制备环境清洁度对纳米粒子结晶形态的影响及其控制原理

本文研究了气体蒸发法制备纳米粒子过程中，制备环境清洁度对金属纳米粒子结晶形态的影响，重点分析了真空度、气体纯度及系统漏放气率三者对纳米粒子制备环境清洁度的影响及其相互关系．结论认为，只有控制这三个因素在一定范围内相互匹配，才能以最少的投入创造一可靠的清洁制备环境，生产出具有明显结晶形态而又具有清洁面的各种纳米材料．文章给出了真空度、气体纯度及漏放气率三者相互匹配的二个判据。     

玻璃钢复合材料无磁杜瓦真空性能研究

讨论了玻璃钢复合材料无磁杜瓦的真空性能。提出了采用三层模式壳体结构、加热、充CO2置换气体、放置活性炭等提高和保持杜瓦夹层真空度、减少抽空时间的方法。同时简述了影响夹层真空度测量的相关因素。研究结果表明:玻璃钢复合材料放气率是影响夹层真空度的主要因素;在液氮温度下杜瓦夹层动态真空度可达5×10-4Pa,并可长期使用而真空度不变。     

波导阀门放气理论计算和改进措施

本文介绍了波导阀门放气量和波导阀附近真空系统的真空度的关系.波导阀门放气量对速调管陶瓷窗附近的真空度有极大的影响.在计算和实验研究的基础上,我们对波导阀门的放气量进行了理论计算,按照BEPCII对速调管陶瓷窗真空度的要求改进了真空系统.     

全超导托卡马克第一壁石墨材料的放气特性研究

全超导托卡马克(EAST)实验中,面向等离子体材料(PFM)的放气特性直接影响到等离子体的品质.因此采用动态流导法的实验装置,在不同温度和真空度下对表面镀有SiC薄膜的GBST1308(B l%、Si 2.5%、Ti 7.5%、C 89%)掺杂石墨材料进行放气实验研究.测试分析了石墨材料在18℃至350℃经140h连续烘烤下的放气特性,并考虑温度对限流小孔流导的影响,计算出石墨材料的单位表面积放气速率和总放气量.通过四极质谱仪(QMS)监测和定性分析石墨材料放出气体的各种成分,利用标准谱图计算出残余气体中H2、H2O、CO和CO2的放气速率.结果表明,温度是影响石墨材料放气成分和放气速率的最主要因素,另外当石墨材料在350℃的高温18h恒温烘烤后能有效地减小杂质气体成分和放气速率.     

特殊器件低温烘烤排气的实验研究

针对特殊器件烘烤温度低于200℃的要求,分析了影响管内真空度的相关因素,进行了升温过程中烘烤温度对真空度影响的实验研究,取得了在约170℃时器件内材料放气量大、真空度相对最低等相关数据,依此确定了升温速率及烘烤工艺。     

聚二甲基硅氧烷膜蒸汽渗透分离低浓度乙醇/水溶液的研究

对聚二甲基硅氧烷(PDMS)膜蒸汽渗透分离低浓度乙醇/水溶液的性能进行了研究,考察了料液浓度、膜器温度、循环气体流量、真空度等因素对PDMS膜蒸汽渗透性能的影响.结果表明,渗透通量和渗透侧乙醇浓度随着料液中乙醇浓度的增大而增大,但分离因子有所降低;随着膜器温度的升高,渗透通量增加,渗透侧乙醇浓度下降,影响显著;随着循环气体流量的增大,渗透通量和渗透侧乙醇浓度均有较大幅度的提升,有利于蒸汽渗透过程的进行;随着真空度的增大,渗透通量上升,渗透侧乙醇浓度下降.     

铯束管超高真空维持特性研究

铯束管超高真空长期维持特性是铯原子钟的关键技术指标之一,真空度会影响铯原子钟的性能指标及寿命。材料表面放气率是影响铯束管真空度的主要因素。在铯束管封装过程中,必须针对不同材料制定相应的真空除气工艺来减小材料的放气率,并在铯束管内安装溅射离子泵来维持真空。本文通过理论分析,得出了铯束管内的工作压力,并测试了溅射离子泵的各项性能指标、真空度与铯炉工作温度之间的关系、铯束管的真空维持特性等,研究结果为磁选态铯束管研制及测试提供了参考。     

小型低温储罐真空性能研究

以真空粉末绝热的低温储罐为研究对象,搭建实验平台,对影响真空度的因素进行了实验研究。研究了5、10和30立方三种规格低温储罐在装砂前和装砂后的抽真空过程中,真空度随时间的变化规律。结果表明:影响真空度的因素主要是珠光砂的紧密度和材料漏气放气。珠光砂填充不实会引起局部漏热,加快真空度的破坏,在填充珠光砂时应使用振动泵。漏气与放气因素影响不可避免,因此在选择材料时应注意材料的结构特性和绝热性能。     

多层绝热出气特性的研究

多层绝热体内吸附及溶解的气体要求在较短时间内释放排除,使残余气体的压力低于1.3×10~(-2)Pa,以保证总传热量中气体传热尽可能减小。为此要求在多层绝热的抽真空过程中能保持尽可能大的放气率。着重介绍了放气率的测量装置以及分析讨论了影响多层绝热放气的各种因素。     

真空开关管真空寿命的计算

引言真空开关管能否正常工作,除与它的机械特性有关外,还取决于真空开关管的真空度。通常,当管内的真空度低于某一极限值时,真空开关就不能正常工作;换言之,真空度的好坏对真空开关管的开断特性有一定的影响。因此,要求真空开关管在储存期与使用期应该具有足够好的真空度。一般情况下,象电子管、显象管、真空开关管一类的真空器件都是在小于或等于1.3×10~(-4)帕的压强下封离的,但是大多数电真空器件不可能做到绝对不漏气,内部的零器件也不可能做到绝对不放气。由于真空开关管外壳焊缝的漏气、外壳材料的渗透、内部零件表面吸附气体的解吸等原因,都会使真空开关管在储存或使用一段时间后造成管内压强的升高。     

Factors limiting the attainment of ultra-high vacuum below 10 torr

The present capabilities of ultra high vacuum pumping systems are such that the major limitation on the attainment of ultra high vacuum is the gas loas presented by degassing and permeation of walls and of internal components. Considerable work has been undertaken, theoretically, and experimentally, to illustrate the effects of high temperature bake-out on minimizing outgassing rates but these usually refer to effects at ambient or constant elevated temperature. The present communication analyzes the rate of degassing of components when subjected to time varying heating cycles, in terms of diffusion from the bulk of the solids. It is shown that measurements of degassing rate as a function of increasing temperature can lead to detailed knowledge of the diffusion process which is important in determining the degree of bake-out necessary for individual systems.     

Outgassing characteristics of a polycarbonate core material for vacuum insulation panels

Performance deterioration with time is one of the most important issues in a vacuum insulation panel (VIP), which is mostly due to the inner gas pressure rise. Outgassing from the interior of core materials is the major gas source when the core material is a polymer. Outgassing characteristics of a polycarbonate as the VIP’s core material are examined theoretically and experimentally. To measure the outgassing rate, specific outgassing tests are carried out using a pressure rise method. Diffusive outgassing mechanism is discussed based on the Fick’s law. As the result, the total amount of dissolved gas and the diffusion coefficients of various gases in the polycarbonate are obtained by using the measured outgassing rate. Temperature dependence of the diffusion coefficient of nitrogen is also examined. It is shown that the outgassing rate of polymer core materials can be significantly reduced to a negligible level by a baking pre-treatment in vacuum and/or by a metal coating on the polymer surface.     

On the vacuum design of vacuum web coaters

The main features which determine the vacuum design of a vacuum web coater are reviewed. Measurements on the outgassing of polymer and paper web rolls as well as on the conductance of the slit configurations usually employed in production roll coaters are presented. On this basis the vacuum design of an advanced web coater concept for coating video type is discussed in some detail. The discussion includes the concept of additional buffer chambers between the deposition chamber and the winding chamber to minimize the gas flow into the deposition chamber.     

Static expansion vacuum standard with extended low pressure range

The main factor to affect lower limit of static expansion vacuum standard is outgassing of the inner surface. A new method has been demonstrated to extend the lower limit by using a non-evaporable getter pump (NEGP) to eliminate the outgassing influence. Because NEGP has no pumping speed for inert gases, it can maintain the ultra-high vacuum background without changing gas quantity in the calibration chamber when an inert gas is used as the test gas, which makes the standard pressure accurately calculable by Boyle’s law. By this method, the lower limit of static expansion vacuum standard has been extended to 10⁻⁷ Pa.     

高真空条件下网状泡沫放气量的测试

利用航天工业行业标准及测试设备对一定真空度条件下的聚胺脂网状泡沫在常温及加温两种不同工况时的出气情况进行测试；对两者的放气量进行比较；对放气机理进行分析探讨。此工作对高真空连续卷绕网状泡沫镀镍设备的真空系统配置具有一定的指导意义。     

钢液炉外精炼设备真空系统的设计分析

本文综合一些国内外有关资料，讨论了钢液炉外精炼设备真空系统设计中的一些技术问题，对放气量的确定、真空系统的气体负荷的等效换算以及真空泵容量的选择和能源消耗等进行了分析。给出蒸汽喷射泵的抽气能力与真空度的关系，可作为钢液炉外精炼设备的真空系统设计时参考。（注：1 Torr=133Pa）     

真空管道TiN膜热出气率实验研究

简要叙述了小孔流量法测量材料出气率实验的原理和实验装置，给出了不锈钢溅射镀TiN膜在不同情况下的热出气率，并对影响不锈钢溅射镀TiN膜热出气率情况的各种因素进行了分析，为使用溅射镀TiN膜表面处理的储存环真空室的设计提供了依据。     

Outgassing of vacuum materials-II

Part II of this two part account examines the methods available for the measurement of outgassing rate. It recounts the results obtained for some selected materials and in particular examines methods for reducing the outgassing rates of materials for use in ultrahigh vacuum. Finally it presents outgassing rates for various materials in tabulated form.     

TiN镀层对真空系统释气率的影响概述

抑制射频真空系统表面二次电子倍增的一种常用方法是在系统内表面镀TiN薄膜,因为TiN薄膜具有较低的二次电子发射率.但对于真空应用来说,必须关注TiN薄膜的真空释气率问题.本文综述了国内外在TiN镀层真空特性方面的研究现状,其中涉及TiN镀层低释气率的物理机制、产生低释气率TiN薄膜的最优化镀膜条件以及两种常用镀膜方法的比较.     

The pressure profile in a long outgassing vacuum tube

As a simple extension of the long tube formula, an analysis is given whereby the pressure profile may be determined along a uniformly outgassing pipe pumped at both ends. The theoretical analysis is extended to include nonuniform outgassing situations such as occur in particle storage rings. These findings are used to determine the optimum vacuum system configuration for various vacuum system parameters, while affording minimum vacuum system cost. Calculations were checked experimentally using a stainless steel tubing with a 5.7 cm inside diameter, and a length of ～50 m.