Fort Wayne, IN — Current industry talk is about the enhancement of seal performance by using nanoparticles as fillers for polytetrafluoroethylene-based (PTFE) sealing materials. Responding to this, Trelleborg Sealing Solutions researched and compared the wear reducing ability of its traditional Turcon additives to nanoparticles as additives.
In these tests the optimized Turcon additives outperformed the nanoparticles.
“Despite the results showing that our traditional additives outperform nanoparticles, Trelleborg will continue to work on sealing nanotechnology,” says Thomas Larsen, who headed up the test program. “Our Turcon compounds are optimized for service conditions using traditional fillers. Even so, we will continue to investigate if improvements can be made using nanoparticles.”
Trelleborg tested PTFE filled with the following nanoparticles: carbon nanotubes (MWCNT), alpha Aluminum Oxide (Al2O3, alpha), beta Aluminum Oxide (Al2O3, beta), Tin Oxide (SnO2), Copper Oxide (CuO), Zinc Oxide (ZnO) and Iron Oxide (Fe2O3) in all cases at 1wt%. Performance was compared to both virgin PTFE and Turcon T05.
Different effects noted
The results demonstrate that different types of nanoparticles have different effects on the wear resistance of PTFE, going from virtually no effect to wear reductions beyond a factor of 50. For some nanoparticles performance was dependent on whether systems were running dry or lubricated. For instance, MWCNT performed very well when dry-running but poor in lubricated conditions, while others, such as Al2O3 alpha, gave good overall performance. None of the nanoparticle filled materials were capable of outperforming the wear resistance of Turcon T05, dry-running or lubricated, according to Trelleborg.
Virgin polytetrafluoroethylene (PTFE) has very low wear resistance and fillers are added to PTFE to increase its wear resistance in dynamic sealing applications. Nanoparticles, which have at least one dimension in the size range of one to 100 nanometers, offer an alternative to traditional fillers. These are currently receiving much attention as fillers for polymers and are promoted as improving mechanical and tribological properties at a low degree of fill as well as reducing the risk of abrasive action against mating counter surfaces.
For more information, visit www.trelleborg.com.