抗菌仿生多孔钛植入体的成骨性能（英文）

采用冷冻铸造和热氧化法制备一种新型兼具抗菌功能和良好骨整合性能的表面改性仿生多孔钛植入体。通过细胞增殖实验、碱性磷酸酶(AKP)活性水平测定实验、X线检测及骨硬组织切片等体内外成骨实验方法评价多孔钛植入体的骨整合性能。结果显示,随着植入体与体外细胞共培养时间的延长,表面纳米改性后多孔钛实验组的体外细胞增殖、分化活性水平较未表面纳米改性的多孔钛和致密钛对照组明显升高(P0.05);随着在动物体内植入时间的延长,处理和未处理多孔钛实验组孔隙中有骨长入和成骨现象,而且成骨细胞在处理组孔隙中分化程度更加成熟。抗菌仿生多孔钛植入体能与骨组织形成牢固的生物性骨嵌合,具有良好的骨整合性能。     

基于TPMS结构的多孔钛制备与表征

多孔钛因具有与人体骨组织相近的弹性模量和允许骨长入的孔隙结构而备受关注。其孔隙结构特征不仅影响骨长入效果,而且决定了多孔钛的力学性能。通过三周期极小曲面(triply periodic minimal surfaces,TPMS)隐函数参数的精确调控可以构建出理想的孔隙结构模型。本实验针对TPMS模型中常用的G单元模型,研究了G单元模型隐函数参数对孔隙率、孔径、杆径等孔隙结构特征的影响规律,设计出了孔隙率约为77%,孔径分别为300(G300)、500(G500)微米的均质孔隙结构;模仿自然长骨径向梯度结构模型,构建了相应的G单元仿生梯度孔隙结构。采用选区激光熔化(SLM)增材制造技术制备了相应的多孔钛样件,利用数字显微镜和扫描电镜观测多孔钛的孔隙结构特征,发现SLM多孔钛实测孔隙率低于设计孔隙率,实测孔径小于设计值,实测杆径大于设计值。力学性能检测结果显示,G300和G500多孔钛弹性模量分别为2.04和3.12GPa,其最大抗压强度分别为63.5和103.5MPa,梯度孔隙结构多孔钛弹性模量和最大抗压强度分别为6.3 GPa和186.9 MPa。研究结果表明,G单元梯度孔隙结构多孔钛是一种理想的承重部位骨缺损修复体。     

纤维烧结多孔钛及其表面生长仿生Ca-P涂层

采用钛纤维烧结法制备了多孔钛，并应用混合碱-热处理对其表面进行活化处理，然后在过饱和钙磷溶液中进行表面钙磷涂覆。测试了多孔钛的压缩性能，分析了涂层的形貌、元素含量和相组成。结果表明，制备的多孔钛为三维贯通结构，孔隙度在29％～84％，孔隙尺寸为100～800gm。当孔隙度为55％～60％时，压缩屈服强度为150～230MPa，弹性模量为4．0～4．2GPa，与骨组织相近。经表面钙磷涂覆处理的多孔钛在模拟体液中浸泡3天后，内外孔壁均被类骨磷灰石覆盖，表现出良好的诱导骨生长特性。     

纳米针状表面改性的仿生多孔钛植入体及体外成骨性能（英文）

通过冷冻铸造和热氧化法制备一种新型兼具抗菌功能和良好骨整合性能的纳米针状表面改性仿生多孔钛植入体。分析和表征仿生多孔钛植入体的孔隙形貌和尺寸、力学性能和体外成骨性能。结果表明:当控制冷冻铸造工艺中浆料中钛粉体积比为10%时,多孔试样的孔隙度为(58.32±1.08)%、孔径为(126.17±18.64)μm、压缩强度为(58.51±20.38)MPa、弹性模量为(1.70±0.52)GPa。在1200°C烧结1 h,多孔试样的孔隙度为(58.24±1.50)%、孔径为(124.16±13.64)μm、压缩强度为(54.77±27.55)MPa、弹性模量为(1.63±0.30)GPa。通过热氧化方法在多孔钛植入体试样的孔隙表面制备出均匀分布的纳米针状结构。通过对工艺的优化,制备出具有良好孔隙形貌和尺寸,同时具备良好力学性能和体外成骨性能的纳米针状表面改性仿生多孔钛植入体,具有重要的临床应用前景。     

表面改性多孔钛植入体孔径和孔隙率对骨长入的影响（英文）

研究表面改性多孔钛种植体孔隙率和孔径对骨整合的影响。用粉末注射成形技术制备3种多孔钛植入体(A30,A40和A50,造孔剂NaCl的体积分数分别为30%,40%和50%)。将改性后的多孔植入体分别植入狗的背部肌肉和股骨内28、56和84 d后,检测多孔钛植入体与宿主骨之间界面成骨活性和骨组织长入孔隙内的情况。结果表明,喂料中造孔剂NaCl的添加量从30%增至50%(体积分数),多孔钛的总孔隙率从42.4%增至62.0%,大孔径(50μm)多孔钛的质量分数从8.3%增至69.3%。组织学和荧光标记结果显示,A50植入体在28 d时骨界面的成骨活性明显高于其他组,在84d时A30植入体骨长入的量低于其他组。因此,A50植入体的孔结构适合新骨组织长入多孔植入体。     

不同过饱和钙化溶液中多孔钛表面磷灰石层的形成

将碱液处理过的多孔钛浸泡在含有不同离子及离子浓度的3种过饱和钙化溶液中，均制得了多孔钛表面磷灰石涂层。所有涂层的钙磷比均小于羟基磷灰石的钙磷化学计量比。在SBF和ACS中形成的涂层的钙磷比与人骨中的钙磷比比较接近。在SCS和ACS中形成的涂层还含有磷酸八钙。过饱和度的增加可以引起磷灰石更快成核与生长。较小的过饱和度和Mg^2 离子的结晶生长抑制作用使SBF中形成了结晶细小且比较薄的涂层，不破坏多孔钛的孔隙结构。在SCS中形成的涂层厚度约70gm，使孔隙尺寸大大减小。在ACS中形成的涂层有孔隙被堵塞的现象。     

采用TiH2粉末和造孔剂NH4HCO3烧结多孔钛（英文）

采用 TiH2和造孔剂 NH4HCO3混合粉末,利用粉末烧结法制备了多孔钛。研究表明,NH4HCO3的添加对于烧结的多孔钛的相组成几乎没有影响。多孔钛的孔隙度、平均孔隙尺寸、压缩强度和压缩弹性模量随 NH4HCO3添加量的增加而急剧下降。多孔钛可用添加不同量的造孔剂来调整孔隙结构和力学性能。独特的孔隙结构和适宜的力学性能满足多孔植入材料的基本要求。表明烧结的多孔钛是有前景的多孔植入候选材料。     

粉末冶金方法制备空心多孔钛零件

多孔钛具有良好的耐腐蚀性,可用来制作医用骨修复植入材料,也可作为过滤材料用于医药、水处理等领域。多孔钛通常采用粉末冶金的方法制备,包括钛粉的压制以及后续的烧结过程。当需要较高的孔隙度时,要向钛粉中加入一定量的空间支撑体。混合粉末经压制后,可以通过热分解等方法去除空间支撑体,留下孔隙结构。     

SLM制备径向梯度多孔钛/钽及其表征研究

利用增材制造技术制作仿天然骨的径向梯度多孔钛/钽骨科植入物具有广阔的前景。基于三周期极小曲面（triply minimal surfaces,TPMS）建模法建立了平均孔隙率为70%的圆柱型径向梯度孔隙结构,孔隙率由中轴线（90%）向圆周面（30%）逐渐降低。利用激光选区熔化(Selected Laser Melting, SLM)工艺制作径向梯度多孔钛/钽。光学显微镜,扫描电镜,Micro-CT检测结果共同显示,SLM径向梯度多孔钛/钽的孔隙结构与设计特征一致。SLM工艺制作的径向梯度多孔钛/钽的孔隙率分别为73.18%与68.18%。力学测试结果表明,梯度多孔钛/钽的弹性模量分别为3.96±0.19GPa与3.47±0.25GPa,抗压强度分别为90.83±3.35MPa与93.27±1.24MPa。梯度多孔钛/钽的弹性模量与抗压强度分别显著高于均匀多孔钛/钽（孔隙率为70.11%的均匀多孔钛弹性模量为2.34±0.48GPa,抗压强度为67.63±1.33MPa,孔隙率为65.39%的均匀多孔钽弹性模量为1.69±0.49GPa,抗压强度为68.56±0.41MPa）。体外细胞相容性实验证明,径向梯度多孔钛/钽均具有良好的生物相容性,适合间充质干细胞与肌肉细胞的粘附生长。SLM工艺制作的径向梯度多孔钛/钽比均匀多孔钛/钽具有与天然骨组织更相近的结构与性能,是理想的骨缺损修复替代物。     

医用多孔金属的制备及其生物活化研究进展

医用多孔金属材料,特别是多孔钛及钛合金能够提供与人体骨组织相匹配的力学性能,并促进骨组织长人以提高其与骨的固定度,在人体硬组织修复与替换方面具有广泛的应用前景。重点围绕多孔钛及钛合金的制备方法及适用于其复杂孔隙结构的表面生物活化方法,综述了各种方法在多孔钛及钛合金上的应用现状。目前适用于多孔钛及钛合金制备的技术主要有粉末冶金法、钛纤维烧结法、自蔓延高温合成法、选区电子束熔化技术和选区激光熔化技术,适用于多孔钛及钛合金表面生物活化的技术主要有溶胶凝胶法、仿生矿化法、电化学沉积法和微弧氧化法。多孔钛及钛合金的力学相容性和表面生物活性需要同时满足临床要求,才能进一步扩大其在医学领域的应用范围。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。