LOW CURIE POINT MAGNETIC RECORD POWDER WITH HIGH COERCIVITY AND MANUFACTURE THEREOF

摘要

PROBLEM TO BE SOLVED: To provide magnetic record powder usable even under a circumstance to be subjected to a magnetic noise and its manufacturing method. SOLUTION: This low gury one-point magnetic powder consists of covered complex oxide powder containing 14 to 20% of one kind or two kinds of strontium oxide and barium oxide, 20 to 30% of chromium oxide, 2 to 15% of one kind or two kinds of zinc oxide and magnesium oxide and 2 to 15% of one kind or two kinds or more of titanium oxide, zirconium oxide, tin oxide and the rest having the component composition consisting of iron oxide and unavoidable impurities and an oxide film either of a magnesium oxide film, a calcium oxide film and a strontium oxide film is formed on the surface of the complex oxide powder having a hexagonal ferrite type crystal structure.