磁控溅射法制备的羟基磷灰石—氧化锆涂层的力学性能(英文)

采用磁控溅射法在Ti6Al4V钛合金基体上制备羟基磷灰石(HA)-氧化锆(ZrO2)复合涂层,通过SEM、EDS、XRD和划痕法对50HA-50ZrO2和75HA-25ZrO2(质量分数,%)涂层进行表征,分析HA含量对涂层残余应力的影响。实验结果表明,HA-ZrO2复合涂层的物相为HA、ZrO2和Y2O3,在复合过程中HA部分发生分解,产生TCP和CaO等杂质相;涂层表面呈多孔状,有利于类骨组织的生长,50HA-50ZrO2和75HA-25ZrO2深层的表面粗糙度分别为1.61μm和2.92μm;涂层结合界面为机械结合方式,划痕法测量的50HA-50ZrO2和75HA-25ZrO2深层界面结合强度分别为30N和17.5N,随着HA含量的增加,涂层结合强度呈现下降的趋势;50HA-50ZrO2和75HA-25ZrO2涂层的残余应力分别为(-399.1±3)MPa和(-343.2±20.3)MPa,适当增加HA可以减小涂层的残余应力。     

微束等离子喷涂氧化锆增韧羟基磷灰石复合涂层

采用微束等离子喷涂方法,在Ti-6Al-4V基体上制备了羟基磷灰石 氧化锆(70HA-30ZrO2,质量分数,%)复合涂层.将复合涂层置于模拟体液中分别浸泡了3,7,14,28 d并观察表面磷灰石的生长情况以评价涂层生物活性.采用扫描电镜(SEM)和X射线衍射(XRD)分析技术对涂层浸泡前后的表面形貌和相组成进行了研究.结果表明,涂层中ZrO2主要以立方相存在;喷涂过程中羟基磷灰石(HA)出现了一定的分解,产生大量的α-Ca3(PO4)2杂质相.HA涂层熔化效果很好,但涂层中有未熔化的ZrO2颗粒.涂层在模拟体液中浸泡28 d后表面可以形成磷灰石,说明涂层具有很好的生物活性.     

微波诱导羟基磷灰石 / 钛合金界面反应的研究

为改善钛合金和HA涂层的界面相容性,采用电泳法在钛合金表面预先沉积均匀的HA涂层,再于1200℃下进行微波处理。通过对涂层相结构的分析,证明在微波诱导作用下,形成了梯度结构的涂层。梯度过渡层由TiO2和TiO组成的致密氧化层、CaTiO3和微量HA组成,能够缓解HA涂层与钛合金热膨胀系数不匹配的问题,减少涂层开裂,提高涂层与基体的结合强度。     

激光熔覆钛基生物陶瓷涂层的制备及其界面研究

利用高功率CO_2激光器在Ti-6Al-4V合金表面制备含有生物活性陶瓷相的梯度生物陶瓷涂层.利用扫描电镜(SEM)、X射线衍射(XRD)和电子探针(EPMA)等对熔覆层和界面的显微组织、相组成及成分进行分析.结果表明:激光熔覆复合涂层中生成了羟基磷灰石和磷酸三钙等生物活性相,凹凸不平的表面出现网络交错的片状结构和微孔(孔径为0.5～2μm),有利于新骨沿着表面及内部连通微孔攀附生长.涂层与基体界面处存在涂层成分(Ca,P)与基体成分(Ti,Al,V)的互扩散,涂层与基体通过扩散反应形成牢固的冶金结合.残余应力在界面结合区域出现峰值,陶瓷层和过渡层界面附近为221 MPa,涂层与基体界面附近为108 MPa,从涂层到基体残余应力逐渐减小.     

水热电化学法制备HA／ZrO2复合涂层

采用水热电化学法成功制备了HA/ZrO2复合涂层,对涂层的组分结构、表面形貌、热稳定性进行了研究,并探讨了ZrO2的复合对涂层结合强度和生物活性的影响.结果表明当温度小于200℃时,得到缺钙磷灰石Ca10-x(HPO4)x(PO4)6-x(OH)2-x(calcium deficient hydroxyapatite,简称CDHA,0≤x≤1)和ZrO2的复合涂层,温度在200℃时,得到HA/ZrO2复合涂层;经焙烧处理后,涂层中四方晶相ZrO2(t-ZrO2)与单斜晶相ZrO2(m-ZrO2)之间发生马氏体相变;800℃焙烧后,HA部分分解为β-Ca3(PO4)2(β-TCP);当涂层中ZrO2小于35.22%(质量分数,下同)时,HA/ZrO2复合涂层的结合强度明显高于纯HA涂层;复合涂层在模拟体液中浸泡7 d后,表面即形成一层碳磷灰石层,ZrO2的复合没有降低涂层的生物活性.     

羟基磷灰石生物涂层材料界面的电镜观察与分析

用扫描电子显微镜和透射电子显微镜对未经热处理的钛合金基体等离子喷涂羟基磷灰石生物材料的显微结构、相组成和界面结合进行了观察与分析. 结果表明 HA涂层的显微结构疏松, 内部有裂纹和孔洞; 涂层的相结构中, HA以结晶态和非晶态两种形态存在; HA和基体的界面结合是以物理结合为主, 界面明显, 没有过渡相, 说明基体和涂层之间化学反应不明显.     

热喷涂NiCr／纳米（ZrO2＋8％Y2O3）梯度涂层的性能研究

针对陶瓷涂层与基体结合强度低、易产生裂纹和剥落的现象,进行了抗高温氧化耐磨损梯度涂层的设计.采用热喷涂技术在45钢基体表面制备由面层[纳米(ZrO2 8%Y2O3)]和中间层(NiCr)组成的梯度涂层,利用扫描电镜(SEM)、测定结合强度、测定显微硬度、X射线衍射等方法研究涂层的性能.结果表明:NiCr/纳米(ZrO2 8%Y2O3)梯度涂层显微组织结构致密,与NiCr合金涂层和纳米(ZrO2 8%Y2O3)陶瓷涂层相比,具有更优良的力学性能;梯度涂层的面层有利于提高基体的耐高温、耐磨损性能,而中间层则有利于改善基体的抗高温氧化性能.     

等离子喷涂生物活性涂层的梯度结构表征

采用自动控制的等离子喷涂系统,在钛合金基体上制备出生物活性梯度涂层,利用纳米硬度计、扫描电镜等对生物活性涂层的梯度结构进行分析.实验结果表明:金属基体与陶瓷界面区域的弹性模量和硬度呈梯度变化;生物活性功能涂层表面分布着不同尺寸范围的孔洞,具有典型的多孔结构特征,整个涂层沿垂直基体方向从底层致密结构向表面层多孔结构过渡;涂层成分底层生物稳定性至表面层生物活性呈梯度变化,涂层表面成分为生物活性的羟基磷灰石.涂层的这种结构特征有利于改善生物活性涂层的综合性能,提高涂层与基体的结合强度,根据ASTM C633-79测试生物活性涂层与基体的结合强度,结合强度达到48.6 MPa.     

亚音速火焰喷涂HA/BG仿生生物涂层

为提高HA涂层结合强度,避免涂层在使用过程中开裂及溶解脱落等问题,采用亚音速火焰喷涂方法及涂层晶化处理,以Ti6Al4V为基体,引入热膨胀系数与基体相近的Ti/G过渡层缓解应力,工作层以HA为主,辅以生物活性玻璃(BG),喷涂制备HA/BG仿生生物涂层.通过调整BG含量,观测涂层形貌、相组成及结构的变化,进而分析HA/BG仿生生物涂层作为骨组织替代材料的适用性.结果表明:亚音速火焰喷涂HA/BG仿生生物涂层具有典型的热喷涂涂层形貌特征,与基体结合较好,没有明显的开裂脱落现象,涂层经700℃晶化处理后析出纳米和微米级HA,可增加与宿主骨组织接触面积,加快其反应,增加生物活性.添加BG后,涂层中有新相Na2Ca(PO4)F析出;当改变BG含量后,可改变HA、Na2 Ca (PO4)F晶相的含量,进而来调控涂层的溶解性和稳定性.     

钛基羟基磷灰石涂层的界面结构及梯度设计

羟基磷灰石是最有发展前途的生物硬组织替代材料之一,临床上采用在钛合金上涂覆HA生物活性涂层,涂基结合及涂基界面的整合是决定HA涂层性能和可靠性的关键因素.评述了钛基羟基磷灰石涂层的界面微观结构,指出界面上存在纳米氧化物薄膜是提高涂层结合强度的关键,并结合纳米多层薄膜和功能梯度膜的优点,提出改善涂基结合强度,发挥羟基磷灰石生物活性涂层的三明治式的梯度设计.     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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).     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.