METAL SPRAYING.

Hawera Star, Volume XLVIII, 5 November 1924, Page 8

METAL SPRAYING.

INTERESTING DESCRIPTION. Great interest was attracted "by a detailed description of the methods and advances made in metal spraying by Mr. T. H. Turner and Mr. W. E. Ballard at the Institute of Metals (states the Morning Post). Although this process has been known for the past ten' years; : its development has been retarded by the war, and it is now only just opening out, and the full possibilities have not yet been realised. Briefly, it consists of treating metals of practically every description as if they were sent in a scent spray, and depositing them on any'desired object in the form of a fine adherent dust. The metal surface thus obtained can be burnished or polished to any degree afld is permanent; The spray is produced and projected by . an instrument resembling a large automatic pistol, but the magazine is loaded with a reel of wire in plane of cartridges, and • the propulsive charge is composed of oxygen, hydrogen, and compressed air. As the wire reaches the muzzle it is converted into a cloud of/tiny metallic particles, which, travelling at a very high speed, become molten on striking the target, and form a solid coating. In spite of .the great heat of the oxy-hydrogen flames used in vapourising the metal, the most delicate as well as the most robust, materials are undamaged by the process, and of this many interesting examples were shown.

Designs produced by spraying silk and cotton fabrics with brass and copper alloys were shown, the method being to place the paper stencil over the material and direct the pistol at it. Fabrics are not affected by washing. Even thin paper i s not scorched,"and the palm of the hand can be plated with pure metal without discomfort, and glass can also he coated in the same manner.

The industrial applications are many and are now used in six European countries as well as America. A coating of the thickness of non-corrosive metal can be applied to any structure, thus preserving it from the action of weather or chemical fumes—a matter of great importance in shipbuilding and engineering in general. It is possible to spray a non-porous coat of tin, lead,- of zinc on any object, and also to preserve wood by spraying it with rustless iron.

A feature of the process that will be watched with interest by chemists is the experiment of coating porcelain and silica, with platinum. The high, cost of this rare metal has hampered many research workers in chemistry, for it is absolutely essential for certain operations and the present cost of even a tiny platinum cruicible is beyond the means of the average private expert* menter. Should the result prove satisfactory, and Mr. Turner told a representative of the Morning Post that there was every hope that 'it would the scope of research of the smallest research worker will be greatly increased. oolid bars that can be filed and machined can also be produced bv the process. Many samples were shown, including bells made from copper and zinc, giving a characteristic ring which has hitherto been regarded as impossible m the case of metal objects built up m this way.