Glass solder technique

As mentioned previously, Schiff bases are chemically relatively unstable. This is especially true of d.c. driven cells incorporating components that favor liquid crystal decomposition. Using the glass solder technique in cell manufacture substantially improves the stability of Schiff bases. The stability of Azoxy-compounds and nematic ester, of which the latter has only been available more recently, is hardly affected by the cell components. 

Indium and some of its alloys can wet to glass, quartz, and other normally unsolderable inorganic substrates with the aid of an ultrasonic soldering tool. Ultrasonic soldering will be discussed in the chapter on soldering techniques. 

Quasi-nondestmctive techniques include several transport measurements that are used to test specific membrane properties. They require sample mounting by compression sealing or glass solders that rarely leave the dehcate membrane surface intact. Gas transport properties of dense and microporous membranes are tested by measuring single gas ji as a function of and and by obtainmg fluxes and a/,from the stationary composition and flow rate of gas mixtures at the membrane feed and permeate side. To use the results of these measurements for comparison and optimized membrane designs, substantial... 

Metal powder can also be coated onto the workpiece. The 3M Company has developed a cold welding technique in which the workpiece, the metal powder, water, glass shot and additives are tumbled together in a barrel. Coatings are limited to ductile metals such as Cd, An, Sn, Pb, In, Ag, Cu, brass, and tin/lead solder the method is generally suitable only for small parts, and it doesn t produce a fine surfaced, cosmetic coating. Costs are comparable to those for electroplating with afterbake (Kirk-Othmer 1981). 

An alternative technique is to use high-melting-point glass capillaries and low-melting-point metals such as indium (Dowben and Rose, 1953 Gesteland et al, 1959) or metal alloys such as silver solder (Svaetichin, 1951 Gray and Svaetichin, 1951). 

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