厚膜高阻电阻浆料的发展概况

1.高阻高压厚膜电阻浆料直到本世纪七十年代初期,国内外使用的高阻高压玻璃釉电阻,仍多为二氧化锡玻璃釉电阻。其中二氧化锡(SnO_2)是由 SnCl_2热分解而生成的氧化物半导体,它具有较高的比电阻,若加进氧化锑(Sb_2O_3)等三价氧化物半导体,则能大幅度地控制比电阻。这类材料的电阻高、成本低、价格便宜、适用于高压。然而,作为厚膜材料,SnO_2会与玻璃激烈反应,故对与之相适应的玻璃和烧结条件目前仍在继续研究中。此外,由该材料制作的电阻器 TCR 值过大(-1000～1500ppm/℃),对潮湿敏感,因而不能满足多种电路的应用。     

氧化钌的比表面积与电阻器特性之关系

1.前言影响钌电阻器特性的因素很多,其中掺杂往往是必不可少的。中、高阻掺CuO,低阻掺MnO_2,这对改善电阻的TCR很有效。MnO_2不但适宜掺入低阻粉料而且也适宜掺入到中、高阻粉料中。厚膜电阻除了导电相氧化钌外,还有玻璃。玻璃本身的成份,玻璃的粒径大小,对阻值的高低起着重要的作用。工艺条件对电阻器特性的影响更不能忽视。作为导电相的氧化钌是厚膜电阻的核心和关键材料,电阻特性的好坏,取决于氧化钌原料的制备方法与处理途径。本文研究不同比表面积的氧化钌与电阻器特性的关系。     

PTC热敏电阻铝电极玻璃成分与电性能的关系

作者通过实验证明PTC热敏电阻器欧姆接触、通电老化、高温老化及潮热老化与铝导电浆料中玻璃组分的关系.在B、Si、Pb玻璃中添加Zr、Al、V和Na的氧化物,PTC热敏电阻器的电性能可以满足使用要求.     

含钌高阻高压电阻器材料

钌系厚膜电阻浆料的阻值在50/(?)～1MΩ/(?)范围内,其性能基本满足各种线路的需要。国内外厚膜电阻可认为是向高精密、低阻、高阻和高频大功率方面发展。能做高阻高压电阻器的材料主要有两种:一是 SnO_2,其耐压性好,电阻率高,适用于高阻高压电路。但此类电阻器在烧成中,SnO_2易在玻璃中扩散,导致电阻体失效或变成绝缘体。但 SnO_2电阻原材料价格便宜,国内已有研究及生产。另一种是钌系电阻器,     

PTC热敏电阻器加热片的老化过程

通过实验分析,证明铝导电浆料经印烧后与PTC热敏电阻器有良好的欧姆接触.其加热片在工作状态时,会发生电阻增大而老化,老化率与瓷片、铝电极及铝浆中的玻璃有关.已老化电阻器经处理可以再生.     

LTCC钌系厚膜电阻电性能影响因素研究综述

钌系厚膜电阻具有阻值精度高、稳定可靠性高、工艺重复性好等优点,在厚膜混成电路制造中占据重要的地位。综述了钌系厚膜电阻电性能的影响因素,阐述导电相、粘接相、改性剂及有机载体与共烧电阻体电性能的关系,并针对国内高品质钌系厚膜电阻浆料面临的主要问题,提出原料粉体性能可控性制备,浆料制备工艺的优化设计与表征,浆料与生瓷带共烧匹配以及浆料无铅化等研究方向。     

化学法制备超细玻璃粉及其在LTCC用厚膜电阻浆料中的应用(英文)

用正硅酸乙酯、硝酸铝、硝酸钙、硝酸镁经化学反应,添加燃烧剂烧结后研磨制成了超细玻璃粉原料;用水合三氯化钌高温脱水法制备了氧化钌粉原料;采用低温共烧(LTCC)制成了混有这两种原料的钌厚膜电阻。采用差热分析仪、激光粒度仪和扫描电子显微镜进行了分析表征。结果表明,制备的电阻浆料与LTCC生瓷烧结性能相匹配,稳定性好,温度系数在±200×10-6/℃以内,制备的电阻器平均方阻为88.5Ω/□。     

化学法制备超细玻璃粉及其在LTCC用厚膜电阻浆料中的应用（英）

用正硅酸乙酯、硝酸铝、硝酸钙、硝酸镁经化学反应,添加燃烧剂烧结后研磨制成了超细玻璃粉原料;用水合三氯化钌高温脱水法制备了氧化钌粉原料;采用低温共烧(LTCC)制成了混有这两种原料的钌厚膜电阻。采用差热分析仪、激光粒度仪和扫描电子显微镜进行了分析表征。结果表明,制备的电阻浆料与LTCC生瓷烧结性能相匹配,稳定性好,温度系数在±200×10^-6/℃以内,制备的电阻器平均方阻为88.5 Ω/□。     

胶体法制备透明导电ITO薄膜

以锡盐和金属铟为原料采用胶体法制备ITO前驱物浆料，通过提拉法在镀有SiO2薄层的浮法玻璃基片上制备透明导电ITO薄膜。用TEM测定ITO前驱物浆料颗粒大小；用XRD、SEM、AES分别对ITO薄膜的结构和表面形貌进行表征；用分光光度计和四探针电阻仪检测ITO薄膜光电性能。结果表明：ITO前驱物浆料的颗粒粒径为2nm～15nm，具有较好的分散性和稳定性：ITO薄膜厚度越大，方电阻越小，平均透过率下降；ITO薄膜在波长为360nm～800nm区的透过率随膜厚增加有不同的影响；退火温度越高，膜方电阻越低；当膜厚为300nm、退火温度600℃时，膜方电阻达到2581Ω／n，其透过率在波长550nm处达到89．6％，且薄膜表面平整。     

玻璃/Ni/BaTiO3基复合PTCR材料的研究

研究在PTC陶瓷中复合金属以达到复合PTC材料低阻化的目的.为了促进烧结,配料中加入了玻璃料.研究了金属Ni和玻璃料的加入对复合PTC材料的室温电阻率和升阻比的影响.结果表明当金属Ni含量为15%(质量分数)、玻璃相含量为2%(质量分数)时,复合材料的性能达到了较好的水平,室温电阻率为25 Ω.cm,升阻比为2.34×102.     

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.