METHOD FOR MANUFACTURING A FIRED CERAMIC BODY INCLUDING A METALLIC WIRE INSIDE

• US 20100194003A1
• Filed: 01/22/2010
• Published: 08/05/2010
• Est. Priority Date: 01/22/2009
• Status: Active Grant

• Current Assignee: NGK Insulators Limited
• Original Assignee: NGK Insulators Limited
• Inventors: Kobayashi, Nobuyuki, Ozawa, Shuichi, Shimogawa, Natsumi
• Granted Patent: US 8,512,628 B2
• Time in Patent Office: Days
• US Class Current: 264/618
• CPC Class Codes: B22F 2998/10 Processes characterised by the sequence of their steps
• CPC Class Codes: C04B 2235/3267 MnO2
• CPC Class Codes: C04B 2235/3279 Nickel oxides, nickalates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3281 Copper oxides, cuprates or oxide-forming salts thereof, e.g. CuO or Cu2O
• CPC Class Codes: C04B 2235/3284 Zinc oxides, zincates, cadmium oxides, cadmiates, mercury oxides, mercurates or oxide forming salts thereof
• CPC Class Codes: C04B 2235/6562 Heating rate
• CPC Class Codes: C04B 2235/9615 Linear firing shrinkage
• CPC Class Codes: C04B 35/265 Compositions containing one or more ferrites of the group comprising manganese or zinc and one or more ferrites of the group comprising nickel, copper or cobalt
• CPC Class Codes: C04B 35/638 Removal thereof
• CPC Class Codes: C04B 35/82 Asbestos; Glass; Fused silica
• CPC Class Codes: C22C 47/04 by coating, e.g. with a protective or activated covering
• CPC Class Codes: C22C 47/064 Winding wires
• CPC Class Codes: H01F 17/04 with magnetic core
• CPC Class Codes: H01F 2017/046 helical coil made of flat wire, e.g. with smaller extension of wire cross section in the direction of the longitudinal axis
• CPC Class Codes: H01F 2017/048 with encapsulating core, e.g. made of resin and magnetic powder
• CPC Class Codes: H01F 27/2823 Wires H01F27/2866 takes precedence
• CPC Class Codes: H01F 41/0246 Manufacturing of magnetic circuits by moulding or by pressing powder magnetic cores made by moulding or by pressing powder H01F27/255; soft magnetic particles H01F1/20, H01F1/36

Abstract

A method for manufacturing a fired ceramic body including a metal wire wherein the metal wire is placed in a mold, and then, a ceramic slurry having a heat-gelling characteristic or a thermoset characteristic is poured into the mold. Subsequently, the ceramic slurry is dried and hardened to form a ceramic-compact-before-fired, and then, the ceramic-compact-before-fired is fired. In this firing process, a degreasing of the ceramic compact is firstly performed, and thereafter, a temperature of the ceramic compact is increased up to a second temperature at which the metal wire is softened and the ceramic compact is fired at a second temperature increasing rate. The second temperature increasing rate is set at such a rate that a shrinkage ratio of the ceramic compact when the temperature of the ceramic compact reaches the second temperature is smaller than or equal to a predetermined threshold shrinkage ratio.

Claims

1. A method for manufacturing a fired ceramic body including a metal wire in its inside comprising the steps of:

a first step of preparing said metal wire, preparing a mold having a space for storing said metal wire, and placing said metal wire in said mold;

a second step of filling said mold with a ceramic slurry having a heat-gelling characteristic or a thermoset characteristic;

a third step of forming a ceramic-compact-before-fired including said metal wire in its inside by hardening and drying said ceramic slurry in said mold; and

a fourth step of firing said ceramic-compact-before-fired;

wherein,

said fourth step including steps of;

a degreasing step of degreasing said ceramic-compact-before-fired by increasing a temperature of said ceramic-compact-before-fired to a first temperature at a first temperature increasing rate, and then keeping said temperature of said ceramic-compact-before-fired at said first temperature for a first time period;

a firing step of firing said ceramic-compact-before-fired by increasing said temperature of said ceramic-compact-before-fired to a second temperature at a second temperature increasing rate, then keeping said temperature of said ceramic-compact-before-fired at said second temperature for a second time period, said second temperature being a temperature between a temperature lower than a melting point of said metal wire by a predetermined temperature and said melting point of the metal wire and at which said metal wire is softened; and

a cooling step of decreasing said temperature of a fired ceramic body fired in said firing step,

wherein,

said second temperature increasing rate is set at such a rate that a shrinkage ratio of said ceramic-compact-before-fired when said temperature of said ceramic-compact-before-fired reaches said second temperature is smaller than or equal to a predetermined threshold shrinkage ratio at which no crack occurs in said ceramic-compact-before-fired.

2. The method for manufacturing the fired ceramic body according to claim 1, wherein said predetermined threshold shrinkage ratio is 17%.

3. The method for manufacturing the fired ceramic body according to claim 1, wherein said second temperature is set at a temperature, which is higher than or equal to a temperature lower than said melting point of said metal wire by 100°

C., and which is lower than said melting point of said metal wire.

4. The method for manufacturing the fired ceramic body according to claim 1, wherein said second temperature is set at a temperature, which is higher than or equal to a temperature lower than said melting point of said metal wire by 80°

C., and which is lower than or equal to a temperature lower than said melting point of said metal wire by 30°

C.

5. The method for manufacturing the fired ceramic body according to claim 2, wherein said second temperature is set at a temperature, which is higher than or equal to a temperature lower than said melting point of said metal wire by 100°

C., and which is lower than said melting point of said metal wire.

6. The method for manufacturing the fired ceramic body according to claim 2, wherein said second temperature is set at a temperature, which is higher than or equal to a temperature lower than said melting point of said metal wire by 80°

C., and which is lower than or equal to a temperature lower than said melting point of said metal wire by 30°

C.