有机介质中TiO2纳米管阵列的制备及生物活性研究

用含氟的有机溶剂二甲基亚砜(DMSO)作电解液,通过电化学阳极氧化法,在纯钛片表面制得长度达微米级TiO2纳米管阵列.研究了TiO2纳米管阵列形貌和晶相的转变,并通过模拟体液浸泡研究了其生物活性.采用扫描电镜(SEM) 、X射线衍射(XRD)、傅里叶红外(FT-IR)和透射电镜(TEM)分别对纳米管阵列的形貌和物相进行表征.结果表明:在40 V电压下,阳极氧化24 h,可以制得长12 μm,外径170 nm的无定形氧化钛纳米管阵列.300 ℃热处理后,TiO2纳米管表面开始收缩,由无定形向锐钛矿型转变, 温度升到600 ℃时,氧化钛纳米管表面形成较深的沟壑,锐钛矿型开始向金红石型转变,700 ℃热处理后,TiO2纳米管阵列被破坏.生物活性研究表明,具有TiO2纳米管阵列的钛片经热处理后具有良好的生物活性,能在模拟体液浸泡14 d诱导生成厚达13 μm的碳磷灰石层.     

TiO2纳米管阵列的热稳定性及生物活性的研究

通过电化学阳极氧化法，在纯钛片表面制备得到TiO2纳米管阵列。研究了TiO2纳米管阵列的热稳定性，并通过模拟体液浸泡研究了其生物活性。采用扫描电镜（SEM）和X射线衍射（XRD）分别对纳米管阵列的形貌和物相进行表征。结果表明，当热处理温度为300℃时，TiO2纳米管由无定形向锐钛型转变，温度升到500℃时转变为金红石型，升到600℃时TiO2纳米管阵列出现坍塌，700℃热处理时其形貌完全被破坏。生物活性研究表明，具有TiO2纳米管阵列的钛片经氢氧化钠溶液活化后具有良好的生物活性，能在模拟体液中诱导生成磷灰石。     

纯钛表面纳米化后沉积铜在润滑条件下的摩擦行为研究

目前钛表面进行纳米结构化改性受到了广泛关注,但是关于钛表面纳米结构化后的摩擦学性能研究报道较少。为了改善钛的摩擦学性能,采用微弧氧化法在纯钛表面制备了Ti O2孔径在400 nm左右的介孔层,利用电化学脉冲沉积法将铜沉积在介孔层上。通过摩擦磨损试验考察了改性层在润滑状态下的摩擦磨损行为,利用扫描电镜对改性层的表面形貌、磨损磨斑形貌进行表征。结果表明,Ti O2纳米介孔层对沉积铜的粒径大小、致密度具有一定影响;微弧氧化沉积铜试样的磨损机制主要表现为犁沟磨损;微弧氧化试样制备的表层铜膜具有优异的减摩性能。     

超声表面滚压处理铝合金钻杆的高温摩擦学性能

为了提高铝合金钻杆的耐磨性,利用超声表面滚压技术(USRP)对2219铝合金钻杆材料进行表面强化处理。采用透射电子显微镜(TEM)表征了USRP处理后铝合金的晶粒大小,采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)和显微硬度计测量了强化层的微观形貌、相组成和显微硬度,并利用高温摩擦磨损试验机评价了试样的摩擦学性能,对磨副为玛瑙球。结果表明,经USRP处理后2219铝合金表面形成了纳米晶和厚度约500μm的塑性强化层,表面硬度由120 HV0.05提高至190 HV0.05。随着摩擦磨损试验温度的升高,未处理试样和USRP试样的平均摩擦因数和磨损率都逐渐增大。在相同试验温度下,USRP试样的平均摩擦因数和磨损率均小于未处理试样的。未处理试样和USRP试样的磨损机制主要是黏着磨损和磨粒磨损。     

钛离子注入对AZ31镁合金表面力学性能及耐蚀性的影响

对AZ31镁合金表面进行了钛离子注入试验,研究了钛离子注入对于镁合金表面改性层的影响。通过XRD、XPS研究了改性层的相结构和元素分布,通过硬度和摩擦磨损试验研究了改性层的力学性能。结果表明,经过钛离子注入之后,改性层中并无新相生成;当注入剂量为2.5×1017ion/cm2时,改性层深度可以达到160 nm,改性层中Ti呈高斯分布,存在形式从外到内为TiO2向Ti过渡。经过钛离子注入之后,镁合金表面硬度大大提高;改性层的摩擦因数并没有降低,但是耐磨性有所提高。随钛离子注入剂量的增加,改性层的耐腐蚀性能呈先上升后下降趋势。     

二氧化钛纳米管阵列电极的光电化学性能研究

采用阳极氧化法在钛片上制备了垂直排列的TiO2纳米管阵列，利用SEMXRD对纳米管阵列的形貌和结构进行了表征，并通过电化学交流阻抗谱、光照开路电位谱和瞬态光电流谱技术对纳米管阵列电极的光电化学特性进行了研究。实验结果表明，TiO2纳米管的内径约为90nm，管壁约为10nm，纳米管阵列厚度约为500nm，经600℃退火处理后，转变为锐钛矿型与金红石型的混晶结构。光电测试结果表明，随着退火温度升高，TiO2纳米管阵列电极的界面电荷转移电阻减小，光电流逐渐增大，光照开路电压增大，至600℃达到最大，当退火温度继续升高，电极的光电性能急剧下降。与TiO2纳米多孔膜电极相比，光电性能显著提高，这主要归因于TiO2纳米管阵列更大的孔隙率和比表面积。     

纯钛表面二氧化钛纳米管阵列结构特征的研究

采用阳极氧化技术在纯Ti表面制备出有序的TiO2纳米管阵列,并通过SEM,XRD,XPS对TiO2纳米管阵列进行表征。结果表明,阳极氧化时间对纳米管的形成有较大的影响。在外加电压为20V,阳极氧化时间为20min时,可制备出长度约480nm、内径约89.90nm、壁厚约7.4nm的TiO2纳米管阵列。经450℃热处理后,可得到锐钛矿型的TiO2纳米管阵列,钛元素以Ti4+氧化态处于八面体的环境中,Ti2p3/2的结合能为459.3eV。     

原位合成Al2O3增强铝基复合材料的摩擦磨损性能

通过采用粉末冶金和原位合成技术相结合的近净成形技术制备Al-5％Si-Al2O3复合材料,并运用M一2000摩擦磨损试验机对该复合材料的摩擦磨损性能进行研究。通过单一变量比较法分析载荷和滑动速度对Al-5％Si-Al2O3复合材料摩擦磨损性能的影响,同时对长时间连续磨损下该材料的摩擦性能进行研究。通过扫描电子显微镜对Al-5％Si-Al2O3复合材料的磨损表面进行观察,并分析其磨损机制。结果表明,随着载荷的增大,试样的磨损量和摩擦因数均增加;随着滑动速度的增大,试样表面的升温使得产生氧化层的速率增加,试样的磨损量和摩擦因数均减少。在长时间的连续磨损过程中,由于初始时发生粘着磨损,试样的摩擦因数随着滑动距离的增大而增大。然后,试样表面氧化层的形成和破坏趋于动态平衡,试样表面相对稳定,其摩擦因数也随之趋于平稳。铝基复合材料的磨损机制主要为磨粒磨损、粘着磨损和氧化磨损。     

脉冲渗氧对工业纯钛表面摩擦磨损性能的影响EI北大核心CSCD

采用脉冲渗氧的方法在不同温度、时间下对工业纯钛进行渗氧处理,以改善其在应用过程中的耐磨损性能。采用X射线衍射仪(XRD)、扫描电镜(SEM)、纳米压痕仪和摩擦磨损试验机分别对试样表层的特征峰强度、形貌特征、压痕硬度、表面摩擦因数及磨痕截面积进行测试。结果表明:经脉冲渗氧处理在工业纯钛试样表面形成氧化层和氧扩渗层;与连续渗氧试样和原始试样相比,700℃脉冲渗氧6 h试样的表面硬度最大,为15.39 GPa,约为同等参数下连续渗氧试样的1.7倍和原始试样的7.3倍;800℃脉冲渗氧4.5 h试样的摩擦因数和磨痕截面积最小,分别为0.24和317.44μm^(2).。试样的黏着磨损被明显削弱,耐磨损性能得到提高。     

氧化钛纳米管阵列的表面聚集控制及光电化学特性

采用阳极氧化法在有机介质中制备垂直排列的厚度达百微米的TiO2纳米管阵列,重点考察TiO2纳米管表面形貌特性的控制,以期从微观修饰角度来提高TiO2纳米管阵列膜的光电化学性能;在此基础上,考察不同处理条件下的TiO2纳米管阵列膜的光电化学特性。实验结果表明:采用无水乙醇作为超声液并结合二次蒸馏水进行漂洗能彻底清除纳米管表面聚集堵塞部分,得到清洁、规整有序的纳米管阵列表面,且不破坏纳米管阵列膜的最佳超声振动时间为20～30s。在对纳米管阵列的表面形貌特性进行控制后,采用一步阳极氧化法+无水乙醇超声制备的样品经500℃退火在全谱段的光转换效率达到1.48%,证实对纳米管阵列的表面形貌特性实施控制能有效提高其光电化学性能。     

Tribological properties of 2024 aluminum alloy plasma-based ion implanted with nitrogen then titanium

1　INTRODUCTIONOwingtolowdensityandhighspecificstrength ,aluminumanditsalloysareextensivelyusedinmanyfields ,especiallyinaviationandspaceindustry .Butlowhardnessandlowwearresistanceoftenlimittheirengineeringapplications .Surfacemodificationforalu minumanditsalloysbyionimplantationoffersthepossibilityofwideningtheirapplicationswherehighwearresistanceandlowdensityarerequired[15] .Sincenitrogenionisconvenienttoobtainandeasytocontrol,andAlNhasexcellentmechanicalproperties ,nitrogenionimplant…     

TC21钛合金表面无氢渗碳层耐磨性分析

将经过预处理的TC21钛合金试样置入真空渗碳炉中进行渗碳。分别用X射线衍射(XRD)、扫描电子显微镜(SEM)及显微维氏(HV)硬度仪、摩擦磨损试验机,对渗碳层的物相结构、组织形貌、硬度和耐磨性进行分析。结果表明:经渗碳处理后,通过渗层组织可判定没有氢化物,XRD未检测发现氢化物及含H相,出现了Ti C等碳化物相,表面硬度提高了2.66倍。渗碳前Ti/Ti对磨的摩擦系数约为0.6,渗碳后Ti C/Ti C的摩擦系数约为0.23,渗碳体与原始表面的摩擦系数介于二者之间。TC21钛合金对磨两方经渗碳处理,改善了摩擦性能;如Ti/Ti部件对磨时,渗碳方可提高耐磨性,非渗碳件在与渗碳件对磨中,加剧了非渗碳件的磨损。渗碳也改变了TC21钛合金部件之间的摩擦状态,TC21基体由Ti基/Ti球之间的粘着磨损变为Ti基/Ti C球磨粒磨损+剥层磨损。     

Tribological properties of TiAlN-coated cermets

Ti(C,N)-based cermets were coated with TiAlN using multi-arc ion plating technology. Sliding wear tests were performed on the coated cermets. The microstructure and morphologies of the coated cermets before and after friction and wear tests were characterized. The results show that the TiAlN coating surface was smooth and its root mean square roughness was 16.6 nm. The hardness (HK) of TiAlN coating layers reached approximately 3200 and the critical load (L _c) under which the coating failure occurred was 59 N. The sliding wear test results show that the friction coefficients of the TiAlN-coated cermets were lower than that of the cermets without any coating. Under the same load, the adhesion phenomenon of the counterpart materials on the specimens was improved and the mean friction coefficient increased with increasing sliding velocity. When the sliding velocity was 0.26 m·s⁻¹, the mass of the coated cermets reduced. At the same sliding velocity, the average friction coefficient of the TiAlN-coated cermets was lower under a higher load. The wear mechanisms of the TiAlN-coated cermets were mainly adhesive and abrasive wear.     

Surface engineering techniques used for improving the mechanical and tribological properties of the Ti6A14V alloy

The microstructure, mechanical and tribological properties of composite intermetallic layers of the Ti-Al system were investigated. The layers on the two-phase (α + β) Ti6Al4V titanium alloy were obtained using the hybrid method, which consist of two stages. First, the titanium alloy was covered with aluminum layer by magnetron sputtering. In the second stage, coated specimens were treated under glow discharge conditions. The surface treatment makes it possible to obtain the diffusional composite layers which considerably improve the mechanical and wear resistance properties of the material. These properties cannot be achieved using simple methods of surface engineering. The chemical and phase composition of the composite intermetallic layers was investigated. It has been shown that the hybrid method significantly increases the hardness and wear resistance of the titanium alloy and can widen the range of application of the material. Because of the diffusional character of the intermetallic layers they possess good adhesion to the titanium substrate.     

Ti13Nb13Zr 合金离子氮化层的摩擦磨损性能研究

目的提高医用钛合金的耐磨损性能。方法应用等离子渗氮技术在Ti13Nb13Zr基材上制备改性层,并对改性层组织、成分及硬度进行测试。利用往复磨损试验机研究改性层在干摩擦条件下的摩擦磨损性能,并与未处理的基材进行对比。结果 Ti13Nb13Zr合金表面经渗氮后形成致密均匀的改性层,硬度高达1110HV0.025,改性层的磨损体积约为基材的1/23。结论等离子渗氮技术有效地改善了Ti13Nb13Zr合金的摩擦磨损性能。     

选区激光熔化成形Ti6Al4V合金摩擦磨损性能的各向异性

基于选区激光熔化技术制备了Ti6Al4V钛合金,研究了不同成形表面(XOY、XOZ)和不同载荷(20、40、60、80 N)对Ti6Al4V合金摩擦磨损性能的影响。通过摩擦系数(COF)结合磨损体积损失对不同成形面的摩擦磨损性能进行评估,采用光学显微镜(OM)、三维轮廓测量仪等设备对磨损轨道的形态和磨损机理进行表征。结果表明:相比XOZ面,XOY面在法向载荷为20N时其磨损体积减少了0.27×10-5 mm3,平均摩擦系数更小;而当载荷大于20N时,XOY面的磨损体积和平均摩擦系数均大于XOZ面。磨损轨道犁槽的深度和宽度随着载荷的增加而增加,犁槽呈现出明显的剥落行为,轨道处分布着块状的"粘合剂",发生着粘着磨损和氧化磨损。从摩擦系数、磨损体积、微观形态的角度定量反映出SLM成形Ti6Al4V合金的XOZ面比XOY面具备更优异的摩擦磨损性能,只有在低载荷下XOY面才表现出更加耐磨的特性。     

Tribological properties of titanium aluminides coatings produced on pure Ti by laser surface alloying

Titanium aluminides coatings were in-situ synthesized on a pure Ti substrate with a preplaced Al powder layer by laser surface alloying. The friction and wear properties of the titanium aluminides coatings at different normal loads and sliding speeds were investigated. It was found that the hardness of the titanium aluminides coatings was in the following order: Ti₃Al coating > TiAl coating > TiAl₃ coating. Friction and wear tests revealed that, at a given sliding speed of 0.10 m/s, the wear volume of pure Ti and the titanium aluminum coatings all increased with increasing normal load. At a given normal load of 2 N, for pure Ti, its wear volume increased with increasing sliding speed; for the titanium aluminides coatings, the wear volume of Ti₃Al coating and TiAl coating first increased and then decreased, while the wear volume of TiAl₃ coating first decreased and then increased with increasing sliding speed. In addition, the friction coefficients of pure Ti and the titanium aluminides coating decreased drastically with increasing sliding speed. Under the same dry sliding test conditions, the wear resistance of the titanium aluminium coatings was in the following order: Ti₃Al coating > TiAl coating > TiAl₃ coating.     

Tribological properties of TiA1N-coated cermets

Ti(C,N)-based cermets were coated with TiAlN using multi-arc ion plating technology. Sliding wear tests were performed on the coated cermets. The microstructure and morphologies oftbe coated cermets before and after friction and wear tests were characterized. The results show that the TiAlN coating surface was smooth and its root mean square roughness was 16.6 nm. The hardness (HK) of TiAlN coating lay-ers reached approximately 3200 and the critical load (Lc) under which the coating failure occurred was 59 N. The sliding wear test results show that the friction coefficients of the TiAlN-coated cermets were lower than that of the cermets without any coating. Under the same load, the adhesion phenomenon of the counterpart materials on the specimens was improved and the mean friction coefficient increased with in-average friction coefficient of the TiAlN-coated cermets was lower under a higher load. The wear mechanisms of the TiAIN-coated cermets were mainly adhesive and abrasive wear.     

氮等离子焰纯钛表面氮化

利用改造TIG焊枪通入N2+Ar混合气体产生氮等离子焰,在大气中直接加热纯钛试件,使基体表面的Ti元素与等离子焰中的N元素相互作用形成氮化层.主要研究了氮化温度和氮化时间对纯钛表面氮化层组织及性能的影响规律,得到了较佳氮化工艺参数.采用金相显微镜、扫描电镜和X射线衍射等检测方法,分析了氮化层的形成机理、表面及截面微观形貌,并测试了表面显微硬度及耐磨性.结果表明,氮化层主要由TiN相组成,组织均匀、致密,与基体为良好的冶金结合,有效地改善了纯钛基体的耐磨性.     

不锈钢等离子渗铪并固体渗碳后的高温摩擦性能

目的提高0Cr18Ni9Ti奥氏体不锈钢的抗高温摩擦性能。方法利用等离子渗金属技术在不锈钢表面等离子渗铪,之后进行固体渗碳,在HT-500型球-盘磨损试验机上进行高温摩擦磨损实验,分析其高温摩擦性能及摩擦机制,并与不锈钢基体试样及不锈钢渗铪试样进行对比。结果渗铪试样的渗层厚度约为45μm,渗铪+渗碳试样的渗层厚度达100μm。渗铪+渗碳层弥散分布着许多粒状和短棒状碳化物颗粒,碳化物类型主要为MC型、M7C3型和M23C6型。基材的摩擦曲线波动起伏大;渗铪试样的摩擦系数较大,但磨损微观表现平稳;渗铪+渗碳试样的摩擦系数最小。磨损失重由大到小依次为:基材渗铪试样渗铪+渗碳试样。在300,500℃下,渗铪试样的耐磨性相对基材分别提高至1.47倍和1.94倍,渗铪+渗碳试样分别提高至2.13和2.28倍。基材划痕尺寸宽且较深;渗铪试样的表面硬度提高,且摩擦磨损过程中出现了合金氧化物;渗铪+渗碳试样的表面硬度高,基体韧性好,仅出现了很浅且窄的磨痕。结论通过等离子渗铪及离子渗铪+固体渗碳,均能提高不锈钢表面的抗高温摩擦性能,相比之下,离子渗铪+固体渗碳的效果更好。