Effects of Ti_(0.5)Al_(0.5)N coatings on the protecting against oxidation for titanium alloys

Ti0.5Al0.5N coatings were deposited on TC11（Ti-6.5Al-3.5Mo-1.5Zr-0.3Si） and silicon substrates using a cathode arc ion-plating system.The microstructure, composition, phase structure, and oxidation-resistance of the alloys and nitride coatings were investigated by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, Auger electron spectroscopy, and thermal analyzer.The results show that the oxidation resistance of the titanium alloy is relatively limited;the compound structures of Ti mixed with Al oxides are formed during the heating process.The phases of the Ti0.5Al0.5N coatings are composed of a TiN solid solution phase.The oxidation kinetics obeys the parabolic law.During the oxidation process, the selective oxidation of Al occurs, thus protecting the underlying coating and substrate.

Low cycle fatigue behavior of zirconium−titanium−steel composite plate

The low cycle fatigue behavior of zirconium−titanium−steel composite plate under symmetrical and asymmetric stress control was studied.The effects of mean stress and stress amplitude on cyclic deformation,ratcheting effect and damage mechanism were discussed in detail.The results show that under symmetric stress control,the forward ratcheting deformation is observed.Under asymmetric stress control,the ratcheting strain increases rapidly with mean stress and stress amplitude increasing.Under high stress amplitude,the influence of mean stress is more significant.In addition,by studying the variation of strain energy density,it is found that the stress amplitude mainly promotes the fatigue damage,while the mean stress leads to the ratcheting damage.In addition,fractographic observation shows that the crack initiates in the brittle metal compound at the interface,and the steel has higher resistance to crack propagation.Finally,the accuracy of life prediction model considering ratcheting effect is discussed in detail,and a high-precision life prediction model directly based on mean stress and stress amplitude is proposed.

CLINICAL COMPARISION OF THE TREATMENT OF CERVICAL PROLAPSE OF INTERVERTEBRAL DISC BY USING CAGE OR TITANIUM PLATE

Objective To compare the clinical effects of treating cervical prolapse of intervertebral disc by using Solis cage, titanium cage and autogenous iliac crest graft (AICG) combined with titanium plate. Methods 64 cases of cervical prolapse of intervertebral disc were analyzed retrospectively. All the patients were followed up for about one year. Group A is composed of 20 patients (30 intervertebral spaces) treated with microdiscectomy and Solis cage fusion; group B is composed of 21 patients(22 intervertebral spaces) treated with titanium cage and group C is involved of 23 patients(28 intervertebral spaces) which were dealt with AICG combined with titanium plate. The differences in the total X ray exposure time, time working on iliac bone, incidence of complications, fusion rate, incidence of JOA score recovery rate more than 50% and rehabilitation time of the three groups are analyzed. Results All indexes from group A and B were more satisfactory than those from group C (P<0.05). The statistic analysis results of the incidence of complications of cervical part, rehabilitation time in group A are 5.0±1.8, 5.1±1.2; and that is 14.3±2.6, 7.5 ±1.6 and 26.1±6.2, 8.6±2.3 in group B and group C respectively. There is significant difference between group A and group B on the incidence of complications of cervical part and rehabilitation time (P<0.05). Results of the incidence of JOA score recovery rate >50% in group A(95.8±3.2) was more satisfactory than that in group B(93.6±2.9), while there was no statistical difference between group A and group B (P>0.05). Conclusion The Solis cage is better in treating the cervical prolapse of intervertebral disc than other ways. Also, it makes the operation easier, rehabilitation time shorter, and it causes fewer complications.

Troubleshooting a Difficult Trans-Tibial/Fibula Amputation: A Case Report

Necrotic feet secondary to vascular compromise in the diabetic patient may require an emergent guillotine amputation. Unrecognized, retained hardware in a distal ankle years after fracture repair may complicate the intraoperative guillotine amputation at the transtibial/fibula level. Troubleshooting such an unexpected surgical problem is not necessarily straightforward depending on the clinical situation. Presented is a case report where a patient with a necrotic burned foot failed to inform the burn team that he had implanted ankle hardware, prior to his surgical intervention. A successful amputation was completed after proceeding down a specific algorithm devised for such a scenario.

QUANTITATIVE RELATION BETWEEN YIELD STRESS AND R-VALUE OF Ti PLATE ALONG PARALLEL AND PERPENDICULAR TO ROLLING DIRECTION

An attempt was made on the quantitative prediction of the relationship hetween the yield stress and R-value along the parallel and perpendicular to the rolling direction of Ti plate based on analysis of the previous experimental data.It is shown that the yield stress along one direction and another is quite synchronized with the R—value.According to the plasticity theo- ry,an formular of σ_(1s)/σ_(2s)=[(1+1/R_2)/(1+1/R_1)/^(1 2) was proposed,In statistic estima- tion.the calculated results are in good agreement with the experimental data.The availability of this formula was briefly discussed also.

Evaluation of characteristics on titanium surface treatment for absorption of functional groups

Background In order to bind or fix bioactive materials directly to the surface of a Ti implant, the prior binding process of functional groups （FGs, -COOH and -OH） to the implant surface is necessary. Conventional binding processes are so high-cost and complex, so it is essential to find a simple and effective procedure for Ti-FG binding.Methods Various electrolyte compositions and electrochemical processing were adopted in this study to develop a relatively simple and effective Ti-FG binding process. The ability of Ti-FG binding and calcium （Ca）/phosphorous （P）absorption and corrosion resistance were evaluated according to various titanium surface treatment in electrolyte involving -COOH and -OH ion by using X ray photoelectron spectroscopy （XPS）, field emission scanning electron microscope （FE-SEM） and potentiodynamic scan method respectively.Results In cases of -COOH, the anodic oxidation process （AN） showed an effective binding ability between -COOH and Ti surface. On the other hand, in cases of -OH, there were no significant differences in the result between the conditions used. In regard to the absorption of Ca and P on Ti surface, there was a minimal amount of Ca absorbed but no P was absorbed. The anodic oxidation series showed homogenous corrosion, whereas the electrolyte immersion （EL）series showed unstable corrosion. Although EL-OH showed a novel corrosion potential, the EL-COOH series showed good corrosion resistance over the anodic potential range.Conclusions The ability of binding between FG and the Ti surface and Ca/P absorption were strongly associated with the surface potential （ξ, potential）, which was dependent on the pH of the electrolyte. Accordingly, in order to achieve the effective absorption of various FGs on the Ti surface, it is needed to develop the combination process in addition to the electric affinity, relation with the ξ, potential.

Comparison of microstructure and mechanical properties of titanium/ steel composite plates by two manufacturing processes

Two types of titanium/steel composite plates with the same thickness were manufactured by parallel explosive welding and double vertical explosive welding and rolling, respectively. The comparative analysis of microstructure showed that the interface of double vertical explosive welding plate （B plate） tended to be straight while the interface of parallel explosive welding plate （A plate） was wavy bonding. Defects near the interface of B plate were extruded, and the thickness of the diffusion layer of B plate was thicker under the effects of preheating temperature and press-working. Comparative tests of mechanical properties indicated that the tensile shear strength of B plate was lower while its micro-hardness was higher. Specimens of these two types of plates were neither separated nor cracked after bending up to 180° in the three-point bending test. From the microstructural observation of tensile fracture characteristics, A plate had strong toughness fracture while B plate had mainly ductile fracture with cleavage fracture as the supplement. Macroscopically, the tensile strength of the latter was 7.9% less than that of the former. However, both satisfied the Chinese standard of tensile strength.

Manufacturing Technology and Application Trends of Titanium Clad Steel Plates

Some of the major manufacturing processes and corresponding mechanical properties of titanium clad steel plates were analyzed, and the consequences of research, manufacturing, and application of titanium clad steel plates in both markets of China and overseas were also summarized. As an economical and environmentally friendly technology, the roll bonding process is expected to become the next-generation mainstream process for the manufacturing of titanium clad steel plate. Some of the crucial and most important technical problems of this particular process, including vacuum sealing technology, surface treatment process technology, application of a transition layer, and rolling process, were discussed along with the advantageous mechanical properties and life-cycle economy of these plates processed by this technology. Finally, the market needs, application trends, and requirements of titanium clad steel plate were also considered from industries of petrochemical, shipbuilding, marine, and electric power.

High-temperature deformation behavior of titanium clad steel plate

In this paper, the single-pass hot compression experiment of titanium clad steel plate was carried out by Gleeble-3500 thermal mechanics simulation test machine,and the effect of deformation temperature(T), strain rate(ε),thickness ratio(k), and friction coefficient(l) on flow pattern of the metal and stress in the deformation zone was analyzed.The results show that the metal flow behavior and the stress during compressive deformation depend strongly on the deformation temperature. At 800 and 850 °C, the bimetal can flow uniformly, while at 900 °C, the TA2 flows faster than Q235 B, and the phenomenon of TA2 wrapping Q235 B is observed. The metal flow of the bimetal material will coordinate each other through the bonding interface. It is noted that the stress increases with the increase of the ε and l and decreases when the metal flows along the contact area.

Effect of Electric Field Imposition on Metal Anodizing Behavior

Anodic oxidation processes for metal surface have been utilized many materials,for example,porous alumina, nano-silicon crystal,and so on.In these materials,anodizing surface treatment for titanium or zirconium is useful for biocompatible material,like artificial bones and joints.In anodizing behavior,successive dielectric breakdown makes the surface microscopic bumpy morphology,which is important for the biocompatibility.Electric field can promote the oxidation behavior at the anodizing surface.As the result of the anodizing experiments using titanium or zirconium plate(10mm × 10mm),it is found that the anodized film becomes thicker and the microscopic honeycomb structure becomes finer and uniform by the imposition of electric field up to 200 kV/m.