of the third component on the activity of oxygen in liquid metal, which causes an increase in oxygen content directly in the melt. Specially synthesized high-dense ceramics based on SnO2, which was received by adding 5, 10, 20 or 40% (mass.) of In2O3 with subsequent sintering, were used for wetting experiments. The experimental data indicate that in vacuum and air copper, added to the silver melt, significantly improves wetting on all types of the studied ceramic substrates, as well as the wetting is improved with increasing of the In2O3 content in the substrate. A dense transition layer of about 10 μm, which contains a large amount of copper, is formed on the interfacial border. A similar phenomenon was observed at the inter-phase boundary of other oxide materials. The improvement of wetting is explained by an increase in the solubility of oxygen in the melt, which acts as an adhesive-active element, with the addition of copper and increased electronegativity of the substrate with increasing content of In2O3. Keywords: tin dioxide, indium oxide, semiconductor, wetting, contact interaction, metal melt.