Different works have demonstrated that tantalum, zirconium, and their nitrides present good biocompatibility. Additionally, TaN and ZrN possess excellent corrosion and wear resistance. Ternary nitrides such as TiAlN have been improved in terms of their mechanical properties with respect to binary systems. Therefore, ternary nitrides as TaZrN have high potential to be used in biomedical applications. This work was focused on studying the tribological and tribocorrosion performance of a TaZrN film. The coating was deposited by DC (Direct Current) magnetron sputtering in a reactive atmosphere using Ta and Zr targets. The tribological characterization was carried out in dry (atmospheric condition) and corrosive environments (synthetic body fluid). The coated surface shows better wear resistance than the uncoated in both conditions. The wear mechanism was studied by FE-SEM (Field Emission-Scanning Electron Microscopy) and Raman confocal microscopy. The wear rate of the coated surfaces was higher in corrosive ambient than in dry conditions. The observed wear mechanism was adhesive–abrasive for lower loads and abrasive at dry conditions for an applied load of 2 N. For corrosive media the principal wear mechanism for 2 N was abrasive–corrosive. For all tests at dry conditions, the formation of a tribolayer of metal oxides, graphite, and amorphous carbon was seen.

Development of carbon based micro electromechanical systems (C-MEMS) has enabled the fabrication of durable, low cost and biocompatible micro devices for specific applications. Thermochemical decomposition of SU-8 (a common photoresist) is often used to fabricate C-MEMS. However, this technique has yielded unreliable results when fabrication on transparent substrates is required due to cracking and detachment of the produced carbon micro structures. We present a methodology for the fabrication of photopatterned carbon films based on SU-8 deposited on transparent fused silica substrates. Specifically, we developed and implemented this methodology for carbon microstructure fabrication derived from SU-8 2035 and SU-8 3035. It was found that SU-8 3035 derived carbon microstructures were crack free and adhered well to the substrate, while SU-8 2035 resulted in fractured and detached carbon microstructures. In addition, we characterized the produced SU-8 3035 derived carbon by measuring its electrical resistivity (1.412 ± 0.011 mΩ m), inter-structure electrical resistance, contact angle (35.7° ± 6.0°), Raman spectrum and adhesion strength to the substrate. In brief, even though SU-8 2035 and SU-8 3035 are useful materials for C-MEMS fabrication, we found that SU-8 3035 is more suitable for the fabrication of crack free and adherent carbon microstructures on transparent fused silica substrates.

In sealing, sliding, and power transmission operations, surface quality and contact tolerances have high impacts on material system efficiency. Although the boriding process improves the wear resistance of metallic surfaces, it increases surface roughness, affecting the tribological efficiency of material systems. This study presents the tribological results of AISI 4140 boriding surfaces tested using a dehydrated paste pack boriding method with and without a finishing polish process to reduce the roughness. The duration of the boriding process was 1 h at 1123, 1173, 1223, and 1273 K using boron paste obtained from a commercial source and using a pot-polishing process with Al₂O₃ with a particle size of 0.5 μm for 25 min. The samples with and without the finishing polish process were structurally characterized using X-ray diffraction, and the boride coating adhesion was determined using Rockwell C indentation. The tribological properties of the boride surface with and without the finishing polish process were determined using a reciprocating sliding test, with a ZrO₂ ball as a counter body. The boride surfaces’ crystalline structure changed with polishing, which revealed the FeB phase and reduced the roughness value. These modifications in the surface characteristics altered the adhesion and tribological performance of the coating, resulting in a more stable tribological performance on the polished boride surfaces, with a reduction in the coefficient of friction (Cof) value from 0.75 ± 0.02 for the tribological test on the 1123 K-P sample to 0.59 ± 0.002 for the 1273 K-P sample surface at 20 N of applied load.

Recently, there has been increasing interest in the use of hot targets to enhance the sputter deposition of materials. However, the actual temperature of the target surface is normally not known. In this work, we directly measured the radial distribution of the surface temperature of a MAK 2 in. Ti water-cooled target using a type K thermocouple during the operation of the sputtering system. Principally, the measurements were made as a function of applied DC power and argon gas pressure. Given the importance of chemical reactions between the gas and the target during reactive sputtering, we have also measured the target temperature as a function of the nitrogen concentration in an argon-nitrogen gas mixture. A few of the reactively sputtered samples were analyzed by x-ray photoelectron spectroscopy.

Food security is one of the main problems in several countries. In food processing the cutting operation is very important as the operation is basic to food preparation. Due to cutting tools being exposed to a high-demand environment that includes high contact pressure, a corrosive atmosphere, and a high-speed process, they are subject to high mechanical and corrosive wear that reduces their lifetime and efficiency. Tribocorrosion is one of the main phenomena that reduces the lifetime and efficiency of cutting tools. This work presents electrochemical and tribocorrosion studies of D2 steel surfaces coated with TiN, TiCN, and TiCrN films. The samples were coated by a commercial source, using the PVD-cathodic arc technique. The crystalline structure of TiN and TiCN films presented a TiN and Ti phase, while the crystalline structure of TiCrN showed CrN and Cr phases. The films exhibited good adhesion, but the surfaces coated with TiN and TiCN films presented lower hardness. Although the TiN, TiCN, and TiCrN films showed better wear and corrosion resistance than the D2 steel surfaces, the inclusion of C and Cr in the TiN films decreased the TiN wear and electrochemical resistance in 3.5% (w/w) of NaCl solution.

The sputtering yield amplification (SYA) is a phenomenon based on doping a sputtering target with atoms of higher atomic mass. This doping changes the depth and the direction of the collision cascade in the target surface promoting a higher ejection of target atoms. In this work, we present a new way of generating the SYA phenomenon without the need of expensive and complex deposition systems. This was accomplished by increasing the working pressure and adding small pieces of W, as dopant element, on the racetrack of a Si target. The physical phenomena necessary to promote the SYA, for our experimental parameters, were analysed in two different deposition chambers and two sizes of sputtering targets. Based on the collisions in the gas phase, a calculation on the number of W atoms returning to the racetrack area was made, considering the number of atoms deposited on the thin films, to determine their effect on the cascade of collisions. In addition, calculations with the simulation of metal transport code were developed to determine the location on the racetrack zone the returning atoms were redeposited. By using reference samples placed on the racetrack of the Si target, we found that the percentage of SYA depends on the number of dopant atoms redeposited as well as the depth distribution these atoms had in the racetrack surface.