真空开关用触头材料

综合介绍德国第１５届阿尔贝特－凯尔电接触研讨会报导的真空触头材料最新的研究进展。讨论集中在用模拟真空开关试验装置对钨基、碳化钨基、铜格等触头材料的分断能力、电弧烧损、截止电流的研究结果以及分析解释。     

我国钨基电触头材料发展的形势和建议

<正> 我国钨基电触头材料的发展前景这一年来,由于我国国民经济的调整和国内市场的相对疲软,钨基电触头材料的需求也受到一定的影响,各个电工合金厂的钨基电触头生产有所下降。面对这种形势,如何看待我国钨基电触头材料的发展前景呢?我们认为:我国钨基电触头材料的发展前景     

钢铁研究总院的三项钨材和一项硬质合金科研成果通过技术鉴定

<正> 1988年12月,冶金部钢铁研究总院在北京市有三项钨材和一项硬质合金科研成果通过技术鉴定,它们是钨基复合燃气舵材料、钨镍铜高压触头合金、钨锡助熔剂和陀螺仪转子轴尖专用硬质合金。其中,钨基复合燃气舵材料和轴尖专用硬质合金系由冶金部和航空航天部共同主持鉴定的鉴定项目。钨基复合燃气舵材料用于大型固体燃料战术导弹,要求能经受高温高速并带有固体微粒的燃气流的强烈烧蚀和冲刷作用,因此要求高的高温强度、表面硬度和抗热震性,研制的技术难度大。但是,课题组全体同志见难而上,研制成钨基复合燃气舵材     

高性能细晶钨基复合材料制备关键技术及开发应用

钨基复合材料具有密度高、熔点高、强度高、热膨胀系数小、热导率高、抗辐射能力强、耐腐蚀性强等优点,在电子信息、机械加工、航天航空、国防军工和核工业等领域可广泛用作穿破甲材料、电子封装材料、电极材料以及核辐射屏蔽材料等。采用传统方法制备的钨基复合材料由于晶粒粗大、组织均匀性差、性能低或致密度低等缺陷,已经难以满足尖端技术领域的发展需要。采用纳米复合技术制备的细晶钨基复合材料具有致密度高、组织细小且均匀、性能好等优点,成为钨基复合材料发展的重要方向。概述了高性能细晶钨基复合材料的制备关键技术与开发应用,并对高性能细晶钨基复合材料的应用前景作出了展望。     

面向等离子体材料用先进钨复合材料的改性研究进展与趋势

核聚变能是解决未来社会能源危机的有效途径之一，但面向等离子体材料在聚变堆体中面临着来自等离子体严重的辐照和热冲击损伤。纯钨因其高热导率、良好的高温强度、低溅射和低蒸气压而被认为是最有希望的面向等离子体候选材料。纯钨在聚变堆工况条件下具有严重的脆性风险，因而对面向等离子体材料用先进钨材料的改性成为近年来的研究热点。钨基复合材料的改性方法主要包括合金化、第二相强化、纤维增韧和复合强化。本文综述了近年来国内外针对核聚变反应堆面向等离子体材料用钨基复合材料的改性方法及其性能，分析了钨基复合材料的改性机制，并展望了面向等离子体材料用钨基复合材料的发展方向。     

熔渗法铜钨触头材料中的钨基体

探讨了钨粉粒度及组成、成形压力、烧结工艺、渗铜效果等因素对铜钨触头基体性能的影响。根据不同的粉末粒度选用不同的烧结工艺,可以获得不同含铜量所需孔隙度的钨基体。     

真空开关用触头材料现状及展望

概述了国内外真空开关用触头材料概况,介绍了Mo-Cu(Ag)等几种触头材料的化学成分、性能和应用,并提出了触头材料的发展方向。     

新型真空触头材料-粉末冶金Cr-Cu系合金

Cr-Cu系触头的研制成功是近年来触头材料的一个重要发展。本文从真空开关的优点及其发展、真空触头材料的技术要求及选择原则,论述了开发Cr-Cu系触头的必要性。介绍了制取Cr-Cu系触头的各种粉末冶金工艺,它们的优缺点以及影响Cr-Cu系触头性能的有关因素。     

钨基合金穿、破甲材料的研究进展

科学技术的发展对钨基合金用作穿、破甲材料的要求日益提高,要求高强韧、自锐性强,好的射流等多功能化,以及材料的多品种化。钨基合金由于密度高、强度和延性好而用作穿、破甲材料越来越引起国内外的关注。作者阐述了国内外近10年来钨合金穿、破甲材料在材料体系、形变强化和动态力学性能等方面的研究进展。     

钨基高比重合金技术的发展

钨基高比重合金是钨的最重要的两大市场之一，是现代工业经济不可缺少的组成部份。近年来，由于钨基高比重合金技术的发展，已造就一系列高性能材料，其使用周期成本及环保方面的优势均明显胜过与之竞争的其它高比重材料。     

Occurrence and type of traumatic experiences among young Bosnian refugees in Denmark

Prior research has shown that young refugees may be especially traumatised. The study includes 123 young Bosnian refugees, living at two Bosnian boarding-schools in Denmark who were given a revised version of the Harvard Trauma Questionnaire (HTQ). The subjects themselves have on average experienced seven traumatic events, and have either witnessed or had a family member experience an additional six events. Three-quarters have been shot at, have lost their homes and private possession and have been exposed to violence in the form of harassment or humiliation. Two-thirds have lost friends. Three-fifths have lived with uncertainty as to whether friends and family were alive or dead. More than half have seen dead and wounded people, have had their lives threatened and have thought that they would die. More than a third have lost close family members, have been wounded and have had their homes destroyed. Just under a third have been exposed to physical violence or have witnessed somebody being killed. A quarter have starved and been ill without being able to receive treatment. About a fifth have experienced captivity, torture and forced labour. 6% have been raped or exposed to other forms of sexual abuse. It is concluded that the young Bosnians examined are a multitraumatised group. Use of the HTQ increased the number of traumatic events quite considerably compared to the case notes.     

Treatment of the epilepsy: new drugs

New advances in the knowledge on the physiopathogenesis of epilepsy and their relationship with sodium and calcium channels and with the excitatory and inhibitory neurotransmitters actions have recently been developed. These knowledges have produced the research on new antiepileptic drugs which action places have specially based on the known impaired mechanisms. As the conventional drugs, the new therapeutic tool have produced a great advance in the therapy of epileptic events, specially in the refractory seizures, which represent 25-30% of the whole group of epilepsies. In the present work, we review the new drugs, ones have been registered, in order to their pharmacological properties, their efficacy their safety and their clinical indications as first-election or adjuvant drugs. We also discuss their known side adverse effects.     

钢板冷弯性能不合原因分析及对策

通过统计、分析和试验研究，找出了导致钢板冷弯性能不合的因素，提出了改进措施，并对其实施效果进行了验证。     

Malpractice liability of physicians to nonpatients

Sometimes physicians assume responsibilities to third parties when undertaking the care of patients. Physicians have been held liable to third parties, though strangers to the patients, for failing to warn regarding the communicability of contagious diseases. Two suits have been allowed against physicians by third parties who were injured by drivers of vehicles who had not been warned by the physician of the danger of driving caused by their medical problem. Hospitals and psychiatrists have been held liable to injured third parties for failing to warn of the dangerous propensities of their patients under psychotherapy. Courts have held that such disclosures do not violate the patient's right to privacy and confidentiality. However, physicians may exercise professional discretion and need not warn if, in their judgment, that would be unreasonable, unnecessary, or harmful. Nevertheless, rights of patients must yield to the public interest when it collides with public safety and welfare.     

Standardized evaluation of red, green and blue perception. Comparison between color arrangement and computer-assisted test procedures

The Canadian Forces have deployed on humanitarian, peacekeeping, and peacemaking operations frequently throughout the 1990s. The circumstances that many Canadian soldiers have found themselves in while deployed have been grim. They have been witness to countless unspeakable acts and carry the burden of their experiences with them. As a result of their operational deployment, many soldiers develop stress reactions that interfere with their daily social functioning. This article reviews the psychological support provided to Canadian soldiers deployed to Rwanda in 1994. The primary intervention known as "debriefing" is also elaborated upon.     

Synthesis and antimicrobial assays of 3-diazoindole-2-carboxamides

Some 3-diazoindole-2-carboxamides have been synthesized and their antimicrobial activity have been tested. Antimicrobial activity was practically lacking.     

提高焦炭质量的技术措施

针对高炉大型化和富氧喷煤对焦炭质量的目标要求,探求提高焦炭质量的技术措施并对这些技术措施的基本原理进行了分析。     

The susceptibility of pure tubulin to high magnetic fields: a magnetic birefringence and x-ray fiber diffraction study

The orientational behavior of microtubules assembled in strong magnetic fields has been studied. It is shown that when microtubules are assembled in a magnetic field, they align with their long axis parallel to the magnetic field. The effect of several parameters known to affect the microtubule assembly are investigated with respect to their effect on the final degree of alignment. Aligned samples of hydrated microtubules suitable for low-resolution x-ray fiber diffraction experiments have been produced, and the results obtained from the fiber diffraction experiments have been compared with the magnetic birefringence experiments. Comparisons with earlier fiber diffraction work and small-angle x-ray solution scattering experiments have been made.     

Hydrogen Embrittlement of Automotive Advanced High-Strength Steels

Advanced high-strength steels (AHSS) have a better combination between strength and ductility than conventional HSS, and higher crash resistances are obtained in concomitance with weight reduction of car structural components. These steels have been developed in the last few decades, and their use is rapidly increasing. Notwithstanding, some of their important features have to be still understood and studied in order to completely characterize their service behavior. In particular, the high mechanical resistance of AHSS makes hydrogen-related problems a great concern for this steel grade. This article investigates the hydrogen embrittlement (HE) of four AHSS steels. The behavior of one transformation induced plasticity (TRIP), two martensitic with different strength levels, and one hot-stamping steels has been studied using slow strain rate tensile (SSRT) tests on electrochemically hydrogenated notched samples. The embrittlement susceptibility of these AHSS steels has been correlated mainly to their strength level and to their microstructural features. Finally, the hydrogen critical concentrations for HE, established by SSRT tests, have been compared to hydrogen contents absorbed during the painting process of a body in white (BIW) structure, experimentally determined during a real cycle in an industrial plant.