Method of making manganese-zinc ferrite

Claim 1

A method of producing a low porosity manganese-zinc ferrite body with high permeability and induction comprising the steps of: (a) heating an isostatically-pressed body comprising Fe 2 O 3 , MnO and ZnO within a temperature range of about 1180°-1230° C in a vacuum environment of 50 to 200 microns pressure for a period of time of about 3 to 5 hours: (b) heating the body within a temperature range of about 1180°-1230° C for at least 18 hours in an atmosphere having an oxygen partial pressure of about 0.2% to 0.4% oxygen, by volume, at atmospheric pressures; (c) cooling the body to a temperature in the range of about 880°-920° C in said oxygen partial pressure atmosphere; (d) then soaking the body at a temperature in the range of about 880° to 920° C in an atmosphere having less than 0.02% oxygen, by volume, for at least 18 hours; and (e) cooling the body to less than 400° C in an atmosphere of less than 0.02% oxygen.

Claim 2

A method of producing a low porosity manganese-zinc ferrite body with high permeability and induction comprising the steps of: (a) heating an isostatically-pressed body comprising Fe 2 O 3 , MnO and ZnO within a temperature range of about 1180°-1230° C in a vacuum environment of 50 to 200 microns pressure for a period of time of about 3 to 5 hours: (b) heating the body within a temperature range of about 1180°-1230° C for at least 18 hours in an atmosphere having an oxygen partial pressure of about 0.2% to 0.4% oxygen, by volume, at atmospheric pressures; (c) cooling the body to a temperature in the range of about 880°-920° C in said oxygen partial pressure atmosphere; (d) then soaking the body at a temperature in the range of about 880° to 920° C in an atmosphere having less than 0.02% oxygen, by volume, for at least 18 hours; and (e) cooling the body to less than 400° C in an atmosphere of less than 0.02% oxygen.

Claim 4

A method of fabricating a manganese-zinc ferrite comprising: (a) forming a cold-isostatically pressed ferrite body comprising Fe 2 O 3 , MnO and ZnO; (b) sintering the ferrite body in a vacuum furnace to about 1180° to 1230° C at a pressure of about 50 to 200 microns vacuum for about 3 to 5 hours; (c) thereafter sintering the ferrite body at about 1180° to 1230° C for a minimum of 18 hours in an atmosphere comprising 0.2% to 0.4% oxygen in nitrogen, by volume, at atmospheric pressure; (d) cooling the body to a temperature of about 880° to 920° C in an atmosphere of 0.2% to 0.4% oxygen in nitrogen, by volume, at atmospheric pressure; (e) soaking the body at a temperature of about 880° to 920° C for a minimum of 18 hours in an atmosphere comprising almost pure nitrogen with oxygen content less than 0.02% by volume; and (f) cooling the body to less than 400° C in almost pure nitrogen with oxygen content less than 0.02% by volume before exposing it to higher oxygen content atmosphere.

Claim 5

A method of fabricating a manganese-zinc ferrite comprising: (a) forming a cold-isostatically pressed ferrite body comprising Fe 2 O 3 , MnO and ZnO; (b) sintering the ferrite body in a vacuum furnace to about 1180° to 1230° C at a pressure of about 50 to 200 microns vacuum for about 3 to 5 hours; (c) thereafter sintering the ferrite body at about 1180° to 1230° C for a minimum of 18 hours in an atmosphere comprising 0.2% to 0.4% oxygen in nitrogen, by volume, at atmospheric pressure; (d) cooling the body to a temperature of about 880° to 920° C in an atmosphere of 0.2% to 0.4% oxygen in nitrogen, by volume, at atmospheric pressure; (e) soaking the body at a temperature of about 880° to 920° C for a minimum of 18 hours in an atmosphere comprising almost pure nitrogen with oxygen content less than 0.02% by volume; and (f) cooling the body to less than 400° C in almost pure nitrogen with oxygen content less than 0.02% by volume before exposing it to higher oxygen content atmosphere.