纳米钛酸钾生物薄膜在模拟体液中的电化学腐蚀

以自行设计制备的低模量Ti-25Nb-6Zr-3Mo医用β钛合金为基体材料,采用阳极氧化与水热处理相结合的方法在该合金表面制备出纳米钛酸钾生物薄膜,并通过扫描电子显微镜、表面能谱仪和X射线衍射仪对该生物薄膜进行微结构表征.采用三电极体系,测试了纳米钛酸钾生物薄膜在模拟生理体液中的耐蚀性能.结果表明,纳米钛酸钾生物薄膜在模拟体液中表现出更好的稳定性和耐蚀性,是一种具有很好应用前景的种植体材料.     

锻造及热处理工艺对Ti-679合金组织和性能的影响

一、前言国产Ti-679合金是仿制英国帝国金属公司研制生产的IMI-679钛合金。该合金的名义成分为Ti-2.25Al-11Sn-5 Zr-1Mo-0.25Si,是一种多组元近α型耐热钛合金。为使国产Ti-679合金用于试制斯贝-202涡扇发动机,国营红旗机械厂,宝鸡有色金属加工厂,西北工业大学锻压教研室师生,组成《Ti-679合金研究小组》,采用抚顺钢厂、宝鸡有色金属加工厂研制生产的Ti-679合金棒材,选取不同的     

航空用钛合金表面处理工艺参数优化

采用正交试验法对航空业最常用的钛合金Ti-6Al-4V表面阳极处理工艺参数优化进行了研究,得出的最佳工艺参数为:溶液浓度250 g/L,处理时间15 min,直流电压10 V,温度25℃.通过阳极化处理,在钛合金表面形成了一层褐色、致密、多孔的氧化层,增加了合金表面积,促进了胶接表面与胶层的机械咬合,增强了胶接强度.力学实验证明,胶接试样的剪切强度可达34.54 MPa.     

合金元素对TiAl合金高温氧化行为的影响

研究了合金元素Nb、Cr、Ag元素对TiAl合金900℃在空气中的高温氧化性能的影响．高温氧化试验存热天平上进行．结果表明，Ti-46．5Al-5Nb合金在900℃形成的氧化膜具有与TiAl合金同样的分层结构，不同之处在于本研究合金形成连续的保护性Al2O3内阻挡层，从而使膜的增长速率相对TiAl合金有所下降．Ti-48Al-8Cr-2Ag在900℃氧化形成连续的保护性Al2O3层，它的抗氧化性优于Ti-46．5Al-5Nb从氧化机理分析了合金相同条件下氧化程度不同的原因．     

TiA(l)-10Nb合金铸态组织演化规律的研究

研究Ti-(44～54)Al-10Nb合金铸态组织的演化规律,并确定全β凝固的TiAl-10Nb合金的成分范围.实验结果表明:Ti-(44～53)Al-10Nb合金的凝固组织为典型的柱状晶组织,Ti-54Al-10Nb合金的宏观组织为等轴组织;在其凝固组织(纵截面)上部存在较多的缩松,这主要是由于Nb元素的添加量加多,...     

非晶SiO2涂层的制备及其对Ti-22Al-26Nb合金的高温防护

以商业硅胶为原料,采用溶胶-凝胶法在Ti-22Al-26Nb合金表面浸涂制备非晶氧化硅涂层.涂层样品和空白样品在800和900℃静态空气中进行等温氧化实验,900℃静态空气中进行循环氧化实验.采用热重分析（TGA）、扫描电子显微镜（SEM）和X射线衍射（XRD）对结果进行分析,研究涂层对Ti-22Al-26Nb合金氧化行为的影响.结果表明：涂层样品的氧化抛物线速率常数较空白样品降低,涂层提高了合金在空气中的抗氧化能力.合金表面生成氧化膜主要由TiO2,Nb2TiO7和AlNbO4组成,涂层抑制了氧化物的生长.探讨了涂层的作用机制.     

钛酸钾晶须增强尼龙

为增强聚酰胺(PA)强度,用硅烷及钛酸酯等偶联剂对钛酸钾晶须进行表面处理,并考察钛酸钾晶须对PA力学性能、工艺性等影响.研究表明,钛酸钾晶须经硅烷偶联剂处理后,可改善复合材料性能,硅烷的表面处理效果较钛酸酯的好,并比较了硅烷偶联剂改性前后晶须对PA增强性能的改变.经硅烷偶联剂KH-550表面改性的PTW能与PA基体更好地相容,达到较好的增强效果.     

新型医用钛合金材料的研究进展

医用钛合金材料以其优良的生物相容性,优越的综合力学性能一直被各国学者广泛研究.本文对比了医用钛合金材料和其他医用金属材料的力学性能和生物相容性,给出钛合金是目前适用于生物材料领域的医用金属材料的依据.对比了各种医用钛合金材料发展和应用,纯钛和Ti-6Al-4V力学性能和人体器官各个部位的可替代性,在此基础上发展的第二代生物医用钛合金Ti-6Al-7Nb研究重点集中在生物相容性和力学相容性上,从20世纪90年代以来,以力学性能和生物相容性较好的Ti-Ta,Ti-Zr为代表的第三代医用钛合金的开发集中在烧结工艺、有益人体金属元素方面的研究.     

Fe代替V制备低成本钛合金:相体积分数的计算

钛合金因其优异的综合性能,如比强度高、耐热性强、耐腐蚀性能优异、低温性能好等特点,而被应用在航天、航空、航海等诸多领域,然而钛合金的高成本严重制约了其大规模的使用。本文以综合性能最好、使用最广泛的Ti-6Al-4V合金为基础,在使用廉价合金元素代替昂贵合金元素的思路下,设计了几组V、Fe元素含量不同的Ti-Al-V-Fe合金。借助稳定系数K_β,分析钛合金中β相的稳定程度和β稳定元素的作用,通过理论推导的方法建立了合金淬火态和退火态的β元素临界晶胞系数的计算模型,并在此基础上确立了α相与β相的体积分数的计算方法,从而实现了对Ti-Al-V-Fe合金中相体积分数的理论计算。本文以Ti-6Al-3V-1Fe合金为例,首先对合金内α相与β相的体积分数分别做了理论计算,继而利用真空非自耗电弧熔炼炉制备了Ti-6Al-3V-1Fe合金的铸锭,取样并进行热处理,最终利用X射线衍射法测定了Ti-6Al-3V-1Fe合金淬火态和退火态α相与β相的实际体积分数。对比发现,实验测定的结果与理论计算的结果较为吻合,说明建立的模型用于预测α相与β相两相的体积分数是切实可行的。     

Ti-15-3合金热变形实验研究

在Cleeble-1500热模拟机上对Ti-15-3合金试样进行了热压缩试验,根据压力应变曲线研究了该合金在高温时的流动特性,由金相观察分析了热变形参数对该合金组织的影响。此研究结果对确定Ti-15-3合金锻造工艺参数提供了重要依据。     

Dynamic Fracture of Ti-5553 Alloy in Taylor Impact Test

The dynamic fracture behavior of a new near-beta Ti-5Al-5Mo-5V-3Cr~(-1)Fe(Ti-5553)alloy under a high strain rate loading was investigated systemically using the Taylor impact test,over the impact velocity ranging from156 ms~(-1) to 256 ms~(-1).An optical microscope(OM)and a scanning electron microscope(SEM)were used to characterize the microstructure evolution.The experimental results have demonstrated that the velocity from deformation to fracture is 256 ms~(-1) for the alloy with anα+βduplex microstructure including more primaryαphase,while the velocity is 234 ms~(-1) for the alloy with a duplex microstructure including less primaryα phase.From the impact fracture morphologies,smooth and smeared surfaces and ductile dimple areas can be observed.The failure mode of the titanium alloy with both microstructures is adiabatic shear banding.According to the fracture analysis,the ductile fracture area with the dimple area in the alloy with much more primaryαphase were more than that with less primaryαphase.Compared to the duplex microstructure with less primaryα phase,Ti-5553 alloy with more primaryαphase exhibited a better capability to resist an adiabatic shear damage.     

Dynamic Tensile Behavior and Constitutive Modeling of TC21 Titanium Alloy

The dynamic tensile behaviors of a newly developed Ti-6 Al-2 Sn-2 Zr-3 Mo-1 Cr-2 Nb-Si alloy(referred as TC21 in China) over a wide range of strain rates from quasi-static to dynamic regimes(0.001-1 200 s~(-1)) at different temperatures were experimentally investigated. A split Hopkinson tension bar apparatus and a static material testing system were utilized to study the stress-strain responses under uniaxial tension loading condition. The experimental results indicate that the tensile behavior of TC21 titanium alloy is dependent on the strain rate and temperature. The values of initial yield stress increase with increasing strain rate and decreasing temperature. The effects of strain rate and temperature on the initial yield behavior are estimated by introducing two sensitivity parameters. The phenomenological-based constitutive model, Johnson-Cook model, is suitably modified to describe the rate-temperature dependent constitutive behavior of TC21 titanium alloy. It is observed that the modified model is in good agreement with the experimental data subjected to the investigated range of strain rates and temperatures.     

Grain size model for continuous dynamic recrystallization of titanium alloy in hot deformation

The continuous dynamic recrystallization(CDRX) through a progressive transformation of a subgrain structure into a grain structure with the increasing of misorientation occurred in the hot deformation of titanium alloy. A grain size model for CDRX of titanium alloy in hot deformation considering work hardening effect, dynamic softening effect and non-homogeneous deformation effect was established. The β grain size was described as functions of the deformation temperature, strain rate and strain by using the dislocation density as an internal state variable. The inside dislocation storage and dislocation annihilation,which respectively resulted from work hardening effect and dynamic softening effect, were described by the Kocks-Mecking and Picu-Majorell theories correspondingly. The dislocation density rate associated with non-homogeneous deformation effect was done in terms of the Ashby theory. The material constants in the present model were determined via genetic algorithm(GA)-based objective optimization technique. Applying the grain size model to the hot deformation of Ti-5Al-2Sn-2Zr-4Mo-4Cr, the maximum difference between the calculated and experimental β grain size was 8.2%. Moreover, the effect of deformation temperature and strain rate on the β grain size in the hot deformation of Ti-5Al-2Sn-2Zr-4Mo-4Cr was calculated, indicating that the β grain size increased with the increasing of deformation temperature and the decreasing of strain rate.     

片状钛酸钡颗粒的熔盐法制备及其形貌

为了得到有利于晶粒择优取向的片状钛酸钡形貌颗粒,采用合成出的片状模板原料,通过熔盐法制备了片状钛酸钡颗粒.首先,以碳酸钾、二氧化钛和钛酸锂为原料,在氯化钾熔盐中制备了具有类纤铁矿层状结构的钛酸盐（K0.8Ti1.73Li0.27O4）.经酸交换后,得到了片状钛酸（H1.07Ti1.73O4,HTO）颗粒.HTO是一种具有层间通道结构和良好的离子交换性的片状模板,以HTO和碳酸钡为原料,氯化钠和氯化钾为熔盐,在820℃保温5h得到纯相的钛酸钡,其颗粒形貌呈现为宽5～8μm、长10～15μm,厚度约1μm左右的片状形貌,而且这些片状颗粒是由1μm的小片状颗粒按特定晶向排列而成.结果表明以HTO为模板的原位反应机制起了主要作用,产生保持了片状HTO模板形状的片状钛酸钡颗粒.该方法有望为制备织构化陶瓷提供良好各向异性钛酸钡粉体.     

Microstructure and property of the Ti-24Al-15Nb-1.5Mo/TC11 joint welded by electron beam welding

The Ti-24Al-15Nb-1.5Mo alloy,in the as-forged and heat-treated states,was joined to the as-forged TC11 titanium alloy by electron beam welding with the heat inputs of 135 and 150 kJ/m.Then the microstructure and property of the Ti-24Al-15Nb-1.5Mo/TC11 welding interface were investigated.The results show that the phase constitution of the weld is not related to the heat input,and is mainly composed of α' phase.Moreover,the intermetallic phases of Ti2AlNb,MoNb,Nb3Al,and TiAl3 are formed in the weld zone.There...     

A New Method for Fractal Dimension Determination by STM at Nanometer Scale

A new method for determining the fractal dimension by STM at nanomeler scale has been proposed.Widerstrass- Mandelbrot fractal curves were used to verify the accuracy and reliability. The Computer simulation showed that fractal dimen- sion obtained with this method generally outran the traditional yard method. The new method has been applied to the fractal dimension determination of the fractures of Ti3Al and Ti-24Al-11Nb alloys. The results show that the fractal dimension of Ti-24Al-11Nb alloy is higher than that of Ti3Al, and it varies with the crark extending orientation.     

Effect of N on microstructure and mechanical properties of as-cast Ti-6Al alloy

Duetotheirhighspecificstrength,goodcorrosionresistance,goodhightemperatureproperties,titanium andtitaniumalloysareconsideredidealmaterialsforspace,oil,chemicalandmedicalindustries[1-3].They alsohavepotentialapplicationintheautomobileindus try[4-7].Titaniu…     

Effect of electropolishing on electrochemical behaviours of titanium alloy Ti-10V-2Fe-3Al

The electrochemical behaviours of titanium alloy Ti-10V-2Fe-3Al after electropolishing in a self-developed electrolyte in comparison with conventional grinding were studied by electrochemical impedance spectroscopy (EIS).Optical microscopy (OM),scanning electron microscopy (SEM),atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used to evaluate the surface characteristics of the alloy.It was found from the EIS experiments that the polarization resistance (Rp) was increased,the double layer capacitance (Qc) was decreased and the electrochemical impedance of the alloy was enhanced by electropolishing.The electropolished surface was flat,smooth and bright and its roughness was 3.310 nm.To underline the advantage of electropolishing process against grinding to provide the anodic oxidation process with a higher quality substrate,the ground and electropolished titanium alloys were anodized in parallel under the same conditions.The corrosion behaviours of the two kinds of anodized titanium alloys were compared.It was revealed that electropolishing generated a high quality substrate and improved the corrosion resistance of anodic oxide film formed on titanium alloy Ti-10V-2Fe-3Al.Furthermore,the mechanism of electropolishing improving the corrosion resistance of the anodic oxide film was proposed.