Method for the production of carbonyl iron containing magnetic devices with selected temperature variation

Claim 1

Method for the production of a ferromagnetic body exhibiting a predetermined temperature coefficient of magnetic permeability of value X, comprising: a. compressing a quantity of a first particulate matter including at least 50 percent by weight of carbonyl iron powder, from 0.05 to 25 percent by weight of an insulator and from 1 to 25 percent by weight of an organic binder, to produce a first test body: b. compressing a quantity of a second particulate matter including at least 50 percent by weight of carbonyl iron powder, from 0.05 to 25 percent by weight of an insulator and from 1 to 25 percent by weight of an organic binder, to produce a second test body; c. measuring the value, Y, of the temperature coefficient of magnetic permeability of the first test body; d. measuring the value, Z, of the temperature coefficient of magnetic permeability of the second test body, which said values, Y and Z, bracket the value, X; e. mixing a first fractional portion by weight, A, of the first particulate matter with a second fractional portion, (1-A), of the second particulate matter, wherein A is selected in accordance with the formula: A = 0.7 [(X-Y)/(Z-Y)]+ 0.15; where A is from 0.15 to 0.85; and f. compressing a quantity of the mixed powder to produce the ferromagnetic body of temperature coefficient of magnetic permeability, X.