丙烯酸酯齐聚物和微凝胶增韧环氧粘接件的湿热耐久性

以铝合金LY12CZ为基材 ,以丙烯酸酯齐聚物和微凝胶分别改性环氧树脂粘合剂 ,进行了湿热老化试验和楔子试验 ,观察了粘接件在湿热条件下剪切强度的变化和耐久性。结果表明丙烯酸酯齐聚物作为增韧剂 ,经湿热老化试验后 ,PACR1、PACR2有较好的湿热老化性 ,剪切强度保留率分别为 81.7%、80 .0 % ,而且PACR2耐久性较好 ;微凝胶作为增韧剂 ,微凝胶 1# 有较好的湿热老化性和耐久性     

硅烷化处理铝合金的粘接耐久性研究

为了考察铝合金硅烷化处理对粘接耐久性的影响,用高强度铝合金YL12作为基材,用HY-97 环氧结构胶粘剂把硅烷化处理和作为参考作用的铬酸盐与表面砂光处理的铝合金件胶接在一起,同时在温度为60℃,95％的相对湿度的湿热恒温箱中进行。16d的楔子试验,用光电子X-射线(XPS)分析了粘接断裂面,结果表明,仅作砂光处理的粘接件的裂纹扩展总长度最长,而硅烷化和铬酸盐处理的这两个粘接件的裂纹扩展总长度基本相当,分析表明,硅烷化处理粘接件的裂纹断裂能略高于铬酸盐处理的裂纹扩展能。     

变形链球菌对医用钛合金Ti-6Al-4V腐蚀行为研究

采用电化学法、扫描电镜法研究了钛合金Ti-6Al-4V在变形链球菌作用下的腐蚀性。将变形链球菌菌液接种至液体培养基中进行培养两天,然后把钛合金金属与培养基菌液一起共同培养,同时设置无菌组为对照组,同时进行电化学测试。腐蚀30天后,用扫描电镜观察。电化学实验结果显示,含有变形链球菌的自腐蚀腐蚀电位比无菌组低,腐蚀电流密度比无菌组大,扫描电镜结果显示,变形链球菌组的合金表面粗糙度更大。实验结果表明,变形链球菌能增加钛合金Ti-6Al-4V的腐蚀倾向和腐蚀速率。     

复合材料湿热老化行为研究及其耐久性预测

本文研究了湿热老化环境对复合材料吸湿性能的影响,分析了材料弯曲强度、弯曲模量随老化时间的变化关系.研究结果表明,在湿热老化初期,材料吸湿变化满足Fickian扩散定律,在湿热老化后期材料增重率出现偏离Fickian定律的现象;随湿热老化时间的增加,复合材料的弯曲强度、弯曲模量均有不同程度的下降,并且在湿热老化后期复合材料弯曲强度受界面性能的影响显著.建立了复合材料力学性能与湿热老化时间的定性/定量关系,在耐久性预测模型中引入界面参数的概念,拟合结果与实测值较为接近.     

阳极电压对钛合金微弧氧化膜性能的影响

摘要：在不同阳极电压下对Ti-6Al-4V合金进行了微弧氧化处理。考察了阳极电压对氧化膜生长速率、表面形貌、相组成及硬度的影响，并对其摩擦学性能进行了表征。研究结果表明，随着阳极电压的升高，氧化膜表面微孔数量减少，表面微孔孔径、粗糙度、氧化膜生长速率均增大，表面硬度先增大后减小。微弧氧化膜主要由Al3TiO5相和金红石TiO2相组成，随着阳极电压的升高，两者相对比例逐渐增大。阳极电压对微弧氧化膜与钢球的摩擦系数影响不大，但对磨损率影响较大，磨损率随阳极电压的升高先减小后增大，氧化膜均具有较好的耐磨性。     

Ti-6Al-4V钛合金长寿命疲劳试验

研究了Ti-6Al-4V在室温空气环境下的疲劳性能,获得疲劳寿命为107下的Goodman曲线.结果表明,用简化的Goodman直线代替Goodman曲线对于Ti-6Al-4V钛合金偏于保守.对断口形貌的观察表明应力比R在0附近时裂纹萌生于内部,而当应力比接近-1和1时裂纹萌生于表面.另外,研究了估算Ti-6Al-4V在不同应力比的疲劳强度估算公式,得出Ti-6Al-4V厚板和挤压件缺口试样估算公式的系数,分别为1.422和1.042.     

Ti-6Al-4V钛合金脉冲阳极氧化工艺

研究了Ti-6Al-4V钛合金脉冲阳极氧化工艺,并对影响阳极氧化膜厚度的主要因素(如温度、电流密度、时间等)进行了研究,得到了满足膜厚要求的工艺参数。将优化得出的工艺参数应用于零件的仿形试件生产,得到厚度均匀的阳极氧化膜,并对其表面形貌、成分等进行了分析。     

Ti-6Al-4V在氯离子环境中的耐蚀性研究

针对腐蚀性环境油气田开发实际,利用高温高压釜,研究Ti-6Al-4V在盐酸溴化锌加重溶液中的失重腐蚀速率,并利用体式显微镜及扫描电镜对试样进行腐蚀形貌观察和腐蚀膜成份分析,试验结果表明:在本文试验条件下,Ti-6Al-4V的腐蚀速率为0.1089mm/a;Ti-6Al-4V蚀坑较浅且呈开放式,未被腐蚀产物所覆盖;腐蚀膜中含有一定量Cl元素,表明Cl-是参与腐蚀反应的主要元素。     

Ti-6Al-4V钛合金环保型阳极氧化及封闭处理研究

选用Ti-6Al-4V钛合金作为基体在环保型电解液中制备阳极氧化膜,然后分别浸没在沸水、氟锆酸铵溶液、乙酸钙溶液中对阳极氧化膜进行封闭处理。采用扫描电镜、能谱仪和X射线衍射仪表征和分析未封闭及封闭处理后阳极氧化膜的微观形貌、化学成分与物相结构,并配制酸性氯化钠溶液作为腐蚀介质,研究未封闭及封闭处理后阳极氧化膜的耐腐蚀性能。结果表明：与未封闭阳极氧化膜相比,在沸水、氟锆酸铵溶液、乙酸钙溶液中封闭处理后阳极氧化膜中微孔数量减少,化学成分发生变化,耐腐蚀性能进一步提高,但封闭处理未影响阳极氧化膜的物相结构。在乙酸钙溶液中封闭过程中发生化学反应,生成水合二氧化钛、氢氧化钛、氢氧化钙和钛酸钙等多种产物,达到协同封闭效果,赋予封闭处理后阳极氧化膜良好的表面致密性,其耐腐蚀性能好于在沸水、氟锆酸铵溶液中封闭处理后阳极氧化膜,对钛合金的防护作用更强。     

湿热老化对环氧灌封胶粘接性能的影响研究

分别制备出脂肪胺、芳香胺、酸酐和潜伏性固化体系的环氧灌封胶产品。利用高加速湿热试验,研究了高加速湿热老化环境下,此四种固化体系环氧的吸湿性能和拉伸剪切性能的衰减情况,并研究了高加速湿热老化环境,对脂肪胺固化环氧树脂灌封胶对不同基材、不同填料下的拉伸剪切的影响。结果表明,芳香胺固化的环氧,在高加速湿热老化环境(120℃,100%RH)下老化480h,拉剪强度衰减最小,约30%。并且,通过添加片状铝粉或硅微粉,芳香胺为固化剂,有望制得耐湿热性能较好的环氧灌封胶产品。     

Growth of TiO2-based nanotubes on Ti–6Al–4V alloy

The possibility of tailoring titania nanotube films on Ti–6Al–4V alloy is investigated using electrolytes based on NH₄H₂PO₄ with the addition of different concentrations of NH₄F. Several morphologies from high aspect ratio nanotubes to barrier layers are achieved by the control of the electrolyte composition, regarding its pH and fluoride concentrations. The morphology and composition of the anodic layers were evaluated by scanning and transmission electron microscopy, Rutherford backscattering spectroscopy (RBS) and Wavelength dispersive X-ray fluorescence spectroscopy.The formation efficiency and the fluoride ions content in the nanotubes depend on the F concentration in the electrolyte. The higher concentration of fluoride ions in the electrolyte promotes an increase of the F incorporated in the nanotubes, about 12 at.% but, reduces the nanotube formation efficiency. However, no significant presence of phosphorus was detected into the films by means of the above-mentioned analytical techniques.     

A novel potential ceramic material for melting Ti6Al4V alloy: A solid solution of BaZrO3 and CaZrO3

Vacuum induction melting technology is a promising low-cost method for producing high-quality titanium alloy. The key challenge lies in the development of ceramic crucibles with excellent chemical stability for titanium alloy corrosion. In this work, (Ba_1−x,Ca_x)ZrO₃ ceramic was designed and synthesised via pressureless sintering of a mixture of BaZrO₃ and CaZrO₃ powders. X-ray diffraction and scanning electron microscopy analyses showed that a new phase, Ba_0.8Ca_0.2ZrO₃, was formed after heat treatment at 1700 °C. Vacuum induction melting experiments of the Ti6Al4V alloy were carried out using a Ba_0.8Ca_0.2ZrO₃ crucible. Compared with the original BaZrO₃ crucible and CaZrO₃ crucible, the erosion layer of the Ba_0.8Ca_0.2ZrO₃ crucible was significantly reduced by approximately 85∼92.5%. The interface between the crucible and the alloy was clearly visible, and there was no obvious element diffusion between the alloy and the material. This shows that Ba_0.8Ca_0.2ZrO₃ is highly promising as a crucible material for melting Ti6Al4V alloys.     

Voltammetric stability of anodic films on the Ti6Al4V alloy in chloride medium

The biocompatibility and mechanical integrity of Ti and Ti6Al4V alloy can be affected by corrosion processes. This paper presents studies on the stability of anodic oxide films on Ti6Al4V and Ti in chloride medium. The oxides were grown potentiodynamically up to 8.0 V in the phosphate buffer saline (PBS) solution (pH 6.8) at 25 and 37 °C. The morphology of the obtained anodic oxides and the type of corrosion that occurred were analyzed by SEM–EDS. The Ti6Al4V alloy presented less corrosion resistance than pure Ti. Elemental analyses showed that the decrease of the alloy corrosion resistance is due mainly to the corrosion of Al.     

Barium titanate-based bilayer functional coatings on Ti alloy biomedical implants

Piezoelectric coatings have the ability to functionalise conventional structural materials into responsive devices. Today, piezoelectric coatings have been applied to both rigid and flexible substrates for sensing, actuating, and energy harvesting applications. We envision (Ba,Ca)(Zr,Ti)O₃ (BCZT) piezoelectric coatings for biomedical use such as in vivo sensing or electrical cell stimulation. However, reliable processing routes for the development of BCZT ceramics as a functionalisation coating on biomedical substrates are required. In this work, the synthesis of bilayer BCZT and CaTiO₃ ceramic coatings on Ti6Al4V metal substrates via spray-deposition and heat-treatment was investigated. For thin coatings, reactions at the metal/ceramic interface led to the development of a porous interface reaction region partly consisting of CaO. The hygroscopicity of CaO affects the adhesion of the coating to Ti6Al4V at ambient conditions. Minimisation of the kinetic contributions to these interface reactions were achieved by increasing the coating thickness.     

Micro-arc oxidation of bioceramic coatings containing eggshell-derived hydroxyapatite on titanium substrate

In the present study eggshells-derived hydroxyapatite (EHA) coatings were successfully produced on Ti6Al4V substrates using micro-arc oxidation process (MAO) at various concentrations of EHA (i.e. 1, 1.5 and 2 g/L) in an electrolyte consisting of tri-sodium orthophosphate. The attributes of the coatings were determine by X-ray diffraction, attenuated total reflectance-fourier transform infrared spectroscopy, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy. The adhesion strength was evaluated using micro scratch tester, while the corrosion behavior of the MAO-coated substrates in phosphate buffer solution was determined by an electrochemical method. The results showed that as the EHA concentration increased, this was accompanied by a reduction in the porosity due to the formation of a dense and thick coating layer. This has also resulted in an increased in the surface roughness and degree of crsytallinity of the HA phase. The MAO-coated substrate prepared with 1.5 g/L EHA concentration exhibited a well-formed coating layer with improved adhesive strength and excellent corrosion resistance. The mechanism of EHA-coating formation as well as the enhanced corrosion resistance of the coated substrates were discussed. This research shows the viability of using calcium-rich waste eggshells to produce phase pure HA suitable for coating on Ti6Al4V substrate using MAO method.     

热处理气氛对溶胶-凝胶法合成纳米羟基磷灰石涂层的影响

采用溶胶凝胶法(sol-gel)在钛合金(Ti6Al4V)基材表面合成了纳米结构的羟基磷灰石(HA)涂层,利用扫描电镜和X-射线衍射仪分析了涂层的组成和结构,采用划痕仪测定了涂层的结合强度。结果表明:用sol-gel法成功合成了均匀无开裂的HA涂层,HA晶粒尺寸为33-60nm。热处理气氛对涂层的成分和结构有直接影响,氮气保护700℃下合成的涂层是单一的HA成分,和基材结合强度较高;而空气中700℃时Ti6Al4V基材会被氧化生成TiO(2金红石型),因此合成的是HA/TiO2复合涂层,产生氧化层会严重破坏涂层与基材的结合强度。     

Effect of sintering on the microstructure and mechanical properties of alloy titanium-wollastonite composite fabricated by powder injection moulding process

Composite biomaterials are in high demand in the medical field of today. The combination of bioactive wollastonite (WA) glass ceramic with the biocompatibility of alloy titanium (Ti6Al4V) could be a good candidate for implant applications. The rheological properties of Ti6Al4V/WA feedstock show a pseudoplastic behaviour with low activation energy. The feedstock was successfully injected as a green part with no defects. The green part was solvent debound for 6?h in heptane and thermal debound in an argon environment for 1?h. The brown part was successfully sintered at 1300?°C for 3?h with 5?°C/min heating and cooling rates. The average sintered density was 4.12?g/cm³; which is 97.5% from the theoretical density. The highest Young's modulus obtained was 18.10?GPa; which is in the range of human bone strength. EDX analysis shows that by increasing sintering temperature, the level of oxygen decreased. Cell viability test shown an absorbance increased with days increasing indicated that the cellular were proliferated on the composite Ti6Al4V/WA composite which also proved that the composite was non-toxic. This indicates that the Ti6Al4V/WA composite is suitable for bone implant applications.     

Non-destructive measurement of residual stress distribution as a function of depth in sapphire/Ti6Al4V brazing joint via Raman spectra

The residual stress distribution as a function of depth in a sapphire/Ti6Al4V brazing joint is non-destructively measured using Raman Spectra for the first time. A modified method that is suitable for brazing joints is developed to deconvolute the actual residual stress value in each depth from the measured averaged stress value. The measured in-plane residual stress is compressive and increases non-linearly from the surface to the interface. While the out-of-plane residual stress is compressive; it increases from the surface to the interface and peaks at a distance of 150?µm from the sample surface. Then the stress begins to decrease and becomes tensile stress, which increases to the interface. This method can also be applied to other brazing/ diffusion bonding joint with a transparent substrate.