| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a magnetic recording medium which is low in noise, high in output and C/N ratio and excellent in overwrite aptitude, and to provide a simple manufacturing method of ferromagnetic metal powder used for it. <P>SOLUTION: In the magnetic recording medium, a magnetic layer includes a ferromagnetic metal powder whose average major axis length is 30-65 nm; coefficient of variation of major axis length is 10-25%; average needle ratio is 3.3-5.5; coercive force (Hc) is 147-205 kA/m; saturation magnetization(σs)is about 85-130 (A m<SP>2</SP>)/kg; and the anisotropy magnetic field distribution of the magnetic layer is 1.1-1.7. The manufacturing method of the ferromagnetic metal powder includes a process which carries out wet classification of a minute particle which exists at least in either suspensions of after goethite generation reaction or after surface treatment to the goethite. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
