Hot spray technology of TA7 titanium alloy coated by molybdenum and its bonding strength

A kind of surface modification test was introduced, by which plasma spray in argon atmosphere with CNC4500 system was applied for TA7 titanium alloy to be coated with molybdenum, and technology to produce metallurgical bonding at interface of coating and base meal was tested by heating in vacuum condition for diffusion after hot spray. With the help of scan electron microscope analysis （SEM）, the effect of argon inlet pressure and heating temperature on coating structure as well as product of diffusion layer were studied. The glued tensile test method was used to measure bonding strength of base metal to coating. The result has shown that both argon inlet pressure and heating temperature exert some effect on coating structure and the width of diffusion layer. A bonding strength of base metal to coating which is greater than molybdenum coating itself may be attained and can be controlled in more than 50 MPa level with tested hot spray technology.

Effect of thermal oxidation on the surface characteristics and corrosion behavior of a Ta-implanted Ti-50.6Ni shape memory alloy

A NiTi shape memory alloy （SMA） modified by Ta ion implantation was subjected to oxidation treatment in air at 723 and 873 K. Atomic force microscopy （AFM）, Auger electron spectroscopy （AES）, and grazing incidence X-ray diffraction （GIXRD） measurements were conducted to investigate the surface characteristics, including surface topography, elemental depth profiles, and surface phase structures. The surface roughness of the Ta-implanted NiTi increases after oxidation, and the higher the oxidation temperature is, the larger the value is. The surface of the Ta-implanted NiTi oxidized at 723 K is a nanolayer mainly composed of TiO2/Ta2O5 and TiO with depressed Ni content. The Ta-implanted NiTi oxidized at 873 K is mainly covered by rutile TiO2 in several micrometers of thickness. Potentiodynamic polarization tests indicated that the corrosion resistance of the Ta-implanted NiTi was improved after thermal oxidation at 723 K, but a negative impact was found for the Ta-implanted NiTi oxidized at 873 K.

Microwave sintering effects on the microstructure and mechanical properties of Ti–51at%Ni shape memory alloys

Ti–51at%Ni shape memory alloys(SMAs) were successfully produced via a powder metallurgy and microwave sintering technique.The influence of sintering parameters on porosity reduction,microstructure,phase transformation temperatures,and mechanical properties were investigated by optical microscopy,field-emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD),differential scanning calorimetry(DSC),compression tests,and microhardness tests.Varying the microwave temperature and holding time was found to strongly affect the density of porosity,presence of precipitates,transformation temperatures,and mechanical properties.The lowest density and smallest pore size were observed in the Ti–51at%Ni samples sintered at 900°C for 5 min or at 900°C for 30 min.The predominant martensite phases of β2 and β19′ were observed in the microstructure of Ti–51at%Ni,and their existence varied in accordance with the sintering temperature and the holding time.In the DSC thermograms,multi-transformation peaks were observed during heating,whereas a single peak was observed during cooling;these peaks correspond to the presence of the β2,R,and β19′ phases.The maximum strength and strain among the Ti–51at%Ni SMAs were 1376 MPa and 29%,respectively,for the sample sintered at 900°C for 30 min because of this sample's minimal porosity.

Electrochemical and Microstructural Study of Ni-Cr-Mo Alloys Used in Dental Prostheses

Ni-Cr-Mo alloys have been widely used as fixed dental prostheses. Recast process influence on corrosion behavior of Ni-Cr-Mo dental alloy in simulated physiological serum has been investigated using chemical and electrochemical techniques. Ni-Cr-Mo alloy recast by induction (induction) or by blowtorch (torch) has exhibited similar dendritic structures with wide and precipitate grains in their boundaries. The torch alloy has presented good corrosion resistance in physiological serum. Passivation process provides this corrosion resistance. Passivation of Ni-Cr-Mo alloy is often attributed to the formation of a thin and compact layer of chromium oxide (Cr2O3). This film is self-limiting because it acts as a barrier to the oxygen transport and metal ions. This film stability will depend on its solubility to the working temperature. Different recast procedures change electrochemical parameters as stabilizing potential in open circuit, current density and passivation interval.

Surface modification of Ti-49.8at%Ni alloy by Ti ion implantation: phase transformation, corrosion, and cell behavior

The Ti-49.8at%Ni alloy was modified by Ti ion implantation to improve its corrosion resistance and biocompatibility. The chemical composition and morphologies of the Ti Ni alloy surface were determined using atomic force microscopy(AFM), auger electron spectroscopy(AES), and X-ray photoelectron spectroscopy(XPS). The results revealed that Ti ion implantation caused the reduction of Ni concentration and the formation of a Ti O2 nano-film on the Ti Ni alloy. The phase transformation temperatures of the Ti–Ti Ni alloy remained almost invariable after Ti ion implantation. Electrochemical tests indicated that the corrosion resistance of Ti Ni increased after Ti ion implantation. Moreover, the Ni ion release rate in 0.9% Na Cl solution for the Ti Ni alloy remarkably decreased due to the barrier effect of the Ti O2 nano-film. The cell proliferation behavior on Ti-implanted Ti Ni was better than that on the untreated Ti Ni after cell culture for 1 d and 3 d.

Microstructures and mechanical properties of nanocrystalline NiTi intermetallics formed by mechanosynthesis

The formulation of nanocrystallinc NiTi shape memory alloys has potential effects in mechanical stimulation and medical im- plantology. The present work elucidates the effect of milling time on the product＇s structural characteristics, chemical composition, and mi- crohardness for NiTi synthesized by mechanical alloying for different milling durations. Increasing the milling duration led to the formation of a nanocrystalline NiTi intermetallic at a higher level. The formation of nanocrystalline materials was directed through cold fusion, fractur- ing, and the development of a steady state, which were influenced by the accumulation of strain energy. In the morphological study, uninter- rupted cold diffusion and fracturing were visualized using transmission electron microscopy. Particle size analysis revealed that the mean particle size was reduced to -93 μm after 20 h of milling. The mechanical strength was enhanced by the formation of a nanocrystalline in- termetallic phase at longer milling time, which was confirmed by the results of Vickers hardness analyses.

Scope for improved properties of dissimilar joints of ferrous and non-ferrous metals

Dissimilar joints(DSJs)of ferrous and non-ferrous metals have huge technological importance in the frontiers of newdesigns in new machineries and improved design of conventional systems.This investigation was undertaken to improve mechanicalproperties of joints of two dissimilar metals:one is Ti-based and the other is Fe-based.DSJs were processed using bonding pressurefrom1to9MPa in step of2MPa at750°C for60min.Properties of the DSJs of these two metals using different mechanisms andmethods were compared with the present research for verification.Experimental results from the diffusion bonding mechanism forjoining the dissimilar metals validated the improvement in properties.Superior mechanical properties of dissimilar-metals joints wereachieved mainly due to the third non-ferrous metallic foil,Ni of^200-?m thickness,which avoided the formation of brittleFe-Ti-based intermetallics in the diffusion zone.DSJs processed are able to achieve maximum strength of^560MPa along withsubstantial ductility of^11.9%,which is the best ever reported in the literatures so far.Work hardening effect was detected in theDSJs when the bonding was processed at5MPa and above.Bulging ratio of the non-ferrous metal(Ti-based)was much higher thanthat of the ferrous metal(SS)of the DSJs processed.SEM analysis was carried out to know the details of reaction zone,while XRDwas carried out to support the SEM results.Reasons for change in mechanical,physical,and fracture properties of the DSJs with theprocess parameter variations were clarified.

Effect of Solution Heat Treatment in α+β Phase Region on Shape Memory Characteristics of Cu-Al-Ni-Mn-Ti Alloys

The effect of aluminium content and solution heat treatment in α+β phase region on the shape memory characteristics and mechanical properties of cold wrought Cu-Al-Ni-Mn-Ti alloy are studied in this paper. Results indicate that the transformation temperature (Tt) of Cu-Al-Ni-Mn-Ti alloy reduces obviously with the increase of the amount of α-phase. During aging at 623 K, Tt increases at first up to a peak value, then decreases with prolongation of aging time. Life time of heat resistance of the alloy at high temperatures is improved with increase of the amount of α-phase, this life time becomes poor with Bainite precipitation. When the amount of α-phase is less than 5%, the ratio of shape recovery brought about by the solution heat treatment in α+β phase region is almost not effected. However, plasticity of the alloy increases obviously as aluminium content decreases. We believe that improving cold workability of Cu-Al-Ni-Mn-Ti alloy and keeping good heat resistant property and shape memory effects are possible by means of reducing the content of aluminium and solulion heat treatment in α+β phase region.

Strengthening bulk metallic glasses with minor alloying additions

Cu47Ti34Zr11Ni8, (Cu47Ti34Zr11Ni8)99Si and (Cu47Ti34Zr11Ni8)99Al bulk metallic glass were prepared by copper mold casting method, and the thermal stability, mechanical properties and microstrucrures of them were studied. With minor alloying of Si and Al additions, the glass transition temperature (Tg), crystallization temperature (Txl) and temperature interval of supercooled liquid region△Tx (=Txl-Tg) and reduced glass transition temperature (Trg) were proved to be changed from 672 K, 734 K, 62 K, 0.575 to 691 K, 752 K, 61 K, 0.592 and to 681 K, 729 K, 48 K, 0.590, respectively. The results indicate that the glass-forming ability (GFA) are improved with minor alloying additions. And the bulk glasses also exhibits high three point-bending flexural strength. Because of the additions of Si and Al, three point-bending flexural strength and flexural modulus of the bulk glass change from 2 350 MPa, 102 GPa to 3 260 MPa, 102 GPa and 2 970 MPa, 108GPa respectively. The obvious strengthening is due to the appearance of the medium-range ordered regions with a size of 2-5 nm under the high-resolution TEM image. The reason that the mixed amorphous and nanocrystalline phases caused by minor alloying of Si and Al additions, is that Si or Al is the third kind of elements, which are different from other constituting elements, and there are a strong bonding and atoms size effects between constituting elements, which cause the glass-forming ability (GFA) and the bulk metallic glasses strength improving.

EVALUATION OF A TUBULAR MESH AND A SPIRAL STENT WOVEN FROM TITANIUM NICKEL ALLOY FOR PROSTATIC OBSTRUCTION IN PATIENTS AT HIGH RISK FOR SURGERY REPORT OF 62 CASES

The use of two urethral stents woven from titanium nickel alloy (TiNi) in the form of a tubular mesh or a spiral stent (both made in China) is described. They were implanted in 62 patients,vith prostatic outflow obstruction. till patients were considered contraindicated for surgery. They were divided into a spiral stent group (group I) treated between March 1992 and May 1993, comprising 35 cases, and a tubular mesh group (group 2) treated between October 1993 and December 1994, comprising 31 cases, including four failures in group 1. Thirty-three out of the 35 patients in group 1 were treated successfully. Good results were achieved in eight cases (22.8%) and significant improvements occurred in 24 (68.5%), giving a total effective rate of 91.3%, with a follow-up of 11 to 27 months. Fourteen stents were removed within 6 months after the insertion and six more were removed within 12 months. The mean effective time of the stent in situ was 10.8 months. All 31 cases in the mesh group were treated successfully. Dramatically good effects were obtained in 28 cases (over 90%) and distinct improvements were achieved in two, giving a total effective rate of over 96.5%, with a follow-up of 6 to 14 months (mean 10.5 months). Cystoscopy was carried out in 12 patients after 6 months following the insertion. The major part of the meshes became covered by urothelium. Compared with the spiral, the mesh makes it possible to insert a prosthesis with a larger diameter and anti-pressure. The spiral, however, can be used as a temporary alternative for the relief of prostatic obstruction. A tubular mesh can work well for the relief of prostatic obstruction and remain in situ without causing major problems for at least I year.

Profile机用根管预备器械预备弯曲根管的效果分析

目的评价Profile镍钛合金机用根管锉保持根管弯曲度的能力、工作安全性和工作效率。方法弯曲根管模型和近中弯曲根管离体下颌磨牙各50颗,并各自平均分为两组:Profile镍钛合金机用根管锉组和K型锉组。分别预备至主尖锉#30和#40,对两组器械预备前后的根管弯曲度、形态、断针情况和工作时间进行测量并统计分析。结果Profile组的根管弯曲度变化和工作时间较手用器械组减小明显,K型锉组根管弯曲度(17±7)°,Profile组(5±4)°,t=7.151,P=0.000;K型锉组根管预备时间(645±90)s,Profile组(487±77)s,t=6.746,P=0.000。结论Profile镍钛合金机用根管锉可以较好地保持根管的原有弯曲度,使用安全,省时。

Fabrication of Mo Ti functionally graded material

Molybdenum alloys and titanium alloys were sintered at 1 473K for 1 h under a pressure of 30 MPa. It was found that the addition of Al can increase evidently the relative density of sintered Mo Fe alloys. The Fe Al additives are also suitable for the sintering of titanium alloys, and the Mo alloy and Ti alloy can be densified concurrently with the same additives 3%Fe 1.5%Al. The experimental results also showed that during the sintering of Mo Ti alloys the Fe Al sintering aids promoted the formation of Mo Ti solid solution, but the solid solution reaction occurred at the low sintering temperature of 1 473 K is inadequate. Finally, Mo Ti system functionally graded material has been successfully fabricated. Its density changed gradually from 9.52 g/cm 3 to 4.48 g/cm 3 in thickness direction. Such a material can be used in dynamic high pressure technology.

High Temperature Oxidation Behavior of NiCrAlY Coating by Arc Ion Plating

A NiCrAlY coating was prepared on the cast Ni-base superalloy K17 using arc ion plating. The coating was uniform, dense and well adhesive to the substrate. The oxidation kinetic curves of the alloy K17 and the coating were obtained. The results indicated that the oxidation resistance of the alloy K17 was evidently improved with NiCrAlY coatings at 900∼1100°C. As oxidation temperature rising, the interdiffusion between the coatings and substrates was enhanced. Ti atoms diffused from the substrate to the surface of coating to form the oxide, which was one of the reasons for the decrement of oxidation resistance. The oxidation resistance of NiCrAlY coating was decreased due to the spalling of pieces of oxide.

Surface nanostructures orienting self-protection of an orthodontic nickel-titanium shape memory alloys wire

Shape memory alloys (SMA) have been applied to a wide variety of applications in a number of different fields such as aeronautical applications, sensors/actuators, medical sciences as well as orthodontics. It is a hot topic to enhance the anti-corrosion ability of orthodontic wires for clinical applications. In this letter, a very nice fractal structure, micro-domains with identical nanometer sized grooves, was ob- tained on the surfaces of the orthodontic wires with an oxygen plasma and acid corrosion. The concave parts of the grooves were dominated by titanium and convex parts were the same as the bulk wires. The micro-nano fractal structure generated a hydrophobic surface with the largest contact angle to water being about 157°. The titanium dominated nanolayer and the hydrophobicity of the surface resulted in jointly the great improvement of the anti-corrosion ability of the orthodontic wires. Because the fractal structures of the wires were formed automatically when they immersed in acidic environment, hence, the self-protection of the oxygen plasma-treated orthodontic wires in acidic environment indicates their potential applications in orthodontics, and should be also inspirable for other applications of SMA materials.

Facile fabrication of novel cobalt-based carbonaceous coatings on nickel-titanium alloy fiber substrate for selective solid-phase microextraction

Fabrication of selective adsorption coatings plays a crucial role in solid-phase microextraction(SPME).Herein,new strategies were developed for the in-situ fabrication of novel cobalt-based carbonaceous coatings on the nickel-titanium alloy(Ni Ti)fiber substrate using ZIF-67 as a precursor and template through the chemical reaction of ZIF-67 with glucose,dopamine(DA)and melamine,respectively.The adsorption performance of the resulting coatings was evaluated using representative aromatic compounds coupled to high-performance liquid chromatography(HPLC)with ultraviolet detection(HPLC-UV).The results clearly demonstrated that the adsorption selectivity was subject to the surface elemental composition of the fiber coatings.The cobalt and nitrogen co-doped carbonaceous coating showed better adsorption selectivity for ultraviolet filters.In contrast,the cobalt-doped carbonaceous coating exhibited higher adsorption selectivity for polycyclic aromatic hydrocarbons.The fabricated fibers present higher mechanical stability and higher adsorption capability for model analytes than the commercial polydimethylsiloxane and polyacrylate fibers.These new strategies will continue to expand the Ni Ti fibers as versatile fiber substrates for metal-organic frameworks(MOFs)-derived coating materials with controllable nanostructures and tunable properties.

Effect of minor aluminium addition in Cu47Ti34Zr11Ni8 bulk metallic glasses

Cu47Ti34Zr11Ni8 and (Cu47Ti34Zr11Ni8)_ 99Al bulk metallic glass with size of 1mm×10mm×50mm were prepared by copper mold casting, and the influence of minor aluminium addition upon the alloy thermal stability and mechanical properties was studied. The results indicate that with the aluminium addition, the crystallizing behavior of the melt changes at the same cooling rate, and the crystallizing behavior of the glass changes at the same heating rate. The glass transition temperature(T_g), crystallization temperature(T_ x1), temperature interval of supercooled liquid region ΔT_x (=T_ x1-T_g) and reduced glass transition temperature (T_ rg) are proved to be changed from 672K, 734K, 62K and 0.578 to 681K, 729K, 48K and 0.590, respectively. Because of the addition of aluminium, three point-bending flexural strength and flexural modulus of the bulk glass are increased from 2350MPa and 102GPa to 2970MPa and 108GPa, respectively.

镀液pH对电沉积镍-钼-磷合金薄膜组织结构及性能的影响

[目的]镀液pH是影响金属电沉积过程的关键因素之一,进而影响着沉积层的组织结构和性能。[方法]采用直流电沉积法在泡沫镍(NF)上制备Ni-Mo-P合金薄膜。采用X射线衍射仪(XRD)、扫描电镜(SEM)和能谱仪(EDS)分析了不同pH下所得Ni-Mo-P合金薄膜的晶相结构、微观形貌及元素组成,并通过电化学方法考察了镀液pH对Ni-Mo-P合金薄膜析氢性能及耐蚀性的影响。[结果]在pH为7~11范围内电沉积所得的Ni-Mo-P合金薄膜均呈现非晶态结构,但组织结构及性能有差异。pH为9时所得的Ni-Mo-P合金薄膜表面最为光滑平整,载量最大,并且耐腐蚀性能最好。pH为10时所得Ni-Mo-P合金薄膜的析氢催化活性最佳。[结论]通过调整镀液的pH,可电沉积得到具备不同组织结构及性能的Ni-Mo-P合金薄膜。

Antibacterial ability and cytocompatibility of Cu-incorporated Ni–Ti–O nanopores on NiTi alloy

Nearly equiatomic nickel–titanium(NiTi) alloy is an ideal implant biomaterial because of its shape memory effect, superelasticity, low elastic modulus as well as other desirable properties.However, it is prone to infection because of its poor antibacterial ability.The present work incorporated Cu into Ni–Ti–O nanopores(NP–Cu) anodically grown on the NiTi alloy to enhance its antibacterial ability, which was realized through electrodeposition.Our results show that incorporation of Cu(0.78 at%–2.37 at%)has little influence on the NP diameter, length and morphology.The release level of Cu ions is in line with loadage which may be responsible for the improved antibacterial ability of the NiTi alloy to combat possible bacterial infection in vivo.Meanwhile, the NP–Cu shows better cytocompatibility and even can promote proliferation of bone marrow mesenchymal stem cells(BMSCs),up-regulate collagen secretion and extracellular matrix mineralization when compared with Cu-free sample.Better antibacterial ability and cytocompatibility of the NP–Cu render them to be promising when serving as NiTi implant coatings.

钛合金化学镀镍前无损活化工艺

[目的]传统钛合金化学镀镍前处理通常采用浸锌,不仅操作繁琐,使用大量腐蚀性试剂,易损伤基材,并且对环境造成不利影响。本研究提出了一种高效且无损的钛合金化学镀镍前活化工艺,旨在解决上述问题。[方法]先采用电磁感应加热装置将钛合金表面加热至一定温度,然后采用雾化装置将活化液均匀喷淋到钛合金表面,形成一层结合牢固的镍颗粒层。通过正交试验对活化工艺进行优化。采用扫描电镜(SEM)、X射线光电子能谱仪(XPS)、能谱仪(EDS)分析了活化层的表面形貌和成分。采用显微硬度计测量了所得Ni-P合金镀层的显微硬度,以及通过热冲击试验和划格试验评估了Ni-P合金镀层的结合力。[结果]经活化处理的钛合金表面生成了一层均匀且结合牢固的镍颗粒,随后通过化学镀得到了显微硬度达588.5 HV、结合力良好的Ni-P合金镀层。[结论]本研究提出的活化工艺避免了使用强腐蚀性试剂,不会破坏钛合金表面,具有环境友好、操作简单、成本低的优点,应用前景良好。

U形钛镍合金线辅助经脐单孔腹腔镜胆囊切除术236例疗效分析

目的:分析U形钛镍合金线辅助经脐单孔腹腔镜胆囊切除术的应用效果。方法:纳入2023年6月至2023年9月采用U形钛镍合金线辅助行经脐单孔腹腔镜胆囊切除术的胆囊结石患者,统计手术时间(麻醉开始到缝合结束)、U形钛镍合金线组装时间、术中并发症、增加Trocar数量、术后住院时间、术后并发症、住院费用等指标。结果:236例患者行U形钛镍合金线辅助经脐单孔腹腔镜胆囊切除术,U形线组装时间1.5(1.2,2.0)min,手术时间50.0(42.0,60.0)min,术中出血5.0(5.0,5.0)mL,无中转开腹,2例术中额外加孔。术后住院20(17,24)h,其中24 h内出院173例(73.3%)。术后并发症发生率为22.0%,术后疼痛发生率为15.7%,恶心呕吐发生率3.8%。随访最长约12个月,无切口疝、迟发型胆道狭窄发生,切口瘢痕隐匿。结论:U形钛镍合金线辅助经脐单孔腹腔镜胆囊切除术可充分暴露胆囊三角,减少筷子效应,腹壁损伤小,初步应用安全、有效。