ISSN:
1573-4803
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Maschinenbau
Notizen:
Abstract A hydrogen treatment followed by calcination, has been developed in order to enhance the intrinsic coercivity of Sr-hexaferrite (SrFe12O19). Fully hydrogen-treated Sr-hexaferrite consists of a mixture of 73%, by weight, of αFe and 27% of Sr7Fe10O22 phases. Calcination of this material to reform the SrFe12O19 phase occurs in two stages. Between room temperature and 600°C, oxygen was absorbed resulting in a large increase in weight with the formation of a mixture of SrFeO3−x and Fe2O3(α and γ). During the second stage, the intermediate phases reacted to form SrFe12O19 at a temperature of between 700 and 800°C. A partial desorption of oxygen occurred until calcination reached completion at 1000°C. The magnetization at 1100 kA m−1 and the remanence were similar to those of the untreated material, but, because of a much refined grain size, the intrinsic coercivity was considerably larger, with values around 400 kA m−1. Grain growth occurs at temperatures 〉 1000°C, resulting in a decrease in the intrinsic coercivity.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1023/A:1004506514713
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