PROCESS - PLATING - TIN ON ALUMINUM AND ALUMINUM ALLOYS - CHEMICAL AND PHYSICAL PROPERTIES - INVESTIGATION OF
Test rept. 1 Oct 1957-20 Jun 1958
GENERAL DYNAMICS CORP POMONA CA POMONA DIV
Pagination or Media Count:
Attractive, adherent tin platings can be produced on 2024-T6 and 7075-T6 aluminum alloys by utilizing the Alumon zincate immersion pretreatment followed by any one of the three tin plating baths stannous fluoroborate, sodium stannate, stannous sulfate. The oxalic acid anodize pretreatment does not produce aluminum surfaces which are receptive to the electrodeposition of tin from any of the baths evaluated. The sodium stannate bath produces tin platings on 2024-T6 and 7075-T6 aluminum alloys which pass 200-hours salt spray exposure with more than one pit per square inch surface area being basis for failure. These platings exhibit less porosity than platings produced from the stannous fluoborate bath, which in turn produces platings of less porosity than the stannous sulfate bath. Neither the fluobrate nor sulfate tin platings passed 200 hours salt spray exposure. Both tin plated aluminum alloys coupled to HK-31 magnesium-thorium alloy exhibit no corrosion after exposure to 100 hours immersion in a three-phase JP-4 - 3 salt water environment.
- Properties of Metals and Alloys