| 摘要 |
1,208,597. Enamels and enamelling. FOSECO TRADING A.G. 8 Oct., 1968 [13 Oct., 1967], No. 46838/67. Heading C1M. [Also in Divisions C3 and C7] In the annealing of steel articles by heating them at 900‹ C. or more in the presence of atmospheric oxygen, sealing of the metal surface is prevented by precoating it with a composition comprising a ceramic-forming frit, a non-ionic cellulose derivative and an organic solvent. In examples the composition comprises a lead aluminium silicate frit (analysis: PbO 61%, Al 2 O 3 7% and SiO 2 32%), hydroxypropyl cellulose and isopropanol optionally with magnesia, silica, nepheline syenite, kaolinite and a synthetic resin. Other specified additives include Al or ferrosilicon as oxidizable materials and Cr 2 O 3 to lower the surface tension. On cooling the steel, the coating falls away readily leaving a bright surface. |
