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

• US 3,953,251 A
• Filed: 03/25/1974
• Issued: 04/27/1976
• Est. Priority Date: 03/25/1974
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Inventors: Terry, Milton Everett, Butherus, Alexander Duane
• Primary Examiner(s): Satterfield, Walter R.
• Application Number:
  US05/454,152
• Time in Patent Office: 764 Days
• Field of Search: 148/105, 148/31.55, 148/103, 148/104, 148/108, 335/209, 264/DIG. 58
• US Class Current: 252/62.54
• CPC Class Codes: H01F 1/20 in the form of particles, e.g. powder H01F1/147 takes precedence

Abstract

Carbonyl iron powder core (dust core) materials whose rate of change of magnetic permeability with temperature are preselected, are produced by a process which includes the mixing together of powders from two source batches. These source batches produce core materials whose temperature coefficients, Y and Z, lie on either side of the desired temperature coefficient, X. The fraction, A, of the Y powder is selected in accordance with the formula:

A = 0.7 [(X-Y)/(Z-Y)] + 0.15; 0.15 ≦ A ≦ 0.85.

exemplary core materials incorporate a phosphate insulator and a phenolic binder.

Claims

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;

space="preserve" listing-type="equation">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.

2. Method of claim 1 in which A is from 0.2 to 0.8.

3. Method of claim 1 in which the first particulate matter and the second particulate matter include from 0.1 to 5 percent by weight of a lubricant, based on the total weight of the other constituents.

4. Method of claim 1 in which the insulator is essentially iron phosphate.

5. Method of claim 4 in which the iron phosphate is produced by reacting the carbonyl iron powder with a solution of phosphoric acid in an organic solvent.

6. Method of claim 4 in which the organic binder is at least one member selected from the class of phenolic or epoxy thermosetting resins.

7. Method of claim 6 in which the organic binder is applied by mixing the insulated carbonyl iron powders with a solution of the organic binder in an organic solvent and evaporating the organic solvent from the resulting slurry.

8. Method of claim 7 in which the particulate matter includes at least 2 percent by weight of organic binder.