Corrosion resistance evaluation of carbon and vanadium-based sputtered coatings on steel substrates

Steels are in constant contact with fluids that could generate corrosion regardless the application in which this steel is located. AISI-SAE 1045 like steels is widely used in different applications in engineering, even several of these parts made of this steel suffers wear processes. The synergy between corrosion and wear phenomena exacerbates the detriment of some physical properties of the material conducing it to a failure. A potential alternative to avoid this issue is to coat the material surface with an anticorrosive material, and among different techniques to produce coatings, physical vapor deposition ones are environmentally friendly, secure and with excellent properties on the final product. We report the production of coatings based on vanadium and carbon on AISI-SAE 1045 steels substrates varying some of the deposition parameters in a sputtering coatings machine. A 23-factorial design of experiments was done with power applied to the vanadium target, power applied to the carbon target and temperature as active factors with two levels each one. A relevant effect of the power applied to V target and temperature on the anticorrosive properties of the coatings was found, thus increasing these factors levels always gives higher surface roughness and higher corrosion rates, this result together provides an important insight into the values that must be considered to achieve good anticorrosive properties on the material. Overall, these results indicate that with low V target power and room temperature, and high C target power the lowest corrosion rates and roughness of the group are achieved, both results agree.

Cr doped MoS2 films: Tribological Properties, Microstructure and Electronic Structure

Cr doped MoS2 films were deposited by magnetron sputtering. The tribological properties of Cr doped MoS2 films under vacuum (VC) and air (AR) environments were investigated. The results show that Cr doped MoS2 film with Cr target power of 0.2 A (0.2 A Cr:MoS2 film) exhibits low friction coefficient and long wear life under both VC and AR environments. The chemical compositions of the films were analyzed by energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). With the increases of Cr target power, the content of Cr increases. The cross-sectional FESEM morphologies show that the structure of the films changed from granular particles to column when the Cr target power increases from 0.2A to 0.4A. The wear mechanism has also been discussed based on the characteristics of worn surface. The 0.4 A Cr:MoS2 film has the lowest wear volume among these films, which can be attributed to the compact microstructure. The bandgap of Cr doped MoS2 films were measured by XPS and the tribological performance of the film is found to be best when there is a modest bandgap. It can be speculated that the tribological performance of Cr doped MoS2 films are closely related to the width of bandgap.

How Social Power Affects the Processing of Angry Expressions: Evidence From Behavioral and Electrophysiological Data

With the help of event-related potentials (ERPs), the present study used an oddball paradigm to investigate how both individual and target power modulate neural responses to angry expressions. Specifically, participants were assigned into a high-power or low-power condition. Then, they were asked to detect a deviant angry expression from a high-power or low-power target among a series of neutral expressions, while behavioral responses and electroencephalogram (EEG) were recorded. The behavioral results showed that high-power individuals responded faster to detect angry expressions than low-power individuals. The ERP analysis showed that high-power individuals showed larger P3 amplitudes in response to angry expressions than low-power individuals did. Target power increased the amplitudes of the P1, VPP, N3, and P3 in response to angry expressions did, but decreased the amplitudes of the N1 and N170 in response to angry expressions. The present study extended previous studies by showing that having more power could enhance individuals’ neural responses to angry expressions in the late-stage processes, and individuals could show stronger neural responses to angry expressions from high-power persons in both the early‐ and late-stage processes.