Comparing Wettability and Frictional Performance of Laser Micro-machined Discrete and Continuous Textures
01 Jan 2021-pp 185-192
TL;DR: In this paper, Dimple and cross-hatch textures are fabricated using laser surface texturing (LST) technique to compare the wettability and coefficient of friction (CoF) of discrete and continuous texture under bio-lubricated condition.
Abstract: TiAl4V is used widely in aerospace and biomedical application due to its high specific strength and good bio-compatibility. Its poor tribological performance restricts usage for hip implant articulation. Various surface characteristics such as surface roughness and wettability affect the tribological behaviour of Ti6Al4V sliding. Surface texturing is the recent technique to modify the surface features and improve the wettability. This study aims to compare the wettability and coefficient of friction (CoF) of discrete and continuous texture under bio-lubricated condition. Dimple and crosshatch textures are fabricated using laser surface texturing (LST) technique. The geometrical parameters such as depth, pitch and area density have been kept the same. Wettability associated with both the textures are analysed by measuring surface contact angles using goniometer. Further, friction behaviour is evaluated for all the textured and non-textured surfaces under biological environment using reciprocating pin-on-disc tribometer. Results show a significant reduction in contact angle for crosshatch texture compared to dimple and non-textured surface. Also, both the texture reduced the friction by 24% compared to non-textured surface.
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TL;DR: In this paper , oriented crosshatch textures were fabricated over Ti6Al4V surface using Nd:YAG laser and the effect of heat treatment over DLC coating morphology, adhesion strength and surface characteristics was analyzed.
Abstract: Superior surface characteristics, tribological performance and adhesion strength are critical for DLC coated surface in hip implant. Incorporating laser surface texturing and heat treatment before DLC deposition can improve surface properties by inducing oxygen diffusion and phase formation. Therefore, oriented crosshatch textures were fabricated over Ti6Al4V surface using Nd:YAG laser. Textured surface was heat treated followed by DLC coating deposition with Cr interlayer. Effect of heat treatment over DLC coating morphology, adhesion strength and surface characteristics was analyzed. Phase formation and bonding behavior at the coating interlayer were characterized and correlated with adhesion strength. Bio-tribological performance of modified surface was evaluated under elliptical sliding contact to replicate hip implant articulation. Increased surface roughness, better wettability and enhanced graphitic characteristics were associated with DLC coating with prior heat treatment. With heat treatment, Cr2O3 and TiO2 phase formation with superior bonding at interlayer demonstrated improved adhesion strength including deformation resistance. Textured, heat treated and DLC coated surface showed relatively increased compressive residual stress with HF1 quality adhesion. The synergic effect of surface texturing and DLC coating achieved lowest friction. Qualitative wear analysis using Raman spectroscopy reveals beneficial effect of heat treatment before DLC coating for long term hip implant application.
9 citations
TL;DR: In this paper , the authors investigated the role of laser scanning and post heat treatment in improving the oxygen diffusion depth and overall surface characteristics of Ti6Al4V surface and found that the combination of LST and heat treatment improves rutile phase fraction, surface hardness and adhesion.
Abstract: The combination of laser surface texturing and heat treatment process was barely investigated in the past, particularly for improved surface characteristics of Ti6Al4V. Hereby, the important role of laser scanning and post heat treatment in improving the oxygen diffusion depth and overall surface characteristics was analyzed. Polished Ti6Al4V surface was scanned using Nd:YAG nanosecond laser and analyzed for the oxygen pickup, phase change and hardness variation. The laser textured surface was heat treated to grow oxide coating over textured surface. In comparison with heat treated surface, the synergic effect of laser scanning and heat treatment improved the surface hardness by 15% and raised the TiO 2 rutile phase fraction from 0.36 to 0.73. The dual engineered Ti6Al4V surface was found to have superior HF1 quality adhesion strength along with the presence of low magnitude tensile residual stress. The increase in oxygen diffusion depth, diffusion coefficient and TiO 2 rutile phase fraction due to synergic effect of laser scanning and heat treatment were associated to the Ti 2 O 3 and C doping assisted anatase to rutile transformation mechanism. • Laser scanning is responsible for oxygen and carbon pickup and forms Ti2O3 phase at the Ti6Al4V surface. • Combination of LST and heat treatment improves rutile phase fraction, surface hardness and adhesion. • Oxygen diffusion depth and diffusion coefficient increase using laser texturing with heat treatment process. • Anatase to rutile transformation is prominent mechanism in laser textured with heat treated Ti6Al4V surface.
6 citations
2 citations
TL;DR: In this paper , the authors combined the laser surface texturing technology and heat treatment process to fabricate a dual surface engineered Ti6Al4V consisting of micro-groove crosshatch pattern texture covered with hard TiO 2 oxide coating to reduce friction and improve the wear resistance at the bio-lubricated interface.
Abstract: This study combines the laser surface texturing technology and heat treatment process to fabricate a dual surface engineered Ti6Al4V consisting of micro-groove crosshatch pattern texture covered with hard TiO 2 oxide coating to reduced friction and improve the wear resistance at the bio-lubricated interface. Crosshatch texture with 25 μm width, 5 μm depth at 25% area density were fabricated using nanosecond Nd:YAG laser over Ti6Al4V surface and then heat treated at 600 °C for 48 hours. XRD result showed rutile TiO 2 phase formation along with the presence of anatase TiO 2 , Al 2 O 3 and Ti 3 O minor phases whereas, the surface hardness was increased to 1538±41 HV. Bio-tribology experiments were carried out for 45 and 90 o oriented micro-groove crosshatch textures, with and without heat treatment, under partially replicating hip implant articulation. Results demonstrated 60% friction reduction corresponding to the 45 o oriented crosshatch texture with heat treatment. Further, the worn-out surface morphology showed reduced wear damage and good wear debris entrapment inside the micro-grooves.
1 citations
TL;DR: In this article , thermal oxidation was performed on micro-blasted Ti6Al4V surfaces for 24 and 48 hours and the electrochemical performance was evaluated using FESEM, EDS, XRD, AFM, and Goniometer.
Abstract: Ti6Al4V alloy is widely used for orthopaedic applications due to its excellent osteointegration, good biocompatibility, great strength-to-weight ratio, and comparable elasticity with bone. However, when this alloy is exposed for long-term in the body fluid, it releases the corrosion products of metals and metal oxides. The released particles react with the surrounding tissue and cause an adverse local tissue reaction (ALTR) which leads to pseudotumor formation, osteolysis (bone degradation). Thus, corrosion is a critical parameter for bio-implants and in this study to minimize corrosion, thermal oxidation was performed on micro-blasted Ti6Al4V surfaces for 24 and 48 h. Surface morphology, phase analysis, surface roughness, and wettability of all types of samples were evaluated using FESEM, EDS, XRD, AFM, and Goniometer. The electrochemical performance was studied in 0.9 wt% NaCl. The combined mechanical and thermal process increases surface roughness and improves the hydrophilic nature of the Ti6Al4V surface by 67 %. The formation of metastable Ti2O3 during micro-blasting and further transformation of anatase and rutile TiO2 during thermal oxidation increases the intensity of anatase and rutile TiO2 formed on the surface and enhances corrosion resistance. Overall, micro-blasting with 48-h thermal oxidation showed 2 times higher corrosion resistance and reduced corrosion rate by almost 50 % as compared with the untreated Ti6Al4V.
References
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01 Apr 2012-Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology
TL;DR: In this article, a numerical model was developed to investigate the effects of groove characteristics on the lubrication condition and friction at the interface between the piston ring and cylinder liners, and the model aims to solve the average Reynolds equation, which depends on the real surface topographies of the cylinder liner.
Abstract: A cylinder liner possesses fairly intricate surface requirements due to its complicated functions. It needs to provide adequate surface roughness to resist wear as well as to store and retain lubricants during high temperatures. The liner surface texture is anisotropic, produced by the honing process, with resultant deep visible scratches left on it [1] . The prominence of the honing grooves observed suggests that surface texture significantly affects ring-pack performance, although this effect is not clearly understood. In this paper, a numerical model was developed to investigate the effects of groove characteristics on the lubrication condition and friction at the interface between the piston ring and cylinder liner. This model aims to solve the average Reynolds equation, which depends on the real surface topographies of the cylinder liner, and describes the influence of surface irregularities on the lubricant flow under hydrodynamic lubrication conditions, considering lubricant film rupture and cavitations. Numerical results help to determine the optimum lateral groove characteristics to reduce friction and then noxious emissions.
121 citations
TL;DR: The fundamentals of wetting are briefly reviewed, with a particular focus on hysteresis and roughness issues, and present knowledge and models of dynamic wetting on smooth and rough surfaces are examined, with particular attention devoted to nano-topographical heterogeneities and solid-fluid-fluids systems.
100 citations
TL;DR: In this paper, the surface wettability properties of laser textured Co-Cr-Mo alloy surfaces were investigated by pin-on-disc reciprocating tribometer under BSA lubrication.
92 citations
TL;DR: In this article, a CNC micro-drilling machine was used to fabricate circular dimples on a flat ceramic substrate and the results showed significant tribological performance gains, including a nearly 22% friction and 53% wear reduction.
83 citations
TL;DR: In this article, a two-step plasma immersion ion implantation technique was developed and applied for the modification of Ti6Al4V alloy; firstly ion implanting with nitrogen at high temperature and followed with oxygen in high dose.
Abstract: In this study, a new two-step plasma immersion ion implantation technique was developed and applied for the modification of Ti6Al4V alloy; firstly ion implanting with nitrogen at high temperature and followed with oxygen in high dose. A graded titanium oxide–titanium nitride film was obtained on the surface of the Ti6Al4V alloy. The contact angle and the microhardness of the modified alloys were measured. The friction and wear properties of UHMWPE rubbing against the modified alloys under lubrication of distilled water were investigated using a pin-on-disc tribometer. The wettability and the microhardness of the alloy surfaces were found to be increased significantly after ion implantation. The friction coefficient decreased by nearly 5 times and the wear resistance of UHMWPE increased by about 40 times against the ion implanted Ti6Al4V alloy. Many deep furrows were found on the surface of the un-implanted alloy and were absent in the ion implanted surfaces of the alloy.
67 citations