Compaction methods
View Patent ↗The present invention is directed to improved compaction techniques for use in powder metallurgical applications using lower temperatures and pressures than are traditionally used in the field.
1. A method of compacting powder metallurgical compositions comprising
compacting an iron-based powder metallurgical composition that comprises an iron-based powder and a lubricant, using a pressure of about 600 MPa to about 800 MPa to form a green compact;
heating the green compact at a temperature of about 300° C. to about 400° C.; and
re-compacting the green compact at a pressure of at least 800 MPa to form a compacted part.
2. The method of claim 1 , wherein the green compact is heated at a temperature above the melting point of the lubricant prior to the re-compaction step.
3. The method of claim 1 , wherein the green compact is cooled to below 150° C. prior to the re-compacting step.
4. The method of claim 1 , wherein the green compact is cooled to ambient temperature prior to the re-compaction step.
5. The method of claim 1 , wherein the density of the compacted part is at least 7.5 g/cm 3 .
6. The method of claim 1 , wherein the resistivity of the compacted part is at least 350 micro-ohm-meter.
7. The method of claim 1 , wherein the core loss of the compacted part is less than 150 watts/kg.