Squamous textures with different texture interaction factors (λ), which characterize the spacing relationship between adjacent textures, were fabricated on SiC surfaces by nanosecond laser texturing to investigate the influence of texture interactions on lubrication and wear behavior under starved lubrication conditions. A texture interaction effect (TIE) was proposed to characterize the relationship between neighboring texture spacing and tribological performance. The results demonstrated that the lubrication and wear behavior was significantly influenced by texture interactions. A moderate texture interaction condition (ST-15, λ = 0.58) exhibited the lowest parallel contact angle of 10.18° and the minimum friction coefficient of 0.114, corresponding to a 34.1% reduction compared with the smooth surface. The superior tribological performance was attributed to the synergistic effects of lubricant transport and retention, local pressure distribution, and wear debris evolution, whereas excessive texture interactions led to interference between neighboring pressure distributions and deteriorated lubrication conditions. These findings deepen the understanding of the relationship between texture interactions and lubrication and wear behavior, providing valuable guidance for the design of textured surfaces operating under starved lubrication conditions.
A porous microchannel tool employing low-temperature air jets is proposed to achieve targeted cooling near the secondary and tertiary deformation zones during cutting, with the aim of realizing efficient and high-quality machining of Inconel 718. Through numerical simulation, an optimized structure of the porous microchannel tool was designed, in which the micropores on the rake face and flank face were located 0.7 mm and 0.9 mm from the tool tip, respectively, and the maximum stress of the porous microchannel tool satisfied the strength criterion. Analysis of the flow-field characteristics showed that, compared with the conventional tool, the temperatures in the cutting zones on the rake face and flank face of the porous microchannel tool were reduced by approximately 65.2% and 74.0%, respectively, while local vortices were generated, effectively enhancing the heat transfer capacity in the cutting regions of the secondary and tertiary deformation zones. Experimental results for turning Inconel 718 with the porous microchannel tool showed that, compared with the conventional tool, the flank wear was reduced by 26.9% at a cumulative cutting distance of 825.57 m, the wear region on the rake face was significantly decreased, and adhesive wear and abrasive wear on both the rake face and flank face were effectively suppressed. The maximum reduction in machined surface roughness reached 58.2%, and the thickness of the subsurface plastic deformation layer decreased by 48.5%, significantly improving surface integrity. This improvement originates from the ability of the porous microchannel tool to precisely regulate the temperature in the cutting regions near the secondary and tertiary deformation zones, thereby achieving a synergistic enhancement of tool life and machining quality. However, the application of the porous microchannel tool under high-speed cutting conditions still has certain limitations. Overall, this study provides an innovative solution for the high-performance machining of Inconel 718.
Detecting and measuring tooth wear is becoming a growing concern in dentistry. This means that there is a need for more accurate and non-destructive advanced techniques to take measurements to help overcome the problem, ideally during , intraoral examinations. This study recreated tooth wear using simulant materials in two types of wear test run in a Universal Mechanical Tester (UMT) using spherical zirconia antagonists run against two layer specimens made from VITA ENAMIC® and Fibrafill® CUBE. One was a reciprocating sliding test; the other a unidirectional wear test where the spherical zirconia probe returned to the start point out of contact, so there was an initial impact and then the sliding motion (“one-way impact-slide” mode).Different approaches were used to measure the resulting wear: Alicona (Infinite Focus) device (wear scar profile and roughness); Optical Coherence Tomography (OCT) (wear scar profile) and ultrasound (US) (wear scar depth), the latter two being options for intraoral measurements. The results demonstrated good comparability, but OCT has the best potential.
This work investigates the relationship between surface microstructure, electrical conductance, and wear resistance under DC electrical current in hydrogenated tetrahedral amorphous carbon (ta-C:H) coatings. Coatings were deposited by filtered cathodic vacuum arc with hydrogen flow rates of 0–90 sccm, producing conductive sp2 clusters (areal fraction 0.25–4.71%) embedded in an insulating sp3 matrix (two-terminal resistance 31–1006 MΩ). Coatings were characterized by Raman spectroscopy, confocal laser scanning microscopy, Kelvin probe force microscopy, and breakdown voltage (VBD) measurements; lubricated ball-on-disk wear tests were run at three severity levels (0.05–0.5 A DC). Every condition was tested three times on independently deposited specimens with individually measured sp2 fractions and matrix resistances. The ta-C:H 90 sccm coating, despite the highest matrix resistance, showed the lowest breakdown voltage (18.6 V) and the lowest specific wear rate (1.43 ± 0.24 × 10-6 mm3 N-1 m-1 at 0.5 A, 96% below the most severely worn coating); damage shifted from interconnected large-scale pitting to discrete isolated pits. At the lowest severity, the four coatings were statistically indistinguishable. An effective surface conductance that treats the sp2 clusters and sp3 matrix as parallel current paths (sp2 cluster resistance 1 MΩ) ranked the coatings in inverse order of wear. Combined with the measured breakdown voltage, K ∝ VBD2/Geff collapsed all twelve specimens onto one power law (slope 1.01 ± 0.11, R2 = 0.90); microstructure alone gave the same collapse. This behavior is consistent with a current-distributing discharge mechanism: discrete sp2 pathways disperse the current before charge accumulation, linking erosion resistance to measurable surface parameters.
Boron (B)-containing coatings have emerged as promising materials for high-speed dry cutting tool applications. This study designed and fabricated three AlCrBN coatings with different gradient layer structures to elucidate the relationship between their gradient layer structure and adhesion, impact fatigue resistance, dry sliding wear and high-speed dry cutting performance of titanium alloys. Gradient changes in their grain sizes and microstructures of the layers as a function of depth below the surface were evaluated using transmission electron microscopy. The T2 coating with a more gentle gradient layer structure showed the highest adhesive strength (Lc2 = 132 N), a higher H/E value, better impact fatigue resistance (0.98 N impact force and 0.9 μm indentation depth with no obvious surface damage), a lower wear rate (2.02 × 10-16 m3/(N·m) under 10 N; 14.23 × 10-16 m3/(N·m) under 20 N) against alumina counter-bodies. This also contributed to its superior high-speed dry cutting length against Ti-6Al-4V (1600 m at 80 m/min; 850 m at 100 m/min). The improved wear resistance, impact fatigue resistance and cutting performance of the AlCrBN gradient coating result from a reduced probability of coating peeling induced by crack deflection at the interfaces between different layers. Based on this work, the high-speed dry cutting performance against Ti-6Al-4V cutting of AlCrBN coated tools could be improved by the design of the appropriate gradient layer structures.
