预浸涂对航空刹车副用C/C复合材料抗氧化涂层性能的影响

采用在C/C复合材料基体表面预先浸涂浸渍剂 ,再涂刷涂层并进行涂层固化处理的工艺方法 ,可制备出抗氧化性能良好的涂层。预浸涂处理可使C/C复合材料的起始氧化温度提高近 2 0 0℃。单独预浸涂以硼酸或TEOS为主的浸渍剂后 ,试样抗氧化效果不明显 ,而预浸涂以磷酸或磷酸 硼酸混合液为主的浸渍剂效果较好 ,90 0℃ ,2h静态氧化质量损失率分别为 0 .4 0 %和 0 .33%。并对以硼酸 ,磷酸和TEOS及其混合液为主的浸渍剂的抗氧化机理进行了分析和探讨     

溶胶-凝胶制备的Al_2O_3-SiO_2复合陶瓷涂层抗原子氧侵蚀性能研究

采用溶胶-凝胶法,以异丙醇铝、正硅酸乙酯为原料制得了稳定、均一的溶胶,浸涂在聚酰亚胺表面干燥后获得了致密透明的涂层.采用空间综合环境地面模拟设备对试样进行了原子氧(Atomic Oxygen, AO)暴露实验.测试表明,溶胶-凝胶制备的Al_2O_3-SiO_2涂层抗原子氧侵蚀性能优异,抗原子氧侵蚀性能比聚酰亚胺基体提高了2个数量级以上.经原子氧暴露后的复合陶瓷涂层质量几乎没有发生变化.经FTIR和XPS分析表明,在原子氧暴露后涂层表面产生的是Al_2O_3-SiO_2复合物.SEM分析表明,无涂层的聚酰亚胺原子氧暴露后表面非常粗糙且表面呈现地毯状形貌,而涂覆涂层的试样暴露前后表面形貌没有发生变化.采用紫外-可见光-近红外分光光度计对涂覆溶胶-凝胶复合陶瓷涂层后的试样分析表明原子氧暴露前后试样表面的光学性能也未发生变化.     

骨植入镁合金表面缓蚀剂覆载的微弧氧化/PLGA复合涂层的制备与表征

目的 在可降解镁合金表面制备缓蚀剂覆载的微弧氧化/聚乳酸-羟基乙酸(PLGA)复合涂层,提高其耐蚀性.方法 首先利用微弧氧化技术在镁合金表面制备出适合复合缓蚀剂涂层的微弧氧化(Micro-Arc Oxidation,MAO)涂层,之后在微弧氧化多孔涂层上浸涂PLGA-缓蚀剂涂层,得到复合涂层,缓蚀剂选择天然植物提取物姜黄素(Curcumin,Cur).利用SEM&EDS、FTIR和AFM等实验对涂层形貌、成分及结构进行分析,通过电化学测试、体外浸泡实验评价涂层的耐蚀性能.结果 FTIR结果表明Cur可成功覆载在涂层中,且不与PLGA发生反应.电化学测试和体外浸泡实验表明MAO/PLGA-Cur涂层能有效提高镁合金的耐蚀性.动电位极化曲线显示MAO/PLGA-Cur涂覆样品的腐蚀电流密度比基体下降了3个数量级,浸泡14 d的质量损失比基体下降62.04％,比未覆载的样品减少26.63％.结论 MAO时间为10 min为最合适复合缓蚀剂涂层的参数.Cur作为缓蚀剂的最佳添加量为0.12％,PLGA的最佳添加量为12％,最佳浸涂角度为0°.     

有机硅/二氧化硅杂化涂层抗原子氧侵蚀性能研究

采用溶胶-凝胶法,以一甲基三乙氧基硅烷(MTES)和正硅酸乙酯(TEOS)为原料,乙醇为溶剂,盐酸为催化剂,通过溶胶-凝胶法制备出分子级复合的SiO2杂化有机硅树脂,浸涂在聚酰亚胺表面干燥后获得了透明致密的涂层。采用自己研制的空间综合环境地面模拟设备对试样进行了原子氧暴露实验。测试表明,溶胶-凝胶制备的有机硅/SiO2涂层抗原子氧侵蚀性能优异,抗原子氧侵蚀性能比聚酰亚胺基体提高了2个数量级以上。经AO暴露后的杂化涂层质量几乎没有发生变化。经FTIR和XPS分析表明,在原子氧暴露后涂层表面产生的是SiO2陶瓷层。SEM分析表明无涂层的聚酰亚胺原子氧暴露后表面非常粗糙,表面呈现地毯状形貌而涂覆涂层试样暴露前后表面形貌没有发生变化。采用紫外-可见光-近红外分光光度计对涂覆有机硅/SiO2涂层试样分析表明,原子氧暴露前后试样表面的光学性能也未发生变化。实验证明,制备抗原子氧侵蚀的防护涂层的溶胶-凝胶法是一种行之有效的方法。     

壳聚糖涂层对Mg-6%Zn-10%Ca_3(PO_4)_2植入材料生物相容性的影响（英文）

研究壳聚糖包覆的Mg-6%Zn-10%Ca_3(PO_4)_2植入材料生物体内的降解特性。采用0.2%的醋酸溶液溶解壳聚糖,将其在60℃下涂覆在复合材料样品表面,固化30 min得到壳聚糖的涂层。壳聚糖涂覆后的样品细胞毒性为0级,说明该涂层完全没有毒性,可以用于生物实验。生物体内实验表明:与无涂层的样品相比,植入涂覆有壳聚糖的复合材料后,在新西兰兔静脉血中的离子浓度较低。壳聚糖涂层可以减缓复合材料在生物体内的降解速率。生物体内实验表明,涂覆壳聚糖的复合材料对新西兰兔的重要器官,如心、肾、肝、肌肉都没有损伤,而新生骨组织会聚集在壳聚糖涂覆的复合材料周围,有利于骨组织的生长。壳聚糖涂层有利于减缓植入材料在生物体中的降解过程,减少氢气析出造成的皮下气泡产生,有利于提高复合材料的生物相容性。     

SiC陶瓷表面高温耐碱腐蚀Ca_(0.6)Mg_(0.4)Zr_4(PO_4)_6涂层的制备

采用浆料浸渍涂覆法在SiC陶瓷表面制备Ca_0.6Mg_0.4Zr_4(PO_4)_6(C_0.6M_0.4ZP)涂层,以改善其高温耐碱腐蚀性能.通过在C0.6M0.4ZP溶胶中加入平均粒径为40 nm的C_0.6M_0.4ZP粉体和聚乙烯醇(PVA),制备高固含量的稳定胶态悬浮浆料,并在SiC陶瓷上制备C_0.6M_0.4ZP涂层.浆料固含量为40% (质量分数, 下同)、pH=6、PVA加入量为6%时,在1400 ℃保温3 h烧成后可获得致密的C_0.6M_0.4ZP涂层,一次涂覆涂层厚度可达200 μm,且涂层与SiC陶瓷基体结合良好.经1000 ℃,96 h碱腐蚀后,涂层试样没有明显的质量损失,而未涂覆试样质量损失达到20.1%;涂层试样的强度衰减5.7%,远低于未涂覆试样的40.5%.     

纳米涂覆对材料表面润湿性的影响

为了探讨纳米涂覆对材料表面润湿性的影响,以塑料为基体进行了Cu、非晶态纳米SiO2涂层对试样润湿性影响的座滴试验研究,并利用扫描电镜(SEM)和接触角测量仪对试样界面微观形貌的变化进行了观察以及接触角的测定,最后采用多项对比和理论分析相结合的方法,对材料润湿性的改善机理做出解释。结果表明,纳米涂覆对材料表面润湿性的改善起到了重要作用,试样经非晶态纳米SiO2涂覆处理后,形成牢固的润湿界面,H2O/PVC(聚氯乙烯)的润湿角从45.2°减小到28.3°,润湿性显著提高。     

溶胶-凝胶制备的Al2O3涂层抗原子氧侵蚀性能研究

以异丙醇铝（Al（C3H7O）3）为先驱物，水为溶剂，HNO3做胶溶剂制得了稳定、均一的Al2O3溶胶，浸涂在聚酰亚胺和银薄膜表面干燥后获得了致密透明的涂层。采用空间综合环境地面模拟设备对试样进行了原子氧暴露实验。结果表明：溶胶．凝胶制备的Al2O3涂层抗原子氧侵蚀性能优异，抗原子氧侵蚀性能比聚酰亚胺基体提高了2个数量级以上。经FTIR和XPS分析表明：在原子氧暴露后涂层表面生成了一层Al2O3，阻止了原子氧对基体材料的进一步侵蚀。涂覆涂层后基体的光学性能没有受到影响。实验证明溶胶．凝胶制备抗原子氧侵蚀的防护涂层是一种行之有效的方法。它工艺简单，可涂覆形状复杂、大面积的器件。     

表面涂覆对碳纤维镁基复合材料组织与性能的影响

通过溶胶凝胶法在短切碳纤维表面涂覆了Mg O、SiO_2、TiO_2涂层,分析了各涂层对碳纤维润湿性能的影响,制备了镁基复合材料,研究了碳纤维表面涂覆对镁基复合材料组织和性能的影响规律。结果表明,Mg O涂层表面较为粗糙,存在团聚的Mg O颗粒,Si O_2、Ti O_2涂层表面较为光洁,沿碳纤维径向连续分布,具有良好的仿形性。而且3种涂层的存在均可显著改善碳纤维的润湿性,润湿角由未涂覆时的120°降低到90°以下,其中Mg O涂层的润湿角仅为42°。采用涂覆后的碳纤维分别制备了镁基复合材料,其中TiO_2涂覆后的复合材料强度最高,Si O_2次之,Mg O最低。这是由润湿性和界面反应共同作用导致的。     

碳纤维表面SiO2涂层的制备及其在镁基复合材料中的应用

利用Sol-Gel方法,通过优化溶胶的配置、纤维提拉过程和干燥烧结等工艺过程,在碳纤维表面制备出均匀的、无裂纹的SiO2涂层.采用SEM、XPS和TEM表征了碳纤维表面SiO2涂层的结构、形貌、元素分布以及涂层碳纤维/镁基体的界面结构.结果表明,涂覆SiO2的碳纤维,抗氧化能力提高,拉伸性能略有降低,但与镁基体复合后其拉伸强度降低了20%.SiO2涂层改善了Mg对碳纤维的润湿能力,有效地促进了熔融Mg液对碳纤维的浸渗.     

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).     

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.     

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.