Improvements in or relating to methods of forming lead-tin alloy surface layers, andarticles provided with such surface layers

摘要

730,090. Forming lead-tin alloy surface layers. NAPIER & SON, Ltd., D. Nov. 20, 1952 [Nov. 28, 1951], No. 27877/51. Class 41. Successive layers of tin and lead are deposited by immersing an article in turn in electrolytes containing tin and lead compounds respectively, and arranging a contact element of a metallic substance which is positive relative to tin and lead respectively in the electro-motive series in contact with the electrolyte and in electrical contact with the article, the resulting layers subsequently being at least partly alloyed by diffusion by heat treatment below the melting points of the two metals and the alloy produced. A tin layer is preferably deposited first, and the tin electrolyte may be a solution of sodium stannate and caustic soda; the lead solution may contain lead fluoborate. The contact element may be aluminium or aluminium alloy. The metals may be alloyed by heating at 140‹ C. for 2 hours. Specification 730,089 is referred to.