两种Ti—Al金属间化合物基合金ISM熔炼过程中Al元素挥发控 …

对水冷铜坩埚真空感应熔炼过程中合金元素的挥发动力学进行了深入的分析,并在此基础上建立了ＩＳＭ熔炼过程中Ａｌ元素挥发控制方式的判断模型。对Ｔｉ－４８Ａｌ－２Ｃｒ－２Ｎｂ（ａｔ％）和Ｔｉ－２４Ａｌ－１１Ｎｂ（ａｔ％）合金中Ａｌ元素挥发控制方式的判断结果表明：随着熔体温度的升高和外压的增大,Ａｌ元素的挥发由低温和高压时的界面挥发控制向高温和低压时的界面挥发和液相中扩散同时起作用的双重控制方式转变,只是对     

S390粉末高速钢真空气淬中纳米碳化物的析出

S390粉末高速钢经1180℃真空加热气冷(4×105Pa)、1230℃真空加热气冷(6×105Pa)后得到以下贝氏体为主的显微组织。结果表明,在片状下贝氏体中部析出成排碳化物是碳按下坡扩散机制和按dr/dt∝t-1/2方程长成260 nm×65 nm椭球状。在残留合金碳化物边缘析出纳米椭球状碳化物是按碳上坡扩散在离碳化物某处形成碳浓度峰,并处于最大过冷条件下进行析出的机制。     

TC4钛合金与Nb—W—Mo—Zr铌合金的真空电子束焊接工艺研究

采用真空电子束焊对TC4钛合金和Nb—W—Mo—Zr铌合金进行了成功焊接,焊接的基本工艺参数为：炉室真空度≤3．0×10^-2 Pa,枪室真空度≤1．5×10^-3 Pa,焊接电压56-60kv,束流20～25mA,工件的移动速度为550～600mm／min。用扫描电镜对焊接组织进行了观测,并作了X射线无损探伤。结果表明,热影响区和熔合区组织致密,焊缝熔透性好,无气孔。熔合区主要为胞状束凝固结构,基本无枝晶出现。X射线探伤结果得出,焊缝质量满足国家一级标准。焊接组件在室温下的力学性能为：Rm=595MPa,Rp0.2=482MPa,A=20％,Z=63％。     

Growth characteristics of MoS2 coatings prepared by unbalanced bipolar DC magnetron sputtering

MoS2 coatings were prepared by unbalanced bipolar DC magnetron sputtering under different argon pressures and for different deposition times, and the structure and morphology of MoS2 coatings were determined and observed respectively by X-ray diffractometry and scanning electron microscopy. The results show that at lower argon pressures of 0.15 Pa and 0.40 Pa, MoS2 coatings are formed with the （002） basal plane parallel to the surface, whereas the coating deposited at the argon pressure above 0.60 Pa has the （002） basal plane perpendicular to the surface. Two stages can be classified for the formation of MoS2 coating. At the initial stage of coating formation, the （002） basal plane with S-Mo-S layer structure grows on the substrate whatever the argon pressure is. And then the coating under 0.40 Pa argon pressure still grows with （002） laminate structure, but the coatings under 0.88 Pa and 1.60 Pa argon pressures turn to grow with the mixed basal and edge orientations. The morphology and structure of MoS2 coatings are highly related to their growth rate and the energy of sputtered particles.     

电子束冷床熔炼TC4合金元素挥发机制研究

建立了TC4合金电子束冷床熔炼过程熔体中各元素饱和蒸气压的数学计算模型,利用该模型计算了TC4合金熔体中各元素的饱和蒸气压及其挥发速率,与实验结果基本一致。计算结果表明,在相同温度下,Al元素的饱和蒸气压最大,是其它两种元素的几百倍,挥发损失也最为严重。随着熔体温度的增加,挥发趋势也增大。V元素的挥发很少,可以忽略。此外,电子束冷床熔炼去除杂质效果显著,熔炼出的铸锭成分符合国家标准。     

气相沉积法制备聚酰亚胺薄膜的初步研究

采用一种新型的成膜技术——气相沉积聚合(VDP)法,利用热蒸发VDP沉积装置,以均苯四甲酸二酐和4,4’-二氨基二苯醚为单体原料,通过控制加热温度、沉积速率和沉积时间,在玻璃衬底上沉积并合成聚酰胺酸(PAA)薄膜,再进行热亚胺化,就得到了成膜性能较好的PI薄膜。采用FTIR,TG,UV,AFM和接触角测试等分析手段对样品的性能进行了分析和探讨。结果表明:VDP法制备的PI薄膜具有高热稳定性、易透光性、低表面粗糙度和低表面能等优点,说明用该方法制备性能优异的PI薄膜是可行的。     

Change law of real vapor pressure of Al element in Ti-xAl （x = 25～50） melt during ISM process

A new model was established to calculate the real vapor pressure of the AI dement in the molten Ti-xAl (x=25～50, mole fraction, % ) alloy. The effects of the holding time, chamber pressure, mole fraction of AI and melting temperature on the real vapor pressure of AI element in the vacuum chamber were analyzed. Because of the impeding effect of the real vapor pressure on the evaporation loss rate, within a short time (less than 10s), the real vapor pressure tends to a constant value. When the chamber pressure is less than the saturated vapor pressure of the AI component, the real vapor pressure of Al is equal to the chamber pressure. While when the chamber pressure is larger than the saturated vapor pressure, the real vapor pressure is equal to the saturated vapor pressure of the Al element of the same condition.     

Pressureless diffusion bonding of ferritic stainless steel foil controlled by metal evaporation

Abstract

Bond formation of thin ferritic stainless steel foils containing 20Cr–5Al (wt-%) was observed under near vacuum pressure of ～10^-3 Pa. Debonded (peeled off) surfaces exhibited a white scaly morphology after bonding above 1400 K. No bond formation was observed below 1400 K, so the critical temperature for bond formation must exist around 1400 K. The critical temperature also depends on the surface roughness of the foil (the thickness of the gap between foils), which can be explained in terms of aluminium evaporation behaviour between foils. A theoretical model is proposed to estimate the effect of aluminium evaporation on the critical temperature. It is also suggested that aluminium evaporation between foils can protect the bonding surface from the residual oxygen gas.     

真空条件下镁蒸气相变形核及冷凝(英文)

描述真空条件下可凝镁蒸气的形核与长大,并从分子水平的研究原理解释这些过程。在平均真空度为40Pa条件下,分析系统压力、冷凝区温度及温度梯度对镁蒸气冷凝的影响。采用自主设计的多级冷凝设备,通过真空蒸发冷凝制备块状镁和镁粉。利用扫描电镜(SEM)与能谱(EDS)进行分析。结果表明:在真空条件下,适宜的气-液转变温度是提高蒸气冷凝富集率的关键所在;而较小的温度梯度则是抑制蒸气发生气-固转变的主要途径;在特定的冷凝温度及温度梯度下,蒸气分压及浓度的提高可以明显改善镁的结晶形貌,降低氧化率。     

真空压强对小模数花键离子渗氮性能的影响

小模数花键零件在离子渗氮过程中,经常出现齿根或节圆位置渗不上和渗层浅等问题。针对这一问题,选取典型转子类零件,通过在300、400、500、600、700 Pa的真空压强下,对其内花键进行离子渗氮试验。研究得出当炉内通入氩气,真空压强为600、700 Pa 时,能够保证内花键齿顶、节圆、齿根的渗层偏差控制在设计所要求的0.02 mm以内,同时显微组织和表面硬度也符合工艺要求。     

不锈钢手术器械真空钎焊与热处理复合工艺的应用

为了提高某些不锈钢手术器械的耐磨性和防滑性能,要对其进行真空钎焊硬质合金与淬火相结合的复合处理．主要工艺参数为：最高加热温度1320℃,极限真空度4×10^-1 Pa,最大气淬压力0．6MPa。这种复合工艺具有被处理产品质量好,能耗低,生产率高,作业环境改善等特点。     

Separation of cadmium and nickel from waste Ni—Cd batteries

To separate the cadmium and nickel resources in waste Ni-Cd batteries,a self-designed vacuum distillation recycling system was studied under laboratory conditions.The effects of system temperature,operating pressure,and time on the separation of Ni and Cd were studied respectively.The mechanism of vacuum thermal recycling was also discussed.Results show that vacuum distillation is a very effective separation method for waste Ni-Cd batteries.At a Constant pressure,the increase of temperature can improve the separating efficiency of Cd.When the temperature is 1173K,Cadmium can evaporate completely from the samples during 3h at 10Pa,The reduction of pressure in a certain range is effective to the separating of Cd from Ni-Cd batteries by vacuum distillation.     

Evaporation of multi—components in Ti—25Al—25Nb melt during induction skull melting process

Based on activity calculation model, t he activity coefficients of Ti, Al and Nb components of Ti-25Al-25Nb (mole fraction, %) melt, the vapor pressu res of correspo nding components and the evaporation loss rates were calculated. Utilizing these activity coefficients and the vapor pressures, the relative evaporation coeffic ient is used to judge the evaporation tendency of these components. The evapora tion tendency among the three components were compared and the result shows that the evaporation tendency is that: AlTi>Nb. Evaporation loss rate increases with the increase of melting temperature and decreases with the increase of chamber pressure. There exists an impeding pressure pimpe of Al element evapo ration during induction skull melting process of Ti-25Al-25Nb alloy. The impeding pressu re can be written as pimpe=8.1pe, where perepresents the equilibrium partial pressure. The calculation of evaporation loss of Al element also showed that when chamber pressure exceeds pimpe, the Al volatilization losses could be ignored. In order to prevent the evaporation loss of components, the pressure in the vacuum chamber should not below pimpe.     

热处理方法改善CdZnTe晶体性能研究

对电阻率为10^3-6Ω·cm的In掺杂Cd0．9Zn0．1Te晶片在Te气氛和Cd／Zn平衡蒸汽压下进行了热处理，对电阻率为10^8-9Q·cm的非掺杂晶片则在In气氛和Cd／Zn平衡蒸汽压下进行了热处理。结果表明，In掺杂Cd0．9Zn0．1Te晶片经处理后电阻率可提高3个数量级。非掺杂晶片在In气氛中热处理可很容易地改变导电类型，在热处理温度700℃，In分压6．1×10^-4Pa，退火时间达48h后，电阻率可以提高到2．6×10^9Ω·cm。     

STUDY ON NANOMETER ZINC PARTICLES FABRICATED BY GAS EVAPORATION METHOD

Nanometer Zn particles with mean diameters 12-100nm made by evaporating its powders in argon gas were studied mainly by X-ray diffraction and electron microscopy. They are collected at various distances and those factors influencing the mean particle size were studied. The optimal synthetic conditions were obtained, i.e., evaporation temperature is 1200℃; argon flow rate is 0.4m3/h; amount of powder charged is 3g; distance from evaporation source is 10cm. It was found that the size of particles was governed by argon flow rate, evaporation temperature, amount of metal charged and distance from the source. The size increases remarkably with distance in the space where no metal vapor exists. This implies that the crystallites grow by coalescence. Electron micrographs and diffraction patterns are reproduced to show the size, shape and state of oxidations. Nanoparticles with definite crystal habits were sometimes observed among those with irregular ones.     

金银合金真空分离的理论研究（英文）

为准确预测金银合金真空蒸馏过程中产品成分与温度和压力的关系,并为工业生产参数的设计提供便捷和有效的指导,根据分子相互作用体积模型(MIVM),计算不同温度下金银合金的分离系数(β)和气-液平衡成分。结合气液相平衡(VLE)理论,绘制金银合金真空蒸馏的温度-成分、压力-成分相图。同时,对金、银三相点和金、银蒸气冷凝温度进行计算。理论研究结果表明：随着蒸馏温度的升高,分离系数减小,金在气相中的含量增加;低温对分离金银具有积极效果;在压强1～10 Pa范围内,金、银冷凝温度相差约450 K。     

Spontaneous volume magnetostriction of Dy2AlFe12Mn4 compound

The structure and magnetic properties of Dy2AlFe12Mn4 compound have been investigated by means of X-ray diffraction and magnetization measurements. The Dy2AlFe12Mn4 compound has a hexagonal Th2Ni17-type structure. Negative thermal expansion was found in Dy2AlFe12Mn4 compound from 229 to 280 K by X-ray dilatometry. The coefficient of the average thermal expansion is α= -3.8×10-5 K-1. The magnetostrictive deformations from 105 to 270 K have been calculated by means of the differences between the experimental values of the lattice parameters and the corresponding values extrapolated from the paramagnetic range. The result shows that the spontaneous volume magnetostrictive deformation ωs; decreases from 6.2×10-3 to near zero with the temperature increasing from 105 to 270 K, the spontaneous linear magnetostrictive deformation λc. along the c axis is much larger than the spontaneous linear magnetostrictive deformation λa in basal-plane at the same temperature except close to 249 K.     

Ti—24Al—11Nb合金感应凝壳熔炼（ISM）过程中Al元素的挥发损失行为

计算了Ｔｉ－２４Ａｌ－１１Ｎｂ中各组元的活度系数,在此基础上系统地研究了该合金在冷坩蜗感应凝壳熔炼过程中Ａｌ的发挥发损失行为。计算结果表明外压为０．１３３Ｐａ时,在１９００－２２００Ｋ的范围内,Ａｌ的挥发由界由挥发反应和液相界面层中的扩散同时控制作用。     

纳米金刚石膜真空窗口的制备

使用自制的微波等离子体化学气相沉积装置,以乙醇为碳源在（100）硅表面制备了金刚石膜;然后用浓硝酸和氢氟酸的混合溶液腐蚀硅,制备出金刚石膜窗口。使用场发射扫描电镜（SEM）、X射线衍射、拉曼光谱（Raman）、原子力显微镜（AFM）表征和分析金刚石膜,并以自制的漏气率测量系统测量金刚石膜窗口的漏气率。结果表明:金刚石膜的厚度为15 μm,平均粗糙度值R_a为39.5 nm,晶粒的尺寸大小为30 nm,漏气率为8.8×10-9 Pa·m3/s。      

真空电子束深熔焊接匙孔前沿蒸发传热分析模型

根据真空电子束焊接过程匙孔深熔效应的特点,建立简化的圆柱形匙孔物理模型.考虑到匙孔前沿的强烈蒸发现象,提出一种基于传热学理论的匙孔前沿气固界面传热分析模型.通过模型分析了AZ系列镁合金材料的主要金属元素Mg,Al,Zn和Mn在匙孔前沿的蒸发效应,以及匙孔半径变化对匙孔前沿气固界面处4种金属元素温度变化的影响.结果表明,...