FINE GRAIN DENSE FERRITES.
Quarterly rept. no. 1, 1 Jul-30 Sep 64,
RAYTHEON CO WALTHAM MASS
Pagination or Media Count:
Fine-grained ferrites of cobalt substituted nickel ferrite Nil-xCoxFe2O4 were hot pressed using powders prepared by flame spraying and ball-milling. An oxygen anneal of the powder prior to hot pressing is an essential step required to reduce the dielectric loss. The hot pressing quality of the flame-sprayed powder was adversely affected by this procedure, whereas the ball-milled powders were not. Several dense samples have been prepared with loss tangents below 0.005, and measurements of threshold fields for subsidiary absorption have been made. A tentative dependence of hcrit on grain size has been observed and there is some indication that a two to fourfold increase in power handling capacity can be achieved with grain sizes of the order of one to two microns. Author