Electron-Beam Techniques Vacuum Degassing Highlight: Fifth Vacuum Metallurgy Conference

A summary report on the Fifth Annual Conference on Vacuum Metallurgy held at New York University on June 18-19, 1962, under the joint sponsorship of the Vacuum Metallurgy Div. of the American Vacuum Society and the Dept. of Metallurgy and Material Sciences of New York University.     

Vacuum metallurgy 1967—Part 2

The following is Part 2 of a 2-part review article of the International Conference on Vacuum Metallurgy. Part 1 appeared in the October issue, pages 35 to 39, and covered the first 3 topics of the conference: I—Plenary Session; II—Vacuum Equipment and Technology and Vacuum Metallurgy Operations; and III—Electron Beam Processing.     

New aluminum composites—A review

During the Fall Meeting of the Metallurgical Society in Cleveland (October 16–20, 1967), the Nonferrous Metallurgy Committee of the Institute of Metals Division sponsored a two-day symposium on “New Developments in Aluminum Technology.” This article reviews the first session, which was devoted to “Reinforced and Powder Products” and consisted of five papers on fiber reinforced composites and one on new powder metallurgy alloys.     

应用真空快淬制备纳米晶和非晶合金

介绍了应用真空快淬工艺制备纳米晶和非晶合金，应用真空快淬工艺可使金属在极大的过冷度下凝固，金属及合金经过真空快淬处理后具有纳米晶、非晶结构，因而具有特殊的力学及物理性能。真空快淬工艺在多种金属及合金的制备中使用，获得了令人满意的结果。真空快淬工艺在制备新型功能及结构材料中发挥了不可替代的作用，而且应用范围日趋广泛。     

Evaluation of the effect of vacuum on mold filling in the magnesium EPC process

The combination of magnesium alloys with the expendable pattern casting (EPC) process will bring a bright future for the application of magnesium alloys. Vacuum is a pre-requisite parameter in the EPC process of magnesium alloys, because without vacuum, the fluidity of the magnesium alloy in the EPC process is too poor to fill the mold completely, especially for the thin-section castings. In this investigation, the effect of vacuum on the fluidity of AZ91 magnesium alloy has been explored. A modified model has been presented to explain the effect of vacuum on mold filling, which was verified by optical microscopy.The results obtained indicate that vacuum is the most effective parameter in improving the fluidity, the effect of vacuum on the fluidity interacting strongly with the pouring temperature and coating. Vacuum greatly changes the mass and heat transfer in the EPC process. Vacuum may not only control the profile of the metal–foam interface, which will influence the mass transfer process, but may also greatly speed up the removal rate of pattern decomposition products at the metal–coating interface. It also changes the primary heat-transfer mode to heat convention, which has a great influence on the distribution of the casting temperature field and solidification process. The microstructures of castings cast with vacuum exhibit a fine grain size and a small amount of precipitated Mg₁₇Al₁₂, but vary insignificantly with the location in the castings.     

真空压铸工艺与锌合金高真空压铸技术研究

近年来,真空压铸技术在国内外得到了广泛的应用,目前国外高真空压铸的方法主要有3种,分别是来自德国的Vacural法和MFT（MinimumFillTime）,以及来自日本的vaccumGolveBox法,国内学者也研制出了各种真空压铸方法。在真空压铸技术领域中,重点要解决是模具密封与真空截止阀的问题,本文总结了目前实际应用中的各种真空压铸方法与工艺,探讨了真空压铸技术在实际运用过程中面临的主要问题,并在此基础上开发设计了具有自主知识产权的锌合金高真空压铸造工艺法。     

响应面分析法优化锆英粉陶瓷型真空干燥工艺

采用胶态浇注成型技术和真空干燥方法制备表面无裂纹的锆英粉陶瓷铸型.通过统计试验设计的方法对陶瓷型真空干燥进行优化.采用单因素试验,对影响真空干燥工艺的真空度、真空干燥温度、真空干燥时间3因素进行考察.利用Box-Behnken设计对此3个主要因素的最佳水平进行进一步研究.结果表明,在真空度、真空干燥温度和真空干燥时间分别为0.06 MPa、81 ℃和5 h时,陶瓷型铸型的干燥收缩率和强度分别为0.686%和6.39 MPa.     

Steels and alloys for chemical apparatus

Conclusions Modern technology has a large assortment of alloys which can be used in any corrosive medium and used in different chemical apparatus.Refractory metals are the most suitable for particularly aggressive media.Although there are still many unsolved problems in the physics of metals concerning the development and use of metals and alloys in the chemical industry, the main problems of today are the application in metallurgical plants of alloys developed in metallurgical laboratories and also provision of the chemical industry with enough equipment made of these alloys.Central Scientific Research Institute of Ferrous Metallurgy Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 10, pp. 3–12, October, 1964     

Potlining Problems in the Aluminum Industry

The articles appearing in the following section are condensations of papers presented at a panel discussion on the subject of “Potlining Problems in the Aluminum Industry”, sponsored by the Extractive Metallurgy Division of The Metallurgical Society. The panel was held during the AIME Annual Meeting in New York City, February 1968. All deletions, and the omission of references, have been made solely because of space limitations, and should not be construed as reflections upon the individual authors or their papers.     

浅析我国热处理设备的更新换代

低真空变压热处理技术（包括设备和工艺）是综合低真空热处理和变压热处理的优点的专利技术。该技术的炉气能快速吐故纳新和精确调控,其炉温也能精确控制,且与真空热处理炉相比,其设备的价格也较低廉,是“老三炉”更新换代的理想产品。广泛采用低真空变压热处理技术是缩短我国同发达国家之间差距的捷径之一。     

Copper converter refractory practices

The articles appearing in the following section are condensations of papers presented at a round table discussion on the subject of “Copper Converter Refractory Practices”, sponsored by the Extractive Metallurgy Division of The Metallurgical Society. The discussion was held during the AIME Annual Meeting in New York City, February 1968. All deletions, and the omission of references, have been made solely because of space limitations, and should not be construed as reflections upon the individual authors or their papers.     

高纯稀土金属Sm、Yb和Tm的制备

采用镧热还原蒸馏法对蒸气压较高的稀土元素Sm、Yb和Tm的制备进行了研究,制得了纯度达4N级的稀土金属Sm和Yb,其纯度分别为99.99%和99.993%（质量分数,相对75种杂质元素）;对于稀土金属Tm,由于还原温度较高,还原蒸馏产物中La的含量偏高,需要对其进行低温、高真空升华提纯,提纯后纯度达到99.995%（同上）;实验结果表明,高纯度还原剂La的制备,尤其是La中金属杂质总量的控制,是获得4N级Sm、Yb和Tm的关键步骤。     

Die Kaltverdichtung anodisch erzeugter Oxidschichten des Aluminiums

The cold sealing of anodic oxide layers on aluminium Vacuum treatment of fresh anodic oxide layers on aluminium changes their electrical properties: the capacity is reduced by 75 % while the electric resistance is increased by the factor 10. Subsequent the sealing of anodic oxide layers in water no such changes are produced during vacuum treatment. The latter gives further rise to changes of reactivity and corrosion resistance which become comparable to the respective properties of sealed layers. An interpretation of these effects of vacuum treatment would require further investigations using IR spectroscopy, NMR and determination of the specific surface area.     

真空炉隔热屏保温效果的数值仿真

金属炉胆的真空炉主要用于处理一些对真空气氛要求较高的金属产品,炉胆的隔热屏制造成本较高并且不易改动。通过对WZDGQ-40型真空炉的金属隔热屏保温效果进行仿真研究,得到每层隔热屏的温度场情况。结果表明,调整中间两发热带的距离为200 mm时,炉胆外层温度降低80 ℃。合理的发热带宽度和发热带间距能够较好提高炉胆的保温效果,为今后该类型装备制造提供一定的参考价值。     

Heat transfer characteristics of lost foam casting process of magnesium alloy

1 Introduction The growing demand for mass reduction in aerospace and automotive industries has greatly increased the magnesium application. Currently, casting is the main industrial forming method for magnesium alloys, but the lag of research and develop…     

VI－EPC铸造法充型特性及其影响因素

在实验研究的基础上，提出消失模型真空吸引铸造法。在用铸铝进行浇注的条件下，对平板模型进行了充型实验，通过改变真空负压、浇注温度、内浇口面积观察充型情况，分析各因素对充型过程影响，获得了在各种条件下金属液充型的等时曲线，找出了其充型形态规律     

超声切割刀具的真空钎焊

介绍了超声切割刀具的真空钎焊技术,主要内容包括钎焊材料、钎焊方法和钎焊工艺。刀具由高速钢刀片和钛合金刀杆组成,所用钎料为Ag-Cu共晶钎料。钎焊工艺参数为：真空度7.5 xPa,钎焊温度830℃,保温时间10 min。     

铝基活性钎料真空钎焊C_f/C复合材料焊接接头的组织及性能

用铝基活性钎料对C_f/C复合材料进行真空钎焊,并对接头的微观组织、形成机理和接头强度进行了试验研究.结果表明,使用铝基活性钎料可以实现C_f/C复合材料的连接,且在试验温度范围内,接头强度随钎料成分不同而发生变化.电子探针观察表明,钎料与C_f/C复合材料钎焊接头润湿性良好,存在成分偏聚层,这种层状结构对缓和焊接残余应力十分有利.室温下接头最高剪切强度可达16MPa.     

Effect of Sublimation in Vacuum Annealing on the Limit of Elasticity of Nonferrous Alloys

Results of analytical and experimental studies of the effect of annealing in vacuum on the limit of elasticity of nonferrous alloys are presented. Vacuum annealing changes the chemical composition of the surface layers due to sublimation of the highly volatile component of the alloy, which leads to a decrease in its limit of elasticity due to the accumulation of crystal structure defects. An empirical equation is suggested for predicting the variation of the limit of elasticity of heterophase alloys as a function of the duration of isothermal annealing in vacuum. The results obtained by solving this equation agree satisfactorily with experimental data.     

Real-time monitoring of transverse thermal strain of carbon fiber reinforced composites under long-term space environment using fiber optic sensors

Composites are promising alternatives for space structures because of their versatile characteristics such as high specific stiffness and strength. When composite structures are exposed to the space environments (low Earth orbit, LEO), however, they are known to undergo considerable temperature change induced by the direct sunlight and the Earth's shadow in addition to ultraviolet, high vacuum, atomic oxygen and so forth. Therefore, for the successful completion of their missions, it is important for the structures to maintain the consistent dimensional stability in such a thermal cycling condition. The coefficient of thermal expansion (CTE) of the structures is suitable to express the dimensional stability, and it is needed to be monitored throughout the mission. For this purpose, fiber optic sensors, which have many advantages, were investigated to check their suitability in this paper.Two fiber Bragg grating (FBG) sensors have been adopted for the simultaneous measurement of thermal strain and temperature to get the CTE change of a carbon/epoxy composite laminate. LEO conditions with high vacuum, ultraviolet and thermal cycling environments were simulated in a thermal vacuum chamber. As a pre-test, a FBG temperature sensor was calibrated and a FBG strain sensor was evaluated through the comparison with the electric strain gauge (ESG) attached on an aluminum specimen in the same temperature range as the thermal cycling. The change of the transverse CTE in a composite laminate exposed to the space environment was measured for intervals of aging cycles in real time. As a whole, there was no abrupt change of the CTE after 1000 aging cycles. After aging, however, the CTE decreased a little all over the test temperature range. These changes are thought to have been caused by outgassing, moisture desorption, matrix cracking, etc. In this paper, embedding application of FBG sensors to composites operated under space environment and their successful real-time monitoring of thermal deformations over a long time was shown.