Abstract:
Under this research, the experimental equipment had been constructed and the effects of colouring time, colouring temperature, and electrolyte concentration of the electrolytic colouring process on the quality of black colour shade of aluminium extrusions had been experimentally studied. Experiments had been conducted on aluminium extrusions with 3 different profiles, namely sample A (swing pole), sample B (flat box), and sample C (key pole) using stannous sulphate as electrolytic solution at colouring temperature of 16, 18, 20, 22 and 24 ํC and at colouring time of 6, 8, 10, 12 and 14 min. The experimental results showed that the colouring time had a significant effect on the quality of black colour shade on all 3 extrusion samples. When the colouring time was increased, the quality of black colour shade was improved. But if the colouring time was too long, the poor quality of black colour shade was obtained. The colouring temperature had very little effect on the quality of black colour shade on all 3 extrusion samples. When the colouring temperature was increased, the quality of black colour shade was the same or changed very little. But if the colouring temperature was high enough, the good or poor quality of black colour shade also depended on the colouring time. Overall, the suitable condition was to do the electrolytic colouring process at 16-24 ํC and at 10-12 min. In addition, the experiment on sample A at colouring temperature of 16-24 ํC and at colouring time of 10 min showed that the concentration of electrolytic solution had an effect on the quality of black shade obtained. When the concentration was reduced, the quality of black shade was poorer. Overall, the suitable concentration was at 14-16 g Sn2+/l.