BLANK MATERIAL OF PLATINUM TYPE NOBLE METALS INCORPORATING CORE OF BRAZING FILLER METAL FOR DECORATION

摘要

PURPOSE:To eliminate discoloration in brazed parts and to obtain finished parts having high grades complying with nominal values in a titled blank material of which the outside circumferential material to be used as a base material is made of Pt alloys by specifying the Pd alloy types and Pd contents of the core of the brazing filler metal and the Pt content of the outside circumferential material. CONSTITUTION:Pd-Ag, Pd-Ni or Pd-Au alloys incorporating >=50% (per mil) Pd are used for the core of the brazing filler metal to be inserted into an outside circumferential material and the content of Pt of the outside circumferential material is made higher by 20% than the grade warranteed by the Mint Bureau of the Japanese Government for finished decorative goods (nominal value). The materials constituted in such a way are subjected repeatedly to heat treatments and drawing over the entire part to obtain a blank material of noble metals incorporating the core of the brazing filler metal having a prescribed diameter. Said material is fabricated into a ring, and is cut at a specified circumference, the joint parts are butted and are brazed in an electric furnace to obtain the ring which is free from oozing of the brazing filler metal and discoloration in the brazed parts and has high joint strength. Further, the contents of Pt therein satisfy the nominal value in all parts.