Mares N.T.,Asbury Graphite Mills Inc. |
Tamashausky A.V.,Asbury Graphite Mills Inc.
International Journal of Powder Metallurgy | Year: 2013
The utility of fine-particlesize graphite materials in powder metallurgy (PM) is generally restricted to their use as a "carbon raiser." Although graphite is considered an effective solidphase lubricant, at the addition rates needed for most PM parts fabrication there is not enough graphite at the die wall-part interface to provide the degree of lubricity needed for proper part ejection. These same PM mixtures contain waxbased lubricants to provide the die-wall lubricity necessary for efficient PM compact ejection. A study was performed to determine the utility of nanographite materials in providing effective die-wall lubrication, reducing or eliminating the need for added wax, while providing metallurgically reactive carbon in place of, or in conjunction with, conventional graphite powders. Test results indicate that nanographite powders provide significant die-wall lubricity, have lubrication synergy with PM mixtures containing reduced levels of wax lubricant, and provide metallurgically active carbon during the sintering process.