Wear Resistance Of Ti6Al4V Alloy Research Articles

Tribological Properties of Ti6Al4V Alloy Composite Texture Fabricated by Ultrasonic Strengthening Grinding and Laser Processing

The Ti6Al4V alloy has been widely used in aerospace equipment and medical devices. However, the poor wear resistance of the Ti6Al4V alloy hinders its further engineering application. In this study, the ultrasonic strengthening grinding process (USGP) and laser texturing process were employed to enhance the wear resistance of Ti6Al4V alloy. The frictional behavior of all samples was determined via a ball-on-disc friction and wear tester under dry conditions. The worn surface morphology, cross-sectional hardness, surface roughness, and microstructure were analyzed. The results demonstrated that the USGP induced high hardness, high dislocation density, and grain refinement, as well as improvements in the wear resistance of Ti6Al4V. Moreover, laser texture could enhance the capacity to capture wear debris and reduce wear probability. When combining the USGP and laser texturing process for the surface treatment of Ti6Al4V alloy, the lowest and most stable friction coefficients were obtained, as well as the best wear resistance. Compared to the polished sample, the steady stage friction coefficient of the sample treated by USGP and laser texturing process was remarkably decreased by 58%. This work demonstrates that combining the USGP and laser texturing process could be a promising solution for improving the wear resistance properties of Ti6Al4V alloy, which makes it more suitable for various engineering applications.

Enhanced Strength and High-Temperature Wear Resistance of Ti6Al4V Alloy Fabricated by Laser Solid Forming

Abstract Strengthening titanium alloys and mitigating their wear degradation at various temperatures is the key to industrial applications. In this study, high-performance Ti6Al4V alloy (here, Ti with 6.25 wt% Al and 4.17 wt% V) was prepared by laser solid forming (LSF). The phase and microstructure of the Ti6Al4V alloys were systematically examined, and the overall improved mechanical properties were achieved. The coefficient of friction (CoF) and wear of LSFed Ti6Al4V alloy against WC-6%Co cemented carbide using a ball-on-disc tribometer at various temperatures revealed a temperature-dependent wear mechanism. During the experiment, the CoF of LSFed Ti6Al4V would increase initially and then decrease with the increased temperature. This trend is determined by the abrasive wear dominating at a lower temperature, and it gradually changes to oxidative wear and fatigue wear under higher temperatures. LSF provides a promising way to achieve supreme mechanical and tribological properties in Ti6Al4V simultaneously.

Increasing Wear Resistance of Ti6Al4V Alloy by Cathodic Plasma Electrolytic Nitriding

A possibility of increasing wear resistance of Ti6Al4V alloy after cathodic plasma electrolytic nitriding in a solution of ammonium chloride and ammonia is shown. The competing effect of the surface erosion by the actions of discharges and high-temperature oxidation on the morphology and roughness of the surface was revealed. The complex effect of the surface roughness and surface layer hardness on the wear resistance of the titanium alloy was determined. It was found that the greatest decrease in the weight wear by a factor of 2.7 was observed for the sample with the maximum microhardness of the surface layer, reaching 820 HV, and the smallest surface roughness. It was shown that the friction coefficient decreased in proportion to the treatment time when the surface layer had low hardness, favoring the sliding of the counter-body.

Preparation of Wear-Resistant Coating on Ti6Al4V Alloy by Cold Spraying and Plasma Electrolytic Oxidation

In order to improve the wear resistance of Ti6Al4V alloy, the alloy was first coated with alumina-reinforced aluminum coating (CS-coating) by cold spraying, and then the alloy with CS-coating was processed by plasma electrolytic oxidation (PEO) under unipolar mode and soft sparking mode, respectively, to prepare wear-resistant PEO coatings. For comparison, Ti6Al4V alloy without CS-coating was also subjected to PEO treatment. The microstructure, phase composition, hardness, and wear resistance of the PEO coatings formed on Ti6Al4V alloy with and without CS-coating were investigated. The results revealed that PEO coatings formed on Ti6Al4V alloy with CS-coating under soft sparking mode contained more α-Al2O3, possessed larger thickness, more compact microstructure, and higher microhardness than that formed under unipolar mode. The PEO coating formed on Ti6Al4V substrate was mainly composed of TiO2 and had pores and cracks. Among all these coatings, PEO coating formed on Ti6Al4V alloy with CS-coating under soft sparking mode exhibited the best wear resistance with a wear rate of 1.18 × 10−5 mm3/(Nm), which was only 15.28% of that of the Ti6Al4V substrate. The investigation indicated that the combination of cold spraying and PEO under soft sparking mode is a promising technique for improving the wear resistance of titanium alloy.

The Effect of Anodization and Glow Discharge Plasma Oxidation Surface Treatments on the Wear Resistance of Ti6Al4V Alloy

Günümüzde titanyum ve alaşımları yüksek biyouyumluluk ve düşük elastisite modülüne sahip olmaları nedeniyle çeşitli implantların üretiminde kullanılmaktadır. Titanyum ve alaşımlarının dezavantajlarından biri, yüksek sürtünme katsayısı ve düşük aşınma dayanımına sahip olmalarıdır. Bu dezavantajı gidermek için titanyum ve alaşımlarının yüzeylerine bir takım işlemler uygulanarak başta aşınma direnci olmak üzere yüzey özelliklerinin iyileşmesi sağlanabilmektedir. Bu çalışmada, yük taşıyan implant üretiminde kullanılan Ti6Al4V (Grade 5) taban malzemesi plazma oksitleme ve anodik oksitleme (anodizasyon) işlemlerine tabi tutulmuştur. İki farklı oksitleme işleminden elde edilen yüzeyler sertlik, yüzey pürüzlülüğü, ıslanabilirlik ve aşınma direnci açısından işlemsiz malzeme ile karşılaştırılmıştır. Bu testlerin gerçekleştirilmesi için XRD, SEM, AFM, Mikro sertlik cihazı, Temas açısı ölçüm cihazı ve Doğrusal aşınma cihazı kullanılmıştır. Çalışma sonucunda sertlik değeri işlemsiz malzemeye göre plazma oksitleme için %116 ve anodik oksitleme için %36 artış göstermiştir. Yüzey pürüzlülüğü incelendiğinde, plazma oksitleme işleminin yüzey pürüzlülüğünde %11 artış ve anodik oksitleme işleminin %33 düşüşe sebep olduğu görülmüştür. Temas açısı değerleri işlemsiz malzeme için 48,31° iken plazma oksitleme işlemi sonrası 73,34° ve anodik oksitleme işlemi sonrası 85,36° olmuştur. Ayrıca her iki oksitleme işlemi sonrası işlemsiz malzemeye nazaran tribolojik özelliklerin iyileştiği gözlemlenmiştir.

Metal transfer and microstructure evolution during wire-feed deposition of TiB/Ti composite coating

A new type of Ti flux-cored wire was used to in-situ synthesize two-scale TiB reinforced Ti composite coatings through wire-feed gas tungsten arc cladding, to enhance the surface hardness and wear resistance of Ti6Al4V alloy. Metal transfer modes during wire-feed deposition were investigated by high-speed camera observation in conjunction with arc voltage analysis. The results showed that the metal transfer modes varied from interrupted bridging transfer, slag column transfer, to continuous contact transfer with increasing the wire-electrode distance in 2–6 mm, accompanied by the improvement of process stability. The volume fraction of TiB in coating was governed by metal transfer modes, and can be arranged as: slag column transfer > continuous contact transfer > interrupted bridging transfer. Microstructure analysis revealed that most of TiB2 particles were melted in arc zone while the rest were fully dissolved among the weld pool through in-situ reaction for slag column transfer, while both other two modes caused the inclusion of TiB2 particle aggregations in coatings. Consequently, the coating formed by slag column transfer possessed the maximum hardness (571 HV0.5) and the minimum wear loss (14.10 mg). Worn morphologies analysis revealed that the load-shearing effect of TiB accounted for the superior wear resistance of the coating. This study demonstrates the feasibility of preparing titanium matrix composite coating through wire-based cladding.

Increasing wear resistance of Ti6Al4V alloy by anodic saturation with carbon and nitrogen

In this paper, anodic plasma electrolytic nitrocarburising (PEN/C) was applied to Ti6Al4V alloy. This treatment was carried out in electrolyte containing ammonia (5 wt.%), acetone (5 wt.%) and ammonium chloride (10 wt.%) during 5 min at treatment temperature from 750 to 900°C. There were investigated the alloy microhardness, surface roughness and wear resistance. It was shown that the PEN/C results in saturation of studied alloy with oxygen, nitrogen and carbon include formation TiO2 with rutile structure and solid solution in titanium of nitrogen and carbon. This structure provides an increase in microhardness of the surface layer up to 940 HV by sealing the crystal lattice. Surface roughness Ra of treated samples decreases by 1.2–1.4 times and wear resistance increases by 9–10 times after PEN/C. Friction coefficient of PEN/C samples was reduced by 1.5-fold after treatment at 750°C.

A significant improvement of the wear resistance of Ti6Al4V alloy by a combined method of magnetron sputtering and plasma electrolytic oxidation (PEO)

Titanium alloys own a series of advantages such as low density, high specific strength, and biocompatibility. However, the poor wear resistance of titanium alloys impedes their wide applications in industry. In this study, we show that the wear resistance of the Ti6Al4V alloy can be greatly improved by a combined method of magnetron sputtering and plasma electrolytic oxidation (PEO). An ~13 μm pure aluminum layer was first applied on the Ti6Al4V alloy by magnetron sputtering and then PEO was employed for the second step treatment of the Al coated Ti6Al4V alloy. The PEO of the Al coated Ti6Al4V was carried out in aluminate (32 g l−1) and silicate (16 g l−1) electrolytes, respectively. Ball-on-disc tribological tests with an applied load of 10 N against a Cr steel ball were used to evaluate the wear performances of the samples. The coating formed in 32 g l−1 aluminate electrolyte for 4 min shows superior wear performance, which sustained 1800 s sliding time against the steel ball and the wear rate is non-detectable. In contrast, the coating formed in the silicate electrolyte for 15 min has been destroyed during the tribological test, showing a wear rate of ~3.9 × 10−4 mm3/(N·m). The excellent wear performance of the coatings formed in the aluminate electrolyte can be attributed to its high growth rate and homogeneity in microstructure. The coating growth mechanisms have also been discussed.

Sliding wear behaviour of Ni-Cr alloying on Ti6Al4V based on double-glow plasma surface metallurgy technology

To improve the wear resistance of Ti6Al4V alloy, Ni-Cr alloy coatings with 40 at.%Ni were prepared on Ti6Al4V alloy surface by double-glow plasma surface metallurgy technique. The friction and wear behaviour of the coatings sliding against Si3N4 at room temperature and 500 °C were comparatively studied. The results show that the alloy coatings comprise a deposited layer, a diffusion-modified layer and a heat-affected zone. The deformed deposition layer plays an anti-friction effect as a soft film. The tribological behaviour of diffusion layer is abrasive wear. Ni-Cr surface alloying process significantly reduces the friction coefficient of Ti6Al4V alloy and improves the wear resistance properties of Ti6Al4V alloy.

Tribological Behavior of Surface-Modified Titanium and Polytetrafluoroethylene-based Composites in Seawater

In order to improve the wear resistance of Ti6Al4V titanium alloy contacted with polytetrafluoroethylene-based composites in seawater, plasma nitriding (PN), micro arc oxidation (MAO) and plasma spray tungsten carbide (PSTC) were used to modify the surface of Ti6Al4V alloy. The tribological properties of Ti6Al4V alloy matrix and its modified layers sliding with polytetrafluoroethylene-based (PTFE) composites in seawater were comparatively investigated. The PTFE composites were made with glass fiber, graphite and bronze separately by compression molding. The results indicate that low friction coefficients were shown in modified layers of the titanium alloy sliding with PTFE composites in the seawater environment. The Ti6Al4V alloy exhibits poor wear resistance and leads to the serious wear of PTFE composites. The above three kinds of surface treatments improve effectively the wear resistance of Ti6Al4V alloy. The PN treatment with reducing the wear of PTFE composites shows better wear resistance than the MAO treatment with accelerating the wear of PTFE composites. The glass fiber reinforced PTFE shows better wear resistance than the bronze reinforced PTFE in the same experimental condition. It has obvious advantages that the titanium alloy with PN treatment contacted with glass fiber reinforced PTFE were chosen as the materials of the tribological components used in hydraulic transmission in the marine environment application.

Wear properties of nonhydrogenated, hydrogenated, and dehydrogenated Ti6Al4V alloy

Wear properties of the nonhydrogenated, hydrogenated 0.5 wt%, and dehydrogenated Ti6Al4V alloys were studied through dry sliding wear tests using an M-200 type pin-on-disk wear testing machine in ambient air at room temperature to reveal the effects of hydrogen on wear properties of Ti6Al4V alloy. Morphology and chemical element of worn surface were investigated by means of scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). Results show that hydrogen decreases the wear resistance of Ti6Al4V alloy. Wear rate of the Ti6Al4V alloy increases after hydrogenation. Wear rate increases by 244.3 % when 0.5 wt% hydrogen is introduced into a Ti6Al4V alloy. Wear rate of the dehydrogenated Ti6Al4V alloy recovers. Wear mechanisms of the nonhydrogenated, hydrogenated, and dehydrogenated Ti6Al4V alloys are determined. The nonhydrogenated Ti6Al4V alloy is controlled by oxidative wear. The hydrogenated Ti6Al4V alloy is dominated by abrasive wear. Wear mechanism of the dehydrogenated Ti6Al4V alloys is a mixture of oxidative wear and abrasive wear.

The Effect of Low Temperature Plasma Nitriding on Wear Resistance of Ti6Al4V Alloy

The e ect of low temperature plasma nitriding on wear resistance of Ti6Al4V alloy were investigated. There have been several studies to investigate the low temperature plasma nitriding on Ti6Al4V alloy. Plasma nitriding processes under gas mixture of N2/H2 = 3 were performed at temperature 535 ◦C for duration of 4, 8 and 12 h. Adhesive wear tests were carried out by using a tribometer in block-on-ring con guration (ASTM G77), in sliding conditions, without lubricants and in air. Surface hardness of the plasma nitrided samples were measured by a Vickers hardness tester machine. Scanning electron microscopy studies were conducted to understand the wear mechanisms involved during the adhesive wear. Wear rate was calculated using weight loss per unit sliding distance. It was found that the wear resistance and surface hardness of the alloy improved considerably after plasma nitriding process. The wear resistance of the plasma nitrided samples were higher than of the unnitrided samples. Extension of nitriding times from 4 h to 12 h in the Ti6Al4V alloy improved remerkably the wear resistance and surface hardness.

Surface modification of Ti-6Al-4V alloy by cathode assiting discharge setup and conventional plasma nitriding methods

In order to improve the wear resistance of titanium alloys, the potential of the plasma nitriding process with a cathode assiting discharge setup was examined. Ti6Al4V alloy was nitrided by the cathode assiting discharge nitriding (CAN) and conventional DC plasma nitriding (CPN) methods, respectively. The micro-topography, phase composition and cross-sectional microhardness distribution of two nitriding layers were studied comparatively. The sliding wear resistance of the nitriding layers was examined by a ball-on-disk test against Si3N4 balls. The results indicated that the surface roughness Ra of the CAN layer was about 1 order less than that of the CPN layer. In addition, the CAN surfaces possessed significantly greater wear resistance than the CPN layer at higher loads, and increased the wear resistance of Ti6Al4V alloy by about 2 orders due to the higher loading bearing ability, higher rate of TiN phase, greater surface microhardness and bigger microhardness improving depth. This is because the double glow discharge effect in CAN strengthened the density of the active nitrogen atoms and the nitriding efficiency. Moreover, the ion bombardment effect on the surface of the nitriding titanium alloy was reduced obviously.

Improvement in Wear and Corrosive Wear Resistance of Ti6Al4V Alloy by Double Glow Plasma Surface Alloying with W-Mo and W-Mo-N

W-Mo and W-Mo-N surface-modified layers on Ti6Al4V alloy were obtained using a double glow plasma surface alloying technique. The morphology, microstructure, and chemical composition distribution of the modified layers were analyzed by scanning electron microscope, Xray diffraction, and glow discharge optical emission spectrometry. The hardness and toughness of the modified layers were measured using a micro-hardness tester, and dynamic repeating press equipment. The wear resistance in ambient air and the corrosive wear resistance in NaCl solution were evaluated using a ball-on-disk wear tester. The results show that W-Mo and W-Mo-N surface modified layers are composed of the alloying layers which vary in composition and phase form along the depth. A microhardness gradient was observed in the modified-surface layers. The surface hardness of the W-Mo-N and W-Mo modified layers was 25.3 and 14.2 GPa, which is seven-fold and 3.9-fold harder than the Ti6Al4V substrate, respectively. W-Mo and W-Mo-N surface-modified layers significantly improved the wear and corrosion resistance of Ti6Al4V. It seems that the wear resistance of W-Mo and W-Mo-N surface-modified layers in NaCl solution is better than that in ambient air owing to the strong lubricating effect of NaCl solution and the excellent corrosion resistance of the modified layers.

Multi-pass scratch test behavior of modified layer formed during plasma nitriding

316L stainless steel and Ti6Al4V alloy were plasma nitrided at different treatment parameters, and the wear behaviors of the modified layers formed on the surface during nitriding were investigated by multi-pass scratch test. Phase structure and cross-sections of modified layers were also examined with XRD and SEM. While a single modified layer formed on surface of the 316L stainless steel, both modified and diffusion layers were observed on the surface of the Ti6Al4V alloy after nitriding. As a result, it was observed that phase structure and thickness for modified layers of 316L stainless steel and Ti6Al4V alloy, respectively, were the significant parameters for friction coefficient and wear rate. In addition, diffusion layer formed during the nitriding process caused on increase of wear resistance of Ti6Al4V alloy by supporting the modified layer on the surface.

Enhanced wear resistance of titanium surfaces by a new thermal oxidation treatment

The wear behaviour of thermal oxidation (TO)-treated as well as untreated Ti6Al4V alloy has been investigated using an Amsler tribometer in rolling–sliding motion under boundary lubrication conditions. The results show that the TO treatment can significantly enhance the wear resistance of Ti6Al4V alloy. Based on the experimental results, in conjunction with systematic analyses, the wear-reduction mechanisms involved in the TO-treated material are discussed. It was found that the significantly reduced tendency to adhesive wear and the improved wettability, which increases the effectiveness of lubrication, have contributed to the enhanced wear resistance of the TO-treated material.