Wettability and Brazing of Iono-Ionocovalent Ceramic Materials by Metal Alloys Containing Electronegative Elements

摘要

High wettability of materials to be joined by brazing alloys determines both very process of joint formation and its high adhesion strength. But ceramics are as a rule hardly wetted by standard brazing alloys. To increase wetting activity traditionally metal additions Ti, Zr, Nb and others with significant chemical affinity to atoms of solid phase must be introduced in brazing alloy. But as to iono-ionocovalent ceramics there is alternative type of active additions to govern wettability: namely electronegative elements of VI-VII groups of periodic system (O, S, Se, F, Cl, Br) with high affinity to electron. Such additions being dissolved in suitable metal strongly decrease surface and interface energy (liquid/gas, liquid/solid) in contrast e.g. Ti, which changes only liquid/solid interface energy. In this work physicochemical interface processes and brazing technology were considered and developed with using AgCuO-alloys for oxides (Al_2O_3), fluorides (CaF_2), perovskite substrates; and with using In(Sn,Pb)-S(Se)-alloys for sulphide and selenide (ZnS, ZnSe). On the base of our investigations the soldered windows of optical and infrared-light transparent for special cryostats, discharge devices and models of capacitors were manufactured.