Porous Layer Characterization of Anodized and Black-Anodized Aluminium by Electrochemical Studies

Table 1

Black anodizing process parameters.

Sl. no.	Process	Concentrations	Process parameters
1	Black dyeing	Jet black—11 g L^−1	pH = 5 ± 0.5
		(Commercial organic black dye procured from Khatau Valabhdas, Gujarat, India)	75 ± 5°C; 15 min
2	Inorganic colouring	Step 1:	25 ± 5°C
		Cobalt acetate, Co(C2H3O2)2—200 g L^−1	15 min
		Step 2:	25 ± 5°C
		Ammonium sulphide, (NH4)2S—25 mL L^−1	15 min
3	Electrolytic colouring	Sulphuric acid, H2SO4—10 mL L^−1	pH = 1.1 ± 0.3
		Stannous chloride, SnCl2—20 g L^−1	25 ± 5°C
		Phenol sulphonic acid—10 mL L^−1	Voltage ~20 V, AC
			15 min

*Each step was followed by demineralized water rinsing.