INTERFERENCE COLORING OF DUAL-ANODIZED FILMS ON ALUMINUM-CONTAINING ELECTROLYTICALLY DEPOSITED THIN METAL LAYERS

This study concerns the properties and structure of oxide films on alu minum, anodized in a sulfuric acid bath, first by DC, and next by AC i n the same bath; Sn-Ni metal was then deposited electrolytically into the micropores. Each film showed fine colors that varied from blue, gr een, and to gold in medium tones as thickness of the AC films increase d, EPMA line analyses disclosed that Sn deposited cleanly at the botto m of the micropores, with maximum intensity increasing with the kind o f colors, In observations with SEM, the back-scattered electron images proved clearly the difference for AC films; also, the secondary elect ron images exhibited metal deposition like tree twigs in very fine mic ropores, The colors obtained indicated good corrosion resistance and l ight fastness.