This paper deals with lacquer adhesion properties of dichromate passivation treated tinplate. The passivation film consists of three kinds of chromium: metallic Cr, Cr_2O_3 Cr(OH)_3 and amorphous tin oxide. Tin oxide is crystallised to α-SnO, orthorhombic SnO and/or SnO_2 when tinplate is baked. Although tinplate on which α-SnO or SnO_2 tends to grow in the course of baking offers poor adhesion to lacquer, the tinplate possessing the tendency that only orthorhombic SnO grows while baking shows good adhesion. This tinplate is obtained by cathodic electrolysis in NaHCO_3 and then immersion in dichromate solution.
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