Commercial Pure Titanium Research Articles

3D‐Printed TiO2 Electrode as a Viable Alternative for Photoelectrocatalytic Purification of Water

AbstractA commercial pure titanium (cp‐Ti) powder was used to produce a photoelectrode substrate via 3D‐printing and a commercial titanium foil (Ti‐foil) was used as substrate for direct comparison. TiO2 nanotubes were prepared on both Ti substrates via electrochemical anodization. Characterisation of electrodes showed similar results in all aspects analysed: morphology, absorbance, crystallinity, and photo‐current response. The efficiency of photoelectrocatlytic treatment of methylene blue dye (MB) in water with a single‐chip UVA‐LED was identical. The cp‐Ti/TiO2 electrode achieved 93±4 % removal of MB after 210 min, when combined with a four‐chip UVA‐LED. The cp‐Ti photoelectrode was also tested for the first time for photoelectrocatalytic treatment of benzothiazole (BTH). The highest degradation of BTH (98±2 %, 120 min) was also achieved using the four‐chip UVA‐LED. This study supports further development of 3D‐printed electrodes, maximizing the potential for the creation of novel electrodes for use in PEC technologies for abatement of organic pollutants.

Synthesis of bioactive TiO2 nanotubular thin films: Exploring biocompatibility and biocorrosion behavior in simulated body environments

Nanotexturization of the surface of metallic implants has been a promising strategy for enhancing their performance but is obtained in relatively long anodization periods (>1 h). This study aimed to investigate the formation of bioactive TiO2 NTs films and evaluate their biocorrosion resistance. TiO2 NTs were grown from commercially pure titanium (CPTi) and Ti6Al4V by potentiostatic anodization varying time (10, 30, 60, and 120-min) in ethylene glycol, NH4F, and 0.5 % simulated body fluid electrolyte. Morphology, microstructure, wettability, and electrochemical behavior (in buffered solution and bacteria inoculum) were investigated. Results show that anodic CPTi-based samples presented optimized wettability, hydroxyapatite deposition, and corrosion resistance in a buffered solution. Anodization time tailors pore diameter and hydroxyapatite deposition of samples from both substrates, beyond a threshold of 30–60 min. Rapid anodized samples (10 min) presented the lower corrosion rates from all investigated samples. Annealing treatment improved the wettability and hydroxyapatite deposition due to anatase stabilization but induced lower corrosion resistance. Upon exposure to bacterial medium, both anodic 10-min (CPTi) and annealed (CPTi and Ti6Al4V) based-samples displayed biocorrosion resistance, except for TiCP-based samples with S. aureus. Thus, chosen surface treatments can enhance some implants' desirable characteristics.

Impact of Er,Cr:YSGG Laser, Sandblast, and Acid Etching Surface Modification on Surface Topography of Biodental Titanium Implants.

Introduction: Several techniques have been used to modify the surface of commercially pure titanium (CPTi) implants to improve osseointegration using lasers, sandblasts, sandblasts with acid etching, and other modalities. For implant-osseointegration, surface features like chemical composition of a surface, topography, and surface energy are essential. The present comparative study aimed to compare the impact of Er,Cr:YSGG laser, sandblasting, and acid etching implant surface modifications on the surface topography, roughness, and element chemical composition of the Ti dental implant. Methods: Thirty CPTi dental implants were divided into three groups according to the surface modification (n=10 for each group): Group A: Sandblasting with acid etching (SLActive), group B: Sandblasting, and group C: Er,Cr:YSGG laser surface modifications. The modified surfaces were analyzed using scanning electron microscopy (SEM), profilometer, and energy dispersive x-ray spectrometry (EDS). Results: One-way analysis of variance (ANOVA) showed that there were significant differences in the mean values of average roughness (Ra) of the three groups (P<0.05). Tukey's post hoc test showed that the average roughness (Ra) of laser-surface modification (group C) of the implant had the highest mean value (2.30 µm) among the different groups, while sandblasted surface modification (group B) of the implant had the lowest mean value (1.39 µm). The SLActive (group A) sandblast with acid etching had a mean value of 1.63 µm. SEM analysis showed that significantly modified surface topographies and different element concentrations were found within all modified groups. Conclusion: The Er,Cr:YSGG laser irradiation increased the implant surface roughness value after implant surface modification, compared to sandblasts and sandblasts with acid etching application. The observations for the SEM-EDS analysis revealed several elements with different concentrations, which were affected by the physical-chemical characteristics of the surface modification techniques. The SEM analysis showed a significant modification in implant surface topographies of the tested groups.

Laser powder bed fusion (LPBF) of commercially pure titanium and alloy development for the LPBF process.

Laser powder bed fusion (LPBF) of titanium or titanium alloys allows fabrication of geometrically more complex and, possibly, individualized implants or osteosynthesis products and could thus improve the outcome of medical treatments considerably. However, insufficient LPBF process parameters can result in substantial porosity, decreasing mechanical properties and requiring post-treatment. Furthermore, texturized parts with anisotropic properties are usually obtained after LPBF processing, limiting their usage in medical applications. The present study addresses both: first, a design of experiments is used in order to establish a set of optimized process parameters and a process window for LPBF printing of small commercially pure (CP) titanium parts with minimized volume porosity. Afterward, the first results on the development of a biocompatible titanium alloy designed for LPBF processing of medical implants with improved solidification and more isotropic properties are presented on the basis of conventionally melted alloys. This development was performed on the basis of Ti-0.44O-0.5Fe-0.08C-0.4Si-0.1Au, a near-α alloy presented by the authors for medical applications and conventional manufacturing, with yttrium and boron additions as additional growth restriction solutes. In terms of LPBF processing of CP titanium grade 1 powder, a high relative density of approximately 99.9% was obtained in the as-printed state of the volume of a small cubical sample by using optimized laser power, scanning speed, and hatch distance in combination with a rotating scanning pattern. Moreover, tensile specimens processed with these volume settings and tested in the as-printed milled state exhibited a high average yield and ultimate tensile strength of approximately 663 and 747N/mm2, respectively, combined with a high average ductility of approximately 24%. X-ray diffraction results suggest anisotropic mechanical properties, which are, however, less pronounced in terms of the tested specimens. Regarding alloy development, the results show that yttrium additions lead to a considerable microstructure refinement but have to be limited due to the occurrence of a large amount of precipitations and a supposed higher propensity for the formation of long columnar prior β-grains. However, phase/texture and microstructure analyses indicate that Ti-0.44O-0.5Fe-0.08C-0.4Si-0.1Au-0.1B-0.1Y is a promising candidate to achieve lower anisotropy during LPBF processing, but further investigations on LPBF printing and Y2O3 formation are necessary.

Interface and microstructural characteristics of titanium and 304 stainless steel dissimilar joints by upset butt welding using a gleeble thermo mechanical simulator

This work discusses joining dissimilar material combinations of commercial pure titanium and 304 stainless steel utilizing an upset butt welding process. The process involves rapid heating to a temperature of 1150 °C at a heating rate of 200 °C/s with simultaneous application of pressure at a level of 1.5 MPa to achieve fusion. Then, the joints are post-heated to 850 °C during the soaking period for 90 min to relieve the welding residual stresses and achieve good bond strength. The upset welding experiments are conducted with the help of a Gleeble thermomechanical simulator. This process does not require the conventional severe metallographic preparation generally used for the typical diffusion bonding process. The weld joint achieves an ultimate tensile strength of 274 MPa, approximately 60% of the strength of commercial pure titanium. Moreover, intermetallic compounds occurred at the interfaces, which were attributed to significant changes in the microhardness of the Ti/SS alloy.

Effect of Ti Corrostion on Separation of Electro-Deposited Cu Foil

Cu foils by electroplating are known for many industrial applications such as PCB and Li ion batteries. Ti metal is commonly used as the cathode for the Cu reduction from sulfate solution. Under an acidic and high temperature environment, the passivation layer on the surface of the titanium metal tends to react with acidic solution. As a result, the corrosion of the active titanium metal was observed. In this study, the corrosion behavior of commercial pure titanium in acid copper sulfate baths was investigated, and several surface treatments were used to improve the corrosion resistance of titanium passive layer. The microstructure of titanium metal after immersion in acid copper sulfate solution was examined by using SEM and FIB. The pitting corrosion of Ti was clearly observed using SEM. The corrosion mechanism of the titanium metal in the sulfuric acid solution was discussed. In addition, the electrochemical characteristics of commercial pure titanium metal in sulfuric acid solution were also analyzed using the three-pole potential measurement method.

Ultrasonic pulsed waterjet peening of commercially-pure titanium

Commercially-pure titanium (CP-Ti) has proven indispensable in critical industries such as aerospace and automotive. To meet the ever-increasing demands of titanium applications, ultrasonic pulsed waterjet peening (UPWJ) has been evaluated for the first time on CP-Ti, as a novel method to optimise compressive surface residual stress. UPWJ offers the potential for an environmentally benign, non-contaminating peening process, paving the way for sustainable surface modification methods. UPWJ treatment involved directing a waterjet at a pressure of 69 MPa onto CP-Ti coupons, maintaining a stand-off distance of 25.4 mm and adjusting traverse speeds from 200 to 1000 mm/s. The effects of stand-off distance were also evaluated (varied from 25.4 to 44.4 mm), at a constant traverse speed of 1000 mm/s. Conventional shot peening was also applied on the same CP-Ti alloy as a baseline. The experimental results revealed relationships between the applied traverse speed and stand-off distance, and the measured surface roughness and residual stress. Furthermore, it was shown that UPWJ improves the surface mechanical behaviour, in terms of both the Rockwell hardness (HRB) and the scratch hardness. A higher stand-off distance and faster traverse speed contributed to increasing the induced compressive residual stress (to a maximum of −391 MPa), while keeping the surface roughness at moderate levels (i.e., Ra <3 μm). Comparing UPWJ with shot peening, this study highlights the potential of UPWJ for CP-Ti alloy surface modification, while removing the potential for surface contamination, which can be detrimental in many applications. Comparison of UWPJ used for peening Ti-6Al-4V (Grade 5) is also briefly discussed.

Unraveling size-affected plastic heterogeneity and asymmetry during micro-scaled deformation of CP-Ti by non-local crystal plasticity modeling

Titanium alloy is prominent in manufacturing of high-performance miniature devices, while size-affected plastic heterogeneity and asymmetry in micro-scaled deformation are not well understood due to its complex deformation mechanism. How the interplay among dislocation slip, deformation twinning, and strain gradient affects the size-dependent plastic heterogeneity and asymmetry is an intractable and non-eluded issue that needs to be unraveled. In this research, a non-local crystal plasticity model (NLCPM) considering discrete twins was established and implemented into a finite element framework. The proposed NLCPM successfully represented the size-dependent asymmetric mechanical response, primary and secondary twinning, and texture evolution. The size-dependent fracture behavior, plastic heterogeneity, and T-C asymmetry during micro-scaled deformation of commercial pure titanium (CP-Ti) were explored by coupling micro-tension/compression test and full-field simulation. Results showed that T-C asymmetry in flow stress was enhanced in the coarse-grained and small-diameter samples. For the sample with D≥0.6 mm, the ductility of CP-Ti was improved with the increase of grain size as there are more prevailing twins and the concentrating stress could be relieved by the abundant slip rather than cracking. Grain-level strain is more homogeneous in compression when d was increased from 60 to 110 μm since more non-prismatic slips were activated that accommodated strain along various directions. Meanwhile, plastic strain was allocated within discrete twin bands and thus alleviated strain concentration. Furthermore, the hardening effect of twin boundaries cancelled out the softening effect near the free surface, resulting in a narrower softening layer in the coarse-grained samples compared to its grain size. With the decrease of the sample size, the proportion of the softening layer increased, while the volume fraction of twinning decreased, leading to a reduction in macroscopic stress and fracture strain. This work enhances the in-depth understanding of size-affected plastic heterogeneity and asymmetry during micro-scaled deformation of CP-Ti and supports the forming of high-quality micro components under complex deformation path.

Contour Analysis of Three-Dimensional Peri-Implant Mucosal Model as an Endpoint Analysis of Photofunctionalization Effects on Implant Abutment Materials.

The objective of this study was to examine the effect of photofunctionalization on the soft-tissue contour formed at the interface of various abutment materials using end-point analyses obtained from the three-dimensional oral mucosal model (3D-OMMs). Commercially pure titanium (CPTi), alumina-toughened zirconia (ATZ), and yttria-stabilized zirconia (YSZ) made into discs shapes were classified into two groups: UV-treated (PTx) and non-treated (NTx). The materials in PTx groups were exposed to UV light for 12 min. Human gingival fibroblasts and TR146 epithelial cell lines co-cultured on the acellular dermal membrane were used to construct the 3D-OMM. After 4 days of culture, the discs were inserted into the holes prepared within the membrane of 3D-OMMs. The contour formed by the tissue was evaluated after 14 days of culture. The UV treatment of abutment materials resulted in the formation of more non-pocket-tissue types among the PTx group (p = 0.002). Of all materials tested, soft tissue contour around YSZ showed higher scores for the non-pocket type in both non- and UV-treated groups. The non-pocket type of tissue attachment was frequently found in all surfaces modified by photofunctionalization, particularly zirconia. The 3D-OMM can be used to evaluate the biological endpoints of implant surface modifications.

Effect of Electrically Assisted Preheating on Microstructure and Properties of Laser-Cladded Co-Based Coating on CP-Ti Alloy Substrate

Co-based coatings were prepared on commercially pure titanium (CP-Ti) with electrically assisted pre-heating (EAPH), followed by laser cladding with the assistance of pulsed current. Conventional pre-heating (CPH) laser cladding was carried out as a control to investigate the effects of a pulsed current on the phase composition, microstructure, microhardness, and wear resistance of the coatings. The results showed that periodically varied pulsed currents generate an induced magnetic field. This field fragments bottom dendrites and transforms columnar dendrites into equiaxed crystals through the influence of the Lorentz force. The phase composition of the coatings remained unchanged under the pulsed current, as well as unassisted and CPH condition, consisting of γ-Co, α-Ti, CoTi2 solid solution, and TiC, Cr7C3 hard phases. The microhardness of the coating increased at 720 A due to grain refinement, compared to unassisted and preheated coatings at the same temperature. Moreover, a suitable preheating temperature can reduce crack generation and improve the wear properties of the coating.

Fusion of Ni Plating on CP-Titanium by Electron Beam Single-Track Scanning: Toward a New Approach for Fabricating TiNi Self-Healing Shape Memory Coating.

The limited wear resistance of commercially pure titanium (CP-Ti) hinders its use in abrasive and erosive environments, despite its good strength-weight ratio and corrosion resistance. This paper reports the first study proposing a novel method for wear-resistant TiNi coating through Ni plating and electron beam (EB) irradiation in an in situ synthetic approach. Single-track melting experiments were conducted using the EB to investigate the feasibility of forming a TiNi phase by fusing the Ni plate with the CP-Ti substrate. Varying beam powers were employed at a fixed scanning speed to determine the optimal conditions for TiNi phase formation. The concentration of the melt region was found to be approximate as estimated from the ratio of the Ni-plate thickness to the depth of the melt region, and the region with Ni-48.7 at.% Ti was successfully formed by EB irradiation. The study suggests that the mixing of Ti atoms and Ni atoms was facilitated by fluid flow induced by Marangoni and thermal convections. It is proposed that a more uniform TiNi layer can be achieved through multi-track melting under appropriate conditions. This research demonstrates the feasibility of utilizing EB additive manufacturing as a coating method and the potential for developing TiNi coatings with shape memory effects and pseudoelasticity.

Effect of ECAP processing routes on the microstructural characteristics of commercial purity titanium

Effect of ECAP processing routes on the microstructural characteristics of commercial purity titanium

Effect of fluoride ion concentration and fluctuating conditions on titanium bipolar plate in PEM water electrolyser environment

In this work, we investigated the corrosion behavior and passive film of commercial pure titanium (TA1) bipolar plates in a simulated proton exchange membrane (PEM) water electrolyser anode environment under different concentrations of fluoride ions and fluctuation conditions. Our findings indicate that the denseness and protective ability of the passive film are weakened by fluoride ions, leading to severe corrosion damage of TA1. The dynamic potential loading altered the anodic reaction process of potentiodynamic polarization, resulting in a reduced corrosion current density. However, the stability of the passive film was still affected, and the Ti-oxides in the passive films decreased.

Surface characterization, electrochemical properties and in vitro biological properties of Zn-deposited TiO2 nanotube surfaces

In this work, to improve antibacterial, biocompatible and bioactive properties of commercial pure titanium (cp-Ti) for implant applications, the Zn-deposited nanotube surfaces were fabricated on cp-Ti by using combined anodic oxidation (AO) and physical vapor deposition (PVD-TE) methods. Homogenous elemental distributions were observed through all surfaces. Moreover, Zn-deposited surfaces exhibited hydrophobic character while bare Ti surfaces were hydrophilic. Due to the biodegradable behavior of Zn on the nanotube surface, Zn-deposited nanotube surfaces showed higher corrosion current density than bare cp-Ti surface in SBF conditions as expected. In vitro biological properties such as cell viability, ALP activity, protein adsorption, hemolytic activity and antibacterial activity for Gram-positive and Gram-negative bacteria of all surfaces were investigated in detail. Cell viability, ALP activity and antibacterial properties of Zn-deposited nanotube surfaces were significantly improved with respect to bare cp-Ti. Moreover, hemolytic activity and protein adsorption of Zn-deposited nanotube surfaces were decreased. According to these results; a bioactive, biocompatible and antibacterial Zn-deposited nanotube surfaces produced on cp-Ti by using combined AO and PVD techniques can have potential for orthopedic and dental implant applications.

Achieving superior mechanical properties and biocompatibility in an O-doping TiZrNb medium entropy alloy

The present work aimed to develop a novel medium entropy alloy (MEA) with superior mechanical properties and biocompatibility for the metallic-bioimplant application. A series of (TiZrNb0.7)100-xOx (x = 0, 0.5, 0.75 at. %) MEAs were carefully designed and prepared. The microstructure, mechanical properties, corrosion resistance, and biocompatibility were investigated in detail. Single-phase body-centered cubic (BCC) structural (TiZrNb0.7)100-xOx MEAs consisted of as-cast dendritic morphology. Interestingly, the yield strength and ductility of (TiZrNb0.7)100-xOx MEAs were improved simultaneously with their O concentration. The (TiZrNb0.7)99.25O0.75 MEA had optimal mechanical properties, exhibiting a yield strength of 911 ± 11 MPa, a fracture elongation of 16.1 ± 0.7%, and an elastic modulus of 70.5 ± 1.2 GPa. According to the potentiodynamic polarization and cell culture experiment, the (TiZrNb0.7)99.25O0.75 MEA exhibited superior corrosion resistance and biocompatibility, equivalent to the commercially pure titanium (CP-Ti). These findings provide a paradigm for achieving outstanding comprehensive properties in MEA via O doping.

Yield surface identification of CP-Ti and its evolution reflecting pre-deformation under complex loading

Uniaxial testing methods to characterize materials provide only limited data that is insufficient to fully understand all aspects of their behaviour, such as initial texture or anisotropy. Therefore, this research aims to conduct complex stress loading experiments to understand the physical mechanism accountable for plastic deformation caused by monotonic tension and tension assisted by proportional cyclic torsion in the CP-Ti (Commercially Pure Titanium). The yield surface approach was applied to assess the variation of mechanical properties in the as-received and pre-deformed material. It was found, that such monotonic tension associated with cyclic torsion caused a significant decrease of the tensile stress. The initial yield surface obtained for the as-received material exhibits anisotropic behaviour, whereas, the sizes of subsequent yield surface reflecting pre-deformation were reduced in all directions with exception of the tension direction.

Thermochemical oxidation of commercially pure titanium; controlled formation of robust white titanium oxide layers for biomedical applications.

This study addresses controlled formation of white rutile surface layers on commercially pure (CP) titanium by gaseous thermochemical oxidation. The formed oxide layers were investigated with light optical microscopy (LOM), scanning electron microscopy (SEM), X-ray diffraction (XRD), glow discharge optical emission spectroscopy (GDOES), transmission electron microscopy - energy-dispersive X-ray spectroscopy (TEM-EDXs), spectrophotometry, thermogravimetric analysis (TGA), and Vickers micro-indentation. The oxidation response of CP titanium in different single gas systems, O2, N2O, or CO2, at temperatures ranging from 750 °C to 1000 °C, showed that the formed oxide scales exhibit oxide stratification, irrespective of the applied gas. Additionally, a two-step oxidation process was found to result in controlled growth of robust, dense, adherent white titanium oxide layers. The two-step process entails a first oxidation step in an atmosphere of CO/CO2 at 750 °C; a second oxidation step is performed in N2/N2O at 650 °C. The oxidation in a CO/CO2 atmosphere results in the incorporation of carbon in the forming oxide layer. TEM-EDXs analysis after oxidation in CO/CO2 revealed that carbon resides in thin interlayers between slightly stratified 200-300 nm layers of rutile. This unique “composite” oxide layer containing carbon was found to be robust and densely adhering to the substrate. After the second oxidation step in N2O carbon was “retracted” (oxidized) from the oxide‑carbon composite layer, resulting in an aesthetically pleasing, adherent white oxide layer. Finally, this two-step process, leading to robust white oxide layer formation, is show-cased on a biomedical demonstrator part for dental applications.

Sliding wear characteristics of FDM-processed polylactic-acid in bovine blood serum

Fused deposition modelling (FDM) has so far been recognized for its reliability and simplicity for manufacturing of geometrically-complex polymeric materials with 3D printing technique. Recently, the studies concerning the properties of materials fabricated by using the FDM have been growing, including those related to their wear resistance which is considered of critical when a 3D-printed material must work sliding over the surface of another material during its application. Up to now, however, the influence of several FDM-printing parameters, including the raster orientations, on the wear resistance of the printed polymeric materials have not yet been fully understood. In this research, the influence of raster orientations on the wear resistance of FDM-processed polylactic-acid (PLA) materials in bovine blood serum were determined. A reciprocating pin-on-plate tribometer was used to evaluate wear resistance of a cylindrical PLA pin that slid over the surface of a commercially-pure titanium (Ti) plate. The results showed that the FDM-printed PLA pins with unidirectional raster orientations had higher wear factors (WF), i.e., ~1.5 ´ 10-4 mm N-1 m-1 than those with crossed raster orientations, i.e., ~0.8 ´ 10-4 mm N-1 m-1. Meanwhile, the WF values of Ti surface that slid against PLA pin with crossed raster orientations, i.e., ~0.09 ´ 10-4 mm N-1 m-1, were also significantly lower than those sliding with the pin having unidirectional raster orientation, i.e., 0.34 – 0.41 ´ 10-4 mm N-1 m-1. The result of analysis of the worn surface morphologies shows the indications of surface abrasion, fatigue and polymer film transfer as the possible wear mechanisms of both the FDM-processed PLA pin and its Ti countersurface material. On the basis of all the findings in this research, it can be concluded that the crossed raster orientation is preferable to be used as one of the parameters in printing of the wear resistant PLA rather than the unidirectional raster orientation.

Fatigue crack growth behavior of titanium with oxygen impurities: Experiments and modeling

The long-term reliability of structural elements in many advanced applications, such as power generation and transportation infrastructures, is paramount, especially under cyclic damage conditions. In this work, fatigue crack growth experiments were performed in commercial purity titanium with different initial oxygen contents and load ratios (R). To model fatigue crack initiation and growth, a fatigue indicator parameter (FIP) along with high-resolution crystal plasticity simulations were carried out. The crack-nucleation along with microstructurally short crack (MSC) growth models are calibrated for R = 0.1 with different oxygen contents. The resulting calibrated parameters along with the average total FIP values for R = 0.2 were used to predict nucleation and MSC growth behavior. Results indicate that this approach can predict the number of cycles required for crack nucleation and MSC behavior.

Microstructure and mechanical properties of heat-treated cold spray additively manufactured titanium metal matrix composites

Cold spray additive manufacturing (CSAM) can produce particle-reinforced metal matrix composites (MMCs) by accelerating metal/metal or metal/ceramic particle combinations towards a substrate surface. The harder reinforcement particles become embedded into the softer metallic matrix. The secondary material may also help reduce the deposit's porosity depending on the particles' relative hardness and density. In this research, four material combinations were investigated by adding one of the following secondary materials at 10 wt% to commercial-purity (CP - Grade 2) titanium powder; (i) yttria-stabilised zirconia - (Y2O3)0.08(ZrO2)0.92, (ii) titanium carbide – TiC, (iii) titanium diboride – TiB2, and (iv) tungsten – W. The mechanical properties of samples following vacuum heat treatment are compared and related to the microstructural interactions between the two materials during annealing. These results show that cold spraying a hard secondary material at 10 wt% with titanium has a reinforcing effect, increasing the material's tensile strength; however, its ductility decreases slightly. The strengthening and ductility loss effect was particularly notable for the Ti blends with W and TiC.