Light metals alloys for heat-treating, e. g. Lloyd, Alcoa 61S 53S, etc., which had been observed as ship-building materials owing to the strength of their mechanical natures and the suitableness for farbrication, have been put to the various tests and studied by the Committee of Light Metals for Shipbuilding Industry scince 1952. As the experiments, which had been made on the questions of process, fabrication and anticorrosion by the said Committee, resulted in finding some weak points in anticorroding, the painting anticorrosive method, as an important theme, has been studied by the Committee of Light Metals for Surface Treatment.
This is one of the reports on testing the adhesion of paints film anticorrosion, and anticlimate of Lloyd sheet, as compared with those of 52S, under the following conditions.
1) the Primer coat is given by Zinc-chromate.
2) The ouer coat is given by Phthalic acid resin enamel.
3) The conditions of undercoats treatment are as follows:
a) Non-treatment
b) Treated by phosphate alchol
c) " " sand paper
d) " " wash primer
e) " " sand paper and wash primer
f) " " wash primer after caustic soda washing
Judging from all the tests abobe, Lloyd sheet is inferior to 52S in adhension of paints film due to the major component of oxide film during heat-treating process.
It is considered as the best way for Lloyd sheet to apply wash primer after eliminating its oxide film dy caustic soda or sand paper.
