In this work, a duplex treatment of laser surface texturing (LST)-thermal oxidation (TO) was conducted on Ti6Al4V alloy to improve its mechanical property and wear performance. Microstructure, ...bonding strength, microhardness and nanoindentation behavior of the TO-Ti6Al4V were characterized. A comparative appraisal of wear performance for related samples of original Ti6Al4V, LST-Ti6Al4V, TO-Ti6Al4V and duplex treated-Ti6Al4V (DT-Ti6Al4V) were performed under dry sliding condition. The results revealed that gradient titanium oxide coatings with a thickness of 17 μm were in situ fabricated on the surface of Ti6Al4V and textured Ti6Al4V. The content of O displayed a gradient distribution across the TO-coating. TO treatment has improved the surface hardness and elasticity modulus of the Ti6Al4V. The specific wear rate of the samples was sorted in the following sequence: DT-Ti6Al4V < TO-Ti6Al4V < LST-Ti6Al4V < Ti6Al4V, which indicates that DT-Ti6Al4V exhibited the most excellent wear performance. It was confirmed that Ti6Al4V could obtain promisingly enhanced wear performance by taking advantages of LST and TO treatment.
•Laser surface texturing (LST) was conducted on Ti6Al4V.•Thermal oxidation (TO) coating was prepared on Ti6Al4V and textured Ti6Al4V.•LST-TO duplex treatment improved the mechanical property and wear performance.
•The effect of laser micro-nano processing on the surface of Ti6Al4V was studied.•The change of wetting angle of solder was investigated during dynamic heating.•The joint is strengthened by chemical ...metallurgical bonding and mechanical bonding.•The formation mechanism of sealing glass/Ti6Al4V interface was presented.
Ti6Al4V alloy and ZrO2 ceramic are both used in similar fields, including electronics, aerospace, and biomedicine. Brazing techniques can be used to join these two materials, broadening their range of applications. One effective joining method is the use of a sealing glass melt of various oxides. This approach provides a strong bond between the ceramic and metal. However, it can be difficult for the glass to wet to the metal surface requiring the alloy to undergo oxidation at high temperatures for an extended period. This study involves the use of laser surface texturing to change the alloy surface roughness and shape. This procedure results in better adhesion of the sealing glass to metal surfaces. When the number of laser scanning is 10, the surface roughness Ra reaches 5.62 μm and the surface energy reaches 46.88, which are the maximum values after comparison. The wetting angle of the sealing glass on the surface is the fastest to reach the wetting state, and the shear strength of the joint reaches the maximum of 46 MPa. This technique created an oxide layer, which contributed to strong mechanical bonding between the grooves and solder, which improved joint performance through chemical and mechanical bonding. This work provides a new approach to the connection of metals and ceramics.
Micro-textures applied on rubbing surfaces have gained tremendous attention in the tribological community. Numerous studies deal with the deduction and testing of beneficial micro-textures. ...Nevertheless, not all questions have been answered yet. Will texturing really deliver as good effects as frequently claimed? Are there optimum texture designs? Are there occasions where texturing could enhance the tribological performance but is questionable from other perspectives?
Therefore, ball-on-disc experiments are carried out with a special emphasis on the relative position of micro-texture and counter body. Furthermore, transient EHL simulations are performed, addressing the effects of structural parameters and relative texture's position on the tribological performance. Finally, meta-modeling with subsequent optimization is applied to predict numerically derived optima and robust texture designs.
•The relative position between micro-texture and contact area influences friction and wear.•Structural texture parameters determine the tribological behavior.•Tribo-simulations and Meta-Modeling support the deduction of robust texture designs.•Appropriate micro-texture designs depend on the applied load.•Shallow textures with a diameter close to contact area are considered to be beneficial.
In this research, three types of vein-bionic texture patterns inspired by five kinds of leaves (Forsythia, Clausena lansium, Ash, Pipal, and Apricot) were designed and fabricated on the raceways of ...the shaft washers of cylindrical roller thrust bearings (CRTBs) through a fiber laser marking system. A vertical universal wear test rig was used to obtain the coefficient of friction (COF) of bearings under starved lubrication, with a customized tribo-pair. The wear losses of the shaft washers and the worn surfaces were characterized. The influence of different veins (chief, primary, secondary) and vein-structure characteristics (pattern symmetry, number of veins) on the tribological behavior of vein-bionic textured CRTBs is investigated and discussed. The results show that the original vein-bionic (V) pattern inspired by the Ash has the best friction-reducing performance, while the texture with the no-chief vein (NC) obtained by Clausena lansium has the best wear resistance. The chief vein mainly contributes to the low friction by enhancing the secondary lubrication effect and facilitating the formation of a protective nylon film. A reasonable mechanism for improving the tribological properties of resulting textures is proposed.
The effect of a rectangular convex/concave shape formed on adherend surfaces in terms of preventing the crack growth of adhesively bonded joints was analytically investigated. The finite element ...method was used to evaluate crack growth resistance along the crack path by simulating a double cantilever beam test in which a single convex/concave shape was formed on the adherend material. The obtained crack growth resistance clearly demonstrated that both concave and convex shapes improved the apparent fracture toughness; i.e., the convex/concave shape functioned as a crack arrester. We identified the cause of the improvement as the dispersion of energy allocated to crack propagation due to the accumulation of the strain energy or the reduction of the stress concentration at the crack tip. It is noteworthy that the crack growth was arrested even when the convex shape did not interrupt the crack path.
An experimental study is presented to evaluate the effect of partially laser surface textured piston rings on the fuel consumption and exhaust gas composition of a compression–ignition IC engine. ...Dynamometer tests were performed with a Ford Transit naturally aspirated 2500
cm
3 engine at a wide range of engine speeds under near-half-load conditions. A comparison was made between the performance of reference non-textured conventional barrel-shaped rings and optimum partial laser surface texturing (LST) cylindrical-shape rings. It was found that the partial LST piston rings exhibited up to 4% lower fuel consumption, while no traceable change in the exhaust gas composition or smoke level was observed.
Laser texturing is a facile method to promote modified surface wetting properties. While most laser textured metal surfaces are natively superhydrophilic, here we establish a quantitative ...relationship between post-texturing chemical modification and water contact angles from ca. 80° < θw < 180°. A nanosecond laser-based high-throughput surface nanostructuring (nHSN) method is used to texture aluminum alloy surfaces. The textured surfaces are immersed in ethanol solutions of chlorosilane reagent CF3(CF2)5(CH2)2SiCl3 (FOTS) at different concentrations and different times to achieve superhydrophobicity. The role played by the two chemical treatment parameters, concentration and treatment time, is investigated and quantified. Water contact angle, reflection-based infrared spectroscopy and energy-dispersive X-ray spectroscopy are used to characterize the functionalized surface. The goal of this research is to quantify the effects of surface chemical modification on the resulting material functionality using surface sensitive spectroscopic techniques. Our results show that both the solution concentration and the immersion treatment time play significant roles in the attachment of functional groups (-CF2-, -CF3) on surface. Further, concentrations of FOTS as low as 0.1% with six hours of chemical immersion treatment, or short treatment times as low as three hours with 0.5% FOTS solution are adequate to achieve superhydrophobicity.
Display omitted
•This study constitutes the first attempt to evaluate the effects of chemical immersion treatment for superhydrophobic functionalization of laser textured surfaces.•A spectroscopic approach is developed to quantitatively measure surface coverage.•The time and amount of chemicals used in chemical immersion treatment can be reduced dramatically for superhydrophobic metal surfaces.
Theoretical analyses can be performed on elastohydrodynamic lubrication (EHL) and mixed lubrication (ML), but not for the boundary due to the complicated contact conditions of the friction pair. More ...importantly, it is difficult to monitor the operating parameters of a line-contact friction pair. Thus, the extreme condition point of the line-contact cannot be determined in the BL. To address this issue, the temperature during the line-contact friction is adopted as a measure to analyze the extreme condition point of the line-contact. The extreme condition is recognized in the experiments, while the friction failure mechanism is analyzed by the temperature. The analysis results demonstrate that the temperature in extreme conditions is higher than the flash point temperature; the extreme condition point falls into the BL range, but its Schipper lubrication number falls into the ML region. As a result, the extreme condition point can be determined by experimental or field testing.
In order to consider the effect of the local surface properties, such as textures and roughness, a mass-conserving model is specifically developed based on the Elrod–Adams model. The classic flow ...factor methodology is incorporated in this model to deal with the roughness scale. Meanwhile, by reformulating the cavitation conditions according the Fischer–Burmeisster equations, the system of discretized equations for this model is changed to be unconstrained. The computational efficiency of the developed model is similar to that when cavitation is not considered. Finally, this model is evaluated in the predicting the performance of the textured ring/liner system under the start-up process.
•A mass conserving model with roughness is presented for mixed lubrication.•Both the JFO cavitation theory and the flow factor methodology are incorporated.•The computational efficiency is similar to that when cavitation is not considered.•Local surface properties such as textures or roughness can be deeply studied.•It shows including the roughness effect can ensure the accurate predictions.
Among various surface modification technologies, laser surface texturing (LST) to introduce texture has attracted more scholars' attention for controlling the tribological performance. The enhanced ...processing quality of the textured surface results in reducing the coefficient of friction and improving the wear resistance. In this study, dielectric transformer oil was used to protect the surface of GCr15 bearing steel from undesired gases in the atmosphere during the laser processing. Three types of dimples, including circle, rectangle and hexagon, were ablated to evaluate their influence on friction and wear. It was found that LST with transformer oil greatly improved the surface texture processing quality, where the edges of dimples were effectively designed and burrs-free. Results showed that the depth of dimples was reduced up to 7%. Compared to the samples fabricated in air, the friction coefficient and the wear of improved surface were reduced up to 55% and 73.8%, respectively. This was attributed to the excellent shielding and coolant property of transformer oil. Additionally, the shapes of the dimples, the applied force and the sliding speed significantly affected the friction coefficient, where dimples operate as lubricant and debris stores. This study provides certain feasibility guidance for the tribological modification of GCr15 bearing material with oil method and expands its application on engineering surfaces.
•Transformer oil-coated LST was introduced to improve the tribological properties.•Circular, rectangular and hexagonal dimples were studied.•LST with oil greatly improved the surface texture processing quality.•The friction and wear were reduced up to 55% and 73.8%, respectively.
