ABSTRACT
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.
Subject(s)
Friction , Lubrication , Materials Testing , Polyethylenes/chemistry , Titanium/chemistry , Alloys , Chromium , Cobalt , MolybdenumABSTRACT
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.
Subject(s)
Lubricants/chemistry , Orthodontic Brackets , Orthodontic Friction , Orthodontic Wires , Dental Alloys , Dental Stress Analysis , Humans , Materials Testing , Nickel , Orthodontic Appliance Design , Plant Oils/chemistry , Saliva/chemistry , Stainless Steel , TitaniumABSTRACT
The object of our study is to release the epidemiological, clinical and mycological characteristics of superficial fugal infections. A retrospective study was carried out during three years (1996-1998). Direct microscopy was positive in 86% cases, the culture in 62% cases. Trichophyton rubrum accounts for 85% of the dermatophytic flora. The superficial fugal infections account for 15% of the reasons for consultation in our service. They would touch according to data's of literature 2 to 13% of the general population. Trichophyton rubrum in accordance with the various series published, is the fungi most frequently insulated with variable rates between 46 and 82% of the superficial fungal infections. Any time, Candida albicans is prevalent on the level of the hands.
