电磁改性T-ZnOw的制备及性能研究

采用化学沉积法制备了电磁改性T-ZnOw样品,用XRD,SEM和EDX对样品进行表征。结果表明:样品存在六方晶系纤锌矿结构ZnO和立方晶系Fe两相,四针结构保持完整,晶须表层沉积了球形颗粒,颗粒粒径约为0.5μm,铁元素和锌元素的质量分数分别为63%,37%;电磁改性T-ZnOw磁饱和强度达到85.66emu/g,电阻率降低到6.9Ω.cm。     

超声波辅助化学镀法制备CoAl_2O_4尖晶石粉体

采用超声波辅助化学镀法在室温条件下制备了Co/Al2O3复合粉体,1200℃下热处理1.5h获得了CoAl2O4尖晶石粉体。用扫描电镜、透射电镜和X射线衍射测定了粉体的微观形貌、成分和相组成;用差热分析法确定了粉体的尖晶石转变温度。结果表明:镀覆制备的Co/Al2O3复合粉体由金属钴和Al2O3两相组成,金属钴相包覆Al2O3相,Co包覆层在Al2O3颗粒表面分布均匀且结构较疏松;复合粉体的尖晶石转变温度为850℃左右;转变后获得的粉体也是一种复合粉体,由Al2O3和CoAl2O4两相组成,由粉体的生长机制可预见,它是以α-Al2O3为核心CoAl2O4尖晶石包覆在其表面的结构。     

液相包裹法制备Al2O3/Fe纳米复合粉体

利用液相包裹法制备了纳米Fe颗粒包裹Al2O3,纳米复合粉体,研究了不同的煅烧和还原温度对复合粉体物相组成的影响,利用X-ray衍射（XRD）、热重/差式-量热扫描法（TG/DSC）、Zeta电位和扫描电镜（SEM）对复合粉体的成分、热学特性以及形貌特征进行了分析.结果表明：煅烧温度为500℃,保温30min,在氢气气氛中700℃还原1h可以得到Fe包裹Al2O3的纳米复合粉体;经SEM发现,包裹层的Fe颗粒呈球形,尺寸约为30 nm,分布均匀.     

TiB_2陶瓷粉末纳米化改性及其增强环氧复合涂层的制备与表征（英文）

低温条件下,以钛酸丁酯为原料,采用胶溶-回流方法在Ti B_2粉体表面包覆纳米Ti O_2颗粒。通过SEM、XRD、BET等分析检测方法对复合颗粒的表观形貌、包覆层相成分、比表面积等进行表征。结果显示,纳米Ti O_2颗粒均匀离散地包覆在Ti B_2粉体表面,包覆层主要为锐钛矿型相,Ti B_2粉体纳米化改性后复合颗粒的表面粗糙度显著增加,比表面积较包覆前提高35倍以上。将包覆后的Ti B_2粉体引入环氧树脂制备耐磨复合涂层,测得其磨损失重仅为包覆前复合耐磨涂层的50%,其耐磨性显著提高,并初步分析了复合耐磨涂层的摩擦磨损性能、磨损形貌及耐磨机理。     

反应机械合金化/退火制备Al2O3/Fe3Si纳米复合粉体

以Fe2O3粉、Si粉和Al粉为原料,采用反应机械合金化/退火法制备出了Al2O3/Fe3Si纳米复合粉体。利用X射线衍射仪（XRD）和扫描电子显微镜（SEM）对复合粉体球磨以及退火过程中的固态反应过程、表面形貌进行表征。研究表明,Fe2O3-Si-Al混合粉体球磨5 h后发生反应生成Al2 O3、Fe5 Si3、Fe3 Si、FeSi,球磨20 h后生成Al2 O3/Fe3 Si,球磨20 h的粉体在900℃条件下退火1 h的组成物相未发生变化,复合粉体颗粒呈球形,其尺寸为5μm左右,分布均匀,组成相Al2O3和Fe3Si的晶粒尺寸分别为26.6 nm和28.3 nm。     

TiB2陶瓷粉末纳米化改性及其增强环氧复合涂层的制备与表征

低温条件下,以钛酸丁酯为原料,采用胶溶-回流方法在TiB₂粉体表面包覆纳米TiO₂颗粒。通过SEM、XRD、BET等分析检测方法对复合颗粒的表观形貌、包覆层相成分、比表面积等进行表征。结果显示,纳米TiO₂颗粒均匀离散地包覆在TiB₂粉体表面,包覆层主要为锐钛矿型相,TiB₂粉体纳米化改性后复合颗粒的表面粗糙度显著增加,比表面积较包覆前提高35倍以上。将包覆后的TiB₂粉体引入环氧树脂制备耐磨复合涂层,测得其磨损失重仅为包覆前复合耐磨涂层的50%,其耐磨性显著提高,并初步分析了复合耐磨涂层的摩擦磨损性能、磨损形貌及耐磨机理。     

包覆结构CeO_2/SiO_2复合磨料的合成及其应用

以正硅酸乙酯水解所得的SiO_2微球为内核,采用均匀沉淀法制备具有草莓状包覆结构的CeO_2/SiO_2复合粉体.利用X射线衍射仪、透射电子显微镜、X射线光电子能谱仪(XPS)、动态光散射仪和Zeta电位测定仪等手段,对所制备样品的物相结构、组成、形貌和粒径大小进行表征.将所制备的包覆结构CeO_2/SiO_2复合粉体用于硅晶片热氧化层的化学机械抛光,用原子力显微镜(AFM)观察抛光表面的微观形貌,测量表面粗糙度,并测量材料去除率.结果表明:所制备的CeO_2/SiO_2复合颗粒呈规则球形,平均粒径为150~200 nm,CeO_2纳米颗粒在SiO_2内核表面包覆均匀.CeO_2颗粒的包覆显著地改变复合颗粒表面的电动力学行为,CeO_2/SiO_2复合颗粒的等电点为6.2,且明显地偏向纯CeO_2;CeO_2外壳与SiO_2内核之间形成Si-O-Ce键,两者产生化学键结合;抛光后的硅热氧化层表面在2 μm×2 μm范围内粗糙度为0.281 nm,材料去除率达到454. 6 nm/min.     

包覆型BN-AlN复合粉体研究

利用包覆法,首先通过将AlN粉体均匀分散到硼酸(H3BO3)和尿素(CO(NH2)2)的无水乙醇溶液中,制备出与硼酸和尿素均匀混合的AlN粉体.然后在氮气氛下,经过氮化处理来制备BN-AlN的复合粉体.DTA/TG分析显示,氮化反应从800 ℃开始,到1100 ℃时结束.XRD和TEM分析发现,复合粉体是由非晶态的BN均匀包覆AlN的复合颗粒组成.     

等离子喷涂 NiCoCrAlY / Al2 O3 高温固体润滑耐磨涂层的抗氧化性能研究

目的研究等离子喷涂NiCoCrAlY/Al2O3高温固体润滑耐磨涂层在850℃时的高温抗氧化性能和抗氧化机理。方法采用喷雾造粒、化工冶金包覆技术制备NiCoCrAlY/Al2O3复合粉体,并采用等离子喷涂技术在45#钢表面制备NiCoCrAlY/Al2O3复合涂层。采用SEM和XRD研究粉体和涂层的显微结构和物相组成,并采用马弗炉研究复合涂层在850℃的恒温氧化动力学曲线,通过研究氧化96 h以后涂层表面的组织形貌,探讨NiCoCrAlY/Al2O3复合涂层的抗氧化机理。结果 NiCoCrAlY合金层均匀致密地包覆在Al2O3颗粒的表面,包覆层厚度约为3~5μm。复合粉体的主要组成为Al2O3相和NiCoCrAlY合金相,没有其他杂质相的存在。等离子喷涂NiCoCrAlY/Al2O3复合涂层氧化动力学曲线分为大斜率直线、抛物线和系数几乎为0的抛物线等3个阶段。氧化96 h以后,涂层的氧化质量增量为4.9 mg/cm2左右,表面形成了一层连续的氧化物保护膜,经EDX分析,氧化膜层主要由Al,O,Cr和Ni组成。结论等离子喷涂NiCoCrAlY/Al2O3复合涂层具有良好的高温抗氧化性能,涂层中Ni,Cr,Al的氧化以及硬质相Al2O3的加入是涂层抗氧化的主要原因。     

Ag包覆Ni复合纳米粉体的制备及其导电性能

用化学镀法,以葡萄糖为还原剂,制备了Ag包覆Ni复合纳米粉体,并用制备的复合纳米粉作为导电相配制了导电浆料。用XRD、TEM和电阻率测定等手段研究了粉体的相结构、形貌、粒度和导电性能。结果表明,制备的Ag包覆Ni复合纳米颗粒具有壳/核结构,核为纳米Ni,壳为Ag,复合纳米颗粒粒度分布为20~100 nm,Ag层的厚度约为4 nm。Ag包覆Ni复合纳米粉导电浆料在1.33 Pa的真空下,采用200℃/60 min的烧结工艺,可制得电阻率为(1.26~2.83)×10-4Ω·cm的导电膜,其导电性能优于纳米Ni粉、纳米Cu粉和纳米Ag-Cu合金粉导电浆料。     

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.     

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。