TPH型真空炉测试方法改进

TPH型真空炉温度均匀性测试系统的温度补偿系统在长时间使用后存在温度补偿性能下降的问题,从而无法实现精确补偿,影响炉温均匀性测试结果。同时,加热设备控温热电偶测量端位置对设备性能有重要影响。本文从以上两个方面对TPH型真空炉测试方法的改进进行了论述。     

Direct determination of carbothermal reduction temperature for preparing silicon carbide from the vacuum furnace thermobarogram

In this study, we combined the traditional vacuum furnace with a sur-high accuracy vacuum gauge for measuring the change of gas pressure in the furnace as a function of temperature. The modified vacuum furnace was used for preparing silicon carbide (SiC), and the recorded data named thermobarogram were applied to detect the reaction temperature for synthesis of SiC, which, in particular, changes as catalysts are used. The results showed that the carbothermal reduction temperature for synthesizing SiC, under dynamic vacuum condition, would decrease to 850 °C when the mole ratio of Fe/Si=0.06 was employed in the SiC precursor.     

Comparison between furnace and rapid thermal annealed iridium silicide Schottky barrier diodes

Abstract

Iridium silicide Schottky barrier diodes fabricated by low temperature rapid thermal annealing (R TA) either in vacuum or in an argon atmosphere are investigated. A comparison with furnace annealed diodes is made in terms of their electrical characteristics. An ideality index close to unity has been obtained. Measured values of Schottky barrier height were close to that reported for Ir₁Si₁/n type silicon <111> diodes. An increase in series resistance with annealing time is detected for diodes fabricated in the gas atmosphere by either furnace annealing or RTA: this effect seems to be related to oxygen diffusion through the iridium layer. The effect of atmosphere control on the grown material is also significant: silicidation and a phase change from Ir₁ Si₁ to Ir₁ Si_1-75 occur at lower temperatures when the reaction atmospheres contain a lower oxygen concentration. Complete silicidation to Ir₁Si₁ is obtainedfor all the 400°C RTA samples, but temperatures above 450°C are required for open tube furnace argon annealed samples to obtain the same reaction. A low barrier silicide phase appears only for RTA in vacuum at 450°C. It seems that RTA in vacuum at low temperature (400°C) is the most promising methodfor diode fabrication.

MST/3334     

真空钎焊系统内材料出气对压升率的影响研究

随着微电子封装向小型化、高密度化、高可靠性的方向发展,各行业对钎焊技术提出了高钎透率、高钎焊接头质量、材料具备高净化度等需求.高真空钎焊技术也随之日益普及、加速发展.该技术通过保障真空室的洁净度及焊接真空度,进而保障元器件的焊接质量及寿命.高真空钎焊技术要求真空钎焊炉具备高真空度、低压升率.高温下材料出气是高真空状态下...     

A New High-Temperature Oscillating Cup Viscometer

A new oscillating cup viscometer for temperatures up to 2,300°C has been constructed. A vacuum furnace with a graphite heater is used for heating the sample. The temperatures of the furnace and sample are measured by both a thermocouple and a pyrometer. The temperature is controlled with a stability better than 1 K. The oscillation of the cup is measured with a reflected laser beam using a position sensitive detector. The measured values of angle and time are then fitted to an analytical oscillation function. From the parameters of this function, the viscosity values are calculated using the Roscoe formalism. Measurements were carried out on pure metals at temperatures up to 1,700°C because of limitations of the thermocouple. The obtained viscosity values showed good agreement with literature data.     

钴铬钼多孔关节烧结工艺的研究

研究了钴铬钼合金关节与珠粒烧结时不同冷却制度对零件组织和性能的影响.即A组铸件按照原生产工艺经固溶处理后,进行1280℃高温真空烧结,炉冷;B组铸件直接进行1280℃高温真空烧结,随炉冷却至1200℃充入氩气快速冷却至室温;C组铸件于铸模中缓慢冷却后不进行热处理;D组铸件进行1200～1240℃固溶处理,油冷;彼此作为...     

真空蒸馏分离锡铁合金的研究

从理论和实验两方面讨论了锡铁合金分离的可能性和规律性。利用真空感应熔炼炉与立式真空蒸馏炉,实验考查了蒸馏温度、蒸馏时间、炉内压力以及电磁搅拌作用对锡铁合金分离效果的影响。结果表明:在真空感应熔炼炉中,蒸馏温度为1885 K,炉内压力为10 Pa,蒸馏时间为42.5 min的条件下,含锡4.54%(质量比)的合金一次蒸馏后,锡的脱除率为99.79%,残留物铁中的锡含量降至0.024%。电磁搅拌作用对脱锡效果的影响显著。     

Modular process control system for photovoltaic thin films manufacturing

A method of temperature control for selenization process conducted in vacuum quartz tube furnace with radial energy transfer and a movable sample holder has been described. Selenization of metallic precursors to obtain CuInSe₂ absorber layer of a photovoltaic cell requires a special approach to the temperature regulation, where two-stage heating process is necessary. The modular process control system was developed in which the first module playing a supervising role was built in LabVIEW environment and the second one, called a predictor, was built in MATLAB. Relatively quick movement of the holder from the cold to the hot regions of the furnace allows for a rapid change of sample temperature, typical of rapid thermal processing processes.     

Analysis of Fracture in High-Temperature Vacuum Tube Furnace

High-temperature vacuum tube furnace (HTVTF) is widely used for processing materials, developing new materials, and sintering various types of material under vacuum or gaseous conditions. A growing concern in engineering research communities and industries is that fracture occurs in the alumina tube after the furnace has run for few hours and this lead to a drainage of huge amount of money when the buyers replace the tube every time. To improve furnace tube longevity and performance in extreme temperature conditions, it is critical to determine the phenomena that take place inside the furnace and cylindrical alumina tube wall. In the present work, mathematical models are developed to understand the effect of stress concentration arising from thermal stresses in tube wall and heat-affected-zones (HAZ) of a HTVTF using multiphysics finite element software Comsol (Stockholm, Sweden). The combination of thermal stress with temperature difference determines the fracture region. Different air flow rates have been considered to find the critical thermal stress region inside the vacuum tube. Analysis suggests that lowering air flow rate and inserting a small copper pipe inside the first block to blow hot air on the second heat-affected zone (HAZ-2) will reduce thermal stress generation inside the tube and prevent the eventual fracture of the vacuum tube. It is expected that this study can lead to a better understanding of the complex phenomena of fracture alumina tube during operation of HTVTF.     

Very high vacuum (VHV) electron beam floating zone (EBFZ) furnace

An electron beam floating zone (EBFZ) furnace, capable of melting cyclindrical specimens up to 10 mm in diameter, was designed and constructed. A circular thermionic tungsten-filament emitter enclosed in a tantalum housing preventing a direct line-of-sight relation between the cathode and the concentrical specimen rod was used to minimized mutual contamination of the emitter and specimen materials. Since the furnace was designed for melting reactive materials, it originally employed an ion-pump vacuum system capable of obtaining lower than 10^?8 torr levels. For highly outgassing materials the throughput of this pumping system was not sufficient and a replacement by a liquid nitogen trapped diffusion pump system was introduced without affecting the basic design of the furnace or the vacuum chamber. This interchangeble vacuum system could successfully cope with the problem of high gas loads released during the melting process, while still attaining vacuum levels in the 10^?7 torr range. More than a dozen metals and intermetallic compounds were melted in this furnace but not in all cases were perfect single crystals obtained. This was mostly caused by certain properties of the materials which were found unsuitable for the EBFZ technique rather than by instrumental shortcomings of the system.     

大型计算机电子元件水冷板的真空钎焊工艺研究

介绍了大功率电子元件水冷板的真空钎焊方法,包括真空度,温度等工艺参数,以及真空钎焊炉的主要技术指标.     

ITO靶材高温真空热压炉的研制

本文介绍了稀有金属行业ITO靶材高温真空热压炉的设备组成、主要技术参数和结构特点,并指出了该设备在稀有金属行业ITO靶材制造行业推广应用的前景.     

杭氧ZH-2060型大型真空钎焊炉工程建设

大型真空钎焊炉是制造大型空分设备等大型板翅式换热器的重要设备 ,介绍了杭氧股份公司大型真空钎焊炉的参数和特点 ,真空钎焊炉工程的建造过程。真空钎焊炉的建造成功发挥了良好的经济效益 ,总结了钎焊炉建造的经验与体会。     

不锈钢材料在真空炉高温除气后的出气性能比较

根据兰州重离子加速器冷却储存环真空系统(HIRFL-CSR)材料处理工艺要求,需要对所有不锈钢元件进行真空炉高温除气处理以降低材料出气率.本文通过一组实验测试数据,介绍了采用除气处理工艺和未经除气处理的不锈钢材料出气情况对比,证明采用真空炉除气处理工艺可以使材料内部的H2、CO、CO2等组分大幅度减少,从而获得较低的材料出气率.     

Ni-Cr-P焊膏钎焊C/C复合材料的组织和性能

用真空熔炼、惰性气体雾化法制备Ni-Cr-P金属粉末,再加入有机黏结剂高速搅拌,制备Ni14Cr10P膏状活性钎料。用制备好的焊膏真空钎焊C/C复合材料,测试钎焊接头的剪切强度,通过OM,SEM,EDS,XRD等对钎焊接头界面组织结构进行分析。结果表明:在钎焊温度1000℃、保温时间0.5 h条件下,获得的接头剪切强度达到28.6 MPa,然后随着钎焊温度上升或保温时间延长,钎焊接头强度下降;通过界面组织结构分析发现焊膏可以增加钎料层与C/C复合材料表面的接触面积,有利于堵塞C/C复合材料表面的孔隙。焊后在界面处形成了交错分布的Cr碳化物相缓冲层,使得界面呈现热膨胀系数梯度增加的结构,有助于缓解热失配,提高C/C复合材料钎焊接头强度。     

大型真空铝钎焊装备--主要技术参数及热工程序设计与控制

本文根据作者多年的实践、试验、理论分析总结了装备设计中工作真空度、抽速容积比、炉室漏气率、加热功率、温度均匀性、控温精度、独立闭环加热区尺寸、加热元件设计计算、工件许用均温度等主要参数的确定方法和计算依据,提供了两种实用的热工工艺程序原理框架.供同行参考.     

1750℃高温钽片真空炉的研制

本文介绍了一种用于高压电容器钽粉高温脱气处理的新型金属热处理炉，这种炉子是针对钽粉高温脱气的特点开发研制的，即使在工作温度，真空度较高，除气量，温度梯度较大的情况下，仍能保证高温脱气的合理性和延长加热器的使用寿命，并能广泛适用于高温脱气，真空钎焊等场合。     

W-Re composite tube fabricated by chemical vapor deposition for application in an 1800 °C high thermal efficiency fuel-processing furnace

Chemically vapor-deposited rhenium was selected as the muffle material for an 1800 °C high thermal efficiency fuel-processing furnace. The muffle is exposed to high vacuum on the heater-insulation-instrumentation side and to a flowing Ar-8vol.%H₂ gas mixture at a pressure of 1 atm on the load volume side. During operation the muffle cycles from room temperature to 1800 °C and back to room temperature once every 24 h. Its operational life is dependent on its resistance to thermal fatigue during the high temperature exposure. For a prototype furnace the muffle has an inner diameter of approximately 13 cm and is 40 cm in length. A small (about half-size) rhenium closed-end tube overcoated with tungsten was used to evaluate the concept. The fabrication and testing of the composite W-Re tube and prototype rhenium muffle are described.     

Genetic-Algorithm-Based Optimization of an Industrial Age-Hardening Operation for Packed Bundles of Aluminum Rods

Industrial thermal processing operations are highly energy intensive, and must be efficiently operated, especially under the current global energy crisis. However, optimization of such complex operations is a nontrivial task and must be formally approached. In the present work, an integrated model has been used in conjunction with a genetic algorithm to optimize industrial age-hardening of packed bundles of aluminum alloy rods. The presence of peak yield strength and the strong dependence of peak time on age-hardening temperature make this operation interesting for optimization studies. Multiobjective optimization problems have been formulated and solved for energy minimization, productivity maximization, and variability reduction during age-hardening by an elitist nondominated sorting genetic algorithm. The Pareto-front for optimum furnace temperature, time, and quality variation has been determined for isothermal as well as multisegment nonisothermal furnace temperature profiles. Subsequently, optimum multisegment furnace temperature-time set-points were obtained and compared with equivalent isothermal profile. The advantage of multisegment nonisothermal profile over isothermal profile in reducing the energy consumption has been demonstrated.     

真空炉高温除气工艺对降低不锈钢出气率的作用

真空炉高温除气工艺可以大大降低不锈钢出气率。通过应用实例,给出了真空炉高温除气和现场烘烤除气及二者结合除气的结果,分析了真空炉高温除气的有利因素,证明采用该工艺对于降低不锈钢出气率,从而获得超高真空具有显著的效果。