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Wear particles are produced as a result of interaction of two surfaces in mechanical systems. After extracting and separating particles by different techniques (filtration, ferrography …), their morphology, which is a function of the condition of tribological system (tribosystem), can be related directly to the wear process. In order to understand wear mechanisms, it is interesting to study the relationship between the characterization of wear particles (aspect ratio, shape factor, spike parameter) and the mechanical factors of wear. Therefore, a series of tests were conducted with polytetrafluoroethylene (PTFE) versus cast iron, and flake graphite versus cast iron. Wear particles were studied in a particular tribosystem to understand debris formation and wear. Consequently, after friction tests according to a plane on plane contact, wear particles were collected. After separation tests, particle morphology obtained through image analysis techniques, was used to determine how debris are produced and to elucidate wear mechanisms. Finally, we propose a wear mechanism with these particular tribosystems.

During hot drawing, work tools are subjected to severe constraints. Thus, tool wear is a main preoccupation for industrial engineers. For this reason, it is important to better understand the phenomena which occur at the interface between tool and sheet in this kind of process. That is why, a pin on disc tribometer for high temperature has been designed and achieved. Its originality consists in having an open contact on a continuously new disc surface. This machine permits the simulation of the contact at the tool/product interface during the hot drawing process. In this paper, this new tribometer is described. Then, a friction and wear comparative study of various tool materials is carried out at a temperature of 400 °C and with a pressure of 20 MPa. The classification of these materials is done according to the measurement of the friction coefficient and the wear characterization. Pins, which represent tools are: X153CrMoV12 steel samples uncoated and coated with TiAlN deposited by PVD process and nodular cast iron GJS 600 ones. Sheets made of steel and representing drawing products are: uncoated and coated samples by bimetallic alloy coating. The tribometer is able to classify and to evaluate the tribological performances of the different combinations of pins and sheets. Tests show that coatings reduce friction. However, they do not prevent adhesive wear of pins.

The aim of this article is to find correlations between the characteristics of the wear particles, the coefficients of friction and the wear rates in order to determine wear mechanisms. In the air compressors, piston rings are made of polytetrafluoroethylene (PTFE) but its wear rate is very high and it must be reinforced. This work is devoted to the influence of temperature with three types of PTFE (pure and filled with glass fibre and carbographite) against flake grey cast iron thanks to a phenomenological study of the contact.

Surface treatments and coatings are the practical approaches used to extend the lifetime of components and structures especially when the surface is the most solicited part of the considered engineering component. Hard thermally sprayed coating is one of the most wear resistance coating widely used in many practical mechanical applications. In the construction of articulating parts of medical devices, titanium and its alloys have to be surface coated to improve their tribocorrosion behavior. In this way, the use of porous thermal coatings is known to be a strategy for better binding bone or tissue on femoral stem for example. It is, thus, important to evaluate the corrosion and the wear behaviors of such materials for biosecurity considerations in the human body. In this study, we investigate the behavior of new nano ZrO2 and Al2O3-13 wt.% TiO2 thermal sprayed coatings on commercially pure (cp)-Ti (grade 4) and titanium alloy substrates. Friction and wear tests against Al2O3 balls showed that the wear resistance of Al2O3-13 wt.% TiO2 is better than that ZrO2 coating. Both plasma sprayings have similar abrasive wear behavior; however, the average friction coefficient is higher for alumina–titania coating. Electrochemical tests, open circuit potential monitoring and potentiodynamic polarization, were performed in simulated body conditions (Hank’s solution, 37 °C). Results showed that corrosion resistance was appreciably higher for alumina–titania coating.