CP Ti Research Articles

Microstructural, mechanical, and fractographical study of Ti–CP brazing with low melting point Ti-based filler

Microstructural, mechanical, and fractographical study of Ti–CP brazing with low melting point Ti-based filler

Numerical prediction of [formula omitted] compression twin activation in commercially pure titanium under uniaxial tension

In this study, the criteria for {112‾2} compression twinning in commercially pure titanium (CP–Ti) were investigated by uniaxial tensile tests, crystal plasticity finite element (CPFE) analyses, and slip operation factor (SOF) calculations. First, the aggregates of the [0001] axes of CP-Ti were inclined in the rolling direction (RD), implying its RD-split texture. The development of the crystal orientation distribution with deformation was observed by electron back-scattered diffraction (EBSD). Active slip systems were identified by kernel average misorientation (KAM) and intergranular misorientation axis (IGMA) analyses. The dominant slip system was prismatic <a>, whereas the non-prismatic <a> slip systems were activated near the grain boundary. Active twin systems were also identified by the rotation angles of the [0001] axes between the twin and matrix. The dominant active twin system was the {112‾2} compression twin, although a uniaxial tensile load was applied. Second, the positions of {112‾2} twinning were predicted by CPFE analysis using the resolved shear stress (RSS) criterion while considering plastic deformation. SOF analysis was also employed for the prediction. The CPFE and SOF analyses yielded almost the same level of prediction accuracy. However, these calculations do not completely predict the twinning positions. Finally, the criteria for {112‾2} twinning were discussed, and it was revealed that hydrostatic pressure and RSS are possible criteria for {112‾2} twinning in the continuum model.

Finite element analysis of class II mandibular unilateral distal extension partial dentures

The current paper aims to investigate the stress distribution developed in Kennedy Class II mandibular distal extension removable partial dentures due to applying a unilateral load condition in both vertical and lateral oblique directions. 3D models of mandible bone and RPD framework were first built based on actual patient data and later exported to ANSYS software to implement the numerical analysis. For realistic analysis, the model considered the frictional contact between the RPD retainers with the teeth and mucosa with the resin denture base by applying the feature of small sliding. To ensure maximum longevity and suitability of restoration, two different metallic RPDs constructed from commercially pure titanium (CP Ti) and cobalt–chromium (Co-Cr) base materials were investigated within the proposed model. It was found that the highest stress value was seen within the Co-Cr framework followed by the titanium framework, particularly within the bar clasp under both loading directions. The principle abutment of the distal extension side carried the highest stress value under both RPD models in both loading cases. Also, it was found that the captured von Mises stress levels within the titanium bar clasps were lower than that in Co-Cr demonstrating both long durability and high flexibility of Ti clasps.

Electrochemical Behavior and Surface Conductivity of C/TiC Nanocomposite Coating on Titanium for PEMFC Bipolar Plate

In this study, a C/TiC nanocomposite coating has been prepared by magnetron sputtering technology and vacuum heat treatment technology on a titanium surface, which is used for bipolar plates (BPs) in a proton exchange membrane fuel cell (PEMFC). This prepared C/TiC nanocomposite coating was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, electrochemical testing and interfacial contact resistance (ICR). The results show that a C/TiC nanocomposite coating consists of a single C surface layer (~28.88 nm) and TiC interface layer (~19.5 nm). In addition, compared with commercially pure titanium substrate (icorr = 345.10 μA cm−2), the corrosion resistance of a C/TiC nanocomposite coating (icorr = 0.74 μA cm−2) was greatly improved in 0.5 M H2SO4 + 5 ppm HF solution at 80 °C. The corrosion current density (icorr) decreased 3 orders of magnitude in a simulated cathodic environment. Moreover, the interfacial contact resistance of a C/TiC nanocomposite coating is 2.34 mΩ cm2 under 1.4 MPa compaction force, which is much lower than that of raw CP Ti (38.66 mΩ cm2).

Effects of selective laser melting process parameters on the accuracy of the intaglio surface of maxillary removable partial denture frameworks

PurposeThis in vitro study aims to explore the effects of selective laser melting (SLM) process parameters on the accuracy of the intaglio surface of cobalt–chromium alloy (Co–Cr), commercially pure titanium (CP Ti) and titanium alloy (Ti–6Al–4V) maxillary removable partial denture (RPD) frameworks and optimize these process parameters.Design/methodology/approachMaxillary RPD framework specimens designed on a benchmark model were built. The process parameters, including contour scan speed and laser power, infill scan speed and laser power, hatch space, build orientation and metallic powder type, were arranged through the Taguchi design. Three-dimensional deviations of the clasps area, connector area and overall area of maxillary RPD frameworks were analyzed by using root mean square (RMS) as a metric. One-way analyses of variance with the above RMSs as the dependent variable were carried out (α = 0.05).FindingsMaxillary RPD frameworks built horizontally had a more accurate intaglio surface than those built at other orientation angles; CP Ti or Ti–6Al–4V maxillary RPD frameworks had a more accurate intaglio surface than Co–Cr ones; the Maxillary RPD framework built with a higher infill scan speed and lower infill laser power had the more accurate intaglio surface than the one built with other levels of these two process parameters.Originality/valueA novel benchmark model for evaluating the accuracy of the intaglio surface of maxillary RPD frameworks manufactured by SLM is proposed. The accuracy of the intaglio surface of maxillary RPD frameworks can be improved by adjusting SLM process parameters. The optimal setting of process parameters concerning the accuracy of the intaglio surface of maxillary RPD frameworks was given.

Additive manufacturing of Ti-Ni bimetallic structures

Bimetallic structures of nickel (Ni) and commercially pure titanium (CP Ti) were manufactured in three different configurations via directed energy deposition (DED)-based metal additive manufacturing (AM). To understand whether the bulk properties of these three composites are dominated by phase formation at the interface, their directional dependence on mechanical properties was tested. X-ray diffraction (XRD) pattern confirmed the intermetallic NiTi phase formation at the interface. Microstructural gradient observed at the heat-affected zone (HAZ) areas. The longitudinal samples showed about 12% elongation, while the same was 36% for the transverse samples. During compressive deformation, strain hardening from dislocation accumulation was observed in the CP Ti and transverse samples, but longitudinal samples demonstrated failures similar to a brittle fracture at the interface. Transverse samples also showed shear band formation indicative of ductile failures. Our results demonstrate that AM can design innovative bimetallic structures with unique directional mechanical properties.

Influence of Gas Temperature and Heat Treatment on Microstructure and Properties of Cold Sprayed Commercially Pure Titanium

Diffusion of oxygen and nitrogen in the cold sprayed commercially pure Ti (CS CP Ti) deposits profoundly impacts their mechanical properties. One plausible approach to additively manufacture a malleable (wrought) and high-density Ti is optimizing CS deposition parameters considering a reduction in porosity for the following heat treatment. Herein, we examined porosity, bulk density, and hardness characteristics of CS CP Ti deposits produced at varying processing gas temperatures (700, 800, and 900°C), which significantly influences the interactions of CP Ti with oxygen and nitrogen. Post-processing heat treatments at 800, 900, and 1000°C were performed in a high vacuum furnace, respectively, which diminished splat boundaries and submicron pores with increasing grain size. SEM images revealed that CS CP Ti had a dense microstructure with low porosity. According to LECO research, low spraying temperatures (i.e. 700°C) maintained oxygen and nitrogen levels in the CS CP Ti deposits at the same level as the stock powders. The bulk density of CS CP Ti produced at 900 °C matched that of wrought CP Ti metal. In addition, to improve the mechanical properties of CS CP Ti deposits, we looked at the link between CS conditions and heat treatment.

Structure and mechanical properties of in-situ synthesized α-Ti/TiO2/TiC hybrid composites through mechanical milling and spark plasma sintering

The main aim of this study was to apply high-energy longer mechanical milling and spark plasma sintering (SPS) techniques to produce in-situ α-Ti/TiO2/TiC hybrid composites from commercially pure-Ti (CP–Ti, HCP structure) powders. The CP-Ti powders were subjected to different milling times (0, 20, 40, 60, 80, 100, and 120 h). The results showed that the powder samples milled for 120 h produced Ti, Ti3O5, TiO, TiO2 phases, and dissolved C atoms from the process control agent (toluene) which were then converted to α-Ti, TiO2, and TiC phases (formed in-situ composites) through spark plasma sintering. This was expected due to more reactivity in the 120 h sample as longer milling introduces severe and robust structural refinements. Structural evaluations with increasing milling time were carried out using XRD, HRSEM, and HRTEM. The synthesized powders were then consolidated by SPS at pressures of 50 MPa and 1323 K for 6 min. The micro-hardness results have shown that the hardness was started to increase from 1.40 GPa to 5.56 GPa with increasing milling time due to more dislocation and pinning effect produced by grain refinement and formed TiO2/TiC intermetallic particles enhancing the strength of α-Ti matrix. The α-Ti/TiO2/TiC in-situ hybrid composite bulk sample yielded an ultimate compressive strength of 1.594 GPa.

Effect of surface treatment and luting agent type on shear bond strength of titanium to ceramic materials.

PURPOSEThis study aimed to compare the effect of different surface treatments and luting agent types on the shear bond strength of two ceramics to commercially pure titanium (Cp Ti).MATERIALS AND METHODSA total of 160 Cp Ti specimens were divided into 4 subgroups (n = 40) according to surface treatments received (control, 50 µm airborne-particle abrasion, 110 µm airborne-particle abrasion, and tribochemical coating). The cementation surfaces of titanium and all-ceramic specimens were treated with a universal primer. Two cubic all-ceramic discs (lithium disilicate ceramic (LDC) and zirconia-reinforced lithium silicate ceramic (ZLC)) were cemented to titanium using two types of resin-based luting agents: self-cure and dual-cure (n = 10). After cementation, all specimens were subjected to 5000 cycles of thermal aging. A shear bond strength (SBS) test was conducted, and the failure mode was determined using a scanning electron microscope. Data were analyzed using three-way ANOVA, and the Tukey-HSD test was used for post hoc comparisons (P < .05).RESULTSSignificant differences were found among the groups based on surface treatment, resin-based luting agent, and ceramic type (P < .05). Among the surface treatments, 50 µm air-abrasion showed the highest SBS, while the control group showed the lowest. SBS was higher for dual-cure resin-based luting agent than self-cure luting agent. ZLC showed better SBS values than LDC.CONCLUSIONThe cementation of ZLC with dual-cure resin-based luting agent showed better bonding effectiveness to commercially pure titanium treated with 50 µm airborne-particle abrasion.

Recrystallization Behavior of CP Ti Welds by Rolling

Electrolytic copper foil is a thin copper film material manufactured by electroplating and is mainly used as a circuit material to transmit electrical signals in printed circuit boards of electronic products such as TVs, PCs, and smartphones. Recently, it has been widely used as a negative current collector for lithium-ion batteries, which is essential for mobile IT and electric vehicles. The electrodeposited drum material is composed of CP Ti, which exhibits corrosion resistance and has a light weight, and welding is essential for processing in the form of a drum. Therefore, when the microstructures of the base metal and the welded part differ, these differences are reflected in the surface of the copper foil, which results in poor quality. Therefore, in this study, a welding process that required a low heat input while minimizing the size of the weld was used, and the change in the grain size was studied through plastic deformation and recrystallization heat treatment of the weld structure. Following the recrystallization heat treatment after the rolling of the plasma welded specimen, it was found that the calculation results of the recrystallization heat treatment were consistent with the actual conditions of the heat treatment, and the microstructure of the weld metal became finer as the rolling reduction rate increased.

Electrochemical Behaviour of Ti and Ti-6Al-4V Alloy in Phosphate Buffered Saline Solution.

The electrochemical behavior of commercially pure titanium (CP Ti) and Ti-6Al-4V (Grade 5) alloy in phosphate buffered saline solution (PBS, pH = 7.4) at 37 °C (i.e., in simulated physiological solution in the human body) was examined using open circuit potential measurements, linear and potentiodynamic polarization and electrochemical impedance spectroscopy methods. After the impedance measurements and after potentiodynamic polarization measurements, the surface of the samples was investigated by scanning electron microscopy, while the elemental composition of oxide film on the surface of each sample was determined by EDS analysis. The electrochemical and corrosion behavior of CP Ti and Ti-6Al-4V alloys is due to forming a two-layer model of surface oxide film, consisting of a thin barrier-type inner layer and a porous outer layer. The inner barrier layer mainly prevents corrosion of CP Ti and Ti-6Al-4V alloy, whose thickness and resistance increase sharply in the first few days of exposure to PBS solution. With longer exposure times to the PBS solution, the structure of the barrier layer subsequently settles, and its resistance increases further. Compared to Ti-6Al-4V alloy, CP Ti shows greater corrosion stability.

Micro-compression of high oxygen doped single-crystal titanium along different orientations

To explore the deformation mechanism of α-Ti with high oxygen doping, micro-pillars of single crystal with orientations of near 0°, 45°, and 90° inclined to c-axis were fabricated via focused ion beam (FIB) milling from a high oxygen content commercial purity Ti (CP–Ti). The micro-pillars were loaded under quasi-static compression. Post-mortem analysis reveals that only prismatic slip activated for 45° and 90° oriented samples with their critical resolved shear stress (CRSS) values of about 457 MPa and 596 MPa, and only {10–11}<c+a> the first-order pyramidal slip activated on the 0° sample with a CRSS of around 1019 MPa. The results suggest that the oxygen addition remarkably reduces the CRSS ratio between non-prismatic and prismatic slips of α-Ti. In addition, the results indicate that the Schmid law may not be applicable for α-Ti single crystal at micro-size level.

Ultrasonic spot welded CP Ti / AA2024 / CP Ti alloy joints

Ultrasonic welding (USW) is a promising technique of solid state joining of similar and dissimilar materials, including aluminum and titanium alloys. Differences in the physical and mechanical properties of the materials to be joined make it difficult to adjust the welding conditions to form high-quality joints. The development of natural aging in aluminum alloys may cause a change in the fracture mode and strength of Al / Ti ultrasonically welded joints. In present study, cryorolled and naturally aged AA2024 alloy sheet and annealed commercially pure titanium sheets were subjected to USW. The pre-treatment provided similar values of the hardness of the initial sheets. To avoid the adhesion of aluminum to the welding tool during welding, the AA2024 alloy sheet was sandwiched between the titanium sheets. Microstructure and properties of the welded joints after natural aging were examined. No cracks, discontinuities, pores were observed near the contact surfaces at magnifications of the microscope up to 1000 times. No diffusional or intermetallic reaction layers were revealed in the welded joints. The microstructure and microhardness of titanium sheets did not change after ultrasonic welding. Recovery / recrystallization development led to a decrease in microhardness of AA2024 alloy sheet. All welded samples fractured along the interface between the AA2024 alloy sheet and the bottom titanium sheet adjacent to the anvil. The average lap shear failure load of the welds was 1612 ± 278 N (shear strength of approximately 57 ±10 MPa).

Analysis of Torque Maintenance and Fracture Resistance after Fatigue in Retention Screws Made of Different Metals for Screw-Retained Implant-Borne Prosthesis Joints.

Purpose The aim was to evaluate the effect of different metallic alloys used in the manufacture of retention screws for universal cast to long abutment (UCLA) abutments for external hexagon (HE) and Morse taper (MT) connection implants, as well as of mechanical cycling on torque maintenance and fracture resistance through electromechanical fatigue testing by mastication followed by compression testing. Methods Sixty implants were used, 30 MT and 30 HE, with their respective titanium UCLA abutments and retention screws of 5 different materials (n = 6): Ti cp grade 2, Ti cp grade 4, Ti cp grade 4 hard, Ti grade 5—Ti6Al4V and surgical steel (DSP® Biomedical). The assemblies were positioned in an electromechanical masticatory fatigue testing machine. The fracture strength test was performed by compression testing in a universal testing machine EMICDL-200. Results The cycled screws and new screws of each alloy group for each connection type were evaluated, obtaining the maximum force (FM), in order to verify the effect of mechanical cycling. The data were tabulated and submitted to appropriate statistical analysis (α = 0.05). Conclusion It was concluded that for the MT, the alloy with the best performance was steel, both in the maintenance of torque and in the compression test, and cycling negatively influenced the maintenance of preload for this connection. The alloy material did not influence torque maintenance for HE. The new screws that were subjected to EMIC showed higher strength. The alloy with the lowest strength was Ti grade 2.

Coordinatively Unsaturated Amidotitanocene Cations with Inverted σ and π Bond Strengths: Controlled Release of Aminyl Radicals and Hydrogenation/Dehydrogenation Catalysis.

Cationic amidotitanocene complexes [Cp2 Ti(NPhAr)][B(C6 F5 )4 ] (Cp=η5 -C5 H5 ; Ar=phenyl (1 a), p-tolyl (1 b), p-anisyl (1 c)) were isolated. The bonding situation was studied by DFT (Density Functional Theory) using EDA-NOCV (Energy Decomposition Analysis with Natural Orbitals for Chemical Valence). The polar Ti-N bond in 1 a-c features an unusual inversion of σ and π bond strengths responsible for the balance between stability and reactivity in these coordinatively unsaturated species. In solution, 1 a-c undergo photolytic Ti-N cleavage to release Ti(III) species and aminyl radicals ⋅NPhAr. Reaction of 1 b with H3 BNHMe2 results in fast homolytic Ti-N cleavage to give [Cp2 Ti(H3 BNHMe2 )][B(C6 F5 )4 ] (3). 1 a-c are highly active precatalysts in olefin hydrogenation and silanes/amines cross-dehydrogenative coupling, whilst 3 efficiently catalyzes amine-borane dehydrogenation. The mechanism of olefin hydrogenation was studied by DFT and the cooperative H2 activation key step was disclosed using the Activation Strain Model (ASM).

Wear and Corrosion Resistance of AlSi10Mg-CP-Ti Metal-Metal Composite Materials Produced by Electro-Sinter-Forging.

Metal–metal composites are a class of composite materials studied for their high ductility and strength, but their potential applications are currently limited by the complex manufacturing processes involved. Electro-sinter-forging (ESF) is a single-pulse electro discharge sintering technique that proved its effectiveness in the rapid sintering of several metals, alloys, and composites. Previous studies proved the processability of Ti and AlSi10Mg by ESF to produce metal–metal composites and defined a correlation between microstructure and processing parameters. This paper presents the wear and corrosion characterizations of two metal–metal composites obtained via ESF with the following compositions: 20% Ti/80% AlSi10Mg and 20% AlSi10Mg/80% Ti. The two materials showed complementary resistance to wear and corrosion. A higher fraction of AlSi10Mg is responsible for forming a protective tribolayer in dry-sliding conditions, while a higher fraction of Titanium confers improved corrosion resistance due to its higher corrosion potential.

Accelerated recrystallization behavior of commercially pure titanium subjected to an alternating-current electropulse

Electropulsing has various engineering benefits compared with the traditional heating method. This study investigated the effect of electropulsing treatment on the recrystallization behavior of commercially pure titanium (CP–Ti) according to the electropulsing duration and direction. The application of a 2-s electropulse barely caused recrystallization, whereas a 4-s electropulse caused microstructural evolutions that significantly varied with the electropulsing direction and the observed sections (i.e., center, quarter, and edge). Static recrystallization was completed in the center section through the application of a 4-s electropulse at a current density of 29 A·mm−2, which suggests the accelerated recrystallization capability of electropulsing. Under the same conditions, electropulsing along the rolling direction of the CP-Ti sheet exhibited a higher recrystallization rate than that along the transverse direction. This is attributed to the different arrangement of the grain boundaries between the two samples.

Galvanic Corrosion of Ti Dental Implants Coupled to CoCrMo Prosthetic Component.

Dental implant systems are composed of an implant, prosthetic components, and a crown. Since the implants are made of commercially pure Ti (cp Ti) and prosthetic components are often made of Ti and CoCrMo alloys, a galvanic couple between these two devices may lead to galvanic corrosion, ions release, and even loss of the implant. This study aimed to investigate the corrosion resistance and measure the galvanic potential between cp Ti alloys (annealed microstructured cp Ti G4 and cold-worked nanostructured cp Ti G4) and a CoCrMo alloy. The corrosion resistance has been characterized by measuring the open circuit potential, the potentiodynamic polarization, the potentiostatic polarization, and the zero-resistance current. The cp Ti has been tested before and after a surface acid treatment. The samples' surfaces have been examined by scanning electron microscopy, and their surface roughness has been measured by a 3D optical profilometer. The polarization results showed that the CoCrMo alloy showed lower corrosion resistance than cp Ti. The surface acid treatment improves dental implant corrosion resistance. The galvanic analysis showed that the cp Ti without surface treatment behaved as an anode and after the acid treatment has a cathodic behavior in relation to the CrCoMo alloy. The highest value of galvanic current was cp TiG4 acid etched in contact with CoCrMo, in pH 2 solution. The galvanic couple with the lowest current has been the nanostructured cp Ti in contact with CoCrMo alloy.

Fatigue Crack Growth Behaviour and Role of Roughness-Induced Crack Closure in CP Ti: Stress Amplitude Dependence

This paper investigated the fatigue crack propagation mechanism of CP Ti at various stress amplitudes (175, 200, 227 MPa). One single crack at 175 MPa and three main cracks via sub-crack coalescence at 227 MPa were found to be responsible for fatigue failure. Crack deflection and crack branching that cause roughness-induced crack closure (RICC) appeared at all studied stress amplitudes; hence, RICC at various stages of crack propagation (100, 300 and 500 µm) could be quantitatively calculated. Noticeably, a lower RICC at higher stress amplitudes (227 MPa) for fatigue cracks longer than 100 µm was found than for those at 175 MPa. This caused the variation in crack growth rates in the studied conditions.

The influence of powder morphology on the microstructure and mechanical properties of as-sprayed and heat-treated cold-sprayed CP Ti

The influence of powder morphology on the microstructure and mechanical properties of as-sprayed and heat-treated cold-sprayed CP Ti