含铍碳化硅陶瓷先驱体聚铍碳硅烷的合成

以氢氧化铍、硫酸和乙酰丙酮为原料合成了乙酰丙酮铍(Be(acac)2).用乙酰丙酮铍和聚碳硅烷在加热的条件下反应一定时间,生成了树脂状的产物.反应中乙酰丙酮铍被消耗,生成产物熔点相对起始聚碳硅烷熔点升高.元素分析表明产物中含有铍元素,凝胶渗透色谱分析表明产物分子量相对起始聚碳硅烷向增大的方向发生变化.傅立叶红外光谱分析表明产物中主要存在如下结构:Si(CH3)2—CH2—,—Si(CH3)·(H)—CH2—.核磁共振1H-NMR分析表明反应物中Si—H键被消耗.根据分析结果推测了反应机理,Si—H键的消耗在产物的形成中起了重要作用.实验与理论分析表明先驱体产物是一种含铍聚碳硅烷,可以命名为聚铍碳硅烷(PBeCS).在1200℃的高温处理下产物作为先驱体可以转化为碳化硅陶瓷,元素分析表明碳化硅陶瓷中含有铍,是含铍碳化硅陶瓷.     

Beryllium colorimetric detection for high speed monitoring of laboratory environments

The health consequences of beryllium (Be2+) exposure can be severe. Beryllium is responsible for a debilitating and potentially fatal lung disease, chronic beryllium disease (CBD) resulting from inhalation of beryllium particles. The US Code of Federal Register (CFR), 10 CFR 850, has established a limit of 0.2 microg beryllium/100 cm(2) as the maximum amount of beryllium allowable on surfaces to be released from beryllium work areas in Department of Energy (DOE) facilities. The analytical technique described herein reduces the time and cost of detecting beryllium on laboratory working surfaces substantially. The technique provides a positive colorimetric response to the presence of beryllium on a 30.5 cm x 30.5 cm (1 ft(2)) surface at a minimum detection of 0.2 microg/100 cm(2). The method has been validated to provide positive results for beryllium in the presence of excess iron, calcium, magnesium, copper, nickel, chromium and lead at concentrations 100 times that of beryllium and aluminum and uranium (UO2(2+)) at lesser concentrations. The colorimetric detection technique has also been validated to effectively detect solid forms of beryllium including Be(OH)2, BeCl2, BeSO4, beryllium metal and BeO.     

Hydrogen bombardment of the oxide layer on beryllium

Beryllium is being considered as a plasma-side material of low atomic number Z for use in fusion reactors. Untreated beryllium surfaces are usually covered by a thin oxide layer which forms during air exposure or from residual gas adsorption in vacuum. Secondary ion mass spectrometry measurements have been made to investigate the durability of this oxide layer during hydrogen ion bombardment at an energy of 1 keV, which is similar to that expected at the plasma edge in a fusion reactor. The surface condition of machined beryllium samples undergoing hydrogen bombardment was monitored by observing secondary ion emission of O^-, OH^- and BeO^-. On the basis of sputtering yield data for BeO, the oxide layer appears to be up to 10² monolayers in thickness. At the metal interface it was possible to determine the cross section for the removal of adsorbed oxygen. The measured value is 1.5 × 10^-17 cm², which is in agreement with bulk oxide sputtering data. This suggests that adsorbed oxygen forms a surface oxide with a binding energy that is similar to that of the bulk oxide. These results are used to predict the conditions in which an oxide layer will exist on exposed beryllium surfaces during fusion reactor operation.     

铍焊接技术研究发展概况

铍及铍合金在航空航天、电子工业和国防工业等方面应用十分广泛.结合铍的焊接性,论述了当前国内外铍的焊接技术概况,针对钎焊、熔化焊、扩散焊等焊接工艺,介绍了一些比较成功的铍的焊接工艺以及部分连接工艺,同时分析了铍焊接中存在的缺陷问题.     

Effect of stress gradients in the surface layer of beryllium on X-ray stress measurement

The effects of stress gradients in beryllium surface layers on traditional X-ray stress measurements are investigated by relationship analysis of d vs. (sin ψ)² plots with stress gradient in the surface layers of beryllium. The results show that over the range of (sin ψ)²≤0.5, there are significant effects of stress gradient on the measurement results. The stress measurement error resulting from the stress gradient is decreased using a vanadium target and high ψ range.     

Surface hardening of beryllium by ion implantation

The effectiveness of ion implantation for the production of a hard wear-resistant surface on instrument grade beryllium of high strength (HP-40) was explored. Samples of beryllium were implanted with boron and were subjected to microhardness tests in both the as-implanted state and after annealing. The implanted region was examined using Rutherford backscattering to determine the depth distribution of the implanted boron. By using ion implantation to produce a buried layer containing boron, the limitations imposed by solubility and diffusivity are avoided and much greater boron concentrations than those attainable with conventional thermal treatments are generated.     

CEMS investigations of AISI M2 steel after ion implantation by nitrogen, boron and carbon

The results of an investigation of the modified surface layers of high-speed steel AISI M2 after various kinds of ion implantation (high current ion implantation (HCII), plasma immersion ion implantation (PIII), implantation with separated ion beams (SIB) are presented. The results partially from our previous works (HCII, PIII) and some new data (HCII, PIII, SIB) are summarized here to compare the phase composition of steel after implantation of various kinds. The main research method was Mössbauer spectroscopy, combined with a measurement of mechanical properties of surfaces. A correlation between a phase composition of modified surface layers and their mechanical properties has been analyzed. Due to formation of thicker modified surface layers of steel with advanced mechanical properties the methods of HCII and PIII are the most perspective from a practical point of view comparing with method of SIB.     

Fabrication of unbacked ultra-thin films of beryllium and other metals

A method is given for preparing ultra-thin unbacked metal films by evaporating the metal onto rock-salt platelets coated with a thin layer of a soluble thermoplastic resin. Beryllium films have been made with thickness ranging from 0.2 to 0.5 μm and free from “optical” pinholes. The beryllium was rapidly and continuously evaporated from a tungsten crucible with very little corrosion of the crucible. Deposition rates of 100 nm s^-1 were achieved with a source-to-substrate distance of 140 mm.     

Investigation on beneficial effects of beryllium on entrained oxide films,mechanical properties and casting reliability of Fe-rich Al–Si cast alloy

The microstructure and tensile properties of cast Al–9·5Si–0·35Mg alloy containing 1·5 wt-%Fe have been studied to investigate the potential influence of beryllium (Be) on the entrained oxide films and its effects on the precipitation of Fe-rich phases from liquid metal. It was found that addition of Be has a great influence on the microstructure and reliability of the cast alloy. Beryllium changes the platelet morphology of Fe-rich phases to less harmful shapes. Meanwhile, this element reduces the entrainment of the double oxide films into the melt probably due to its effect on changing the strength of surface oxides in a manner that resists tearing. These effects, in turn, lead to an increase in mechanical properties and casting reliability of the alloy.     

Solubility of beryllium in CuAl2

Abstract

Energy dispersive X-ray spectroscopy, X-ray diffraction, precipitate extraction, microhardness, and metallographic techniques have been used to determine the degree of solubility of beryllium in CuAl₂, which was found to be in the range 0·8–2·07 wt-%. Beryllium in the alloy was found to concentrate in the precipitate phases.

MST/542     

氧等离子体注入对PET亲水性及抗菌性能影响

利用氧等离子体浸没离子注入技术对聚合物材料(PET)进行表面改性后接枝有机抗菌剂赋予PET薄膜抗菌性能.试验结果表明:PET薄膜表面接枝上的抗菌剂在改性表面呈针状分布.经氧等离子体处理后的PET薄膜表面水接触角从78°降低到33°.红外光谱显示PET薄膜表面的分子结构被破坏,苯环的对位氢发生取代反应,分子链中形成了C-O亲水基团.氧等离子体的注入时间和注入电压均对抗菌持久性有重要的影响,较高的注入电压能够使PET薄膜表面获得较深的改性层,利于改性表面亲水性的保持.注入时间超过10min,电压超过-10kV的样品在空气中放置40天后的抗菌率仍能达到90%以上.     

Characterization of beryllium foil produced by hot rolling

Beryllium foil is important for a number of aerospace applications including honeycomb structures and metal-matrix composites. In this study, a method of producjng beryllium foil directly from powder or flake is demonstrated. A variety of foils were produced in the thickness range 90–300 m, free from defects such as pinholes and excessive surface roughness, and exhibiting sufficient formability for honeycomb manufacture. Foil produced directly from powder or flake exhibits crystallographic texture, microstructure, and formability equivalent to foil produced from more massive precursors.     

Superconducting beryllium films

Resistance-vs.-temperature measurements were made on a series of beryllium films condensed on liquid-helium cooled surfaces. Two vapor sources designed to reduce contamination were used and films were prepared on both crystalline quartz and glass substrates. The samples were superconducting with a transition temperature ofT _c =9.6±0.1 K as indicated by a sharp falloff of resistance on cooling. This qualitatively confirms earlier reports of the superconductivity of quenched beryllium films. The transition curves were, however, appreciably sharper and the transition temperature about a degree higher than previously reported. Good agreement found from sample to sample indicates that the residual impurity concentration was small enough to be unimportant and that the observed transition temperature is characteristic of pure beryllium. The phase of beryllium responsible for the highT _c value disappeared on annealing in the range 40–60 K. No indication was found of a reportedT _c 6-K phase. Beryllium films thicker than about 750 Å broke up during deposition, indicating the presence of large stresses.The work at Karlsruhe was supported by the Deutsche Forschungsgemeinschaft, Germany.     

Effect of Ta2O5/TiO2 thin film on mechanical properties,corrosion and cell behavior of the NiTi alloy implanted with tantalum

The NiTi shape memory alloy has been modified by plasma immersion ion implantation (PIII) with Ta at different incident currents to improve the corrosion resistance and other surface and biological properties. The surface topography, chemical components, mechanical properties, corrosion resistance and cytocompatibility are investigated. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) revealed that Ta implantation led to the formation of compact Ta₂O₅/TiO₂ nano-film on the surface of the NiTi alloy. The results of Auger electron spectroscopy (AES) showed that Ni was suppressed in the superficial surface layer of the modified NiTi alloy samples. The results of nano-indentation illustrated a lower level of nano-hardness and Young's modulus after Ta implantation. Potentiodynamic anodic polarization curves showed that the corrosion resistance of NiTi alloys was enhanced by Ta implantation. Cells reached confluency and a double-layered structure had developed after cultured for three days. The NiTi alloy modified by a moderate incident current possesses a uniform and slippery surface morphology and the largest surface roughness, leading to the best corrosion resistance and the highest cell proliferation rate, respectively.     

钽离子注入对镍钛合金表面生物学性能的影响

镍钛合金血管支架植入后可引发血栓和支架再狭窄,且对损伤的血管内壁无修复作用,需进行表面改性赋予其抗凝血和促内皮化生物学功能。本研究采用等离子体浸没离子注入与沉积(PIII&D)技术将钽(Ta)注入至镍钛合金,研究Ta离子注入对镍钛表面理化特性及生物学性能的影响规律。结果表明,调控Ta离子注入时间,可在镍钛表面分别构建含Ta、Ta/Ta₂O₅、Ta/Ta₂O_5–x/Ta₂O₅三种不同组分的改性层。各种改性样品中,含Ta/Ta₂O_5–x/Ta₂O₅的改性镍钛表面亲水性均更好,可提供更多细胞附着位点,促进人脐静脉内皮细胞早期粘附和铺展,并提高其增殖能力。相比仅含单质Ta的改性镍钛表面,含Ta/Ta₂O_5–x/Ta₂O₅改性镍钛表面的血液相容性更高,血小板粘附数量显著减少,且基本保持...     

铍中Be2C及硅基夹杂对铍材伸长率的影响

铍材伸长率是目前限制铍材使用的关键因素.对高伸长率和低伸长率铍材的拉伸断口进行对比分析,发现在铍材的断裂源处往往含有非金属夹杂,夹杂造成的微裂纹是铍材解理断裂的裂纹核心.通常情况下,这些夹杂是以硅为基的杂质,一般不会造成铍材伸长率的明显降低.而当杂质中存在碳元素时,形成脆、硬稳定的Be2C,因Be2C难以变形,其断裂强度较铍材更低,因此在Be2C处容易位错集束而加重应力集中,并沿Be2C内部生成主裂纹,该主裂纹与原有的微裂纹合并后,裂纹长度加长,导致铍材解理速度加快,伸长率显著降低.     

Fe+注入增强Ti6Al4V表面喷丸强化层的生物摩擦学性能

为改善Ti6A14V表面喷丸强化层的生物摩擦学性能,把不同参数Fe+注入到直径4 mm喷丸的强化层中.用Nano IndenterⅡ型纳米显微力学探针测定试样改性层的纳米硬度,在MRTR多功能摩擦磨损试验机上以ZrO2球/改性层为摩擦副进行人工唾液和透明质酸钠溶液润滑下的生物摩擦学试验,使用S-3000N扫描电子显微镜分析改性层组织形貌和生物摩擦学试验后的磨痕形貌.结果表明:Fe+注入Ti6A14V表面喷丸强化层的形成相为Fe2Ti.随着注入能量和剂量增加,Fe2Ti含量从3.7％增至4.7％;Fe+注入改性层的纳米硬度从8.46 GPa增至10.29 GPa,都远高于单一喷丸强化层的5.59 GPa;在人工唾液和透明质酸钠溶液润滑下的摩擦因数分别从0.53降至0.38和从0.49降至0.28,都低于单一喷丸强化层的0.62和0.59,磨损呈现不同程度的减轻.Fe+注入能显著提高Ti6AI4V表面单一喷丸强化层的减摩抗磨性能.     

铝合金等离子体基离子注入形成AlN/TiN层结构研究

用X射线光电子能谱和小掠射角X射线衍射研究了铝合金LY12等离子体基离子注入形成的AlN/TiN改性层的结构。结果表明 ,N和Ti能注入铝合金表面 ,N在注入层呈类高斯分布 ,而Ti沿注入方向呈梯度递减。后注入的Ti和N对先注入的N的含量和分布有重要影响。同时注入Ti和N ,能在试样表面形成一层稳定的Ti,N层。所形成的AlN/TiN改性层主要由TiO2 ,TiN ,TiAl3 ,Al2 O3 ,AlN相组成     

注入能量对304不锈钢离子注N表面改性层组织与性能的影响

注入能量对离子注入影响明显,但目前探究注入能量对304不锈钢离子注N层影响报道较少。研究在N剂量相同的情况下,离子注N时不同注入能量(30~75 keV)对304不锈钢表面改性层的组织及性能的影响。采用离子注入软件SRIM2013模拟离子注入对304不锈钢的注N深度,并采用扫描电镜(SEM)、显微硬度仪、X射线衍射仪(XRD)、万能摩擦磨损试验机对表面改性组织、硬度、相结构、摩擦系数进行测试,并对微观机理进行了分析与讨论。研究表明:在相同剂量下(9.0×10~(17)cm~(-2)),在注入能量范围为30~60 keV时,表面生成了γN相。但随着注入能量达到75 keV,304不锈钢表面出现多孔形貌,且硬度、摩擦系数等力学性能下降。经注入能量60 keV注N后,所得注N试样的显微硬度约为基材的1.9倍,摩擦系数有所降低,从基材的0.62下降为注N后的0.32;注入能量60 keV是离子注入的最佳注入能量。     

The effect of surface finish on the pressure-induced ductility of beryllium

An investigation has been made of the effect of specimen surface finish and sheathing on the tensile properties of both cast and extruded ingot and hot-pressed powder beryllium, under the influence of an applied hydrostatic pressure of 78.7 kg mm^–2 (7.72 kbar). Three surface finishes — as-machined, chemically etched and electropolished — were investigated. For each surface finish, specimens of both materials were tested with their gauge length sections bare and sheathed with a rubberized coating. The chemical etching and the electropolishing treatments were designed to remove the damage induced by the specimen machining operations and the rubberized coating was applied to prevent the pressurizing fluid wetting the specimens. Other workers have claimed that electropolishing alone is sufficient to enable the maximum ductility of beryllium to be realized in a hydrostatic environment. However, the present investigation shows that both a post-machining surface treatment and the application of a rubberized coating are necessary before this condition is attained. The data also suggest that beryllium exhibits a Rebinder effect.