镀铬/高能束复合表面处理研究进展

根据高能束对镀铬涂层及其界面强化机制的不同,镀铬/高能束表面复合技术可分为两类:高能束强化镀铬涂层复合技术和高能束预处理基体/镀铬复合技术.前者典型代表有激光表面强化或等离子体氮化/镀铬涂层;后者主要代表是激光预淬火基体/镀铬复合表面处理.综合阐述了上述3种典型的复合处理技术的原理、目的及实际综合效果;通过试验初步探讨了激光预淬火基体/镀铬复合技术延长镀铬身管寿命的主要机理.     

中性束发射光谱在等离子诊断中的应用研究

Tokamak是一种通过磁约束实现核聚变反应的装置,光谱诊断是测量该装置中等离子体运行参数的重要手段,本课题便是通过使用中性束发射光谱(BES)光谱诊断中性束装置产生的束流与Tokamak中的等离子体相互作用,诊断出等离子体的运行参数,测量与中性束有关的数据。     

低温等离子体对聚合物表面改性的研究

本文对低温等离子体作用在聚合物表面的机理做了简要介绍 ,指出这一过程有四种作用 :产生自由基 ,发生表面交联 ,引入极性官能团 ,表面变粗糙 ;对国内外利用等离子体对高分子材料的表面改性方法做了简要介绍 ,同时指出低温等离子体技术在各类高分子材料加工中的巨大应用前景。     

焊接纳米线可只用一束光

美国科学家设计出一种新的纳米线焊接技术，可使用表面等离子体光子学，用一束简单的光将纳米线焊接在一起。发表于刚刚出版的《自然·材料学》杂志上的最新研究有望促成新式电子设备和太阳能设备的出现。     

纳米材料

美研究称焊接纳米线可以只用一束光据美国每日科学网站2月7日报道,美国科学家设计出一种新的纳米线焊接技术,可使用表面等离子体光子学,用一束简单的光将纳米线焊接在一起。发表于刚刚出版的《自然.材料学》杂志上的最新研究有望促成新式电子设备和太阳     

美研究称焊接纳米线可以只用一束光

据美国每日科学网站2月7日报道，美国科学家设计出一种新的纳米线焊接技术，可使用表面等离子体光子学，用一束简单的光将纳米线焊接在一起。发表于刚刚出版的《自然·材料学》杂志上的最新研究有望促成新式电子设备和太阳能设备的出现。     

高能束技术在镁合金表面改性中的应用

针对如何提高镁合金强度、硬度、耐磨性、耐腐蚀性等综合性能这一热点问题,系统地介绍了激光束、电子束、离子束3种高能束表面改性技术的原理、方法以及在镁合金表面改性中的应用进展,总结了各工艺方法的优缺点,展望了高能束技术在镁合金表面改性中的发展前景。     

淬火温度对7Ni钢低温力学性能的影响

使用OM、SEM、TEM和XRD等手段观察并表征在不同温度淬火的7Ni钢的组织形貌和逆转奥氏体含量的变化,研究了淬火温度对7Ni钢的低温强度和低温韧性的影响。结果表明:当淬火温度从830℃提高到930℃时钢的低温韧性急剧下降,低温抗拉强度和屈服强度明显降低。同时,随着淬火温度的提高延伸率下降,与低温强度的变化趋势基本一致。在830℃淬火的试验钢,原奥氏体晶粒和马氏体板条束最为细小。而当淬火温度超过830℃时钢中的原奥氏体晶粒和马氏体板条束都显著长大,钢的低温强度和低温韧性随着晶粒尺寸与板条束宽度的增大而下降,粗化的组织对钢的低温强度与低温韧性都有不利的影响。随着淬火温度的提高钢中的逆转奥氏体含量基本上呈下降趋势,在830℃淬火的试验钢中逆转奥氏体含量最高,其低温冲击功也最高。     

等离子体表面处理技术的应用

作为表面处理技术之一的等离子体表面处理技术已经获得广泛的应用。等离子体表面处理方法的优点是利用其处理后的表面化学活性状态增快反应速度。在较低温度下,这类反应也能进行。在这种处理方法中,使置放在等离子体中的固体表面产生新的化合物,改变固体表面的性质。等离子体表面氧化是使半导体表面经过辉光放电处理形成表面氧化膜。若把试样放在等离子体中进行表面处理,试样会直接受到带电粒子的冲击。为了弥补这个缺点,可以在半导体上加盖保护膜,使其产生界面氧化。这个方法叫做界面氧化。作为保     

等离子体基低能离子注入技术的研究与发展

将低能离子注入技术引入等离子体基离子注入,一方面利用低能离子注入的低能优势,另一方面利用等离子体基离子注入的全方位优势,开发出等离子体基低能离子注入技术。等离子体基低能离子注入技术包括等离子体基低能氮、碳离子注入和等离子体源低能离子增强沉积两类工艺。低能离子的注入能量（０．４～３ ｋｅＶ）达到常规等离子体热化学扩散处理的电压范围,而工艺温度（２００～５００℃）则降至常规离子注入的上限温度范围。通过大量的工艺实验研究,实现了工艺过程的优化和控制,完成了对等离子体基低能离子注入改性铁基材料的金属学问题及物理、化学和力学性能的系统研究。证明了等离子体基低能离子注入技术满足铁基材料的表面改性要求。同时具有产业化发展潜力。     

Determination of surface heat-transfer coefficients of steel cylinder with phase transformation during gas quenching with high pressures

In numerical simulation of quenching process, the boundary conditions of temperature field and stress field are very important, in which the boundary conditions of temperature field are very complicated. In order to simulate the thermal strains, thermal stresses, residual stresses and microstructure of the steel during gas quenching by means of the numerical method, it is necessary to obtain an accurate boundary condition of temperature field. The surface heat-transfer coefficient is a key parameter. The explicit finite difference method, non-linear estimate method and the experimental relation between temperature and time during quenching have been used to solve the inverse problem of heat conduction. The relationships between surface temperature and surface heat-transfer coefficient of cylinder have been given. The non-linear surface heat-transfer coefficients include the coupled effects between phase transformation and temperature. In calculation, physical properties were treated as the function of temperature and volume fraction of constituent. The results obtained have been shown that this technique can determine effectual the surface heat-transfer coefficients during gas quenching.     

微波电子回旋共振等离子体技术及其应用

微波电子回旋共振等离子体是淀积薄膜、微细加工和材料表面改性的一种重要手段。由于这种等离子体电离水平高,化学活性好,可以用来实现基片上薄膜的室温化学气相淀积和反应离子刻蚀,因此对于微电子学、光电子学和薄膜传感器件的发展,这种等离子体会具有重要的意义。此外,采用微波电子回旋共振等离子体原理,没有灯丝的离子源可以提高离子源的使用寿命,可以增加离子束的束流密度。可以确信,微波电子回旋共振等离子体的发展,将把离子源技术提高到一个新的水平。显然,这必将对材料表面改性工艺,包括离子注入掺杂等工艺的发展发挥作用。自从1985年以来,为了得到大容积等离子体而发展了微波电子回旋共振多磁极等离子体,这些技术在薄膜技术、微细加工以及材料表面改性中的应用前景是乐观的。我们将在本文中,介绍微波电子回旋共振等离子体的原理及其应用。     

Pulsed high energy density plasma processing silicon surface

Pulsed high energy density plasma (PHEDP) is a new material modification technique, which has the features of: high energy density (1–10 J/cm²), high plasma density (10¹⁴–10¹⁶ cm⁻³), high electron temperature (10–100 eV), high directed plasma velocity (10–100 km/s) and short pulse duration (10–100 μs). PHEDP interacting with material will result in rapid melting and re-solidification of surface layer with a quenching rate up to 10⁸ K/s; thus the material surface properties are modified. At the same time, PHEDP contains condensable ions or/and atoms, so a thin film layer can be formed on the modified surface and the deposited layer can be mixed with the substrate (or previous deposited layer) during following pulses. Therefore, this technique actually combines film deposition and mixing into one step. In this paper, we have reported the research results on the metallization of Si by PHEDP. The Ti---Si reactions under PHEDP are also discussed.     

Surface Finishing by Atmospheric Pressure Micro Plasma Beam Irradiation

A metal surface finishing method by micro plasma beam irradiation was examined and presented in this study. Gray cast iron was used as the experimental material to examine the finishing effect by the micro plasma beam. This experimental setup consists of a compressed air system, a plasma torch, and a power supply. The compressed gas was ignited by high voltage direct current pulsed gas discharge and facilitated the generation of plasma, as well as a plasma beam with a maximum diameter of 0.6 mm was used for finishing the metal surface instantly. The experimental results show that it was possible to remove the peak points which exist on the metal surface. It was showed clearly that after the irradiation by the micro plasma beam, the initial rusty and rough surface becomes a clean and smooth surface under a proper finishing condition.     

利用大气中放电来测量表面特性的新方法

研制了一种新型的探测器，利用气体放电和外部电路猝灭的方法测定样品表面发射的低能光电子。它能在大气或各种气氛中工作。可用于测定表面功函数、膜厚、表面污染及材料缺陷。有较大实用价值。     

W18Cr4V合金工具钢在不同介质淬火后性能比较

通过对W18Cr4V合金工具钢在清水、锭子油和高压气体等淬火介质中淬火对比实验,研究W18Cr4V合金工具钢在不同介质淬火工艺处理后的硬度和微观结构.研究结果表明,水淬火时试件表面与中心的温差较大,锭子油次之,高压气体较小;试件高压气体淬火时,温度剃度小,内部冷却比较均匀,可以预计,相应的热应力和热变形也比较小;应用较小压力的氮气能够实现淬透性比较好的W18Cv4V工具合金钢的高压氮气淬火处理.     

Solution of an Inverse Problem of Heat Conduction of 45 Steel with Martensite Phase Transformation in High Pressure during Gas Quenching

In order to simulate thermal strains,thermal stresses,residual stresses and microstructure of the steel during gas quenching by means of the numerical method,it is necessary to obtain an accurate boundary condition of temperature field.The surface heat transfer coefficient is a key parameter.The explicit finite difference method,nonlinear estimation method and the experimental relation between temperature and time during gas quenching have been used to solve the inverse problem of heat conduction.The relationship between surface temperature and surface heat transfer coefficient of a cylinder has been given.The nonlinear surface heat transfer coefficients include the coupled effects between martensitic phase transformation and temperature.     

充电前的淬火对Teflon FEP薄膜驻极体电荷贮存能力的影响EI

研究了充电前的淬火对Teflon FEP等驻极体材料电荷贮存能力的影响。淬火前的升温率、淬火期间的冷却率、淬火温度、淬火后和充电前的储存时间等热处理参数的调节,导致了TSD电流谱线峰值的变化和峰温的漂移,影响了电荷的贮存寿命。如果合理地控制淬火参数,在样品结晶度降低并不明显而平均晶粒直径显著减小时,能改善电荷贮存稳定性。利用初始上升法和峰值清洗术估算了Teflon FEP在淬火前后的活化能和试图逃逸频率。此外,还利用热传输方程和电晕、电子束充电及TSD实验从理论和实验方面研究了FEP样品在淬火期间的淬透性和样品厚度的关系。     

Finite element calculation and measurement of thermal stresses in quenched plates of high–strength 7075 aluminium alloy

Abstract

Thick parts of high–strength aluminium alloys usually undergo a drastic quench which gives rise to thermal stresses and may cause distortion of products. The control of complex phenomena involved during quenching is achieved by determining the temperature distribution, thermal strains, and residual stresses using the MARC finite element program. In this approach, the thermo mechanical problem is assumed to be uncoupled, i.e. the thermal and mechanical calculations are solved consecutively. First a non–linear heat transfer analysis is performed taking the temperature dependence of the thermophysical properties and transient conditions of convection at the surface of the plate into account. This is followed by a thermo–elastoplastic stress analysis using the predicted temperature distributions, assuming an isotropic behaviour of the material and taking the temperature dependence of its mechanical properties into account. The calculation of thermal stresses occurring during the cold and hot water quenching of a 70 mm thick plate of 7075 alloy using this method shows a good agreement between theoretical predictions and experimental values of residual stresses, as measured by the layer removal method.

MST/2     

Numerical modelling of laser beam-target interaction near the plasma-formation threshold

Experimental investigations of laser-produced plasmas often determine plasma parameters as averaged values only and these data cannot be compared with actual conditions at a target surface. In this paper, numerical modelling of target heating with non-constant target material properties was used to estimate the temperature at the surface of the target as a function of time. Three target materials (magnesium, aluminum and silicon) and an experimentally determined laser pulse profile were used for modelling. Gray-body radiation of the target surface and thermal diffusion losses are taken into account during numerical modelling. It was assumed that radiation from the laser impacts perpendicularly onto the target surface. The results obtained by modelling are in good agreement with the experimentally observed plasma parameters and they are consistent with thermal target heating in which the laser beam is treated as a source of very intense input heat energy.