Since their discovery in 1991 carbon nanotubes (CNTs) have attracted much interest due to their remarkable mechanical, thermal, electrical, chemical and optical properties. In connection with their mechanical properties, CNTs have been studied in various forms for tribological applications including their use as lubricant additives for oil and water. In this work, the tribological properties of functionalized nanotubes (single and multi-walled) modified with carboxylic acid when used as lubricant additives at different concentrations (0.01, 0.05%) were studied under rolling-sliding conditions in a twin-disk testing machine. The tests were performed using 5% of creepage and pressures of 0.8GPa and 1.1GPa. The results indicated that the presence of carbon nanotubes leads to a decrease in both friction coefficient and wear rate for both systems studied (oil and water)

Wear of wheels and rails is a major problem in railway transportation industry. Solid lubricants constitute a cost-efficient alternative to control wear and friction at the wheel–rail interface, especially when a fine-tuned balance between traction force and energy consumption is sought. In this work, composite friction modifiers (CFMs) composed of a vinyl ester matrix reinforced with molybdenum disulfide and carbon nanotubes were developed. The total solid additive content was less than a half in comparison with a commercial product available on the market, which was used as a reference. A benchmarking study of the CFM was carried out by means of tribological tests in a twin-disc machine at a contact pressure of 1.1 GPa and different slip values. The results indicated that the developed CFM reduce coefficient of traction by 10% compared to unlubricated conditions that is similar to the reference. However, the total mass loss of steel components due to wear under CFM lubrication was lower than in the reference test.

Los nanotubos de carbono (CNTs) han atraído un enorme interés debido a sus muchas características que los convierten en un material prometedor para aplicaciones biomedicas. Un desafío importante cuando se trabaja con CNTs es la dificultad de dispersarlos homogéneamente en un fluido. Esta investigación es un análisis comparativo de la dispersión de nanotubos de carbono de pared múltiple (MWCNTs) en diferentes fluidos (agua destilada, agua ultrapura de tipo I [Milli-Q], etanol, dimetilsulfóxido [DMSO] y medio de cultivo celular [RPMI-1640]). Utilizando dos diferentes técnicas de sonicación (sonicación con lanza ultrasónica y sonicación ultrasónica de baño), así como la determinación del efecto de la esterilización en presencia y ausencia de fluido antes de la dispersión. Los resultados indican que el mejor método de dispersión de los CNTs es usando un sonicador tipo lanza y esterilizarlos en presencia de fluido.