Application of fullerene-added nano-oil for lubrication enhancement in friction surfaces

This paper presents the friction and antiwear characteristics of nano-oil composed of refrigerant oil and fullerene nanoparticles in the sliding thrust bearing of scroll compressors. The nano-oil was evaluated using a sliding thrust bearing tester. The friction coefficient of fullerene nano-oil at the lower normal loads (<∼1200 N) under the fixed orbiting speed (∼1800 rpm) was ∼0.02, while that of pure oil was ∼0.03, indicating that the fullerene nanoparticles dispersed in the base refrigerant oil improved the lubrication property by coating the friction surfaces. However the difference between friction coefficients for both nano-oil and pure oil was found to be negligible at higher normal load conditions (>∼1200 N), indicating that the nanoparticles in the base oil have little effect on the enhancement of lubrication between the friction surfaces. The friction coefficient of nano-oil at various speeds of the orbiting plate in the sliding thrust bearing was found to be less than that of pure oil over the entire orbiting speed ranges between 300 and 3000 rpm. This is presumably because fullerene nanoparticles, which were inserted between the friction surfaces, improved the lubricating performance by increasing the lubricant oil viscosity and simultaneously preventing direct metal surface contacts.