フッ化物添加アミンアルカリ性浴中でのアルミニウムダイカストの陽極酸化
1989 年 40 巻 12 号 p. 1409-1414
詳細
1989 年 40 巻 12 号 p. 1409-1414
The bath compositions and conditions suitable for anodizing of aluminum die casting were investigated in baths of amine alkalinity (etheylenediamine, diethylamine and triethylamine) with additions of ammonium fluoride and ammonium carbonate.
In the amine baths (0.1mol/L) with added ammouium fluoride (0.3mol/L) and ammonium carbonate (0.3mol/L), thick, grayish-black coatings (about 13μm) were obtained by anodizing for 30min at a current density of 2A/dm2.
The effects of the addition of polyhydric alcohols on the thickness and hardness of the anodized-coatings were also investigated in the above amine baths.
The thickest (about 16μm) and hardest (about 50 by Marten's scratch hardness test, load of 50g) coating was formed in triethylamine (0.1mol/L) with ammonium fluoride (0.1mol/L), ammonium carbonate (0.3mol/L) and polyethylene glycol (20%), by anodizing for 30min at 2A/dm2.
It was considered that the formation of the thick coating in the bath containing polyethylene glycol was caused by diffusion of the Joule heat produced by anodizing, and the prevention of the dissolution of the anodized coating.
SEM showed that the anodized coatings formed in amine alkaline haths have larger pores (about 1000Å) than those in sulfuric acid bath.
