| 摘要 |
<p>Vitrified material (ceramics, glass, glazes, enamels, sintered masses of oxides) which has stannic oxide present at part or all of its surface is provided with a coating of nickel from a solution of the nickel cation-hypophosphite anion type. The presence of stannic oxide may be achieved at the surface of the vitrified body by (a) applying a glaze, or oxide mixture, containing stannic oxide, (b) deposition from the vapour or atomised solution of a tin compound which is converted to the oxide in situ, (c) dipping the hot body into an alcoholic solution of stannic halide and acetic acid, or (d) rumbling the body in powdered oxide. Alternatively, stannic oxide may be included as one of the materials of which the body is composed. Other oxides may be present at the surface, e.g. oxides of boron, antimony or indium. Part only of the surface of the body may coated with stannic oxide (and hence with nickel) by (a) appropriate masking during its application, or (b) by coating all over with stannic oxide, masking that part of the surface which is to retain the oxide, treating the reset with a reducing agent which reduces the oxide to tin, and then dissolving the tin with acid. Nickel may be deposited from a solution containing nickel sulphate, sodium hypophosphite and sodium citrate. Specifications 803,885 and 814,674 are referred to.</p> |
