Dust core and method for producing the same

A process for producing a powder magnetic core comprising:

• a coating step of coating an insulation film on a surface of an iron-based magnetic powder;
• an applying step of applying a higher fatty acid-based lubricant to an inner surface of a die;
• a filling step of filling the iron-based magnetic powder with the insulation film coated into the die with the higher fatty acid-based lubricant applied;
• and
• a forming step of warm pressure compacting the iron-based magnetic powder filled in the die.

A process for producing a powder magnetic core comprising:

• a coating step of coating an insulation film on a surface of an iron-based magnetic powder;
• an applying step of applying a higher fatty acid-based lubricant to an inner surface of a die;
• a filling step of filling the iron-based magnetic powder with the insulation film coated into the die with the higher fatty acid-based lubricant applied;
• and
• a forming step of warm compacting the iron-based magnetic powder filled in the die;
• whereby a powder magnetic core obtained is that:
• the saturation magnetization Ms is Ms≧1.9 T in a 1.6 MA/m magnetic field;
• the specific resistance ρ is ρ≧1.5 μΩm;
• the magnetic flux density B2k is B2k≧1.1 T in a 2 kA/m magnetic field;
• and
• the magnetic flux density B10k is B10k≧1.6 T in a 10 kA/m magnetic field.

A powder magnetic core obtained by:

• a coating step in which an insulation film containing Fe is coated on a surface of an iron-based magnetic powder;
• an applying step of applying a higher fatty acid-based lubricant to an inner surface of a die;
• a filling step of filling the iron-based magnetic powder with the insulation film coated into the die with the higher fatty acid-based lubricant applied;
• and
• a forming step of warm compaction of the iron-based magnetic powder filled in the die so that a metallic soap film is formed by a reaction between Fe in the insulation film and the higher fatty acid-based lubricant, wherein:
• a saturation magnetization Ms is Ms≧1.9 T in a 1.6 MA/m magnetic field;
• a specific resistance ρ is ρ≧1.5 μΩm;
• a magnetic flux density B2k is B2k≧1.1 T in a 2 kA/m magnetic field;
• and
• a magnetic flux density B10k is B10k≧1.6 T in a 10 kA/m magnetic field.

A process for producing a powder magnetic core comprising:

• a coating step in which an insulation film containing Fe is coated on a surface of an iron-based magnetic powder;
• an applying step of applying a higher fatty acid-based lubricant to an inner surface of a die;
• a filling step of filling the iron-based magnetic powder with the insulation film coated into the die with the higher fatty acid-based lubricant applied;
• and
• a forming step of warm compaction of the iron-based magnetic powder filled in the die so that a metallic soap film is formed by a reaction between Fe in the insulation film and the higher fatty acid-based lubricant.