低温容器真空夹层中绝热材料放气特性实验研究

绝热材料放气是造成低温容器真空夹层真空失效、绝热性能恶化的主要原因。利用自建的材料放气速率实验装置,对绝热材料的放气特性、残余气体成分及影响因素进行了实验研究。实验结果表明：绝热材料的放气特性曲线符合非金属材料扩散放气模型,残余气体成分包括H₂O、N₂、O₂及CO₂,且主要成分为H₂O;真空夹层内的真空度越高,材料的放气速率越大;材料表面粗糙度越大,其放气速率越大;氮气置换空气的抽真空工艺亦可引起绝热材料的放气速率大幅度提升。     

钛膜的电解抛光技术研究

 分析了硫酸、硝酸、氢氟酸；硫酸、乙酸、氢氟酸；乙醇、正丁醇、氯化锌、氯化铝；高氯酸、乙酸；硫酸、甲醇这５种不同电解液组成对钛薄膜表面粗糙度、表面形貌的影响，得出硫酸、甲醇混合溶液是一种较理想的电解液体系。设置合适的抛光电压、温度、时间、泵速等工艺参数，制备出了表面平整光滑，平均粗糙度小于30 nm的钛膜。分析了硫酸、甲醇电解液阳极电压与试样表面减薄速率的关系：试样的减薄速率开始随电压的升高而增大；当电压达到28～34 V时，减薄速率随电压变化很慢，当电压继续增大时，减薄速率又会迅速增大，金属膜继续溶解。     

微通道粗糙度对甲烷催化燃烧影响的数值研究

采用详细化学反应机理对甲烷空气预混气体在不同粗糙度下微通道内催化燃烧进行了数值模拟。结果表明:粗糙度的存在使得微通道内甲烷转化率减小,出口温度降低,粗糙表面将阻碍催化反应的进行,而且粗糙度越大这种阻碍作用越大;在同一粗糙度下,随着当量比、混合气入口速度的增加,粗糙度对催化反应的阻碍作用越明显,粗糙度越大,燃烧效率越低。     

化学激光器用文氏咀的临界背压比

 建立了一套文氏咀临界背压比的测量系统,分别以氮气、氩气和氧气为工作介质,对两种加工工艺、不同规格文氏咀的临界背压比进行了测量,得到了各文氏咀对应不同工作介质的临界背压比,讨论了实验系统中第一个文氏咀的作用和温度对测量结果的影响。实验结果表明:设计合理、工艺合适的Laval喷管,临界背压比明显高于临界压力比,而且,比热容比越小,表面粗糙度等级越高,喉道直径越大,对应的临界背压比越大。     

热舟蒸发LaF3薄膜的紫外性能研究

研究了沉积温度对热舟蒸发氟化镧薄膜结构和光学性能的影响,沉积温度从200℃上升到350℃,间隔为50℃.采用分光光度计测量了样品的透射率和反射率光谱曲线,并在此基础上进行了光学损耗、光学常数以及带隙和截止波长的计算.采用表面轮廓仪进行了表面形貌和表面粗糙度的标定,采用X射线衍射(XRD)方法测量了不同沉积温度下样品的微结构.发现在短波长波段,随着沉积温度的升高,光学损耗增加,晶粒尺寸增大,表面粗糙度略有增加.不过散射损耗在光学损耗中所占比例均很小,光学损耗的增加主要由吸收损耗引起.随着沉积温度的升高,折射 关键词： 光学薄膜 沉积温度 3')" href="#">LaF₃ 光学损耗     

多孔型热致变色材料表面辐射特性研究

分别采用固相反应法和胶晶模板法制备出了块状和多孔型的钙钛矿锰热致变色材料。研究了不同制备工艺对材料居里温度的影响,探讨了不同掺杂比例、表面粗糙度和表面微结构对材料表面辐射特性的影响。结果表明,由于制备工艺不同,两种不同结构钙钛矿锰材料的居里温度相差较大,但其发射率均随温度升高而增大;而在室温以上,多孔材料的发射率明显比块状材料要大。同时,表面粗糙度对材料表面辐射特性的影响较大。     

二氧化钛薄膜表面粗糙度研究

为了探究二氧化钛(TiO₂)薄膜表面粗糙度的影响因素, 利用离子束辅助沉积电子束热蒸发技术对不同基底粗糙度以及相同基底粗糙度的K9玻璃完成二氧化钛(TiO₂)光学薄膜的沉积。采用TalySurf CCI非接触式表面轮廓仪分别对镀制前基底表面粗糙度和镀制后薄膜表面粗糙度进行测量。实验表明, TiO₂薄膜表面粗糙度随着基底表面的增大而增大, 但始终小于基底表面粗糙度, 说明TiO₂薄膜具有平滑基地表面粗糙的作用; 随着沉积速率的增大, 薄膜表面粗糙度先降低后趋于平缓; 对于粗糙度为2 nm的基底, 离子束能量大小的改变影响不大, 薄膜表面粗糙度均在1.5 nm左右; 随着膜层厚度的增大, 薄膜表面粗糙度先下降后升高。     

可变温条件下材料表面的双向反射分布函数测量

基于双向反射分布函数单一参考测量法的测量原理,研制了一套测量温度最高可达500℃的双向反射分布函数测量系统。系统利用转角装置来实现不同角度位置的变换,用加热炉对试样进行加热,采用模糊PID控制器进行温度的控制。在25℃～500℃的温度范围内,对铜表面的双向反射分布函数进行了测量实验,光源采用可见光波长0.6328μm,功率约8mW的He-Ne激光器,选用Si1336-5BK光电探测器。实验表明：随着试样表面温度的升高,铜表面的BRDF测量值发生了改变;在温度上升或下降到同一温度时,铜表面的BRDF测量值不同。最后,对实验现象的形成机理进行了深入分析。上述实验结论对材料表面空间反射特性的研究具有重要意义。     

退火温度对声表面波检测器电极 表面粗糙度的影响*

该文实验研究了退火温度对声表面波检测器电极表面粗糙度的影响。电极表面的粗糙度随着退火温度不同而变化,实验中分别选择常温(25?C)、200?C和300?C作为退火温度对两种镀膜方式制备的声表面波器件进行退火,最后得到退火温度和电极表面粗糙度的对应关系。从实验结果来看,退火温度为200?C时,得到的电极表面粗糙度最大。该研究为声表面波检测器表面粗糙度优化及灵敏度提升提供了基础。     

表面粗糙度的分形特征及其对微通道内层流流动的影响

基于分形几何学,研究了表面粗糙度的分形特征.采用Weierstrass- Mandelbrot函数对多尺度自仿射的表面粗糙度进行了描述;建立了微通道内层流流动的三维模型并对表面粗糙度的影响进行了数值模拟,分析了雷诺数、相对粗糙度和分形维数对流动阻力特性的影响.研究结果表明,与常规尺度通道不同,粗糙微通道的Poiseuille数不再是常数,而是随雷诺数近似线性增加;相对粗糙度越大,流动产生的回流和分离所导致的流动压降越明显.在相同的相对粗糙度下,粗糙表面的分形维数越大,表面轮廓变化就越频繁,这也将导致流动阻 关键词： 粗糙度 层流阻力系数 微通道 分形     

介质表面高功率微波击穿中释气现象的数值模拟研究

建立了一个简单的高功率微波(HPM)介质表面击穿释气模型,并采用PIC(partiele-in-cell)-MCC(Monte Carlo collisions)方法,通过自行编写的介质表面击穿数值模拟程序对不同释气条件下的介质表面HPM击穿过程进行了数值模拟研究,得到了击穿过程中电子数量等的时间图像和不同释气速度下的击穿延迟时间.模拟结果表明,对于具有一定时间宽度的HPM脉冲,当介质表面气体脱附速度较小时,由于介质表面气体层形成太慢而不会发生击穿;只有当脱附速度大于一定值时,击穿才会发生且击穿延迟时间在一定范围内随着脱附速度的增加而缩短.最后,将数值模拟得到的介质表面HPM击穿数据,与单极性表面击穿的实验诊断图像进行了对比,两者的发展趋势符合很好. 关键词： 释气现象 介质表面击穿 高功率微波 数值模拟     

Spectral emissivity of type E235B low carbon structural steel with different roughnesses

A self-built experimental apparatus was employed to study the spectral emissivity of type E235B low carbon structural steel in the wavelength range 2–15 μm at different temperatures by energy comparison method. The surface roughness and topography of the steel E235B were determined by a roughness tester and a scanning electron microscopy, respectively. And then, the spectral emissivity of steel E235B with six different roughnesses was measured before and after oxidation. The measurement results showed that the spectral emissivity increased with the increasing temperature and surface roughness before oxidation. The effect of roughness on the spectral emissivity is different at different wavelength and temperature ranges. However, the oscillatory behavior of the spectral emissivity was observed after oxidation. To explore the possible reasons for emissivity variation, the changes of surface roughness and optical roughness were investigated after oxidation. It is found that both the surface roughness and optical roughness increased after oxidation. Although the optical roughness can be used as one of the parameters to evaluate the effect of surface roughness on the spectral emissivity, it is insufficient to describe the effect of surface morphology on the spectral emissivity.     

Influences of various cutting parameters on the surface roughness during turnings stainless steel

This paper presents an investigation of the process factors affecting the surface roughness in ultra-precision diamond turning with ultrasonic vibration. Stainless steel was turned by diamond tools with ultrasonic vibration applied in the feed direction with an auto-resonant control system. Surface roughness was measured and compared along with the change of the cutting parameters. The relation curves between the cutting parameters and surface roughness were achieved by comparing the experimental results with different cutting speeds, feed rates, cutting depths. Experimental results indicate that cutting parameters have an obvious effect on the surface roughness. The conclusions are draw in given conditions, the smaller amplitude of the vibration, the worse the surface quality and the higher vibrating frequency, the better surface quality, and the deeper the cutting depth and the more the feed rate, the worse the surface quality. Among these parameters, the feed rate was the most important factor on surface quality.     

Adhesion studies of latex film surfaces on the meso- and nanoscale

In this paper the effects of surface roughness and annealing temperature (T) of latex coating films on adhesion are discussed for the different stages of the film formation process. The surface free energy of latex films was assessed in terms of practical work of adhesion (W) (or adherence) using a custom-built adhesion-testing device (ATD), atomic force microscopy (AFM), and contact angle measurements. For preannealed latex films surface roughness averages (R_a) were determined from AFM height images and were related to the values of W obtained from ATD measurements at room temperature. The results obtained using these tests exhibiting surface behavior on different length scales indicate a dependence of the measured adhesion on surface roughness and temperature, as well as on the length scale of the measurements.First preannealed samples were studied, which were obtained by heat treatment above the respective glass transition temperatures (T_g). Increasing the temperature of preannealing resulted in a decrease of the adherence observed in ATD experiments at room temperature. However, on the nanoscale, using AFM, no significant variation of the adherence was observed. This observation can be explained by roughness arguments. Preannealing decreases roughness which results in lower adherence values measured by ATD while for essentially single asperity AFM experiments roughness has an insignificant effect. Specimens were also annealed over a constant period of time (90 min) at different temperatures. At the end of the heat treatment, adhesion was measured at the treatment temperature by ATD. The amplified effect of temperature observed in this case on adherence is attributed to the combination of roughness decrease and increasing test temperature. In a third set of experiments completely annealed samples were studied by ATD as well as by AFM as a function of temperature. With increasing T values ATD showed a decrease in adherence, which is attributed to a decreasing surface free energy of the annealed films at elevated T values. AFM, on the other hand, showed an opposite trend which is assigned to increasing penetration of the tip into the tip/wetting polymer samples versus increasing temperature. Finally, annealing isotherms as a function of time were investigated by ATD in situ at different temperatures. This last set of experiments allowed us to optimize annealing time and temperature to achieve complete curing.     

退火对电子束热蒸发Al2O3薄膜性能影响的实验研究

 用电子束热蒸发方法镀制了Al₂O₃材料的单层膜，对它们在空气中进行了250~400 ℃的高温退火。对样品的透射率光谱曲线进行了测量，计算了样品的消光系数、折射率和截止波长。通过X射线衍射仪（XRD）测量分析了薄膜的微观结构,采用表面轮廓仪测量了样品的表面均方根粗糙度。结果发现随着退火温度的提高光学损耗下降，薄膜结构在退火温度为400 ℃时仍然为无定形态，样品的表面粗糙度随退火温度的升高而增加。引起光学损耗下降起主导作用的是吸收而不是散射，吸收损耗的下降主要是由于退火使材料吸收空气中的氧而进一步氧化，从而使薄膜材料的非化学计量比趋于正常。     

Hydrogen outgassing mechanism in titanium materials

This paper addresses a hydrogen outgassing mechanism in titanium materials with extremely low outgassing property by investigating the distribution of hydrogen atoms concentration in depth below the surface, and the activation energy for desorption of dissolved hydrogen atoms into the boundary region between the surface oxide layer and the bulk titanium and that of adsorbed hydrogen atoms on the surface. The distribution of hydrogen atoms concentration in depth below the surface was analyzed by a time-of-flight secondary ion mass spectrometry (TOF-SIMS). The activation energy for desorption of dissolved hydrogen atoms was estimated by the thermal desorption spectroscopy (TDS) measurement with various heating rates. The activation energy for desorption of adsorbed hydrogen atoms was estimated by the temperature dependence of the outgassing rate in titanium material. In the titanium material, hydrogen atoms show maximum concentration at the boundary between the surface oxide layer and the bulk titanium. Concentration of hydrogen atoms decreases rapidly at the surface oxide layer, while it decreases slowly in the deep region below the surface layer-bulk boundary by the vacuum evacuation without/with the baking process. The activation energy for desorption of 1.02 eV of dissolved hydrogen atoms into the surface layer-bulk boundary is about three times as large as that of 0.38 eV of the adsorbed hydrogen atoms on the surface. These results suggest that the hydrogen outgassing mechanism in the titanium material is composed the follows processes, i.e. the slow hydrogen atoms diffusion at the surface layer-bulk boundary, quick hydrogen atoms diffusion at the surface oxide layer and rapid desorption of adsorbed hydrogen atoms on the surface. This outgassing mechanism gives very low hydrogen concentration near the surface, which results in the extremely low outgassing rate in titanium materials.     

高温下镜面纯Fe的表面质量研究

研究了真空状态下保温60min不同退火温度对镜面纯铁的表面粗糙度、表面形貌及晶粒取向的影响。结果表明:在纯铁的多晶型性转变温度点以下,面均方根粗糙度随退火温度的升高而缓慢增大;在多晶型性转变温度及以上发生突变,从面均方根粗糙度为4~5nm的镜面突变到700nm;用扫描电子显微镜(SEM)观察样品表面,发现在810℃出现再结晶细小晶粒。研究了原材料及860~960℃之间几个温度点的X射线衍射{200}晶面极图,结果发现:晶粒在860℃开始择优取向,随温度升高,取向越来越明显;再结晶对表面粗糙度的影响不大,晶粒的择优取向使得晶粒在不同方向的膨胀系数不同,以及多晶型性转变导致体积的变化使得晶粒之间挤压造成晶粒之间的凹凸不平和表面较深较粗的晶界,这是造成粗糙度突变的主要原因。     

Influence of surface roughness on surface plasmon resonance phenomenon of gold film

We experimentally investigate the effects of the surface roughness of gold thin films on the properties of surface plasmon resonance. By annealing at different temperatures, film samples with different surface morphologies are obtained. Specifically, due to the diffusion of the gold atoms towards the films3 surface, the surface rootmean-square roughness decreases with the increasing annealing temperature. Then, we measure the surface plasmon resonance of the samples. The results show that the resonance angle of the surface plasmon resonance is sensitive to the root-mean-square roughness, and it gradually decreases by reducing the surface root-mean-square roughness.Yang