溶胶-凝胶法制备纳米MoCu复合粉体

以硝酸铜和二钼酸铵为原料，采用溶胶-凝胶法制备了纳米MoCu复合粉体，研究了热处理工艺，溶液pH值，添加剂等对纳米粒子形貌及粒径的影响。结果表明，在600℃热处理的钼铜氧化物通过氢气还原之后可以得到粒径小于60nm的纳米MoCu复合粉体；溶液中添加剂的用量影响微粒的粒径，当添加剂用量K为0．5时，能得到尺寸较小，粒度均匀的纳米粉体；不同酸度条件下所得粉体的粒径各不相同，当pH值在1～4之间变化时粒径随pH值的增大而增大，pH值取1较合适。     

NiO纳米晶的溶胶-凝胶法制备及电化学性能

采用溶胶-凝胶(Sol-Gel)法并结合热处理工艺制备氧化镍粉体,研究烧结条件对NiO粉体组成、结构和形貌的影响,并对其电化学性能进行初步研究.结果表明:以醋酸镍、乙醇、柠檬酸为原料,在一定温度下合成了稳定的溶胶和凝胶,凝胶热处理过程中在400℃左右基本分解完全并逐渐形成NiO纳米晶;随着烧结温度的升高,纳米NiO晶粒尺寸逐渐增大,晶型趋于完整;600℃烧结2h获得纳米NiO粉体晶粒大小分布均匀,晶型较好且没有明显团聚现象,表现出良好的充放电稳定性.     

高能球磨过程中Ti与BN的反应

通过研究高能球磨工艺制备纳米复合粉体过程中Ti与BN的反应过程和机理,对所制备粉体的显微结构进行了表征．实验结果表明,采用金属Ti和BN为原料,球磨10h后,即形成球状纳米复合粉体,其中球状粉体颗粒的尺寸在随后的球磨过程中基本保持不变．BN由于球磨而发生解理进而包裹Ti颗粒可能是形成稳定的球状纳米颗粒的原因．球磨30h后,Ti与BN开始反应生成TiN．TiN纳米粒子与未反应的Ti,B和BN共同形成平均粒径约100nm的、较均匀分布的球状纳米复合粉体．     

单相BaTi4O9柠檬酸凝胶法制备、表征及介电性能

采用柠檬酸凝胶法两步热处理工艺制备了单相BaTi4O9.干凝胶在750℃热处理得到了物相为BaTi5O11和Ba4Ti13O30、尺寸为30～50 nm前驱体粉体.纳米前驱体具有高表面活性,促使单相BaTi4O9在1200℃热处理温度下形成.两步热处理所得的粉体比一步热处理所得的粉体具有更好的烧结和介电特性,两步热处理所得的粉体,在1250℃保温4 h,可获得理论密度为97%的BaTi4O9微波陶瓷,其介电性能:εr=36.33,Q×f=28100GHz,τr=16.2×10-6/℃.     

热处理温度对有序介孔碳微结构和电磁屏蔽性能的影响(英文)

通过模板法制备了有序介孔碳(OMC),研究了有序介孔碳粉体在8.2～12.4GHz(X波段)范围内作为轻质电磁波吸收剂的电磁屏蔽性能。在氮气保护的条件下对OMC粉体分别在1400、1600和1800℃进行2h热处理。研究了热处理前后OMC微结构的变化,并测试了所得OMC粉体的介电常数。在1400℃下热处理所得OMC粉体试样的损耗正切(tanδ)高达3.1,远远高于未进行热处理的OMC试样的。通过将总的屏蔽效能分解为吸收和反射两部分,研究了OMC试样的电磁屏蔽效能。于1400℃和1600℃热处理后,OMC得到最高的电磁屏蔽效能其屏蔽机制以吸收为主,表明OMC具有作为微波吸收剂的潜力。     

Ag掺杂SnO_2纳米粉体的合成与抗菌性能研究

采用水热法制备得到了Ag掺杂SnO2纳米粉体。以XRD、BET、TEM等手段对粉体进行了表征。研究发现,200℃水热合成得到的SnO2纳米粉体的晶粒尺寸为数纳米,Ag离子的掺杂抑制了SnO2晶粒的长大。经600℃热处理后,纳米粉体的晶粒明显长大,分散性能良好。抗菌测试显示,直接水热法制得的Ag掺杂SnO2纳米粉体的抗菌能力较差,而经过600℃热处理后的粉体具有优良的抗菌性能。     

热处理对制备纳米氧化铟锡(ITO)粉末的影响

以共沸蒸馏工艺辅助的共沉淀法制备了纳米氧化铟-氧化锡（ITO）粉体，研究了不同热处理温度对制备粉体的影响，结果表明，随着热处理温度的提高，粉体发生从四方结构向体心立方结构转变，晶粒出现长大现象，比表面积变化明显，化学组分保持高纯状态，综合比较，在700～800℃进行热处理可以得到尺寸均匀，晶形完整的纳米级粉体。     

机械合金化过程中Fe50Als50二元系的结构演变

利用高能球磨和后续热处理技术制备纳米晶Fe5A150（摩尔分数，％）合金粉体。采用X射线衍射、透射电镜和扫描电镜对元素混合粉在机械合金化过程中的结构演变及热处理对合金化粉体结构的影响等进行分析，讨论其机械合金化合成机制。结果表明：球磨过程中Al向Fe中扩散，形成Fe（A1）固溶体。机械合金化合成Fe（Al）遵循连续扩散混合机制；球磨30h后，粉体主要由纳米晶Fe（A1）构成，晶粒尺寸5．65nm；热处理导致Fe（A1）纳米晶粉体有序度提高，转变为有序的B2型FeAl金属间化合物，粉体的晶粒尺寸增大，但仍在纳米尺度范围。     

焊后热处理对Ti180电子束焊接头组织与性能的影响

对7 mm厚Ti180双相钛合金电子束焊接接头采用不同焊后热处工艺(550～700℃，8 h)，研究热处理温度对接头的显微组织和力学性能的影响。结果表明：热处理后Ti180电子束焊接头焊缝区和热影响区的残余β相上生成纳米级针状α相和球状亚微米级颗粒Ti₅Sn₃。随着热处理温度的升高，次生针状α’相逐渐减少，纳米级针状α相逐渐粗化，球状亚微米级颗粒逐渐回溶，使得接头的焊缝区和热影响区的显微硬度逐渐减小。此外，接头的常温抗拉强度和伸长率逐渐下降，而高温抗拉强度和伸长率整体上呈现随热处理温度先下降后上升的变化趋势。在热处理参数为550℃、8 h时，Ti180焊接接头具有最优的力学性能。且焊后热处理可以显著减小Ti180焊焊接接头的残余应力，在热处理温度为650℃时，接头的残余应力消除效果最佳。     

热处理温度对机械合金化合成Ti3AlC2粉体纯度的影响

采用放电等离子烧结(SPS)系统对含有TiC等杂质相的机械合金化(MA)合成的Ti3AlC2粉体进行热处理,研究了热处理温度对粉体中Tti3AlC2纯度的影响.结果表明:SPS无压加热处理可以显著提高机械合金化合成粉体中Ti3AlC2的含量.经SPS热处理的粉体中Ti2AlC2的含量在600～1000℃范围内随热处理温度的提高而增加,温度不高于900℃时处理后的粉体还基本保持粉体特征.当温度为1000℃时,得到产物中Ti3AlC2纯度可达到93%.通过对点阵常数测定可知随着热处理温度的提高Ti3AlC2点阵常数逐渐接近理论值.     

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.     

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.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.