A MOST OBSTINATE METAL

New Zealand Herald, Volume LXXV, Issue 23145, 17 September 1938, Page 9 (Supplement)

A MOST OBSTINATE METAL

something approaching a quarter of a million tons of aluminium is being used every year there has probably never been a metal so obstinate to man's handling of it. The difficulty with which aluminium is soldered is well known, nnd even to-day, in spite of fortunes which have been spent upon this problem, soldering aluminium is extremely difficult. Rut for the last twenty years similar efforts have been made to nickel-plate and silver-plate aluminium, and here again it is a long story of disappointment on account of the chemical obstinacy of tho metal. The whole trouble lies in the greediness with which aluminium combines with oxygen; a piece of brightly polished aluminium left in tho air will

almost instantly become coated with an infinitely thin layer of aluminium-oxide, and it is this "skin" which not only prevents solder from getting into intimate contact with the metal, but has made any form of electro-plating impossible. Now, however, a process has been invented by which, after a simple chemical treatment, aluminium can be electro-plated with nickel, silver, and chromium. This discovery is likely to be of immeasurable importance in the world of engineering., for it makes possible the use of aluminium and aluminium-alloy in parts of high-speed machinery which, without the plating, would last onlv a very short time. The plated aluminium is also easily soldered, so that here again a thousand new uses for this once obstinate metal will be found.