No abstract

No abstract

Surface treatment of medical CoCr alloys L605 by nitrogen plasma immersion ion implantation (PIII) leads to the formation of a hard and wear resistant surface layer, consisting of nitrogen in solid solution. However, a detailed investigation of the corrosion properties by potentiodynamic polarization and electrochemical impedance spectroscopy shows that even at processing temperatures of 350 °C, where no CrN precipitates are observed, no complete passivation of the surface by formation of a protective Cr 2 O 3 layer is possible leading to enhanced corrosion rates further increasing with increasing PIII processing temperature. It is postulated that the enhanced affinity of chromium for nitrogen leads to a reduced mobility inside the alloy, thus prohibiting a timely surface passivation. Nevertheless, a surface modification where a moderate decrease in corrosion resistance coupled with a significant reduction in generated wear particles should be feasible for biomedical applications.

No abstract

During the last few decades, diamond-like carbon (DLC) coatings were widely used for tribological applications, being an effective tool for improving the performance and the useful life of different machining tools. Despite its excellent properties, among which stand out a high hardness, a very low friction coefficient, and even an excellent wear resistance, one of the main drawbacks which limits its corresponding industrial applicability is the resultant adhesion in comparison with other commercially available deposition techniques. In this work, it is reported the tribological results of a scratch test, wear resistance, and nanoindentation of ta-C and WC:C DLC coatings deposited by means of a novel high-power impulse magnetron sputtering (HiPIMS) technology with “positive pulses”. The coatings were deposited on 1.2379 tool steel which is of a high interest due to its great and wide industrial applicability. Finally, experimental results showed a considerable improvement in the tribological properties such as wear resistance and adhesion of both types of DLC coatings. In addition, it was also observed that the role of doping with W enables a significant enhancement on the adhesion for extremely high critical loads in the scratch tests.

No abstract

No abstract

No abstract