Papers by Keyword: Fretting Corrosion

Abstract: Fretting and fretting-corrosion processes in elements of kinematic pairs used for medical applications are observed in metallic orthopedic implants, dental prosthetics elements, and orthodontic appliances. In most cases, the degradation of biomaterials significantly limits their useful life and the comfort of patients. The products formed as a result of wear may lead to poisoning of the body and the occurrence of inflammatory states, which often results in the failure of medical therapy. Fretting-corrosion processes are being paid more and more attention, although there is not much data concerning the stomatognathic system. This article presents the results of fretting-corrosion studies of one of the most frequently used metallic biomaterials, CoCrMo cobalt alloy, in the presence of human saliva and its substitutes. The results of studies indicate that friction has a large influence on corrosion processes (fretting-corrosion). Artificial saliva compositions with favorable tribological and anti-corrosion properties were successfully developed and may find applications in the stomatognathic system, e.g. for the purpose of reducing the unfavorable effects of bruxism. Fretting-corrosion studies were performed using a self-designed original device. The obtained results of studies are of great significance in scientific and applicatory terms.

Abstract: In this paper, the fretting corrosion wear behaviors of steel wires were researched when the wires were lubricated with alkaline solution. Then, the wear mechanism was analyzed. Results showed that the friction coefficients of wires lubricated with alkaline solution were little influenced by the loads, while greatly affected by the electrochemical corrosion existing on the surfaces of the friction pairs. The shape of most of the fretting wear debris was tuberous or near spherical which owns smooth edges. This kind of wear debris was beneficial to reduce the fretting wear of steel wires. The depth of wear scar, used to evaluate the fretting corrosion wear of the steel wires, was increased with the increase of load. In addition, the wear depth of the wire lubricated with alkaline solution was not only less than which obtained in dry friction condition, but also less than which lubricated with deionized water and acid solution. Analysis showed that the corrosion solution played an important part in the fretting corrosion wear. And the effect of corrosion solution to the wear was stronger than which to the corrosion of steel wire materials.

Abstract: Electroplated nickel coatings provide ductility, excellent corrosion resistance and good wear resistance, which qualifies them to meet complex demands of engineering, microtechnology and microelectronics. The co-deposition of particles is a promising alternative to deposit layers with adequate microstructure and properties avoiding the rise of residual stress. The incorporation of the sufficient quantity of particles, monodisperse distribution and downsizing to nanometre scale affect the amount of strengthening by dispersion hardening. To avoid agglomeration in the electroplating bath as well as in the layer is a challenge which has been met by simple Watts nickel electrolyte with a minimum of organic additives and adequate bath agitation comprising sonication, i.e. the exposure of the bath to high-frequency sound waves. Well-dispersed hard particles (titanium oxide and silicon carbide) were incorporated in nickel films. The focus was set on the correlation between the gained microstructure of the composites with particles from micron to nanometre scale and the electrochemical and mechanical properties. Corrosion was quantified from polarisation curves and volumetric erosion measurements. Wear resistance was evaluated by scratch energy density studies, oscillating sliding wear testing and cavitation wear testing and compared to indentation hardness results. Sonication and particle downsizing result in matrix grain refinement and dispersion hardening. Incorporation of different particles with respect to different material and size proved to meet different demands. Submicron TiO2 is best for high corrosion resistance, sonicated nickel without particle incorporation is best for high abrasion resistance, nano TiO2 is best for oscillating sliding wear resistance and submicron SiC is best for cavitation wear resistance.