Research and development of metal powder for magnetic recording

Since its first application within the compact cassette in 1978, magnetic r ecording media using metal powder have been improved at a rate of roughly 1 dB per year as a result of advances in such fields as tape materials, tape -making technologies, etc. Today, metal tapes have a widely expanded applic ation area, including video and data-information applications. Dowa Mining Co., Ltd., began its research regarding magnetic powder for recording media in 1978. The Company successfully developed metal powder for 8 mm video ta pe. Since then, Dowa has endeavored to improve the magnetic properties and reduce the particle size of metal powder. It accomplishes these goals throu gh the full use of the Company's unique Al doping method. Especially, durin g the past several years, significant improvements of the magnetic properti es of metal powder have been achieved. These improvements have resulted fro m the introduction of new technologies, including Fe-Co alloying, sintering prevention, new reaction processes, and many other new techniques. Current ly, Dowa Mining is supplying a new type of metal powder for the most techno logically advanced high-density recording media. Dowa's new metal powder ha s an axis length of 0.1 mu m, H-c of 2400 Oe, and sigma(s) of 155 emu/g. (C ) 1998 Elsevier Science B.V. All rights reserved.