Study on Vacuum Materials Outgassing Rate Using the Method of Switching Between Two Pumping Paths

A new measurement apparatus for vacuum materials outgassing rate was developed, which is mainly composed of three systems, including ultra-high vacuum system, high vacuum system, switching between two pumping paths (SPP) measurement system. The test principle of the modified SPP method is described in details, and the newly-developed technique has two main advantages over the conventional one. Firstly, the errors due to the use of two gauges with different physical properties are avoided by using only one gauge during data processing. Secondly, the outgassing rate of sample chamber, the test chamber and the outgassing or pumping effect of the gauge head can be eliminated enormously. Based on the SPP method, this paper gives the details of the experiments and the results on specific outgassing rate of the 7075 aluminum alloy sample in different conditions, namely, at different times and at different temperatures generated by infrared light irradiation heating.     

Comparative Study of Dense Bulk MgB2 Materials Prepared by Different Methods

We report on the results of a comparative investigation of highly dense bulk MgB₂ samples prepared by three methods: (i) hot deformation; (ii) high pressure sintering; and (iii) mechanical alloying of Mg and B powders with subsequent hot compaction. All types of samples were studied by AC susceptibility, DC magnetization, and resistivity measurements in magnetic fields up to μ₀ H = 160 kOe. A small but distinct anisotropy of the upper critical field $\psi {\rm H}_{c2}^{\alpha ,b} /H_{c2}^c \sim 1.2$ connected with some texture of MgB₂ grains was found for the hot deformed samples. The samples prepared by high pressure sintering as well as by mechanical alloying show improved superconducting properties, including high upper critical fields H _c2 (μ₀ H _c2 (0) ～ 23 T), irreversibility fields H _irr which are strongly shifted towards higher values H _irr(T) ～ 0.8 H _c2(T) and high critical current J _c (J _c = 10⁵ A/cm² at 20 K and 1 T).     

Outgassing Kinetics Testing of Spacecraft Materials

Solid materials contain impurities from manufacturing/cleaning processes which diffuse (out‐gas) to the exterior during exposure to vacuum, especially at elevated temperature levels. Materials like plastics and resins tend to disintegrate under space conditions. In addition to the above mentioned diffusion process, contaminants adsorbed and absorbed from the environment encountered previously, e.g. during manufacturing, cleaning, integration, test and launch phases, might be desorbed from the surfaces. The released products represent a permanent source of potential contamination. This paper provides an overview of a research program carried out at the Austrian Research Centers Seibersdorf (ARCS), Aerospace Materials Technology Testhouse (AMTT), by means of the AMTT Sublimation Test Facility to acquire in‐depth knowledge of the outgassing kinetics characteristics of a set of non‐metallic materials, selected by Alenia on the basis of their usage on the International Space Station (ISS) and Scientific Satellites.     

Comparative Study of Dense Bulk MgB2 Materials Prepared by Different Methods

We report on the results of a comparative investigation of highly dense bulk MgB₂ samples prepared by three methods: (i) hot deformation; (ii) high pressure sintering; and (iii) mechanical alloying of Mg and B powders with subsequent hot compaction. All types of samples were studied by AC susceptibility, DC magnetization, and resistivity measurements in magnetic fields up to ₀ H = 160 kOe. A small but distinct anisotropy of the upper critical field connected with some texture of MgB₂ grains was found for the hot deformed samples. The samples prepared by high pressure sintering as well as by mechanical alloying show improved superconducting properties, including high upper critical fields H _c2 (₀ H _c2 (0) 23 T), irreversibility fields H _irr which are strongly shifted towards higher values H _irr(T) 0.8 H _c2(T) and high critical current J _c (J _c = 10⁵ A/cm² at 20 K and 1 T).     

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...     

不同保鲜方式对葡萄保鲜效果影响的对比研究

目的研究气调包装和微孔膜包装对葡萄贮藏期间品质的影响,为延长葡萄货架期提供依据。方法以新鲜葡萄为实验材料,分别采用O2(5%)+CO2(5%)+N2(90%)(气调1)和O2(10%)+CO2(10%)+N2(80%)(气调2)等2种气体比例(均用体积分数表示)的气调包装,以及PE参尼龙多层共挤材质的微孔保鲜膜(微孔膜)对新鲜葡萄进行包装,在温度为4℃的条件下进行贮藏,每隔48h对葡萄的硬度、pH值、可溶性固形物、可滴定酸、抗坏血酸、色度和质量损失率等变化进行测定,并进行感官评价。结果在贮藏0～12 d,从整体保鲜效果来看,微孔膜气调2气调2裸放组。结论葡萄在采后贮运期间,当葡萄的货架期≤12d时,使用3种包装均有利于延缓其衰老进程,PE参尼龙共挤微孔膜保鲜膜的保鲜效果最好。     

不同温度下环氧玻璃钢材料放气特性研究

为探究环氧玻璃钢材料在不同温度下的放气特性,以扩散放气模型为基础,建立了环氧玻璃钢材料放气速率随抽空时间变化关系的数学表达式,并结合实验数据拟合获得了其经验模型。同时,采用静态升压法对不同温度下环氧玻璃钢材料放气速率随抽空时间的变化关系进行了研究。结果表明,温度一定时,环氧玻璃钢材料的放气速率随着抽真空时间逐渐减小;温度升高,环氧玻璃钢材料放气速率增大,且放气速率随着抽真空时间呈现出指数衰减规律。此外,采用四极杆质谱仪分析了不同温度下环氧玻璃钢材料的放气成分,放气成分以H₂O为主,并含有微量的H₂、CO、N₂及O₂等。温度升高,玻璃钢材料放气各组分的占比无明显变化,表明温度对玻璃钢材料放气组分的占比几乎没有影响。     

基于三种不同材料的超光滑表面性能测量结果的对比研究

为了研究目前主流微加工表面检测方式,本文选择三种基本材料：K9玻璃、金属、陶瓷三种不同材料在同等条件下采用不同工艺进行加工,并使用目前主流超光滑表面测试仪器对其进行检测。通过对照结果,分析各仪器测量原理、分辨力决定因素,区分造成测量误差的原因及它们各自对粗糙度参数的影响。     

不同前驱体制备三氧化钼的对比研究

分别以钼酸铵和钼酸钠为反应前驱体,十六烷基三甲基溴化铵(CTAB)为模板剂,在室温条件下制备出具有不同形貌的三氧化钼.采用FE-SEM、XRD和UV-Vis等表征手段对不同形貌的样品进行了对比表征分析,考察了陈化时间对以钼酸钠为前驱体的产物形貌的影响.结果表明,以钼酸铵和钼酸钠为前驱体时,在相同的反应条件下,可得到具有不同形貌和尺寸的氧化钼.纳米氧化钼颗粒与大尺寸片状氧化钼相比,在形成过程中产生晶胞收缩,且其紫外-可见吸收光谱发生明显蓝移.     

Comparative Study of Nano Crystalline Ceria Synthesized by Different Wet-Chemical Methods

Cerium oxide (CeO₂) nanoparticles were synthesized by using sol–gel methods and the Composite Mediated Hydrothermal Method (CMHM). Sol–gel synthesis was done for 0.6 M molarity of the precursor solution of cerium nitrate hexa hydrated [Ce(NO₃)₃?6H₂O] and the hydrothermal synthesis was done at 180 °C for 45 min. X-Ray diffraction (XRD) was used to measure the structural properties of the prepared ceria. Scherrer’s formula was used to calculate the crystallite sizes of average and most intense peak. Temperature dependent (200 °C to 700 °C) dc conductivity was measured and found to be increasing with the increase in measuring temperature. The frequency dependent (20 Hz to 3 MHz) ac conductivity and dielectric properties were measured at different temperatures. The comparison of electric and dielectric properties was studied. Both synthesis techniques were further analyzed by the Raman spectrum at 514 nm excitation laser line for the different bands of cerium oxide and oxygen vacancies.     

不同材料的绝热剪切行为研究

在分离式Hopkinson压杆装置上对不同材料和形状的试样进行了冲击实验.用光学显微镜和扫描电子显微镜对材料的微观组织进行了观察和分析,观察到有些材料的试样中出现绝热剪切带这一变形局域化现象.试验结果表明,材料的常规性能和试样的形状对绝热剪切过程有明显影响.     

不同方法测试粒度分布的比较研究

介绍了不同原理仪器粒度测试结果间存在差异的原因以及对测试结果准确性应如何评价。用筛分法和激光法对氧化铝样品进行测试对比,初步分析结果间的差异。结果表明,筛分法和激光法测试粒度分布在质量(体积)累积分布达到50%时,测试结果相差最小,不同的粒度组成、颗粒的形状都会造成两种方法测试结果的差异。     

测量文物保护材料可逆率的探索性研究

在文物保护研究领域，保护材料的“可逆性”是经常争议的问题之一：什么样的材料是可逆性材料？能否定量地表达可逆性？可逆性材料渗入砖、石、陶等多孔性材质中还可取出来吗？可逆性材料老化以后的可逆率会如何变化等等。为了探索这一类基础理论问题，本实验室提出运用“可逆率”来定量地表征材料应用过程的可逆性，可逆率可以通过清除实验来测量。通过测定B72、氟橡胶、纯丙乳液、环氧树脂在釉面瓷片、光面大理石、山西砂岩、凝灰岩和四川沙岩表面的取出率，计算出了它们的可逆率。实验表明许多保护材料都有一定的可逆性，其可逆率的大小与被保护基底材料的孔隙率（吸水率）呈反比，也与清除剂的种类和清除工艺有关，同时保护材料的紫外光老化过程也会明显影响保护材料的可逆率。文物保护材料可逆率的测量将会是研究其功能和机理的重要方法。     

重庆环境空气质量与材料腐蚀的相关性

在重庆主城区进行的材料腐蚀暴露试验表明:(1)碳钢、铜、铜合金和大理石等材料,其完全暴露的腐蚀速度约为遮蔽暴露腐蚀速度的2倍;(2)铜、铜合金的腐蚀速度与SO2浓度非常相关,与NO2浓度显著相关,碳钢的腐蚀速度与SO2、NO2和TSP浓度没有明显的相关性;(3)碳钢的腐蚀速度约为青铜的20倍,纯铜的25倍,古铜的28倍,大理石的19倍.     

SiO2不同的掺杂方式对聚氨酯树脂材料性能的影响

采用溶胶凝胶法制备纳米SiO2颗粒,然后在聚氨酯弹性体/SiO2复合材料的不同制备方法方面进行了尝试,并针对SiO2不同的掺杂方式对聚氨酯树脂材料性能的影响进行了研究,为聚氨酯弹性体性能的优化提供了一条最佳的思路和方法.利用红外分光光度计(IR)、万能电子试验机、动态力学分析仪(DMA)、量热示差扫描仪(DSC)、紫外/可见/近红外分光光度计(UV/VIS/VIR)分别表征了纳米复合树脂材料的结构、力学性能、热稳定性、展色性和干爽性.     

金属材料疲劳裂纹扩展速率不同模型应用分析

金属材料疲劳裂纹扩展速率是对金属材料及其零构件含有裂纹体后安全服役评价及疲劳寿命评估的一项重要力学性能指标。基于金属材料疲劳裂纹扩展过程的不同阶段、闭合效应、应力比对疲劳裂纹扩展速率的影响等多个方面,对几种常见金属材料疲劳裂纹扩展速率模型的应用特点进行了对比分析,为安全设计及寿命评估时不同模型的选择应用提供参考。     

Electrical Properties of PbSnF4Materials Prepared by Different Methods

Data are presented on the electrical conductivity of fluorine ion conducting PbSnF₄solid electrolytes prepared by different methods—aqueous (precipitation from solution and hydrothermal synthesis) and nonaqueous (melt solidification).     

The Effect of Different Sterilization Methods on the Mechanical Strength of Magnesium Based Implant Materials

The research on the development and characterization of potential magnesium biomaterials is a steadily expanding. Commonly, implants present a high risk of infection for their recipients. For this reason, a pre‐operative sterilizing process is required. Due to the temperatures and media which are used while sterilizing, effects may occur which cause a change in the mechanical strength of certain magnesium alloys. Four commonly used sterilization methods (autoclave sterilization, dry heat sterilization, gamma sterilization and ethylene oxide sterilization) were investigated to gain information about their influences on the quasi‐static mechanical behavior of LAE442 (Mg 90 m.%, Li 4 m.%, Al 4 m.%, RE 2 m.%), MgCa0.8 (Mg 99.2 m.%, Ca 0.8 m.%) magnesium alloys as well as pure magnesium. The mechanical properties exhibited by the sterilized and non‐sterilized alloys refer to susceptibilities of the mechanical strengths to the investigated sterilization methods. Such susceptibilities appear to be dependent on the combination of alloy and method of sterilization. However, the maximum changes in mechanical strength appear in the range of ±10%. Within this study, ETO sterilization caused the least changes in the mechanical strength of the alloys and appears to be the best performer.     

多类型食品包装材料的迁移研究

食品应具备的首要品质就是食用安全性,可目前与食品接触的包装材料中添加剂的迁移成为了一个关于健康问题的隐患.国外学者研究了各种类型的食品接触包装材料中化学物向食品(模拟物)的迁移,对研究进展进行了概述,简介了迁移的有关基础知识:迁移极限的规定、食品模拟物的选择、(加速)迁移试验要求、迁移机理、迁移预测模型.介绍了国外研究者在各迁移研究领域所进行的研究现状及结论,包括常规使用条件下塑料、再生塑料、纸和纸板、金属罐,非常规使用条件如微波加热、γ辐射、高压处理下包装材料中化学物成分的迁移.