Ti6Al4V Surfaces Research Articles

Microstructure and Wear Resistance of TiCp/Ti6Al4V Composite Coatings by Follow-Up Ultrasonic-Assisted Laser Additive Manufacturing

With the increasing demand for the high agility and fast response of high-level equipment in the aerospace and energy power fields, it is increasingly urgent to improve the performance of the high-temperature and wear resistance of the corresponding high-level components. Ceramic-reinforced titanium matrix composites have excellent high-temperature and wear resistance, but, in laser additive manufacturing, the primary ceramic phase is coarse, and the morphology of the ceramic phase is difficult to control, which limits their further development. In this investigation, a follow-up ultrasonic-assisted laser-additive-manufacturing method was proposed to prepare a 30 wt.% TiC/Ti6Al4V composite coating on a Ti6Al4V surface. Under the effects of ultrasonic cavitation and acoustic streaming, the content of the unmelted TiC was reduced, the dendritic primary TiC in the solidification process was broken and the distribution uniformity of the primary TiC was improved. The content of the unmelted TiC in the composite coating decreased significantly under ultrasonic action, and it was only 50.23% of that without ultrasonic action. At the same time, the average size of the dendritic primary TiC in the composite coating decreased from 61.59 μm to 27.04 μm, which was 56.10% smaller than that without ultrasonic action. The average microhardness of the composite coating reached the maximum of 656.70 HV0.2 under ultrasonic power, and it was 83.21% higher than that of the Ti6Al4V substrate, and 26.44% higher than that of the composite coating without ultrasonic power. Due to the ultrasonic-cavitation and acoustic-streaming effects, the content of the unmelted TiC obviously decreased, so that the average friction coefficient of the composite coating increased, and the wear mechanism changed from abrasive wear to adhesive wear.

Influence of Y2O3 addition on the microstructure of TiC reinforced Ti-based composite coating prepared by laser cladding

TiC reinforced Ti-based composite coatings were prepared on the Ti6Al4V surface via laser cladding with Ti6Al4V/NiCr-Cr 3 C 2 /Y 2 O 3 mixed powders. Influence of Y 2 O 3 on forming quality and microstructure of composite coatings was investigated systematically. The cracks were eliminated completely and the number of pores was drastically minimised when 2 wt% Y 2 O 3 was added. In addition, the reinforcement TiC and the matrix sloid solution β-Ti were the main precipitated phases within the coating. The addition of Y 2 O 3 inhibited the generation of Ti 2 Ni at the grain boundary, however, promoted the generation of Cr 1.93 Ti 1.07 in the coating. With the addition of Y 2 O 3 , the dendrites became largely developed and a large number of tertiary dendrites were found. Besides, a more obvious regional segregation appeared in the distribution of Ni and Cr elements in the coating with 2 wt% Y 2 O 3 . Furthermore, some nano-sized β-Ti were distributed on the surface of small TiC particles in both coatings. Combined with the theoretical analysis of the two-dimensional mismatch degree, the β-Ti and TiC interface exhibited a semi-coherent relationship. Therefore, β-Ti can nucleate with TiC as the heterogeneous nucleation matrix. In the meanwhile, there was a certain dependent growth relationship between the β-Ti and TiC. • Y 2 O 3 addition eliminated cracks completely and reduced porosity of the coating. • Y 2 O 3 addition led to sufficient growth of the developed dendrite TiC. • Irregular Ti 2 Ni disappeared and Cr 1.93 Ti 1.07 precipitated in coating with Y 2 O 3 . • Y 2 O 3 addition resulted in severe regional segregation of Cr and Ni. • β-Ti can nucleate with TiC as the heterogeneous nucleation center.

Construction of a Hierarchical Micro-/Submicro-/Nanostructured 3D-Printed Ti6Al4V Surface Feature to Promote Osteogenesis: Involvement of Sema7A through the ITGB1/FAK/ERK Signaling Pathway.

Constructing hierarchical hybrid structures is considered a facile method to improve the osseointegration of implants. Herein, a hierarchical micro-/submicro-/nanostructured surface feature of Ti6Al4V implants (3DAT group) was successfully constructed by combining the inherently formed three-dimensional (3D)-printed microscale topography, acid-etched sub-micropits, and anodized nanotubes. Compared with the classical SLA surface, the microscale topography and sub-micropits increased the three-dimensional space for the cell growth and mechanical stability of implants, while the modification of nanotubes dramatically improved the surface hydrophilicity, protein adsorption, and biomineralization. Most importantly, the 3DAT surface feature possessed excellent osteogenic performance in vitro and in vivo, with the involvement of semaphorin 7A (Sema7A) as revealed by RNA-seq through the ITGB1/FAK/ERK signaling pathway. The present study suggested that the hierarchically structured surface design strategy could accelerate the osseointegration rate of 3D-printed Ti6Al4V implants, promising personalized reconstruction of bone defects.

Comparative Investigation on Wear Properties of Composite Coatings with Varying CeO2 Contents

Several innovative mixed powders of Ti6Al4V and NiCr-Cr3C2 with different CeO2 contents (0, 1, 2, 3, and 4 wt.%) were designed, and Ti2C-reinforced CrTi4-based composite coatings were prepared on the Ti6Al4V surface via laser cladding technology. The effects of CeO2 amount on the forming quality, microstructure, hardness, and wear resistance of the composite coatings were studied. The results showed that the CeO2 amount had a significant influence on the forming quality of the composite coatings. The cracks were eliminated completely when the CeO2 content was 2 wt.%; furthermore, the lowest porosity was obtained with the addition of 3 wt.% CeO2. The primary phase constituents of the coatings were non-stoichiometric Ti2C and a β-type solid solution (CrTi4) as the reinforcement and matrix, respectively. CeO2 and a low quantity of Ce2O3 were re-precipitated at the Ti2C/CrTi4 interface and CrTi4 grain boundary in the coatings with CeO2 addition. In addition, the average hardness of the composite coatings was 1.28–1.34 times higher than that of the Ti6Al4V substrate. The wear resistance of the composite coatings was significantly higher than that of the substrate. However, both the composite coatings and the Ti6Al4V substrate exhibited a mixed-wear mode, i.e., abrasive and adhesive wear.

Coating of Nanotube Ti6Al4V Alloy with Hydroxyapatite-Chitosan-Polyvinyl Alcohol Composite

Hydroxyapatite (HAp) can be applied as a bone implant material. HAp was composited with chitosan and polyvinyl alcohol (PVA) and coated to Ti6Al4V to improve its biocompatibility. The composite HAp-chitosan-PVA coated to anodized and unanodized Ti6Al4V. Modification of the Ti6Al4V surface by anodizing was done using a 20 V voltage. The Ti6Al4V metal alloy was coated with a composite using the electrophoretic deposition (EPD) method with a voltage of 80 V. The coated composites in Ti6Al4V nanotubes and non-nanotubes were characterized by Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR), corrosion test with potentiostat, and in vitro bioactivity test with Atomic Absorption Spectroscopy (AAS). The XRD results showed a distinctive peak indicating that the composite comprises HAp and Ti. The SEM Ti6Al4V nanotube results show a pore size of 24 nm. The FTIR results show that there were functional groups of HAp, chitosan, and PVA. The corrosion rate on Ti6Al4V nanotubes without coating was greater than with coating. The In vitro bioactivity test showed that the decrease of Ca2+ Ti6Al4V nanotube concentration was faster compared to non-nanotube Ti6Al4V.

Laser hexagonal texture on surface of Ti6Al4V for the improvement of fluid spreadability and tribological properties

The joint capsule removal after artificial joint replacement surgery have led to improper lubrication, causing the pair to wear out quickly and reducing the joint lifespan. In this paper, laser processing and chemical corrosion were used to prepare a hexagonal convex texture on the surface of titanium alloy (Ti6Al4V). After etching and laser polishing, SEM images indicated the presence of secondary micro-nano textures in the grooves around the hexagonal texture, and the formation of anatase oxides on the surface, resulting in an increase of the surface energy and a very small contact angle (CA). The surfaces’ CA increases with the texture ratio, and the surface is super-hydrophilic when the texture ratio is less than 0.84. Furthermore, the effect of texture parameters and directions are studied by using UHMWPE and Ti6Al4V as friction pairs and simulated body fluid as lubricant. The COF is 0.068 with 0.84 area ratio, which is 51.4% lower than the original surface. The wear rate of UHMWPE on the textured surface decreases by 74.5% after two hours of tribological testing. In addition, high speed camera images and calculation results proved that creating grooves can promote fluid distribution on the textured surface. The surface texture on titanium alloy results in a significant COF and wear reduction, extending the service life of artificial joints.

Fabrication of micro-array structures on material surface by a piezo-driven device

Fabricating micro-array structures on material surface is a useful method to enhance the functional application of materials. In this study, for fabricating micro-array structures on material surface in a convenient operation and low cost way, a three-axes piezo-driven device with features of compact structure and easy control strategy was developed. The device mainly consisted of a two-degrees of freedom piezo-driven positioning stage for controlling the sample movement along x and y axes, an indentation unit for generating the indent, and a frame. Micro-array indent structures were attempted to be fabricated on Ti6Al4V and Al1015 material surfaces, and experimental results showed that regular micro-array indent structures were successfully produced. Furthermore, by tuning the time-sequential control waveform of three piezoelectric stacks (PESs), the size, depth, and interval between two adjacent indents can be easily changed, forming various micro-array indent structures.

Enhancing the hydrophobicity of Ti–6Al–4V through multi-level electrical discharge texturing

ABSTRACT In the current work, single and multi-level micro-texturing on Ti–6Al–4V surfaces was performed through electrical discharge micromachining. The wetting properties of the single-level features obtained through EDMM have been studied, which revealed a higher water contact angle (CA) of ∼110° with respect to an untextured surface (water CA ∼38°). The concept of dimples overlapping (% of overlap between adjacent dimples) has been adopted to propose a novel technique for the simultaneous machining of multiple micro-features through a simpler cylindrical tool electrode, which otherwise necessitates multi-step fabrication or preformed tools. Adopting the proposed concept, multi-level textures consisting of micro-dimples surrounded by micro-pillars were machined on the Ti–6Al–4V surface. With multi-level textures, the water CA increases significantly compared to the untextured surfaces. The maximum water CA ∼ 104.2° was obtained with a 300 µm diameter tool and 25% dimple overlap, thereby rendering the surface hydrophobic.

Facile, fluorine-free fabrication of bacterial antifouling titanium alloy Ti6Al4V surfaces for surgically implanted devices

The demand for hip arthroplasties and other joint replacement orthopedic surgeries is on the rise. Combined with the emergence of antibiotic drug resistant strains of pathogenic bacteria, there is an increasing need for the development of bacterial antifouling surface treatment technologies which can be applied to titanium alloy medical devices. Herein is reported the development of a durable, fluorine-free superhydrophobic surface treatment for Ti6Al4V, fabricated through facile means without the use of HF or fluoropolymers, utilizing safe reagents under mild reaction conditions. Nanoscale texturing was created with an alkaline hydrothermal process. An alkyl surface chemistry was imparted via the deposition of an alkyl self-assembled monolayer to achieve superhydrophobic, non-wetting behavior. This superhydrophobic surface is capable of imposing 1.55 ± 0.13 and 1.72 ± 0.23 log10 reductions in the adherent populations of Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Pseudomonas aeruginosa (P. aeruginosa) bacteria, respectively. This represents a safe route to a significant potential mitigation in the costs and dangers arising from medical device associated infections.

CARD2: Demonstrating the Combined Effects Of Shear And Surface Roughness On Thrombosis On Titanium Alloy

Study: Titanium alloys used as blood contacting materials in a variety of artificial organs are often roughened on the nano- to micrometer scale during manufacture, requiring extensive and sometimes tedious polishing. However, there is no consensus of the tolerable limits of roughness. This study investigated the combined effects of supraphysiological shear and surface roughness on platelet deposition to provide guidelines for manufacturing. Methods: Microfluidic devices with roughened Ti6Al4V surfaces were used to create shear-controlled, clinically relevant micro-scale environments to quantify platelet deposition and aggregation. Ti6Al4V surfaces were roughened using diamond and glass abrasive techniques. A fresh human blood analog comprised of hemoglobin-depleted red blood cells, for optical clarity, and platelet-rich plasma with mepacrine-labeled platelets was perfused through the microdevices at three shear rates: 1000 s-1, 2000 s-1 and 5500 s-1. Four surface roughness levels were used: mirror finish, Ra 0.3 µm (data not shown here), Ra 0.8 µm and Ra 2.1 µm. Platelet deposition was visualized using fluorescent microscopy. Adherent platelet properties such as mean fluorescence intensity, aggregate area and number were quantified from processed microscopy images. Results: For all three roughnesses < 2.1 µm Ra, platelet adhesion demonstrated sustained growth in confluent monolayers at 1000 s-1 (figs 1a, 2a), formed stable, growing platelet aggregates at 2000 s-1 (fig 1b, 2b); and formed round, fibrous platelet aggregates at 5500 s-1 with increasing intensity and density with time (figs 1c, 2c). Embolization was observed with all surfaces after an initial increase in aggregate intensity (yellow shading, fig 2c). On the Ra 2.1 µm surface, platelet aggregates formed at all three shear rates, indicative of higher shear rates and gradients as a result of the roughness. Conclusions: These findings demonstrate that surface roughness and supraphysiologic shear act synergistically to promote platelet adhesion and thromboembolism. These results suggest a threshold of surface roughness, for the shear rates studied, between 0.8 and 2.1 µm Ra that provokes development of fibrous aggregates that are unstable and embolize. Ongoing work is investigating a wider combination of roughness textures, shear rate, and material chemistry. Figure 1. Platelet adhesion on Ti6Al4V (a) monolayer at 1000s-1, mirror finish), (b) aggregates 2000s-1, Ra 0.8 µm, and (c) fibrous aggregates at 5500s-1. (Scale bar length is 100 µm) Figure 2. Mean fluorescence intensity of aggregates versus time (900 seconds). Error bars represent standard error of the mean at each timepoint.

SWOT Analysis of Electrical Discharge Coatings: A Case Study of Copper Coating on Titanium Alloy

The electrical discharge machine (EDM) has been one of the most widely used non-traditional machines in recent decades, primarily used for machining hard materials into various complex shapes and different sizes and, nowadays, used for surface modifications/hard coatings. In this study, the SWOT (strengths, weaknesses, opportunities and threats) of electrical discharge coating was analyzed by conducting a case study. For the purpose of the case study, copper was deposited on the titanium alloy surface (Ti6Al4V). Three electrodes of different copper alloy materials, viz., brass, bronze and copper, were selected for coating the Ti6Al4V surface. Input parameters such as current, pulse-on, pulse-off, flushing pressure and the electrode material were optimized to develop a uniform coating. Experiments were designed according to the L18 orthogonal array, and among them, the samples that showed proper coating, as seen with the naked eye, were selected for morphological and elemental analyses by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX. Further, the output responses, viz., the material deposition rate (MDR), electrode wear rate (EWR), surface roughness (SR), elemental data (copper (Cu) and zinc (Zn)) and coating thickness (CT), were considered for the optimization of coatings. Implementing the Technique for Order Performance by Similarity to Ideal Solution, copper coating with a thickness of 20.43 µm, developed with an MDR with input parameters of 20 A current, 600 µs pulse-on, 120 µs pulse-off, 0.5 bar flushing pressure and the brass electrode, was selected as the optimum coating. The most influential parameters in this coating process were the current and pulse-on time. In this study, a SWOT table was developed to depict the strengths, weaknesses, opportunities and threats of electrical discharge coating.

Laser gas oxidising of Ti–6Al–4V surface: experimental and numerical investigation

ABSTRACT The laser gas oxidising of Ti–6Al–4V surface was studied. Confocal laser scanning microscopy techniques were used to investigate its two- and three-dimensional surface topographies. Gas flow behaviour was simulated to define the minimum O2 concentration required for Ti–6Al–4V to self-sustain combustion. To understand the flow behaviour of the Ti–6Al–4V fluid, a high-speed camera monitored the evolution of the Ti–6Al–4V fluid, and the flow behaviour was simulated. Experimental and simulation results show that Ti–6Al–4V can self-sustain combustion with a high O2 to Ar gas flow ratio, and the oxidising layer is rough with macroscopic cracks, while a low O2 to Ar gas flow ratio results in a smooth oxidising layer without cracks. Ti–6Al–4V can self-sustain combustion when the O2 concentration exceeds 65%. Furthermore, the laser molten pool and self-sustaining combustion zone mix and flow together, and a large self-sustaining combustion zone leads to a low convection velocity.

Moderated crevice corrosion susceptibility of Ti6Al4V implant material due to albumin-corrosion interaction

● Albumin adsorption was regulated by localized corrosion. ● Non-uniform albumin adsorption inhibited crevice corrosion of Ti6Al4V. ● Mechanism of albumin-corrosion interaction was disclosed. Localized corrosion of metallic biomaterials is a concerning problem for implant applications. In the present work, the interaction between localized corrosion of Ti6Al4V implant material and adsorption of bovine serum albumin (BSA) was investigated by electrochemical tests, surface morphological and compositional analysis. The artificial crevice was set up on the Ti6Al4V surface to simulate the crevice corrosion of metallic implants. The results show that the BSA adsorption is regulated by the heterogeneous metallic ion release resulted from the crevice corrosion. The negatively charged BSA prefers to aggregate at the interior of artificial crevice due to electrostatic interaction with the concentrated metallic cations in the crevice. In return, the non-uniform BSA adsorption can decrease the crevice corrosion susceptibility of the Ti6Al4V implant material, even though the presence of BSA accelerates the dissolution of passive films. For the Ti6Al4V alloys with artificial crevice, stable localized corrosion occurs after 96 h of immersion in the PBS free of BSA while no stable localized corrosion can be determined in the presence of 4% BSA. It is deduced that the presence of BSA can reduce the surface potential discrepancy between the crevice interior and the crevice exterior. The disclosed mechanism of albumin-corrosion interaction is vital to the localized corrosion control of metallic implants in clinical use.

DLC coating over pre-oxidized and textured Ti6Al4V for superior adhesion and tribo-performance of hip implant

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.

Water versus Oil Lubrication of Laser-Textured Ti6Al4V Alloy upon Addition of MoS2 Nanotubes for Green Tribology

A Nd-YAG laser was used for texturing the Ti6Al4V surface with dimples of diameter 50 and 100 µm and centre-to-centre distance 100, 200 and 400 µm, defining the surface texture density. The tribological evaluation was conducted to analyse and compare the behaviour of un-textured and laser-textured samples under water in comparison to oil (PAO6) lubrication without and with the addition of MoS2 nanotubes into the lubricant. MoS2 nanotubes had a positive effect on friction in both media for laser-textured Ti6Al4V. Evaluation of friction and wear in water and PAO6 showed a comparable tribological response in water to oil for specific laser-textured configurations, proving the novel concept of green tribology for laser texturing in combination with MoS2 nanotubes/water lubrication.

Sliding Corrosion Fatigue of Metallic Joint Implants: A Comparative Study of CoCrMo and Ti6Al4V in Simulated Synovial Environments

Mechanical contact in a corrosive synovial environment leads to progressive surface damage at the modular interface of the joint implants. The wear debris and corrosion products degrade the synovial fluids and change the lubrication mechanisms at the joints. Consequently, the unstable joint lubrication and corrosion products will further induce the undesirable performance of the joint implants. In this study, the two major joint materials, CoCrMo and Ti6Al4V, were tested during the course of reciprocal sliding contact in simulated synovial liquids. Open circuit potential and coefficient of friction were monitored to describe electrochemical and mechanical responses. Potentiostatic test results illustrated electrochemical damage on both surfaces that modified oxidation chemistry on both surfaces. However, more significant modification of the CoCrMo surface was detected during wear in the simulated joint liquid. Even with a reduced coefficient of friction on the CoCrMo surface in sodium lactate environments, fretting current density drastically increased in corrosive sodium lactate with pH 2. However, the test results from the Ti6Al4V surface presented less coefficient of friction values, and moderate change in fretting current. Therefore, the experimental study concluded that the biocompatibility of Ti6Al4V is superior to that of CoCrMo in the combined effect of mechanical loadings and an electrochemical environment.

The effects of simultaneous laser nitriding and texturing on surface hardness and tribological properties of Ti6Al4V

The low hardness and poor tribological properties of titanium and its alloys significantly hinder their practical engineering applications, so surface nitriding or texturing is widely employed to improve the surface performances. However, previous studies mainly used the single method (surface nitriding or texturing), and simultaneous nitriding and texturing are rarely reported. Therefore, their combined effects on the surface mechanical and tribological properties are rarely investigated as well. In this study, by nanosecond pulse laser irradiation in nitrogen atmosphere, simultaneous nitriding and texturing of the Ti6Al4V surface were achieved. The effects of laser parameters including laser power, laser overlap rate, and number of scanning cycles, on the surface hardness and tribological properties of laser irradiated surfaces were comparatively studied. The experimental results showed that after simultaneous laser nitriding and texturing, the surface hardness of Ti6Al4V surface was increased by 50%~95%, and the coefficient of friction (COF) was reduced by 70%~80%. Furthermore, the laser processed surfaces obtained under various irradiation parameters presented quite different scratching characteristics, and the corresponding deformation mechanisms during scratching were analyzed. This study provides a simple and effective method by simultaneous laser nitriding and texturing for improving the surface properties of Ti6Al4V, which would be meaningful for its practical engineering applications.

Effect of processing parameters on Tribo-mechanical properties of developed Nano-Composite Coating of h-BN & B4C on Ti6Al4V Substrate by Laser Surface Alloying

ABSTRACT This work deals with the development of hard coating of h-BN + B4C mixed powder on the Ti6Al4V surface through laser cladding under different processing conditions of laser power and scanning speed. A hard multicomponent nanocomposite coating has constituent phases of TiB2-TiC-TiCN-h-BN-B4C-C3N4-B13C2. This composite coating has been synthesised by laser cladding of pre-placed h-BN and B4C mixed powders on the Ti6Al4V substrate. In this investigation, the average thickness of the coating has been taken up to 50 µm with a maximum microhardness of 2814 HV0.05. The developed coatings have been characterised by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy and hardness and wear test, and a correlation is established between the microstructure and the hardness value. TEM analysis reveals the formation of an intricate nanostructure in the coatings during laser cladding. The results indicate the significant improvement in the hardness and tribological characteristics of the coated Ti6Al4V substrate. Improvement in the hardness and wear resistance is attributed to the presence of nanocrystalline phases of C3N4, B13C2 and TiCN, which are formed due to the addition of titanium boride and titanium carbide elements. The present investigation provides valuable insights into the development of nanocomposite coating on the metal surfaces.

Tribological Performance of Crosshatch Pattern Textured and Heat Treated Dual Engineered Ti6Al4V Surface under Bio-Lubricated Line Contact Configuration

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 TiO2 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 TiO2 phase formation along with the presence of anatase TiO2, Al2O3 and Ti3O 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.

Bio-Tribology and Corrosion Behaviors of a Si- and N-Incorporated Diamond-like Carbon Film: A New Class of Protective Film for Ti6Al4V Artificial Implants.

Ti6Al4V artificial implants are increasingly demanded for addressing human dysfunction caused by an aging population and major diseases. However, they are restricted due to the release of vanadium and aluminum ions in the process of corrosion and wear. This work is aimed to provide a protective film for Ti6Al4V artificial implants, and then, a Si-incorporated diamond-like carbon (Si-DLC) film and Si- and N-incorporated DLC (SiN-DLC) film were deposited on the surface of Ti6Al4V by plasma-enhanced chemical vapor deposition. Results suggest that the thickness of the as-deposited DLC film is approximately 2 μm, and the SiN-DLC film shows the lowest surface roughness (53.0 ± 3.6 nm) compared with the Ti6Al4V and DLC films. The above DLC film possesses high mechanical properties compared with Ti6Al4V, and the SiN-DLC film shows the best resistance to plastic deformation. In addition, the DLC film exhibits high adhesive strength (>13 N) with Ti6Al4V, which is a prerequisite for service in liquid environments. Whether in SBF solution or SBF + BSA solution, the friction coefficient and wear rate of the above DLC film are much lower than those of Ti6Al4V, and the SiN-DLC film displays the optimal tribological properties (0.072 and 1.82 × 10-7 mm3·N-1·m-1, respectively). Moreover, Si-DLC and SiN-DLC films possess similar corrosion resistance but are far better than Ti6Al4V. Cytotoxicity test results show that the SiN-DLC film can significantly improve cell viability and promote cell proliferation to a certain extent. Consequently, the SiN-DLC film is a protective film with more potential for artificial implants.