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Axial piston pumps with compact structures and high efficiency are widely used in construction machinery. The efficiency and lifetime strongly depend on the tribological performance of the pump's valve plate pair. To enhance the tribological performance of the valve plate pair, surface textures, and H-DLC coatings were fabricated to modify the CuAl10Fe5Ni5 surfaces. The influences of elliptic textures of different sizes and textured H-DLC coatings on the surface friction and wear properties of the valve plate surface under oil lubrication were evaluated using a ring-on-disk tribometer. The results reveal that the friction and wear properties of the CuAl10Fe5Ni5 surfaces are significantly enhanced by elliptic textures, and the friction coefficient and wear rate of textured CuAl10Fe5Ni5 with E90 are maximally decreased by 95% and 87%, respectively. Compared with the surface textures and H-DLC coatings, the textured H-DLC coating has the greatest ability to reduce wear and adhesion. The wear rate of the textured H-DLC coating is further reduced by 98%. This improvement can be explained by the synergistic effect of the elliptic textures and H-DLC coatings, which are attributed to the reduced contact area, debris capture, and secondary lubrication of the elliptic textures, and increased surface hardness. [ABSTRACT FROM AUTHOR]

Abstract This work investigates how the surface textures and morphology of pyroxene grains evolve during their source‐to‐sink history. This study applies to detrital clinopyroxenes concentrated in coastal dune sands of the Gulf of Mexico which were sourced in the Trans Mexican Volcanic Belt then transported and deposited in environments subject to limited chemical weathering. The composition and morphology of the pyroxenes was characterised using single‐grain geochemical analysis and surface texture imagery with a novel approach based on the compactness property to assess the shape of minerals. This reveals heterogenous diopside‐augite populations, displaying mineral morphologies dominantly controlled by impact breakage along cleavages, little physical abrasion along their edges and with limited evidence for chemical weathering. Mechanical surface textures dominate over mechanical/chemical and chemical surface textures. These mechanical surface textures are preserved primarily as flat cleavage surfaces and rounded edges inherited from fluvial‐intertidal and aeolian transport, respectively. Mechanically/chemically induced surface textures are preserved as elongated depressions. Chemical surface textures are sparse and mostly represented by mammillated textures that suggest local dissolution under subaqueous conditions. The scarcity of chemical surface textures is attributed to frequent fragmentation of the clinopyroxenes along cleavages and limited chemical weathering during transport of the observed populations. Clinopyroxene grains in the coastal dune sands primarily retain surface characteristics from fluvial transport. Although the breakage of minerals along cleavages can obscure their original morphology under a weathering‐limited erosion regime, this study shows how surface textures and morphology of pyroxene grains is used to determine episodes of transport and deposition close to volcanic environments. The use of the compactness property as a shape descriptor measurement of particles provides an alternative approach to observe how clinopyroxene remains unaltered despite the high energy conditions of the coastal area.

This work investigates how the surface textures and morphology of pyroxene grains evolve during their source‐to‐sink history. This study applies to detrital clinopyroxenes concentrated in coastal dune sands of the Gulf of Mexico which were sourced in the Trans Mexican Volcanic Belt then transported and deposited in environments subject to limited chemical weathering. The composition and morphology of the pyroxenes was characterised using single‐grain geochemical analysis and surface texture imagery with a novel approach based on the compactness property to assess the shape of minerals. This reveals heterogenous diopside‐augite populations, displaying mineral morphologies dominantly controlled by impact breakage along cleavages, little physical abrasion along their edges and with limited evidence for chemical weathering. Mechanical surface textures dominate over mechanical/chemical and chemical surface textures. These mechanical surface textures are preserved primarily as flat cleavage surfaces and rounded edges inherited from fluvial‐intertidal and aeolian transport, respectively. Mechanically/chemically induced surface textures are preserved as elongated depressions. Chemical surface textures are sparse and mostly represented by mammillated textures that suggest local dissolution under subaqueous conditions. The scarcity of chemical surface textures is attributed to frequent fragmentation of the clinopyroxenes along cleavages and limited chemical weathering during transport of the observed populations. Clinopyroxene grains in the coastal dune sands primarily retain surface characteristics from fluvial transport. Although the breakage of minerals along cleavages can obscure their original morphology under a weathering‐limited erosion regime, this study shows how surface textures and morphology of pyroxene grains is used to determine episodes of transport and deposition close to volcanic environments. The use of the compactness property as a shape descriptor measurement of particles provides an alternative approach to observe how clinopyroxene remains unaltered despite the high energy conditions of the coastal area. [ABSTRACT FROM AUTHOR]

Veneered zirconia ceramics are widely used for dental restorations. However, the relatively poor bonding strength between the ceramic core and veneer porcelain remains a common problem in clinical applications. To address this issue, this study focused on enhancing the core–veneer bond strength of zirconia restorations through the implementation of surface textures using digital light processing (DLP) technology. The light intensity was precisely tuned to optimize mechanical strength and minimize light scattering. Subsequently, hexagonal or square grids were printed on the surface of the zirconia ceramic core. Following veneering procedures, the shear bond strength (SBS) test was conducted using a universal testing machine. Dates were compared using analysis of variance (ANOVA) and the least significant difference (LSD) test. Furthermore, optical microscopy and scanning electron microscopy (SEM) were used to examine the failure modes and observe the cross-sectional structures, respectively. The results indicated that the presence of a 0.09 mm high hexagon grid led to a significant 21% increase in the SBS value. However, grids with heights of 0.2 and 0.3 mm showed less improvement, owing to the formation of large defects at the interface during the fusion process. This study demonstrated the potential of DLP technology in preparing zirconia ceramics with complex structures and high mechanical strength, thereby offering promising solutions for overcoming challenges associated with dental applications. [ABSTRACT FROM AUTHOR]

A CuCoBe–diamond composite was used to reinforce a laser textured 410 stainless steel piston ring by hot-pressing. Different hot-pressing parameters were used to optimize the sintering process of the CuCoBe particles (P = 25 and 50 MPa, T = 820 and 980 °C, and t = 15 and 30 min). The results showed an increase in the hardness of the hot-pressed samples (50.5% and 48.5% for P = 25 and 50 MPa, respectively). Three textures with different track widths and distances between them were produced by laser on the compression piston rings' surface. The composite powders were used for the reinforcement of the textures by hot-pressing at the optimized sintering parameters (T = 980 °C, P = 25 and 50 MPa, and t = 15 min). The tribological results revealed that larger texture dimensions led to enhanced tribological performance. [ABSTRACT FROM AUTHOR]

Haptic rendering of surface textures enhances user immersion of human–computer interaction. However, strict input conditions and measurement methods limit the diversity of rendering algorithms. In this regard, we propose a neural network-based approach for vibrotactile haptic rendering of surface textures under unconstrained acquisition conditions. The method first encodes the interactions based on human perception characteristics, and then utilizes an autoregressive-based model to learn a non-linear mapping between the encoded data and haptic features. The interactions consist of normal forces and sliding velocities, while the haptic features are time–frequency amplitude spectrograms by short-time Fourier transform of the accelerations corresponding to the interactions. Finally, a generative adversarial network is employed to convert the generated time–frequency amplitude spectrograms into the accelerations. The effectiveness of the proposed approach is confirmed through numerical calculations and subjective experiences. This approach enables the rendering of a wide range of vibrotactile data for surface textures under unconstrained acquisition conditions, achieving a high level of haptic realism. • A neural network-based method for vibrotactile haptic rendering of surface textures under unconstrained acquisition conditions is proposed. • A coding method is designed based on human physiological physics characteristics. • Required no strict data segmentation methods. • Tactile perception of vibration with high realism is achieved. [ABSTRACT FROM AUTHOR]

To enhance the tribological properties of Si 3 N 4 based ceramics, surface textures of dimples combined with DLC coatings are fabricated on Si 3 N 4 /TiC ceramic surface by nanosecond laser and plasma enhanced chemical vapor deposition (PECVD). The dry friction and wear performances are evaluated by unidirectional sliding friction tests using a rotary ball-on-disk tribometer. Results reveal that the friction and wear properties of Si 3 N 4 /TiC ceramics are significantly enhanced by DLC coatings or dimpled textures, and the DLC coatings combined with dimpled textures show the best efficiency in reducing friction, adhesion and wear. This improvement can be explained by the synergistic effect of DLC coatings and surface textures, and the synergistic mechanisms are attributed to the formation of lubrication film and secondary lubrication, debris capture of dimpled textures, increased surface hardness and mechanical interlocking effect, and reduced contact area. [ABSTRACT FROM AUTHOR]

Passive heat exchangers (HXs) form an inseparable part of the manufacturing industry as they provide high-efficiency cooling at minimal overhead costs. Along with the aspects of high thermal cooling, it is essential to monitor pressure loss while using plate-fin HXs because pressure loss can introduce additional power costs to a system. In this paper, an experimental study was conducted to look at the effects of dimples on the pressure drop characteristics of single plate-fin heat exchangers. To enable this, different configurations of National Advisory Committee for Aeronautics (NACA) fins with smooth surfaces and 2 mm-diameter dimples, 4 mm-diameter dimples and 6 mm-diameter dimples were designed and 3D printed using fused deposition modelling (FDM) of ABS plastic. The depth to diameter ratio for these dimples was kept constant at 0.3 with varied diameters and depths. These were then tested using a subsonic wind tunnel comprised of inlet and outlet pressure taps as well as a hot wire velocimeter. Measurements were taken for pressure differences as well as average velocity. These were then used to calculate friction factor values and to compare the smooth fin to the dimpled fins in relation to their relative pressure drop performance. It was observed that for lower velocities the 4 mm dimples provided minimum pressure drop, with a difference of 58% when compared to smooth fins. At higher velocities, 6 mm dimples increased the pressure drop by approximately 34% when compared to smooth fins. It can also be concluded from the observed data in this study that shallower dimples produce lower pressure drops compared to deeper dimples when the depth to diameter ratio is kept constant. Accordingly, deeper dimples are more effective in providing drag reduction at lower velocities, whereas shallower dimples are more effective for drag reduction at higher velocities.

Micro-dimples are the basic surface textures that have played an important role in reducing or increasing friction, anti-wear, decreasing vibration, anti-adhesion, and creeping. Electrochemical micromachining (EMM) is a popular method for preparing micro-dimples. The method of sandwich-like electrochemical micromachining (SLEMM) can be used to enhance machining accuracy of micro-dimples, due to the electrolytic products accumulated on the workpiece surface in the enclosed unit of SLEMM. Therefore, this paper focuses on exploring the influence of bubbles accumulated on the workpiece theoretically and experimentally. The theoretical analysis indicated that 0.2 s machining time is required, and the theoretical maximum depth of micro-dimple is 7.3 μm when the electrochemical dissolution reaction is terminated. The CCD camera was employed to observe the process of SLEMM, and the observations indicated that the changes of gas bubbles are very complex and the electrolytic products accumulated on the workpiece surface have a significant influence on the preparing of micro-dimples. In addition, the experimental results indicate that the dimensions of micro-dimple vary little and the maximum depth of 4 μm for micro-dimples could be prepared with the increase of applied voltage, machining time, and thickness of mask, because of the electrolytic products accumulated on the workpiece during SLEMM. [ABSTRACT FROM AUTHOR]

The performance of surface textures with dimensional uncertainty due to the manufacturing process is investigated with statistical models. The uncertainty parameters are geometrical dimensions (i.e., dimple diameter, area ratio, and dimple depth) and the performance parameters include the friction force, the load-carrying capacity, and the coefficient of friction. The results show that logarithmic models provide an excellent fit to the data and can explain more than 99.98% of the variance in data. The most critical geometric parameter for the coefficient of friction and the load-carrying capacity is found to be the dimple diameter, whereas the most critical geometric parameter for the friction force is the area ratio. Manufacturing errors that follow normal distribution with three-sigma quality are found to be insignificant. Under the conditions simulated, it is determined that a dimple diameter of 1883 μm and a dimple depth of 5.5~6.5 μm yield optimal performance when operating in the hydrodynamic lubrication regime. The area ratio is the key parameter and must be determined based on the requirements of the load-carrying capacity and the coefficient of friction.

The present work aims to introduce the findings of the investigations of the surface textures of the quartz sand grains and their contribution to the history of sedimentation and diagenesis processes of the studied northern, middle and southern khors sediments in Lake Nasser. The surface textures observed in the quartz grains of the studied sediments emphasize both mechanical (i.e., upturned plates, meandering ridges, mechanical V-shaped pits, conchoidal fractures and oriented cleavage like plates) and chemical (i.e., silica precipitation and dissolution) features. The precipitation and dissolution phenomena are represented by silica globules, silica overgrowths, dissolved upturned plates, and diatoms plastered on sand grains. Such features imply a history of sedimentation of the khors sediments in Lake Nasser including deposition by aeolian processes, then fluvial sedimentation. The effect of consequent diagenetic processes in the khors sediments is represented by silica precipitation and dissolution features. The quartz surface texture reflects implications of the original aeolian environment of some grains in spite of the diagenesis effect.

The tribological interactions between skin and textured surfaces has profound impact on both the tactile perception of the product being used, as well as the functionality of the product with regards to friction coefficient. Previous work has shown that parallel-ridged textures have vastly different friction coefficients with regards to the direction of skin sliding, and that penetration of the skin into the voids between ridges not only add contact area but also potential for interlocking. The ability to model skin penetration into textural elements would prove to be very useful for predicting friction; however, the mechanics of the problem are incredibly complex such that they rule out a closed-form analytical solution. The authors investigated soft-body penetration using a non-dimensional computational approach based on the elastic properties of skin, as well as the texture ridge geometry parameters, as well as the normal loading. Model results were verified experimentally. The model was applied to a number of different combinations of ridge parameters and it was found that the amount of penetration could be predicted very well using a simple exponential relationship among the nondimensional terms. Texture groove width and applied normal load played a dominant role in penetration. These results yield a quantitative mechanics model which can be integrated into an overarching frictional model to predict skin on texture behavior due to both adhesion and edge interlocking. [ABSTRACT FROM AUTHOR]

The singular phenomenon is common in five-axis machining process. Most of the existing methods try to solve the problem by deforming the tool orientations or inserting extra cutter locations after the tool path is generated, with the drawbacks that (1) the machining geometry errors are not respected and (2) irregular machined surface textures might be caused. This paper dedicates to improve the machined surface textures in the scenario of avoiding the five-axis singularities. In this paper, the acceptable-texture orientation region (ATOR) concept is proposed. If the tool orientation is picked inside the ATOR, the resulted surface texture is considered to be acceptable. Based on this concept, the tool orientations are optimized locally. For a given tool path, if the orientation curve crosses the singular circle, it is locally modified out of the circle with a bridge point locating schema and a cubic B-spline interpolation technique. Eventually, the obtained new orientation curve goes around the singular circle like a rubber band to avoid the singular problem and remains unmodified to achieve the best machined surface qualities for the rest pieces. As the process is implemented at the tool path planning stage, the machining geometry errors can also be respected. [ABSTRACT FROM AUTHOR]

This paper looks into the irregular machined surface textures appearing in the process of avoiding five-axis singularities using the C-space based tool orientation translation method. At first, the mechanism for the appearances of the irregular surface textures is analyzed. A cutting simulation in VERICUT reveals that irregular surface textures are actually caused by lacking control of the tool orientation angles in the orientation modification process. Realizing that, a modified particle swarm optimization (PSO) is intergraded into the previous tool orientation translation method. In the PSO, the particle evolving equations are redefined and a mutation operation is added. The objective of the PSO is to find an optimal translating vector in the C-space so that the changed tool orientation angles can reach minimum values. In this way, the surface textures can be controlled. Three comparative cutting experiments with fillet endmills are carried out to verify the effect of the proposed method. The experimental results show that: (1) with the tool orientation translation method, the five-axis singular problem can be well avoided; and (2) with the optimal translating vector found by the PSO, the machined surface textures can be greatly improved. [ABSTRACT FROM AUTHOR]

This work concentrated on the machined surface properties produced by the multi-axis ball-end milling process in order to enhance the high-performance application of multi-axis ball-end milling technology. The cutting speed of the engaged cutting edges and machining characteristics under various inclination angles were analyzed. The effects of inclination angles on the machined surface hardness, residual stresses, surface textures, topographies, and roughness were investigated under up-milling and down-milling conditions. Under up-milling condition, the machined surface hardness with regard to various tilt angles are larger than the ones under corresponding lead angles, and the variations of surface hardness with increasing lead angles are not apparent. In down-milling condition, double-peaks shape appears in the changing curve of surface hardness with increasing tilt and lead angles. The residual stresses present the overall trend of firstly increasing, then decreasing, and finally increasing with the increasing tilt angle from −45 to 45°. The surface residual stresses in both feed and cross-feed directions firstly decrease, and then increase with the increasing lead angle. Under both up-milling and down-milling, the compressive residual stresses significantly appear at the tool inclination angles near 0° due to extrusion action of the cutting edges close to tool tip and the low effective cutting speed. For down-milling condition, the surface textures are approximately parallel with the feed direction when using tilt angles with large values, and are approximately perpendicular to feed direction under varying lead angles. The apparent machining marks under negative tilt angles with relatively larger absolute values and obvious regular surface patterns corresponding to positive tilt angles could be observed. More surface pits and burrs and circular arc textures probably appear under small tilt angles and lead angles near 0°. [ABSTRACT FROM AUTHOR]

The present work aims to introduce the findings of the investigations of the surface textures of the quartz sand grains and their contribution to the history of sedimentation and diagenesis processes of the studied northern, middle and southern khors sediments in Lake Nasser. The surface textures observed in the quartz grains of the studied sediments emphasize both mechanical (i.e., upturned plates, meandering ridges, mechanical V-shaped pits, conchoidal fractures and oriented cleavage like plates) and chemical (i.e., silica precipitation and dissolution) features. The precipitation and dissolution phenomena are represented by silica globules, silica overgrowths, dissolved upturned plates, and diatoms plastered on sand grains. Such features imply a history of sedimentation of the khors sediments in Lake Nasser including deposition by aeolian processes, then fluvial sedimentation. The effect of consequent diagenetic processes in the khors sediments is represented by silica precipitation and dissolution features. The quartz surface texture reflects implications of the original aeolian environment of some grains in spite of the diagenesis effect. [ABSTRACT FROM AUTHOR]

A study was made of the surface textures of about 100 gold nuggets (diameter 2-56 mm) sluiced and panned in the Lemmenjoki, Ivalojoki and Tankavaara areas of northern Finland. The placer gold localities all represent a recently glaciated environment. Surface textures were identified from acetate peels using optical microscopy, image analysis and experimental wear tests. Classification of the surface markings into primary (origin in bedrock), secondary (origin in sediments) and anthropogenic (man-made) groups resulted in a scheme including 6 subgroups and 16 types. The diagnostic features of each surface marking type are described and defined. The relative extents of surface marking types were measured as areal percentages with a point counting procedure, facilitating the comparison of individual nuggets. Applications of the technique range from fingerprinting of individual valuable nuggets in jewellery trade to mineralogical reconnaissance studies as a guide for gold transport.

Concrete pavements are well known for long structural life. The major challenge, however, is to provide a durable surface with adequate skid resistance for economy and safety. This paper examines the long-term frictional performance of eight different surface textures on 197 sections of concrete pavements within the long-term pavement performance (LTPP) program database. Analysis shows that tined and (or) grooved textures maintain consistently higher skid resistance over time and the surface friction of concrete pavements is less sensitive to ambient temperature. Cumulative traffic passes are more sensitive to longevity of friction than the cumulative axle loads. Five alternative models have also been successfully developed for prediction of the long-term skid resistance of concrete pavements as a function of texture type, cumulative traffic passes, speed, and concrete compressive strength. These models were shown to be statistically significant at 95% confidence levels with reasonable prediction accuracy. Les chaussées en béton sont reconnues pour leur longue durée de vie structurale. Le principal défi est toutefois de fournir une surface durable présentant une antidérapance adéquate pour la sécurité et l’économie. Le présent article examine le comportement au frottement de huit différentes textures de surface sur 197 sections de chaussées en béton dans la base de données du programme « long-term pavement performance (LTPP) ». L’analyse montre que des textures crantées et (ou) rainurées conservent de façon constante une meilleure antidérapance dans le temps et le frottement à la surface des chaussées en béton est moins sensible à la température ambiante. Le cumulatif des passages de la circulation est plus sensible à la longévité du frottement que le cumulatif des charges par essieu. Cinq autres modèles ont été développés avec succès pour prédire l’antidérapance à long terme des chaussées en béton en fonction du type de texture, du cumulatif des passages de la circulation, de la vitesse et de la résistance en compression du béton. Ces modèles se sont avérés statistiquement significatifs avec des coefficients de confiance de 95 % et une précision raisonnable de prévision. [ABSTRACT FROM AUTHOR]

Abstract: Groundwaters of the Murgia carbonate aquifer represent the main groundwater resource of the Apulia region (SE Italy). In the highlands (Alta Murgia) karst crops out in different forms and textures which have been preserved up to the 1970s: little evolved agriculture and sheep rearing produced only a marginal modification of the epikarst while a high degree of division into parcels by drystone walls helped in preserving soils from erosion. In the last years the original scenery of the Alta Murgia changed due to widespread transformations of surface karstic textures for agricultural purposes, with undeniable negative consequences on the hydrogeological balance, concerning both the infiltration and the runoff terms. Stone shattering led to flattening and deep alteration of a large part of the original karstic landscape and to demolition of drystone walls. In a study area of about 139 km2 located in the Alta Murgia, the comparison of aerial photos related to the period 1950–2001 indicated that stone shattering had occurred for about 42% of the area. The hydrological behaviour of the first soil layer of experimental parcels representing both shattered stone and natural karstic surface textures was analysed by using the numerical model Hydrus-2D with the aim of estimating the variation on infiltration rate due to stone shattering. Intensive field and laboratory measurements concerned soil texture, soil water content, pressure head, saturated hydraulic conductivity, pan evaporation and meteorological parameters. [Copyright &y& Elsevier]

The extent of subsurface deformation belowtheworn surface influences friction and transfer layer formation during sliding. Thus, in this study, the extent of plastic deformation and strain localization events that occur at various depths beneath the worn surface in the subsurface zones of Cu pins slid against steel plate with various surface textures have been determined using simple metallographic techniques. Results showed that the magnitude of plastic strain gradient and the depth of highly deformed zone depend on both coefficient of friction and transfer layer formation, which in-turn depends on the surface texture of harder counterface, under both dry and lubricated conditions. In addition, it was seen that the gradient of equivalent strain, as it approached the worn surface,was higher under dry conditions when compared to that under lubricated conditions. [ABSTRACT FROM AUTHOR]

Fluids play a key role in the transfer of both heat and mass within the crust and in the attainment of chemical equilibrium in metamorphic rocks, controlling both reaction rates and deformation mechanisms. However, our understanding of fluid movement through the deep crust is limited because rocks readily recrystallize, and fluids are invariably lost from grain boundaries. Little is known about how textures evolve during metamorphism since minerals rarely preserve much textural history that can be directly related to grain-boundary processes. Here we report on a study of the surfaces of apatite within gneisses. A variety of textural features is preserved on these surfaces, including imprinted texture of fossil grain boundaries. This texture is linked to deformation that caused a temporary excursion to fine grain size in the surrounding silicates. The geometry of paleoporosity is also recorded by microhollows on the apatite surface and gives a unique insight into both fluid behavior within the crust and the textural evolution of rocks. [ABSTRACT FROM AUTHOR]

• Based on generation mechanism of surface texture in UVAM, the shape and dimension of texture are designed quantitatively. • A "step-increment" simulation method is proposed to predict the surface texture. • The study of interference among textures is proposed for the first time. • The relationship between the generation accuracy and machining parameters of the surface texture is revealed. Functional microstructure surfaces exhibit excellent performance in many interfacial contact fields. Owing to high-frequency periodic vibration applied to the machining path, the surface texture generated by ultrasonic vibration assisted milling (UVAM) has unique characteristics. Besides, the texture generation mechanism is still unclear because of the complicated interaction of machining parameters, which limits application of UVAM. In this paper, the surface texture generation mechanisms including ultrasonic vibration end milling (UVEM) and ultrasonic vibration peripheral milling (UVPM) are systematically studied. The shape and dimension of textures were designed by analytical calculation. In addition, the corresponding parameters were determined by an established parameters selection model. The effect of interference on surface texture generation is studied for the first time in UVAM, and the texture topography after interference was also characterized. Furthermore, a "step-increment" discrete simulation model was developed to predict the topography of typical textures and interference textures. For improving the accuracy of texture topography prediction, the profile of cutting edge was also considered into the simulation model according to coordinate transformation. Then, the UVAM experiments were carried out on difficult-to- machine materials (Ti6AL4V) to verify the accuracy of numerical design, surface simulation and texture generation. The relationship between the machining quality and the ultrasonic milling parameters was also revealed. In addition, the wettability of surface textures was observed. The results indicated that the micro textures generated by UVAM contribute to the interface modification. To sum up, the research on the texture generation and interference in UVAM can expand the scope of application in the field of interface contact. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper presents the effort to reduce friction and wear of gear washers under low-speed and heavy-load conditions by designing the arrangement of surface textures. The influence of distributional parameters of textures on load-bearing capacity and friction coefficient of gear washers are studied numerically to obtain a preferable surface texturing design. Then, experimental tests were carried out to plot the Stribeck curves of the obtained texture arrangement compared with bare surface and another unoptimizable texture distribution arrangement to facilitate the verification of the simulation results. Theoretical predictions illustrate that the annular gear washers with partial surface texturing provide lower friction coefficients than bare washers. Textures having a sector angle of 20°, a coverage angle of 12°, a circumferential number of 8, and a radial number of 6 are selected as the final optimal surface texture distribution design. Experimental results confirm that the obtained texture arrangement moves the Stribeck curve towards the lower left, indicating thickening of oil film thickness and reduction in friction coefficient. In addition, the weight loss caused by wear is also reduced by the optimized texture design. [ABSTRACT FROM AUTHOR]

During dry machining of titanium alloys, severe friction exists at the tool-chip interface, which causes excessive heat generation and tool wear. To limit the tool-chip interface friction and to change tribological characteristics, texturing of the tool rake surface is one of the feasible solutions. In this study, innovative dual texture geometries consisting of grooves in the sticking and dimples in the sliding regions over the tool-chip contact area were fabricated. The other combinations included grooves or dimples spread over the entire tool-chip interface and the non-textured tools. Turning experiments showed that the dual textured tools reduced cutting and thrust forces by 31.2% and 16.2%, respectively, over non-textured tools. Surface morphology and elemental dispersive spectroscopy of dual textured tools rake surface had lower workpiece adhesion and less built-up-edge formation due to wear debris entrapment inside the textures. Dual textured tools produced almost continuous chips with very thin segmentation at low feeds compared with non-textured tools which produced highly segmented chips. The analytical model captured the effect of textures on the tool surface in the same way as the reduced contact area tools, and it was in good agreement with corresponding experimental cutting forces. • Innovative dual texture geometries consisting of grooves and dimples are fabricated on tool rake surface. • Machining experiments were performed using various cutting tools. • Cutting and thrust forces were measured and coefficient of friction was calculated. • Tool wear and chip morphology were analyzed. • An analytical model is proposed relating cutting force and contact area of the textured tool. [ABSTRACT FROM AUTHOR]

This work describes and interprets the presence of heavy minerals in the WNW Portuguese continental margin using a set of 78 bottom samples collected from three distinct areas of this margin: the Porto, Aveiro, and Nazaré canyon head areas. The main transparent heavy mineral assemblage (mineral grains with frequencies ≥1% identified under a petrographic microscope) is composed of amphibole, andalusite, tourmaline, biotite, garnet, staurolite, pyroxene, zircon, and apatite. The felsic igneous and metamorphic rock outcrops in the main Northern Portuguese river basins and the relict sedimentary continental shelf deposits explained the presence of most of these mineral grains (both considered as distal sources). However, the presence of pargasite, augite, diopside-hedenbergite, enstatite-ferrosilite, and forsterite in the Porto and Aveiro areas (minerals identified by electronic microprobe analysis) is probably related to the presence of an igneous basic source next to dolomitic limestones affected by thermal metamorphism. These geological formations are considered as local sources. The high concentration of biotite observed in the Nazaré area is the result of the selective transport of the most lamellar sand particles of this mineral. [ABSTRACT FROM AUTHOR]