Titanium Alloy Substrate Research Articles

A microabrasion wear study of nitrided α-Ti and β-TiNb PVD metallic thin films, pre-deposited onto titanium alloy substrates

In this paper, we study the structure, mechanical properties and abrasion resistance of two triode-plasma nitrided (TPN) titanium alloys, pre-coated with metallic α-Ti or β-TiNb layers deposited by physical vapour deposition (PVD). The chosen alloys were Ti-6Al-4V and Ti-4Al-10V-22Mo, which are predominantly alpha- and beta-phased, respectively – each presenting different challenges, in terms of their nitriding response. Although duplex nitriding + PVD coating is now quite widely employed on steels (and increasingly on titanium alloys) to improve load-bearing capacity and wear resistance, the use of PVD coatings prior to diffusion treatment to control surface roughness – and, in the case of Ti-alloys particularly, to optimise their ‘challenging’ diffusion kinetics has received little or no attention so far. The TPN process enables diffusion treatments to be carried out at 700 °C – which is lower than the beta-transus temperature of Ti (and of most Ti alloys). Optical microscopy, scanning electron microscopy, atomic force microscopy, X-ray diffraction, nanoindentation, and surface profilometry were used to characterize the nitrided and coated/nitrided samples. It was found that the nitrogen concentration and surface hardness for all samples was significantly increased, and that the surface roughness values significantly increased for uncoated Ti alloy substrates after TPN treatment – due to intense, grain orientation-dependent plasma etching effects. However, our novel approach of PVD pre-deposition of a nanostructured metallic coating prior to nitriding reduces surface roughening effects quite dramatically. The micro-abrasion resistance of Ti- and TiNb-coated Ti-6Al-4V substrates was significantly enhanced after nitriding treatment; on the other hand, similar improvements were not found for the metastable-beta Ti-4Al-10V-22Mo substrates – due to the different nitriding behaviour of the pre-deposited PVD surface layers. The “sputter removal” rates for the metallic coatings were high, but all coatings survived in part until the end of the nitriding process.

A heterogeneous TiO2/SrTiO3 coating on titanium alloy with excellent photocatalytic antibacterial, osteogenesis and tribocorrosion properties

In order to meet the clinical demand for titanium implants, the heterogeneous structure of TiO2/SrTiO3 coating was in situ fabricated on the surface of Ti6Al4V alloy by a facile way. The well-designed Ti6Al4V/TiO2/SrTiO3 composite exhibits a strong photocatalytic antibacterial efficiency against Escherichia coli (E. coli). The suitable energy band structure, improved light absorption and enhanced carrier separation of TiO2/SrTiO3 heterojunction facilitate the generation of bactericidal reactive oxygen species (ROS) under the illumination of UV light. The biocompatible SrTiO3 component effectively favors the adhesion, proliferation and osteogenic differentiation of human bone mesenchymal stromal cells (hBMSCs) in vitro. It is worth noting that the dense oxide coating provides a reliable barrier against tribocorrosion for the titanium alloy substrate, and the wear volume loss of the Ti6Al4V/TiO2/SrTiO3 reduces to 1/8 of that of the bare Ti6Al4V alloy in simulated body fluid. In this work, a multifunctional coating system was proposed to provide inspiration for the development of novel artificial bone implant materials.

Enhancement of Tensile Plastic Stability in Ti-Based Metallic Glass Composite with Substrate of Titanium Alloy

Enhancement of Tensile Plastic Stability in Ti-Based Metallic Glass Composite with Substrate of Titanium Alloy

Исследование формирования многослойного функционального композиционного материала с градиентной структурой “нитрид титана – титан – основа”

Composite materials based on aluminum alloy D16 and titanium alloy Ti – 10 Nb – 3 Mo with surface layers of titanium, titanium nitride and a multilayer composition consisting of alternating layers of titanium and titanium nitride for biomedical and tribological purposes by high-vacuum magnetron sputtering at direct current in inert and reactive media were obtained. The structure and phase composition were studied using SEM, AES, X-ray diffractometry and probe microscopy. The rate of formation of a surface layer of pure titanium on a substrate made of alloy D16 was 185 nm/min, and the rate of synthesis of a surface layer of titanium in a reactive medium was significantly slowed down and was no more than 70 nm/min due to nitrogen poisoning of the target. The transition layer formed as a result of the synthesis of a titanium layer on an aluminum alloy substrate had a thickness of about 600 nm, which is significantly greater than the thickness of the transition layer when titanium is obtained on a titanium alloy substrate. During the formation of titanium nitride on a titanium sublayer, a greater concentration of nitrogen was observed than during the formation of nitride on a substrate with the same deposition parameters. The intensity of the TiN phase reflexes in the X-ray diffractometry diagrams were weakly expressed in all variants of the applied ratios of working gases Ar/N2 during spraying. The speed of the titanium sublayer makes it possible to form a greater thickness of the titanium nitride layer than without the sublayer, as well as a more nitrogen–saturated surface layer - up to 38% by weight.

Fabrication of hierarchical structures on titanium alloy surfaces by nanosecond laser for wettability modification

Titanium alloy is widely used in aerospace industry due to its low density, high specific strength and high-temperature resistance. To broaden its application scope, superhydrophobicity of titanium alloy is required in certain situations, such as self-cleaning and anti-icing. In this study, direct nanosecond laser ablation was applied to fabricate distinct pits with hierarchical structures on titanium alloy substrates, followed with chemical treatment to modify the wettability of the surfaces. The effects of laser processing parameters on surface morphology and surface wettability were explored systematically. Results show that, increasing the number of scans improves the depth of the pits and the accumulation of the micro-nano structures around the craters. The scanning space mainly affects the overlap of the heat affected zones, and hence the distribution of the laser-induced hierarchical structures. The wettability of a laser processed surface is determined by both surface roughness and surface chemistry, and the solid fraction of the rough surface is regulated by the number of scans as well as the scanning space. Moreover, superhydrophobic surfaces are obtained on the laser processed titanium alloy after chemical treatment, which has great potential for the as-mentioned applications.

Preparation and tribological performance of CrAlTiCN coatings on 316L and TC4 substrates in sea water

ABSTRACT The CrAlTiCN coatings have been prepared by multi-arc ion plating technology on 316L and TC4 substrates, respectively. The microstructure of the prepared CrAlTiCN coatings has been characterised by X-ray diffraction, scanning electron microscopy and energy disperse spectroscopy, respectively. The mechanical properties, electrochemical corrosion behaviour and tribological performance of the prepared coatings were tested by microhardness tester, scratch tester, electrochemical workstation, and friction and wear tester, respectively. Results show that all the coatings includes many nanocrystalline and presents compact structure, weak columnar crystal structure and refine grain. The prepared coating on TC4 titanium alloy substrate presents a better tribological performance than that on 316L stainless steel substrate.

The damage effect of weld seam and groove area of titanium alloy with ceramic laser resistant coating

In order to explore the effect of weld area and groove structure on the damage effect of laser irradiation on titanium alloy and ceramic coating, the experiment of continuous laser irradiation on welding seam and groove area of titanium alloy was studied, while the surfaces of the specimens were coated with or without anti-laser ceramic material. The following conclusions were obtained: the ceramic coating can protect the titanium alloy substrate from the damage of high power laser effectively; the laser resistance of ceramic coating on the welding seam area is weakened, but it still protects the titanium alloy effectively; the damage of laser on the edge and the corner structure of titanium alloy with groove structure is aggravated with the increasing of laser power density, and under the same laser density, the damage inside the groove is less than that outside, while that of corner is less than edge. Micromorphology results show that the ceramic coating undergoes a series of physical and chemical changes and phase transformation to absorb a large amount of thermal energy converted from luminous energy, which has a protective effect on the titanium alloy.

Titanium Nitride Coated Implant Abutments: From Technical Aspects And Soft tissue Biocompatibility to Clinical Applications. A Literature Review.

To review the most up to date scientific evidence concerning the technical implications, soft tissue biocompatibility, and clinical applications derived from the use of titanium nitride hard thin film coatings on titanium alloy implant abutments. A review was performed to answer the following focused question: "What is the clinical reliability of nitride coated titanium alloy abutments?". A MEDLINE search between 1980 and 2021 was performed for investigations pertaining to the clinical use of nitride coated titanium alloy implant abutments (TiN) in case reports, case series, and short- and long-term non/randomized controlled clinical trials. Literature analysis led to addition evaluation of research related to the technical and biological aspects, as well as the physicochemical characteristics of TiN hard thin film coatings and their impact on titanium abutment biocompatibility, mechanical properties, macroscopic surface topography, and optical properties. Therefore, preclinical data from biomechanical and in vitro investigations were also considered as inclusion criteria. The limited number of clinical investigations published made a systematic review and meta-analysis not possible, therefore a narrative review was conducted. TiN coatings have been applied to dental materials and instruments to improve their clinical longevity. Implant abutments are coated with titanium nitride to mask the titanium oxide surface and enhance its surface characteristics providing the TiN abutment surface with a low friction coefficient and a very high chemical inertness. TiN coating is suggested to reduce early bacterial colonization and biofilm formation and enhance fibroblast cell proliferation, attachment and adhesion when compared to Ti controls. Additionally, studies indicate that hard thin film coatings enhance the mechanical properties (hardness and wear resistance) of titanium alloy and appears as a yellow color when deposited on the titanium alloy substrate. To date, clinical investigations show that nitride coated titanium abutments provide promising short-term clinical outcomes. Published research on nitride-coated abutments is still limited, however, the available biomedical research, mechanical engineering tests, in vitro investigations, and short-term clinical trials have, to date, reported promising mechanical, biological, and esthetic outcomes.

Surface characterization of TiO2 nanotube arrays produced on Ti6Al4V alloy by anodic oxidation

A highly well-ordered TiO2 (titanium dioxide) nanotube arrays were prepared at different voltages (20 V, 30 V, 40 V, 50 V, 60 V, 80 V and 100 V) for 60 min on Ti6Al4V (titanium alloy) substrate in the ammonium fluoride-containing ethylene glycol electrolyte by a DC (direct current) power supply through AO (anodic oxidation) technique. The anatase-based TiO2 phases were observed at post-heat treatment although the titanium phase was obtained on TiO2 nanotube surfaces at post-production AO technique. Up to 40 V, the nanotube structures were uniformly distributed and the surface roughness increased. The roughness and thickness of the nanotube surfaces were measured as 7.57 nm – 47.08 nm and 0.18 μm – 0.83 μm, respectively. The nanotube array surfaces indicated hydrophobic properties compared to uncoated titanium surface. The hardness and elastic modulus of plain titanium alloy and TiO2 nanotube surfaces were investigated under a Berkovich indenter by a nanoindentation test device. The elastic modulus values of TiO2 nanotube surfaces were close to bone structure with respect to plain Ti6Al4V substrate. Moreover, hardness values of nanotube surfaces were measured between ~203.7 MPa and ~ 932.2 MPa. The adhesion properties such as critical load of the nanotube surfaces were investigated by micro scratch tester. Adhesion strengths of the nanotube surface were obtained between ~2.2 N and ~4.6 N.

Effect of titanium dioxide intermediate layer on scratch and corrosion resistance of sol-gel-derived HA coating applied on Ti-6Al-4V substrate.

Modification of dental and orthopedic implants' surface by coating themwith bioactive materials, such as hydroxyapatite (HA), diminishes the implants' fixation time. Appropriate adhesion to the substrate and stability in biological conditions are essential requirements for these coatings. In this study, sol-gel-derived HA coating was applied on the Ti-6Al-4V substrate, which is a high-performance alloy for manufacturing bone implants. Also, titanium dioxide (TiO2) which was prepared by the sol-gel method was used as an intermediate layer between HA coating and the substrate. The nano-scratch and potentiodynamic polarization tests were employed to evaluate the effectiveness of TiO2 intermediate layer on improving the scratch resistance, as an indicator of coating adhesion strength, and the corrosion resistance of the coated samples. The quality of the coating bonded to the substrate was studied by cross-sectional SEM images. The XRD tests indicated that HA and TiO2 coatings were formed with predetermined phase compositions. The biocompatibility of sol-gel-derived HA coating was established by simulated body fluid (SBF) immersion tests. The SEM images, along with the results of electrochemical and nano-scratch tests, proved the significant effect of a TiO2 intermediate layer on improving the scratch resistance and stability of HA coating on titanium alloy substrate.

Pulsed laser cleaning of resin-based surface coating on the titanium alloy substrate

In this work, the laser cleaning process of the surface coating for the Ti-6Al-4V titanium alloy was investigated using a pulsed laser, including cleaning time, laser power, and scanning speed. Meanwhile, the corresponding mechanism of laser cleaning was analyzed using the surface morphology, element content change, coating fracture cross section, and phase change. Results demonstrated that the quality of the coating removed by laser cleaning increased first and then decreased with the increase in the three key process parameters of laser cleaning time, laser power, and scanning speed, respectively. The superior laser cleaning efficiency was achieved when the laser power was 15 W, the cleaning time was 8, and the scanning speed was 400 mm/s. It is concluded that the removal of the titanium alloy surface coating is the result of the coupling of the cleaning mechanisms such as ablation and thermal expansion.

Study on corrosion resistance of TC4 titanium alloy micro‐arc oxidation/(PTFE + graphite) composite coating

AbstractMicro‐arc oxidation (MAO) coating was prepared on the surface of TC4 titanium alloy and sealed with (polytetrafluoroethylene [PTFE] + graphite) emulsion to obtain MAO/(PTFE + graphite) composite coating. The surface morphology and phase composition of the MAO coating were studied by scanning electron microscope (SEM) and X‐ray diffractometer (XRD). The corrosion resistance of the coating was studied by the potentiodynamic polarization curve and the scanning Kelvin probe (SKP) micro‐area voltage. The results show that the TiO2 ceramic oxide coating formed on the surface of the titanium alloy substrate has the characteristics of porous structure, which will become a channel for corrosive media to enter the coating and accelerate the corrosion of the MAO coating. However, the MAO/(PTFE + graphite) composite coating can prevent corrosive media from entering the coating and improve the corrosion resistance of the composite coating. The corrosion potential increased from 0.146 V to 0.241 V, the corrosion current density decreased from 4.31 × 10–7 A/cm2 to 7.92 × 10–8 A/cm2, and the self‐corrosion current dropped to one fifth of the MAO coating. In addition, the charge transfer resistance has also increased from 5.305 × 104Ω·cm2 to 2.493 × 105Ω·cm2.

Strengthening mechanism of Y2O3 nanoparticles on microstructure and mechanical properties of the laser additive manufacturing joint for large thickness TC4 titanium alloy

The laser additive manufacturing technology with laser melting deposition as the core technology presents superior efficient connectivity of titanium alloy components with large thickness and complex structure in the aerospace field. The content of nanoparticles affects the microstructure and properties of TC4 large thickness titanium alloy joint when it is manufactured with laser additive manufacturing. A pair of TC4 titanium alloy test plates with a thickness of 80 mm were connected by laser additive manufacturing technology with the mixed powder as filler material which was produced by adding different content Y2O3 nanoparticles into TC4 powder. Optical microscopy, scanning electron microscopy, micro-hardness test and tensile test were conducted to study the effect of Y2O3 content on the microstructure and mechanical properties of the TC4 titanium alloy joint. The strengthening mechanism and agglomeration weakening mechanism of Y2O3 nanoparticles on microstructure and mechanical properties was investigated based on the experimental results. It was found that the addition of more Y2O3 nanoparticles resulted in partial powder agglomeration and degradation of tensile strength. The results indicated that the columnar grains in the middle of the deposition zone with Y2O3 nanoparticles were finer than those without Y2O3 nanoparticles. The joint fracture mode gradually changed from plastic fracture to quasi-cleavage fracture with the increase of Y2O3 content. The average hardness values of the joint with various Y2O3 contents are all higher than that of the TC4 titanium alloy substrate.

Field emission behavior of titanium alloy nanosheets

In this study, the field emission behavior of titanium alloy nanosheets is observed for the first time. The titanium alloy nanosheets on titanium alloy substrate display low turn-on and threshold field, whose values are 3.02 V/μm and 4.51 V/μm, respectively. In addition, the titanium alloy nanosheets exhibit excellent emission stability over a period time of 1200 min. Such good field emission properties can be attributed to the relatively low work function and abundant tip structures for electrons emitting. These results show the potential of titanium alloy nanosheets as a cathode material in field-emission devices.

CОЗДАНИЕ МЕХАНИЧЕСКИМ ЛЕГИРОВАНИЕМ Ti-Al ПОКРЫТИЙ С ДОБАВКАМИ КОБАЛЬТА И НИКЕЛЯ

The work is dedicated to the formation of TiAl titanium aluminide coatings with cobalt and nickel additives by means of the method of mechanical alloying with the further maturing at high temperature in vacuum. Coatings were applied with the use of the ball mill of the planetary type upon VT1-0 titanium alloy substrate which were placed in the mill cup filled with metal powders. There is studied growth kinetics, a coating thickness is measured. A specific rate of metal powder sedimentation upon a titanium substrate makes from 4.6 to 11 g/(min•m2). Deposited layers have a mean thickness 70-180 mkm. There are studied thoroughly compositions and microstructure of mechanical-alloyed coatings. For that there were used methods of X-ray diffractometry and raster electronic microscopy. It is defined that the inner structure of coatings is heterogeneous. After deposited layer thermal treatment a metal interpenetration takes place first aluminum into particles of titanium, cobalt or nickel. Coatings are composite material the basis of which makes aluminide of RiAl titanium, and as inclusions there are other inter-metallides, titanium, cobalt or nickel and also aluminum oxide. Mean values of micro-hardness of coatings obtained are 1.2 - 3.4 times higher than of titanium substrate. The highest values of micro-hardness (more than 6.5 GΠa) after thermal treatment in vacuum are observed in TiAl-5%Co and TiAl-10%Co coatings. Micro-hardness of VT1-0 titanium alloy after annealing, vice versa, decreases by 1.3 times.

Enhancing SERS detection on a biocompatible metallic substrate for diabetes diagnosing.

A method to realize surface-enhanced Raman spectroscopy (SERS) at a titanium alloy substrate for glucose detection has been experimentally demonstrated. A silver-coated laser-induced periodic surface structure (LIPSS) was prepared via femtosecond laser micro-processing. The low detection limit of glucose is 10-7mol/L and, a good linear relationship between the glucose concentration and Raman intensity is found in the range between 1×10-7 and 1×10-3mol/L. Moreover, we investigate SERS detection for glucose sensing in human urine samples, while the results are in good agreement with clinical results. The Letter provides a facile method for producing a structure-controlled SERS substrate to realize glucose detection, which is promising for long-term in vivo diagnostics.

Development of Microstructure and Properties of Multicomponent MoS2/HA/PEEK Coatings on a Titanium Alloy Via Electrophoretic Deposition and Heat Treatment

In this study, molybdenum disulfide nanosheets, bioactive hydroxyapatite particles of two types in various amounts, and PEEK 704 microparticles were electrophoretically co-deposited to fabricate multicomponent coatings on Ti-13Nb-13Zr alloy substrates. A mixture of pure ethanol and cationic chitosan polyelectrolyte was used as a dispersion medium. The kinetics and mechanism of deposition were investigated. The kinetics depended significantly on the suspension’s chemical composition and the voltage used during EPD. Cationic chitosan provided the steric stabilization of the suspension and enabled cathodic co-deposition of all coating components. Green macroscopically homogeneous coatings were subsequently heat treated. The treatment densified the coatings and caused the formation of a stable semi-crystalline PEEK matrix consisting of spherulites. The MoS2 nanosheet packages, separate HA particles and their agglomerates were embedded in the coating matrix. After heat treatment, both types of coatings, differing in HA type, were characterized by excellent adhesion to the substrate and moderate scratch resistance. During surface topography investigation, it was found that coatings containing smaller HA nanoparticles had a slightly lower surface roughness. The coatings raised the corrosion resistance of the titanium alloy substrate in Ringer’s solution. The possibility of the electrophoretic co-deposition of various ceramic and PEEK particles to develop multicomponent coatings, as well as their contribution to enhancing titanium alloy surface properties, represents an important input in further developing superior bioactive titanium implants.

MICROSTRUCTURE EVOLUTION OF IN SITU COMPOSITE COATINGS FABRICATED BY LASER CLADDING WITH DIFFERENT POWERS

In situ reaction-synthesized TiB-reinforced titanium-matrix composite coatings were fabricated using the rapid, non-equilibrium synthesis technique of laser cladding. The Ti and B mixture was the original powders, while the Ti-matrix composite coatings enhanced with TiB were treated on a Ti-6Al-4V surface with different laser scan powers of 2.5 kW, 3.0 kW and 3.5 kW. The phase composition, microstructure evaluation, and microhardness of the cladding coatings were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and microhardness. The composite coatings mainly consist of black fishbone-shaped -Ti dendrites and white needle-like TiB phases. The microstructure evolution from the top to the bottom of the coatings was investigated. The TiB reinforcement dispersed homogeneously in the composite coatings and a fine microstructure was obtained in a sample fabricated with a laser power of 3.0 kW. The microhardness of the cladding coatings fabricated by different powders was over 2-fold greater than that of the Ti-6Al-4V titanium alloy substrate and achieved a maximum average of 792.2 HV with the laser power of 3.0 kW. The microstructures and properties of the coatings were changed by adjusting of the laser cladding power. The effects of the laser scan power on the microstructure, hardness and friction and wear properties of the laser cladding coatings were investigated and discussed.

MICROSTRUCTURE EVOLUTION OF IN SITU COMPOSITE COATINGS FABRICATED BY LASER CLADDING WITH DIFFERENT POWERS

In situ reaction-synthesized TiB-reinforced titanium-matrix composite coatings were fabricated using the rapid, non-equilibrium synthesis technique of laser cladding. The Ti and B mixture was the original powders, while the Ti-matrix composite coatings enhanced with TiB were treated on a Ti-6Al-4V surface with different laser scan powers of 2.5 kW, 3.0 kW and 3.5 kW. The phase composition, microstructure evaluation, and microhardness of the cladding coatings were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and microhardness. The composite coatings mainly consist of black fishbone-shaped -Ti dendrites and white needle-like TiB phases. The microstructure evolution from the top to the bottom of the coatings was investigated. The TiB reinforcement dispersed homogeneously in the composite coatings and a fine microstructure was obtained in a sample fabricated with a laser power of 3.0 kW. The microhardness of the cladding coatings fabricated by different powders was over 2-fold greater than that of the Ti-6Al-4V titanium alloy substrate and achieved a maximum average of 792.2 HV with the laser power of 3.0 kW. The microstructures and properties of the coatings were changed by adjusting of the laser cladding power. The effects of the laser scan power on the microstructure, hardness and friction and wear properties of the laser cladding coatings were investigated and discussed.

Bioactivity of Ti6Al4V alloy with bioglass and corrosion protection by silane coating

The Ti6Al4V alloy is usually employed as a biomaterial, however, when in use, exhibits a few drawbacks such as corrosion, caused by the release of aluminum and vanadium ions besides the bioinert behavior. Bioactive coatings offer a barrier effect and bioactivity, promoting biocompatibility and osseointegration processes. The present work aims to study the biocompatibility behavior of a bioglass-containing silane film deposited on a titanium alloy (Ti6Al4V) substrate. The effect of the surface roughness of the metallic substrate was also evaluated. Film/substrate systems were characterized as their morphological, chemical, physical, electrochemical behavior, and cell cytotoxicity and cell viability. The main results pointed out that silane films augment corrosion resistance of titanium alloy substrates. The biological results indicated a growth of osteoblast cells (MG-63), for all the test conditions. The bioglass film deposited on the ground substrate exhibits the highest cell density.