Method of making copper tubing

Claim 1

A METHOD OF PREPARING AND EXTRUDING A SINTERED SHAPE ADAPTED FOR USE IN AN EXTRUSION PRESS TO FORM A WROUGHT METALLIC OBJECT SUBSTANTIALLY 100% DENSE COMPRISING THE STEPS OF: PROVIDING A POWDER OF A DUCTIBLE METAL HAVING A LIMITED NUMBER OF PARTICLES LESS THAN 10 MICRONS AND HAVING AN AVERAGE PARTICLE SIZE DISTRIBUTION IN THE ORDER OF 12 MICRONS; MIXING A QUANTITY OF LUBRICANT IN SAID POWDER TO LUBRICATE THE PARTICLES AND TO FORM A LUBRICANT-POWDER MIXTURE HAVING A SUBSTANTIALLY UNIFORM POWDER SIZE DISTRIBUTION; COMPACTING THE LUBRICATED PARTICLES TO FORM A POROUS GREEN COMPACT HAVING A UNIFORM DENSITY IN THE ORDER OF 18% OF FULL DENSITY BUT SUBSTANTIALLY LESS THAN 100% DENSE; SINTERING SAID GREEN COMPACT IN A REDUCING ATMOSPHERE AT A SINTERING TEMPERATURE FOR SAID METAL POWDER AND FOR A PERIOD OF TIME SUFFICIENT TO CAUSE INTER-PARTICLE BONDING, THE RATE OF HEATING BEING SUCH AS TO FIRST VOLATILIZE THE LUBRICANT WHEREBY WHEN THE SINTERING TEMPERATURE IS REACHED SUBSTANTIALLY ALL OF SAID LUBRICANT IS REMOVED; AND EXTRUDING THE SINTERED SHAPE AT AN EXTRUSION PRESSURE CAPABLE OF FURTHER COMPRESSING IT TO FULL DENSITY WHEREBY THE WROUGHT OBJECT FORMED IS FREE OF PIN HOLES OR INTERNAL VOIDS.

Claim 2

A METHOD OF PREPARING AND EXTRUDING A SINTERED SHAPE ADAPTED FOR USE IN AN EXTRUSION PRESS TO FORM A WROUGHT METALLIC OBJECT SUBSTANTIALLY 100% DENSE COMPRISING THE STEPS OF: PROVIDING A POWDER OF A DUCTIBLE METAL HAVING A LIMITED NUMBER OF PARTICLES LESS THAN 10 MICRONS AND HAVING AN AVERAGE PARTICLE SIZE DISTRIBUTION IN THE ORDER OF 12 MICRONS; MIXING A QUANTITY OF LUBRICANT IN SAID POWDER TO LUBRICATE THE PARTICLES AND TO FORM A LUBRICANT-POWDER MIXTURE HAVING A SUBSTANTIALLY UNIFORM POWDER SIZE DISTRIBUTION; COMPACTING THE LUBRICATED PARTICLES TO FORM A POROUS GREEN COMPACT HAVING A UNIFORM DENSITY IN THE ORDER OF 18% OF FULL DENSITY BUT SUBSTANTIALLY LESS THAN 100% DENSE; SINTERING SAID GREEN COMPACT IN A REDUCING ATMOSPHERE AT A SINTERING TEMPERATURE FOR SAID METAL POWDER AND FOR A PERIOD OF TIME SUFFICIENT TO CAUSE INTER-PARTICLE BONDING, THE RATE OF HEATING BEING SUCH AS TO FIRST VOLATILIZE THE LUBRICANT WHEREBY WHEN THE SINTERING TEMPERATURE IS REACHED SUBSTANTIALLY ALL OF SAID LUBRICANT IS REMOVED; AND EXTRUDING THE SINTERED SHAPE AT AN EXTRUSION PRESSURE CAPABLE OF FURTHER COMPRESSING IT TO FULL DENSITY WHEREBY THE WROUGHT OBJECT FORMED IS FREE OF PIN HOLES OR INTERNAL VOIDS.