Abstract
Deterioration of anodic films and chemical films for aluminum alloy by heating was investigated. Material kinds of specimens were 2S and 24S-T4, and surface treatments used were sulfuric acid anodizing, chromic acid anodizing and chemical film treatment.
Those finished specimens were heated for 8 hours and 100 hours at 80°C, 120°C, 160°C, and 200°C, respectively.
Then, deteriolation of those finishes was examined by salt spray tester, running continuously for 500 hours.
Test results are shown in fig. 1 to 6, and summarized as follows:
(1) The appearance of specimens, of both anodic coating ane chemical films were some what changed at 80-120°C or higher.
(2) After salt spray exposure little or no corrosion attack was found on 2S specimens, but severe one was found on 24S specimens heated to 80°C or higher.
(3) Chemical films were more sensitive to heat than anodic coatings.
(4) Sulfuric acid anodized 2S specimens were crazed by heating, nevertheless their corrosion resistance were not reduced.
