Strength Of Titanium Research Articles

Effect of ultrasound on interface morphology and strength of titanium and aluminum alloys joints produced by friction stir welding

Effect of ultrasound on interface morphology and strength of titanium and aluminum alloys joints produced by friction stir welding

Titanium mesh-reinforced calcium sulfate for structural bone grafts

Calcium sulfate (CS) possesses many of the requirements for an ideal bone graft material: it is biodegradable, biocompatible, and osteoconductive. However, its relatively low strength and brittleness are major obstacles to its use as a structural bone implant. Although the strength of CS can be improved by reducing porosity, its brittleness remains a major obstacle towards its use as bone graft. Here we combine two powerful toughening strategies which are found in advanced ceramics and in natural bone: Multi-layered architectures and ductile reinforcements. We first used stress analysis and micromechanics to generate design guidelines that ensure the proper failure sequence and maximize properties. We then fabricated and tested fully dense CS by hydrostatic compression layered with layers of titanium woven mesh. Flexural experiments in hydrated conditions confirmed that the ductility and strength of titanium and the adhesion at the titanium-CS interfaces (controlled by the size of the Ti mesh) are critical factors in the mechanical performance of the composite. Our best design exhibited a toughness 180 times larger than that of plain CS, together with a 46% increase in strength.

In-situ synthesis and superhigh modulus of network structured TiC/Ti composites based on diamond-Ti system

Abstract In order to enhance the elastic modulus and strength of titanium, novel continuous network structured TiC particle reinforced Ti (TiC/Ti) composites were successfully fabricated by hot pressing sintering based on diamond-Ti system. The results showed that 5 vol% fine diamond powders can be homogeneously adhered onto the surface of large Ti powders by lower energy ball milling process of 250 rpm/5 h/3:1. The mixed powders resulted in equiaxed network microstructure of TiC/Ti composites formed by continuous TiC particle reinforcement around large Ti powders after in-situ reaction between diamond and Ti. However, high energy ball milling process of 300 rpm/10 h/10:1 must be employed due to excessive diamond powders, which can result in TiC/Ti composites with a novel flattened network microstructure. Among the composites, the one introduced by 10 vol% diamond exhibited the highest elastic modulus of 184 GPa, which was increased by 64% compared with pure Ti (112 GPa). The composites with 5 vol% and 7.5 vol% diamond presented 830 MPa and 1480 MPa compressive yield strengths respectively, which were 1.9- and 3.4-fold that of pure Ti (429 MPa). The superior elastic modulus and strength of the composites was mainly attributed to the continuous TiC network microstructure and remained reinforcement-lean region based on the Hashin-Shtrikman theory.

Effects of Sintering Temperature on the Porosity and Mechanical Behavior of Porous Titanium Scaffolds Prepared by Freeze-Casting

The purpose of this study was to investigate the effects of sintering temperature on the microstructure, and associated mechanical properties of porous titanium scaffolds prepared by freeze-casting. Sintering temperature significantly influenced the porosity and the mechanical properties of the titanium scaffolds. The porosity decreased from 60 to 20% as the sintering temperatures increased from 800 to 1100 °C. The scaffolds were of an open pore structure with pore sizes ranging from 2 to 20 μm. The average wall thickness of the porous titanium was measured, using a micro-computed tomography, to be in the range from 9.2 to 26.2 μm. Elastic modulus was between 2 to 7 GPa, depending on vacuum annealing conditions. The compression strength of the scaffolds may exceed 1000 MPa as the sintering temperature higher than 1000 °C. The increase in titanium strength and stuffiness could be mainly attributed to the decrease in porosity as well as the increase in wall thickness.

High strength metallic wood from nanostructured nickel inverse opal materials

This paper describes a nickel-based cellular material, which has the strength of titanium and the density of water. The material’s strength arises from size-dependent strengthening of load-bearing nickel struts whose diameter is as small as 17 nm and whose 8 GPa yield strength exceeds that of bulk nickel by up to 4X. The mechanical properties of this material can be controlled by varying the nanometer-scale geometry, with strength varying over the range 90–880 MPa, modulus varying over the range 14–116 GPa, and density varying over the range 880–14500 kg/m3. We refer to this material as a “metallic wood,” because it has the high mechanical strength and chemical stability of metal, as well as a density close to that of natural materials such as wood.

Microstructure and Strength of Titanium After Heat Treatment at Different Temperatures in the Range of 680-1000°C

The main purpose of this research is to determine the effect of brazing treatment on mechanical properties of both titanium Grade 2 and titanium Grade 5 alloys. The research group obtained Grade 2 and Grade 5 titanium alloys and brazing- treated them at temperatures of 680, 800, 850, 900, 920, 950, and 1000°C. Afterward, each sample was tensile tested, mounted, hardness tested, and observed by optical microscope to investigate corresponding microstructures. Based on the result sheets, it was revealed that the yield strength and tensile strength and ultimate strength of Ti Grade 2 alloys showed drastic fall after heating to 680°C, then no change up to 850°C, fall again up to 950°C, and remained unchanged strength to 1000°C However, the Ti Grade 5 samples showed completely different behavior. The yield strength was unchanged after heating to different temperatures. When heating to 680°C. It didn’t affect the strength at all, then after heating to 800°C, the strength decreased about 100MPa. But after this, higher temperatures didn’t change strength anymore. The Ultimate strength however showed a different trend as it continuously went down at elevated temperature. Meanwhile, the hardness of both alloys decreased constantly when temperature increased. Regarding Ti Grade 2 alloys, the initial drop in strength was due to annealing. Around 800°C, alpha laths started to form and that caused strength to increase. When the temperature reached at 850°C, the basketweave alpha laths were formed. Over that temperature, the grain sizes were significantly large which caused the strength to decrease. However, there was not much of change in alpha/beta ratio for Ti Grade 5 alloys. EBSD could be a helpful method since the alpha grain size can be determined from that.

Oxide layers on titanium obtained by anodizing in orthophosphoric acid

Purpose: Titanium is an essential material used in modern dentistry, mostly due to its tissue compatibility. However, there are another physicochemical assets, which can be harnessed. One of these is enhancing the bonding strength of titanium with another materials. In view of the advantageous effect of oxide layers on the bond with the ceramics, an attempt was made at creating oxide layers on samples of commercially pure titanium applied as the material for metal frameworks of prosthetic restorations. Design/methodology/approach: As the research material cylindrical wet grinded commercially pure titanium, Grade II samples were used. The samples were divided into three groups and underwent anodic oxidation in 1 M orthophosphoric acid, with the voltages: 120 V, 160 V, 200 V. After the anodizing process, the samples were subjected to the X-ray diffraction, analysis of the element distribution from the surface towards the inside of the materials using an optical spectrometer, finishing with the tests performed with a scanning microscope to determine the morphology of the obtained layers. Findings: Layers of 0.26 μm to 0.65 μm thick were achieved. The performed studies demonstrated that increasing reaction voltage contributes not only to thickening of the oxide layers but also influences to porosity. The layers obtained in the electrolyte which contained monomolar orthophosphoric acid consist of only one allotropic type of titanium oxide – anatase. The spectrometric tests showed that the content of titanium and oxygen in the layer is not constant, which proves that the formed layer does not have a strictly stoichiometric composition TiO2, but rather TiO2-x. Research limitations/implications: It is necessary to provide the optimal voltage directly related to the employed acid solution to preserve the usable thickness of oxide layers. Too thick (over 1 μm) coating may lead to exfoliating. Contrary, distinctly thin layers present fractures and decrements, accordingly do not veneer entire surface of titanium sample. Originality/value: Usually oxide layers obtained by anodic oxidation are examined paying special attention to tissue integration and usability in implantology. Following paper is focused on bonding titanium with dental ceramics to facilitate process of designing porcelain-fused-to-metal fixed dentures.

Titanium strength system

Titanium strength system

Increase in the Surface Strength of Titanium Implanted with Argon Ions

We have studied the influence of argon-ion implantation at accelerating voltages within 40–130 kV in a dose range of (1–4) × 1016 ion/cm2 on the morphology, microhardness, and fatigue strength of titanium. A method of titanium surface strengthening and modification by Ar+-ion implantation is proposed, which opens new possible applications of this material in electrical devices for power engineering, chemical industry, and metallurgical equipment.

Strain-Rate Dependence of Compressive Yield Strength of Titanium Grade 4 with Coarse-Grained and Ultrafine-Grained Structures: Experimental Results and Theoretical Calculation

The nanocrystalline (NC) and ultrafine-grained (UFG) structures of metallic materials can lead to their extraordinary high strength. However, most of the papers on this topic consider deformation parameters of NC and UFG materials only for the case of quasi-static tensile tests. Characteristics of dynamic strength and fracture of such materials remain unexplored. This paper presents a study of the mechanical behavior of pure titanium Grade 4 with a coarse-grained (CG) and UFG structure under uniaxial compression with different strain rates. The UFG structure was provided using the method of equal-channel angular pressing. The dynamic compression was carried out on a setup with the Split-Hopkinson pressure bar. It is found that in the observed range of strain rates 10–3-3×103 s–1, the yield stress of the CG titanium increases by 20%, and does not exceed the yield stress of the UFG titanium. However, the yield stress of the UFG titanium remains close to a quasi-static value. It is shown that these strain-rate dependencies of the yield strength can be predicted by the incubation time approach. The calculated curves show that at strain rates above 104 s–1 the yield stress of the CG titanium becomes higher than the yield strength of the UFG titanium.

New Titanium Alloy Feedstock for High Performance Metal Injection Molding Parts

Ti 6-4 and other Titanium alloys have great potential for Metal Injection Molding of high performance parts. Markets like Automotive, Aerospace, 3C and sporting goods can benefit from the low density and high strength of Titanium. A new feedstock has been developed that incorporates pre-alloyed Ti 6-4 and discrete additions that simplify MIM processing and enhance properties. Processing and sintering parameters are presented together with mechanical and metallurgical properties of completed parts.

Effect of electrospark deposited surface layers on bond strength of titanium–porcelain

Casting of titanium can be successfully used in prosthodontic applications, but it demands special machines and protection gas to avoid oxidation of the metal. The aims of this study are to investigate the bond compatibility between porcelain and titanium using three-point bending, oxide adherence and thermal expansion tests, and to compare the results with those of a conventional titanium–porcelain system. Titanium alloy surfaces were modified with Nb, YG8 and silicon electrode by electrospark surface modification process. The effect of electrospark surface depositing (ESD) layers on bond strength of titanium to porcelain was evaluated comparatively. Some reasons about bond strength of titanium to porcelain were discussed. Results indicate that ESD modified layer prepared in atmosphere using Si electrode can obtain the strongest bonding to porcelain. The ESD modified layer show metallurgical bond to Ti substrate. In addition, the facts that rough surface can help to improve physic bond, similar nature can also help to chemical link and compact ESD layer represent good high temperature oxidation resistance are the reasons that enhance good bond strength of titanium to porcelain.

Effects of different treatments on the bond strength of titanium to porcelain

This study focused on the effects of micro-arc oxidation on the bond strength of the porcelain-titanium system. The phase, morphology, and oxide layer thickness of titanium were evaluated. In particular, the bond strength of porcelain fused to titanium was measured using a three-point bending test. Statistical analyses were performed using a one-way analysis of variance. Differences in the surface morphologies and the phase components were observed in three groups. For micro-arc oxidation specimens, the bonding of titanium and porcelain was compact with a thin oxide layer. The mean bond strength of the micro-arc oxidation group, pre-oxidation group and control group was 42.40 ± 4.35 Mpa, 34.28 ± 2.84 Mpa, and 28.58 ± 2.74 Mpa, respectively. When titanium was subjected to micro-arc oxidation treatment, the bond strength was significantly increased compared with the pre-oxidation group and the control group (p < 0.05). These results suggest that the micro-arc oxidation treatment could be an effective but simple method for increasing the titanium-ceramic bonding strength.

Effect of equal-channel angular pressing on the fatigue strength of titanium and a zirconium alloy

The static and fatigue strength of commercial-purity VT1-00 titanium and a Zr-2.5% Nb alloy subjected to equal-channel angular pressing (ECAP) are studied. The formation of a submicrocrystalline structure after ECAP is shown to result in significant hardening, an increase in the fatigue life at high stress amplitudes, and an increase in the fatigue limit as compared to the annealed state. The mechanisms of fatigue fracture of the materials in various structural states are investigated.

Structure and mechanical properties of titanium subjected to high-rate channel angular pressing and deformation by rolling

The macro- and microstructure have been analyzed and the tensile mechanical properties have been measured for commercial titanium subjected to dynamic channel angular pressing (DCAP) at high temperatures using one or two passes, as well as to additional warm rolling and low-temperature annealing. The structure of titanium after DCAP at a high temperature consists of a dispersed mixture of fine recrystallized grains (1 to 2 μm in size) and deformed nonrecrystallized regions. The deformed regions have a subgrain structure with sub-grains 200–300 nm in size. After the second pass, the size of the recrystallized grains becomes less by two times as compared to their size after one-pass DCAP, the subgrains in the deformed regions acquire a more equiaxed shape, and the microstructure becomes more uniform. The warm rolling of the samples subjected to DCAP at high temperatures increases the total density of dislocations and provides a high level of internal stresses. After two-pass DCAP at 530°C, the ultimate strength of titanium was 650MPa and the relative elongation was 19%. Additional rolling to 50% at 300°C and low-temperature annealing increases the ultimate strength to 790 MPa, while the relative elongation is retained at a high level of 15%.

Influence of Friction Stir Welding Process on the Weld Formation and Tensile Strength of Titanium and Aluminum Dissimilar Alloys Welded Joint

Titanium alloy TC1 and Aluminum alloy LF6 were jointed by friction stir welding (FSW), and the influence of process parameters on formation of weld surface, cross-section morphology and tensile strength were studied. The results show that, Titanium and Aluminum dissimilar alloy is difficult to be joined by FSW, and some defects such as cracks and grooves are easy to occur. When the rotational speed of stir head(n) is 750r/min and 950r/min, the welding speed(v) is 118mm/min or 150mm/min, a good formation of weld surface can be obtained, but the bonding of titanium/aluminum interface in the cross-section of weld joint is bad when n is 750r/min which results in a low strength joint. When n is 950r/min and v is 118mm/min，the strength of the FSW joint of Titanium/Aluminum dissimilar materials is 131MPa which is the highest．

Evolution of Microstructure and Mechanical Properties of Titanium Grade 4 with the Increase of the ECAP-Conform Passes

This work reports on the results of investigation of microstructure change of commercially pure titanium Grade 4 with the increase of the number of ECAP-Conform passes. There has been investigated influence of continuous equal-channel angular pressing by the scheme “Conform” (ECAP-C) on the structure and properties of commercially pure titanium Grade 4. It has been demonstrated that as a result of first two ECAP-C cycles titanium structure is strongly fragmented and deformation bands are formed. With the further increase of ECAP-C passes to 6 the band structure is transformed into ultrafine-grained (UFG) structure with the grain size of about 250 nm. The strength of titanium regularly grows with the increase of the number of ECAP-C passes, while ductility, which settles after first cycle on the level of 12%, is almost not changed with the further strain degree increase. As a result of the subsequent drawing of titanium after ECAP-C its strength additionally increases to 1300 MPa, with retention of ductility about 11%.

Effect of ZrN coating by magnetron sputtering and sol–gel processed silica coating on titanium/porcelain interface bond strength

In this study, a coating technique was applied to improve the bond strength of titanium (Ti) porcelain. ZrN coating was prepared by magnetron sputtering, and silica coating was processed by a sol-gel method. The treated surfaces of the specimens were analyzed by X-ray diffraction, and the Ti/porcelain interface was investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy. The coated specimens appeared fully coherent to the Ti substrate. The fractured bonding surface was also investigated by SEM. The residual porcelain on the metal surface could be observed in the ZrN group and silica group, but there was no obvious porcelain remaining in the control group. A three-point-bending test showed that the bonding strength of the ZrN group (45.99±0.65MPa) was higher than the silica group (37.77±0.78MPa) (P<0.001) and control group (29.48±1.01MPa) (P<0.001), while that of the silica group was significantly higher than the control group (P<0.001). In conclusion, conditioning the ceramic surface with ZrN and silica coatings resulted in a stronger Ti/porcelain bond. ZrN coating by magnetron sputtering was a more effective way to improve the bond strength between Ti and porcelain compared with sol-gel processed silica coating in this study.

Effect of Surface Modifications on the Bonding Strength of Titanium–Porcelain

Investigations of surface modifications on cast titanium surfaces and titanium–porcelain adhesion were performed. Cast pure titanium was subjected to surface modifications by sandblasting, preoxidation, and SnO x coating by sol-gel process. The adhesion between the titanium and porcelain was evaluated by a three-point flexure bonding test. The X-ray diffraction (XRD) and scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS) results revealed that failure of the titanium–porcelain predominantly occurred at the titanium–oxide interface after sandblasting and preoxidation treatments. The SnO x film with small spherical pores obtained at 300°C served as an effective oxygen diffusion barrier and improved titanium–porcelain adhesion. With the temperature elevated, SnO was oxidized to SnO2 and the film microcracked, which resulted in the decrease of the titanium–porcelain bonding strength.

Synthesis and Characterization of SiO2 Coating on Cast Pure Titanium

The silicon coating was deposited by sol–gel dipping process as intermediate layer to minimize titanium oxidation for Ti-porcelain restorations. The effect of silicon coating on bonding strength of titanium–porcelain was investigated. The adhesion between the titanium and porcelain was evaluated by three-point flexure bonding test. The result of TG-DSC analysis showed that the optimal treating temperature for SiO2 coating was 300°C. Silicon coating was effective in preventing titanium oxide layer formation and improving bonding strength. The improvement in bonding strength of titanium–porcelain was about 10%. At the same time, the in vitro bioactivity of the titanium and SiO2 coating was studied by cytotoxicity test. The methyl thiazolyl tetrazolium assay results demonstrated that the cytotoxicities of SiO2 coating were ranked as 0. The SEM results revealed the existence of microcrack on the SiO2 coating surface. Failure of the titanium–porcelain predominantly occurred at the titanium-oxide interface. The SiO2 coating increased bonding strength of titanium–porcelain and could be used for dental implant materials.