Oxygen-free copper - Musansodo

Also known as OFHC copper. It is pure copper with an extremely low oxygen content of over 99.99% by mass, produced by melting and casting electrolytic copper in CO gas or _N2 gas, or in a vacuum. The oxygen content is 30-50 ppm. Oxygen-free copper is tougher than tough pitch copper and phosphorus-deoxidized copper (oxygen content 200 ppm), which has had the oxygen in tough pitch copper removed by adding phosphorus, and it also has good corrosion resistance and extremely high electrical conductivity. Because it does not become brittle when heated in reducing gas, it is used in vacuum tubes, electric refrigerators, and as copper coating for steel and aluminum wire, and as a deep-drawing material.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

OFHC銅ともいう．電気銅をCOガスまたは N₂ ガス，あるいは真空中で溶解，鋳造した酸素含有量がきわめて低い，純度99.99質量％ 以上の純銅である．その酸素量は30～50 ppm である．無酸素銅は，タフピッチ銅およびタフピッチ銅中の酸素を，リンを添加して除去したリン脱酸銅(酸素量200 ppm)より柔靭性に富み，耐食性も良好で，電気伝導率がきわめて高い．還元ガス中で加熱してももろくならないので，真空管用，電気冷蔵庫用，鋼およびアルミニウム線の銅被覆，深絞り材として使用されている．

出典　森北出版「化学辞典（第2版）」化学辞典 第2版について　情報