Anti-corrosive treatment for magnesium and magnesium alloys

863,746. Corrosion - resistant magnesium articles. NAPIER & SON Ltd., D. Sept. 16, 1959 [Oct. 22, 1958], No. 33844/58. Class 41. Articles of magnesium or magnesium alloy are made corrosion-resistant by the following steps: (1) anodizing electrolytically using ammonium bi-fluoride solution and a voltage of 90-120 volts; (2) washing with hot chromic acid solution; (3) neutralizing, e.g. with hot alkali and rinsing; (4) anodizing electrolytically with sodium silicate solution containing a little phenol; (5) sealing the anodized coating with chromic acid solution; (6) wash, dry and impregnating the surface with an epoxide resin which is then cured by heating. The final stage is effected by placing the dried article in a vacuum chamber to which is admitted a condensation product of epichlorhydrin and a diphenolic resin dissolved in a solvent, e.g. butyl alcohol or xylol, and after 15/20 minutes immersion, vacuum is relieved and article submitted to pressure of up to 100 lbs. sq. inch for 10 minutes. Pressure is relieved, resin solution run off, the article washed in solvent, dried, and cured at 170‹ C. for 1 hour.