Thanks to their outstanding mechanical properties, Bulk Metallic Glasses (BMGs) are new alternatives to traditional crystalline metals for mechanical and micromechanical applications including power transmission. However, the tribological properties of BMGs are still poorly understood, mostly because their amorphous nature induces counter intuitive responses to friction and wear. In the present study, four different BMGs (Cu₄₇Zr₄₆Al₇, Zr₄₆Cu₄₅Al₇Nb₂, Zr₆₀Cu₂₈Al₁₂, and Zr₆₁Cu₂₅Al₁₂Ti₂) underwent ball-on-disc friction tests against 100Cr6 steel balls (American Iron and Steel Institute (AISI) 52100) at different relative humidities (RHs) ranging from 20% to 80%. Controlling humidity enabled to observe a high repeatability of the friction and wear responses of the BMG. Interestingly, the friction coefficient decreased by a factor of 2 when the humidity was increased, and the wear rate of BMGs was particularly low thanks to a 3rd-body tribolayer that forms on the BMG surface, composed of oxidized wear particles originating from the ball. The morphology of this tribolayer is highly correlated to humidity. The study also identifies how the tribolayer is built up from the initial contact until the steady state is achieved.

Sliding electrical contacts are commonly used with a slip ring to collect the current in moving system generators, alternators, or electrical motors. These contacts are also found in electrical transports without batteries, which are mostly supplied by means of a pantograph–catenary system. These systems are fraught with numerous issues. Among them, it is worth highlighting wear and heating, which lead to failures and pre-worn materials. Moreover, with the increase in speed and improvements in technologies and materials, new problems emerge. This is the case with the substitution of the classic copper strip with graphite or copper-impregnated graphite. Multiple works that studied sliding electrical contacts have been achieved recently, some by trying to create a model of the system based on experimental results, and others only based on experimental works and measurements. This paper aims to review articles from this last category by making a synthesis of different test benches used and then by opening a discussion based on different results highlighted by scholars. This discussion is divided into five points that constitute the system inputs. These are the environment, material, normal load, sliding speed, and current. Based on this discussion, a conclusion attempts to evaluate topics where results and trends are commonly established by authors and topics where there is a lack of work or some conflicts in the results or trends between different articles. For this last point, some perspectives are given for further experimental works.

To achieve thermoplastics-based composites with high tribological performances, molybdenum disulfide (MoS₂) and graphite (Gr) were incorporated separately to a polyamide 66 (PA66) matrix. Two different development methodologies of composites were used. The morphological features and the micromechanical properties of composites were investigated to stress the influence of the filler surface treatment and its dispersion. The friction coefficient was evaluated using a ball on flat micro-tribometer. The wear mechanisms were also characterized. The best tribological performance was exhibited by 10 wt.% of graphite. The surface treatment of the filler inclusions by 3-aminopropyltriethoxysilane (AMPTES) showed an improvement in the morphological aspects of adhesion at the filler/matrix interface.

This paper deals with the vibroacoustic behavior of an electric window-lift gear motor for automotive vehicle which consists of a direct current (DC) motor and a worm gear. After describing the overall vibroacoustic behavior of this system and identifying the various excitation sources involved, this study focuses on the excitation sources associated to the contacts between brushes and commutator. To that end, a specific test bench is designed. It makes use of a modified gear motor for which various specific rotors are driven with an external brushless motor. It allows the discrimination of some excitation sources associated to the contact between brushes and commutator by removing them one after the other. The respective weight of friction, mechanical shocks, electrical current flow, and commutation arcs occurring jointly at the brush/commutator interface are dissociated and evaluated. The friction and the mechanical shocks between brushes and commutator blades increase the vibroacoustic response of the window-lift gear motor. The flowing of electrical current in brushes/commutator contacts tends to moderate the frictional component of excitation sources, while commutation arcs induce their rising, leading to a global additive contribution to the dynamic response.

Titanium-boron-nitrogen (Ti-B-N) thin films were deposited by RF reactive magnetron sputtering using a titanium diboride (TiB₂) target in an argon + nitrogen mixture. The argon mass flow rate was kept constant, whereas that of nitrogen was pulsed during the deposition. A constant pulsing period of P = 10 s was used, and the introduction time of the nitrogen gas (duty cycle (dc)) was systematically varied from dc = 0 to 100% of the pulsing period. This reactive gas pulsing process allowed the deposition of Ti-B-N thin films with various boron and nitrogen concentrations. Such adjustable concentrations in the films also led to changes in their electronic transport properties. Boron and nitrogen contents exhibited a reverse evolution as a function of the nitrogen duty cycle, which was correlated with the transition from a metallic to semiconducting-like behavior. A percolation model was applied to the electrical conductivity as a function of the nitrogen pulsing parameters, assuming some correlations with the evolution of the Ti-B-N thin film nanostructure.

Adding movement sonification to haptic exploration can change the perceptual outcome of a textured surface through multisensory processing. We hypothesized that auditory-evoked emotions would influence the appraisal of textured surfaces, with corresponding changes reflected in cortical excitability. Participants actively rubbed two different textured surfaces (slippery and rough) either without movement sonification, or with pleasant or disagreeable movement sonification. We found that sounds, whether agreeable or disagreeable, did not change the texture appraisal. However, the less pleasant surface was associated with a stronger negative hedonic valence, particularly when paired with disagreeable movement sonification. Time frequency analyses of EEG activities revealed a significant reduction in beta-band power [15-25 Hz] within the source-estimated sensorimotor and superior posterior parietal cortices when contrasting both pleasant and unpleasant sound with the silent touch. This suggests that the primary somatosensory cortices together with the superior parietal regions participated in the audio-tactile binding, with both pleasant and unpleasant sounds. In addition, we observed a significant increase in beta-band power in medial visual areas, specifically when disagreeable movement sonification was paired with tactile exploration. This may reflect a disengagement of visual cortical processing, potentially amplifying auditory-driven emotional responses and intensifying the perceived unpleasantness of the explored surfaces.