Patent ID: 7473469
Filing Date: 2009-01-06
Classification: B22F,C22C,G11B,H01F,Y10T

Abstract:
1. A ferromagnetic metal powder of acicular particles comprised primarily of iron for a magnetic recording medium, wherein the acicular particles have a long axis length of not more than 80 nm and the surface of the acicular particles has an iron system oxide, characterized in that the powder has an ESCA-measured binding energy peak of from 525 to 532 electron volts (eV) at the point oxygen O(1s) appeared and exhibits a saturation magnetization percentage decrease Δσs of less than 15%, herein, alter being stored for one week at a constant temperature of 60° C. and a constant relative humidity of 90%, taking σs(i) as the saturation magnetization prior to being stored at a constant temperature and constant humidity and σs(ii) as the saturation magnetization after said one week, Δσs=100 ×((σs(i)−σs(ii))/σs(i).