PLATINUM AND PLATINUM ALLOY POWDERS WITH HIGH SURFACE AREAS AND LOW CHLORINE CONTENT, AND PROCESSES FOR PREPARING THESE POWDERS

摘要

PPROBLEM TO BE SOLVED: To provide a process for preparing a platinum or platinum alloy powder for forming a metal powder having a finely and uniformly divided particle size, a large surface area and a low chlorine content and also to provide a platinum or platinum alloy powder prepared by the process. PSOLUTION: The process comprises: a step of forming a melt which contains a low-melting mixture of alkali-metal nitrate, a chlorine-free platinum compound and a chlorine-free compound of alloying elements; a step of heating the melt up to a reaction temperature at which the platinum compound and the compound of the alloying elements are thermally decomposed to give an oxide; a step of cooling the me and a step where the melt is dissolved in water and the resulting oxide or mixed oxides are converted into a powder of platinum or platinum alloy by successive reduction. The powder of platinum or platinum alloy includes a powder having a BET specific surface area larger than 40 mSP2/SP/g and a chlorine content lower than 100 ppm. PCOPYRIGHT: (C)2009,JPO&INPIT