Nb含量对制氢转化炉管HP合金组织转变规律影响的研究

离心铸造的HP40和HP40-Nb合金被广泛用作制氢转化炉炉管材料,通常管壁温度可高达1000℃。通过观察HP40和HP40-Nb合金在原始铸态和高温状态下的显微组织,研究了不同Nb含量对合金共晶组织稳定性的影响。采用扫描电镜和X射线衍射仪研究了炉管材料的显微组织和相结构。研究结果表明:在碳含量0.4%左右的HP合金中,Nb含量0.210%~0.357%时主要起到固溶强化作用,共晶碳化物主要是M7C3,仅有少量的富Nb共晶MC散布在晶界上;当Nb含量0.89%~1.55%时,HP40-Nb原始铸态组织中析出了富Cr的M7C3碳化物和富Nb共晶MC。对于高温状态下的HP40-Nb合金,在晶界和枝晶间形成的富Nb共晶的MC提高了原始共晶组织的稳定性,使得炉管材料的使用温度可向高温推移。     

铌及铌合金的氧化行为

铌及铌硅化合物具有优良的力学性能，可替代现有的镍基合金超高温材料。通常，这类材料的高温抗氧化性能较差，铌在高于350℃时即发生剧烈氧化，而抗氧化性能较好的NbSi2在1000K附近也会出现“pest”现象。铌硅化物的氧化行为与钼(或钨)硅化物存在很大区别，其氧化产物无挥发性。通过增加硅的含量，或添加钛、铝、铬等元素，涂敷高温抗氧化涂层等，可有效提高铌及铌硅化合物的高温抗氧化能力。     

水泡式激光扫平仪

主要介绍了水泡式激光扫平仪的原理及其精度测试方法。     

真空-氦质谱检漏技术在真空绝热深冷压力容器制造中的应用

介绍了真空-氦质谱检漏技术在夹套式真空绝热深冷压力容器制造中的应用,阐述了真空与检漏的基本概念,真空-氦质谱检漏技术的使用方法及效果。     

一种异形轨弯轨机

市场上不封闭薄板“J”形截面的异型轨弯轨机较少见。文中介绍了该种异形轨弯轨机的结构及工作原理，并论述了弯轨过程及变形过程。     

异形重载摩擦离合器

本文介绍一种非平面摩擦重载摩擦离合器 ,该离合器体积小 ,传递扭矩大 ,接合分离迅速、结构简单、工艺性好 ,造价低廉、易于装配、寿命长 ,是一种较为理想的新型重载摩擦离合器     

盐浴渗铌在模具上的应用

介绍了五氧化二铌硼砂盐浴渗铌的基本原理和工艺方法，以及渗层的结构和性能，通过该工艺得到的碳化铌渗层具有高硬度、高耐磨性、抗咬合、耐腐蚀等优点，在拉伸模、挤压模、冷锻模等冷作模具上应用，可大幅度提高模具寿命。     

不规则钣金件加工

对一不规则钢板零件的加工方法进行分析,此钢板零件设计时摆放位置主要考虑装配要求,在机械加工和检验时有很大的难度,容易产生变形尺寸。分别从设计基准与工艺基准转换和选择加工方式、装夹方式来解决加工和检验难题。     

机盖胶泡问题解决方法

车身胶泡是涂装技术中难以彻底消除的问题,主要出现在机盖与车门的包边处,严重影响整车外观品质,造成顾客对整车的评价降低。针对此问题,通过试验知道胶泡产生的位置为包边处机盖内外板搭接缝隙处,初步判定包边处存在缝隙是产生胶泡的主要原因。对折边胶涂布和包边间隙进行整改,经生产验证及数据测量达到预设目标要求。     

二维不规则冲裁件排样算法研究

冲裁件的排样是一个NP问题,在工业界具有广泛的需求.从矩形包络和遗传模拟退火算法这两个角度探讨了包含不规则形状的冲裁件的排样算法.随着冲压设备的不断发展,二维冲裁件的组合优化排样将会得到越来越广泛的普及和应用.     

活塞式氦气压缩机的可行性研究

介绍了一种由7 5kW商用空调压缩机改进而来的氦气压缩机。由于采用了独特的喷油内冷却方式,使得最终的氦气排气温度在压缩机吸气压力为5bar,排气压力为22bar的情况下,降至低于110℃,从而使压缩机在更换工质后的正常运行成为可能。我们同时设计了一套高效的除油净化系统,以保证排气的含油量满足制冷机的长期工作要求。经过近1000h试验运行,证明了这种改进方法是完全可行的。     

Helium ion microscopy of Lepidoptera scales

In this report, helium ion microscopy (HIM) is used to study the micro and nanostructures responsible for structural color in the wings of two species of Lepidotera from the Papilionidae family: Papilio ulysses (Blue Mountain Butterfly) and Parides sesostris (Emerald-patched Cattleheart). Electronic charging of uncoated scales from the wings of these butterflies, due to the incident ion beam, is successfully neutralized, leading to images displaying a large depth-of-field and a high level of surface detail, which would normally be obscured by traditional coating methods used for scanning electron microscopy (SEM). The images are compared with those from variable pressure SEM, demonstrating the superiority of HIM at high magnifications. In addition, the large depth-of-field capabilities of HIM are exploited through the creation of stereo pairs that allows the exploration of the third dimension. Furthermore, the extraction of quantitative height information which matches well with cross-sectional transmission electron microscopy measurements from the literature is demonstrated.     

Investigation of Chemical/Mechanical Polishing of Niobium

A chemical/mechanical method for polishing flat niobium sheets to a mirror finish was developed. Various polishing slurries with different open circuit potentials and pH values were considered. All slurries fell within the niobate region of the Pourbaix diagrams, indicating that slurries are in a thermodynamically stable region. Oxidation characteristics of the niobium in the various slurries were determined by XPS and confirmed previously published work that niobium forms various layers of stable niobium oxides roughly 4.5–4.7 nm in thickness on the surface. A multi-step polishing method that relies on mechanical abrasion of the surface proved to be effective, and particles of different hardness and size were explored. Niobium wafers with initial peak-to-valley (PV) surface roughness of 3 to 7 μm were polished. The multi-step process utilized a slurry containing 1 μm diameter alumina particles to polish this initial roughness down to a submicrometer level. The final polish was provided by a slurry containing smaller particles. The oxide slurry with 70 to 100 nm silica particles gave the best mirror finished surface, with PV = 235 nm, Ra = 32 nm, and RMS = 39 nm. While polishing caused some disorder in the niobium metal, using the oxide slurry gave results closer to those obtained by buffered chemical polish (BCP), which exhibits the highest degree of atomic order based on XPS studies. A polishing process starting with mechanical abrasion, followed by a two-step mechanical polish, is successful for obtaining smooth niobium surfaces on flat wafers.     

不规则形状的加工方法和应用

某轮胎起重机行走减速机里的法兰盘精度要求较高,因形状复杂,加工时定位不准,经常需要返修,为此设计了与工件外形完全一致的按内孔定位的钻模,钻孔后定位销以钻模的孔和已钻好的法兰盘孔为定位基准,划不规则的外形位置线,在镗床上加工保证了所要求的尺寸公差和形位公差,提高了工作效率.     

液压系统油液中气泡的防范

论述了气泡对液压系统的危害及气泡混入液压系统的主要途径．介绍了液压系统设计和使用过程中防范气泡危害的具体措施。     

氦气体轴承透平膨胀机研制

根据氦制冷系统的要求设计氦透平膨胀机,按透平膨胀机的整体热力性能及机械性能进行多目标优化方法设计,对氦透平膨胀机的结构形式、热力性能进行优化设计。对传统的 Riccati 传递矩阵法改进推导进行临界转速求解,提出一种切向进气的静压气体轴承结构形式,通过设置回气孔和轴向排气孔,提高主轴的失稳转速。通过现场氦气试车,氦透平膨胀机运转平稳,热力性能优异,表现出良好的整机性能,完全达到了氦制冷系统的设计要求。     

Tribological Properties of DLC Coatings in Helium

The aim of this research work was to investigate tribological properties of low-friction DLC coatings when operating in helium atmosphere. Two commercial DLC coatings (a-C:H and Me-C:H) were included in the investigation and compared to reference PTFE-based coatings, normally used on components operating in helium. Coatings were deposited on hardened 100Cr6 bearing steel discs and tested against uncoated steel balls in low-load pin-on-disc contact configuration. Investigation was focused on the effect of substrate roughness (R _a ?=?0.05?C0.2???m) and contact conditions, including contact pressure (150?C350?MPa) and sliding speed (0.2?C0.4?m/s) on the coefficient of friction of DLC coatings operating in helium. Results of this investigation show that for low-load sliding contact DLC coatings provide low friction in helium atmosphere, similar to soft PTFE-based coatings. At the same time DLC coatings investigated were found to substantially reduce wear of the coated surface. However, while the wear of the coated part has been more or less eliminated, application of DLC coating prolongs running-in and increases wear of the steel counter-part. Furthermore, also in helium atmosphere tribolgical behaviour of DLC coatings showed dependence on the coating type and contact conditions.     

钛制压力容器的氦泄漏试验

氦泄漏试验作为一种致密性试验,它的检漏灵敏度远远超过了气密性试验和氨渗漏等试验方法。随着国产化钛制压力容器的不断增多,一些高温高压和密封性要求高的压力容器,制造完成后除了进行常规的致密性试验外,还需要进行氦泄漏试验。钛制压力容器与其它相比,在结构上有较大的区别。选择合理的氦泄漏试验方案,可做到既能检漏又能及时发现漏点,有效地保证钛制容器安全性和可靠性。     

非规则几何体的可靠性仿真分析

根据机械零件的应力-强度干涉理论,运用有限元分析软件MD.NASTRAN,通过对非规则几何体在严重工况下的应力分析,判定零件可靠度是否满足设计要求.     

薄铌板电子束焊接工艺研究

超导铌腔是高能加速器的重要组成部分,采用高真空电子束焊接工艺对超导铌腔进行加工制造时,铌板焊接试验可以为超导铌腔的制造提供可行的焊接参数。据此,主要研究了薄铌板的焊接试验流程。在不同焊缝质量要求下,通过改变聚焦电流和焊接电流大小的方式,快速找到符合要求的参数值,然后对这些参数进行试验,观察其焊缝是否可行。结果表明,试验方法切实可行,效率高,焊缝质量可以达到预期目标。