Tribological behavior of UHMWPE against TiAl6V4 and CoCr28Mo alloys under dry and lubricated conditions.

This work is focused on the study of the tribological behavior of TiAl6V4 and CoCr28Mo against UHMWPE. Wear tests were achieved on a reciprocating pin-on-disc tribometer under dry and lubricated conditions. Four bio-lubricants were retained namely: saline solution (NaCl 0.9%), sesame oil, nigella sativa oil and Hyalgan® which is a pharmaceutical intra-articular injection containing sodium hyaluronate active agent (20mg/2mL). The coefficient of friction and wear volume of UHMWPE were evaluated after tribological tests. It is found that, the friction and wear behaviors of CoCr28Mo/UHMWPE pair under dry and bio-lubrication were the best. Results show that the use of natural oils improved significantly the tribological behavior of CoCr28Mo/UHMWPE and TiAl6V4/UHMWPE pairs. Microscopic and chemical analyses of wear tracks on UHMWPE were carried out and wear mechanisms were proposed for each materials pair. The tribological performance of the used oils was linked to their chemical composition and to their adsorption ability on the metallic surfaces.

Influence of bio-lubricants on the orthodontic friction.

The Friction force of Stainless Steel (SS) and Nickel-Titanium (Ni-Ti) rectangular archwires against stainless steel brackets was investigated. Two types of brackets were used namely: Self-ligating brackets (SLB) and conventional brackets (CB). The friction tests were conducted on an adequate developed device under dry and lubricated conditions. Human saliva, olive oil, Aloe Vera oil, sesame oil and sunflower oil were used as bio-lubricants. The friction force was examined as a function of the ligation method and oil temperature. It is found that under oil lubrication, the friction behavior in the archwire/bracket assembly were the best. The SLB ligation was better than the conventional ligation system. The enhancement of the frictional behavior with natural oils was linked to their main components: fatty acids.

Effect of Test Parameters on the Friction Behaviour of Anodized Aluminium Alloy.

The tribological behaviour of anodic oxide layer formed on Al5754, used in automotive applications, was investigated against test parameters. The friction coefficient under different normal loads, sliding speeds, and oxide thicknesses was studied using a pin on disc tribometer. Results show that the increase of load and sliding speed increase the friction coefficient. The rise of contact pressure and temperature seems to cause changes in wear mechanism. Glow-discharge optical emission spectroscopy (GDOES) was used to investigate the chemical composition of the oxide layer. Morphology and composition of the wear tracks were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). On the basis of these characterization techniques, a wear mechanism was proposed. The observed mechanical properties can be related to the morphology and the chemical composition of the layer.