| 摘要 |
1285604 Vehicle headlamps RITTER ALUMINIUM GmbH 16 Sept 1969 [17 Sept 1968] 45482/69 Heading F4R [Also in Division C7] Headlamp components such as screens or lampholders having at least one surface made from aluminium or aluminium alloy are given a dark or black light-absorbing surface by anodization. The components are preferably formed by die casting an aluminium alloy containing about 5-12% silicon, up to 0À5% copper and about 1À5-2% magnesium or by drawing an alloy of the aluminium-manganese, aluminium-magnesium-manganese or aluminium-zinc-magnesium type, anodic oxidation then being performed either by a process in which the colour of the coating is determined by the composition of the alloy or by a process in which the colour is determined by the composition of the bath. In a first example, a component made from an aluminium-magnesium alloy is anodized for 30 to 40 minutes at 20-30‹ C. and at a current density of 2-3 A./dm.<SP>2</SP> in a bath containing 0À4% sulphuric acid and 200 g./l. maleic acid. Up to 3% oxalic acid may be added to the bath if desired. In a second example, a lampholder made from an aluminium alloy containing 6% silicon, 0À5% copper and 1À5% magnesium is anodized at 15-25 volts and at a current density of 1À7 A./dm.<SP>2</SP> in bath containing 15% sulphuric acid and a small quantity of oxalic acid, the bath being cooled to between 15‹ and 17‹ C. during the process. |
