The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 13, 2008
Filed:
Jul. 29, 2005
Kenji Masada, Okayama, JP;
Takayuki Yoshida, Okayama, JP;
Takafumi Amino, Okayama, JP;
Dowa Electronics Materials Co., Ltd., Tokyo, JP;
Abstract
A high-reliability iron nitride-based magnetic powder with markedly improved weatherability with respect to deterioration over time of the magnetic properties in fine particles smaller than 25 nm is formed by adhering one or more of the elements Si and P to the surface of an iron nitride-based magnetic powder constituted primarily of FeNwith an average grain size of 25 nm or less, where the total content of Si and P in the magnetic powder may be 0.1% or greater as an atomic ratio with respect to Fe. In particular, the invention provides an iron nitride-based magnetic powder such that the value ΔHas defined by Equation (1) below is 5% or less and the value Δσas defined by Equation (2) below is 20% or less.Δ=()/100  (1)Δσ=(σ−σ)/σ100  (2) Here, Hand σare the coercivity and saturation magnetization, respectively, of the magnetic powder after being kept for one week at a constant temperature and constant humidity of 60° C. and 90% RH. Hand σare the coercivity and saturation magnetization of the magnetic powder before being kept at constant temperature and constant humidity.