GB693127A - Electroconductive coating on a refractory base and process for the manufacture thereof - Google Patents

Abstract

Refractory bases, especially soda-lime glass, but also, for example, borosilicate glass, china, porcelain, mica, tungsten carbide, silicon carbide, aluminium oxide, asbestos, glass fibre, iron, copper, tungsten, are provided with an electroconductive coating primarily of tin oxide by heating the base to a temperature above 400 DEG F but below that at which the base melts, say, at 800-1200 DEG F and applying a solution of a tin compound and an ionizable fluoride. The film may have a thickness of 25-600 millimicrons, or more; thick films may be peeled from the glass plate. As the tin compound, stannic chloride in say 10-70 per cent aqueous solution is particularly suitable; many other tin compounds, e.g. stannous chloride, various other halides, stannic sulphate, organic compounds, e.g. tetraethyl tin, diethyl tin oxide, are specified. Many fluorine compounds are listed, e.g. hydrofluoric acid, ammonium acid fluorides, alkali metal fluorides, other metal fluorides, fluoboric acid, fluosilicates, fluostannates &c., the amount used, calculated as fluorine, being 0.01-20 per cent by weight of the stannic chloride. Water soluble alcohols, glycols, or aldehydes, of which a number are specified, may also be added to the solution. Aqueous or organic solutions may be used. Antimony compounds may also be present in solution. The solutions may be applied to the glass &c. by spraying. The specific resistivity of the coating is usually of the order of 0.001-0.005 ohm-centimetres. Specification 632,227, [Group XI], is referred to.