BakerHostetler
Enhanced techniques for production of golden bronze by inter-diffusion of tin and copper under controlled conditions
Golden bronze appearance article, multiple-layer substrate, related methods and uses thereof, particularly for coinage blanks. Methods of producing an article having a golden bronze appearance include annealing a multiple-layer substrate at an annealing temperature for an annealing residence time. The multiple-layer substrate includes a core, contiguous to a copper layer and subsequent tin layer. The annealing temperature and annealing residence time are controlled in accordance with each other for allowing diffusion of the tin layer into the copper layer and producing an annealed substrate comprising an inter-diffused outer bronze layer having a golden appearance. The tin layer thickness is in accordance to the copper layer thickness such that the inter-diffused outer bronze layer has a tin content between about 8% wt. and about 15.8% wt. The core has a sufficiently low content of nickel to reduce or prevent formation of intermetallic compound comprising tin and nickel proximate to the core during annealing.
MONNAIE ROYALE CANADIENNE / ROYAL CANADIAN MINT
C C C C A C Y C C C C Y C C B C C C B
C22F C25D C25D C25D A44C C25D Y10T C22F C25D C25D C25D Y10T C23F C25D B32B C25D C23F C25D B32B
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Xianyao Taixiang Sridhar
Li Jiang Bushigampala