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1.
易赟  赵晖  王小辉  朱其柱  陈燕 《材料导报》2011,25(5):101-105
强流脉冲电子束(HCPEB)表面处理是一种新兴的高能束表面处理技术.综述了脉冲电子束处理,表面熔坑的形成机制及熔坑、弥散颗粒、裂纹、波状起伏、条形纹理、胞状晶等典型形貌影响因素和演变规律方面的研究成果,总结了表层结构变化与表面显微硬度、耐磨性、耐蚀性能等改性工艺的研究现状,并认为扩大强流脉冲电子束应用范围和系统的探究是目前研究的重点.  相似文献   

2.
从实测大生产物料的动态表面张力和静态表面张力数据,用表面活性剂在涂布液的扩散和在新表面吸附过程,分析涂布过程出现的余布弊病,并提出解决的办法。  相似文献   

3.
A heterogeneous catalytic process involves many surface elementary steps that affect the overall catalytic performance in one way or another. In general, a high‐performance heterogeneous catalyst should meet the main criteria: excellent catalytic activity and high selectivity toward target products. Using surface science techniques, the two‐sidedness of the surface reaction mediations can be explored, from the perspectives of the surface and the molecule manipulations. The surface manipulation refers to a reaction that is mediated by composition and structure of the substrate as well as surface species, while the molecular manipulation relates to a reaction that is mediated by the reacting molecule via the precursor selection, environmental control, or external excitation. The best catalytic system should consist of the most efficient catalyst and the best suitable reacting molecule, in addition to its economic benefit and environmental amity. Recent research progress in surface reaction mediation is outlined, and its two‐sidedness is governed by the Arrhenius equation. This should shed new light on the connection between basic theory and surface reaction mediation strategies. To conclude, challenges and possible opportunities are elaborated for efficient surface reaction mediations.  相似文献   

4.
杨佳玲 《影像技术》1998,(4):19-19,45
平衡法测定的是静止表面的表面张力,但若两相界不断更新,则溶质面表面的扩散和吸附未必能达到平衡本文介绍的动态表面张力的测定试验,就是基於测定到达平衡表面张力的时间。  相似文献   

5.
Heterogenous reactions under transport control can be modelled in terms of a film of reaction products covering the reaction surface. Such a surface defines a unique direction in space which may be used to classify transport processes as transverse or longitudinal. Since crossed-gradient transport occurs, a Péclet number Pe is introduced, representing the ratio of the velocities characterizing transverse and longitudinal transport, with transverse transport being by film diffusion of some reacting species and longitudinal transport corresponding to film flow as with wetting processes. If the influence of viscosity is taken into account in terms of a Schmidt number Sc, the long-wave approximation for the evolution of thin films on reaction surfaces is shown to be equivalent to a distinguished limit Pe 0, Sc , while keeping 1/ . The long-wave approximation is derived by an application of the method of strained variables which leads to a film equation for the spatio-temporal evolution of the film thickness h which represents the crucial element for a complete solution of the thermo-hydrodynamics of the layer. Since film generation due to chemical reaction and film removal due to evaporation may compensate for certain thicknesses h, surface phases are found to occur which correspond to stationary layers of uniform thickness. The evolution of the surface layer is shown to be a generalized reaction-diffusion process, with surface waves representing dynamical transitions between surface phases.  相似文献   

6.
一种曲面裁剪的快速新算法   总被引:1,自引:0,他引:1  
曲面裁剪算法是曲面造型的关键算法之一。传统的裁剪算法是通过对重点和重边进行较复杂的特殊处理并基于环的两两并、交、差来实现的。本文首先提出并严格的定义了入点、出点等概念,在此基础上,提出了一种 对被裁剪曲面参数域进行快速组环的分裂、组环方法,从而实现了对曲面的快速裁剪,该算法已实现并用在SupermanCAD/CAM曲面造型系统。  相似文献   

7.
介绍了膜表面光接枝技术的研究进展,并对接枝表面结构:表面形态和接枝链长度和密度作了综述.列举了接枝表面的性质,如接触角、吸附性、功能化、蛋白质固定化、环境敏感性等的变化.  相似文献   

8.
A set of equations is proposed that makes it possible to obtain calculation equations for experimental determination of the specific free surface energy of solids. __________ Translated from Izmeritel’naya Tekhnika, No. 10, pp. 68–69, October, 2007.  相似文献   

9.
反应烧结碳化硅反射镜表面改性技术   总被引:1,自引:1,他引:1  
为了解决新型优质光学材料-反应烧结碳化硅(RB-SiC)由SiC和要Si两相结构引起的光学表面缺陷问题,提出了反射镜表面改性方案并且从加工工艺的角度介绍了改性工艺流程.以空间反射镜的使用环境为依据,对几种适用的RB-SiC改性材料进行了较为全面的分析比较.本文采用新的离子辅助沉积碳化硅(LAD-SiC)材料为改性层,对改性层的表面形貌及部分性能进行了测试,证明IAD-siC膜层能够满足改性要求.在厚度为(6±0.5)μm的IAD-SiC膜层表面进行了一系列抛光工艺实验,文中给出了超光滑表面抛光工艺参数和实验结果.对改性层进行精抛光后,100 mm口径样片的面形精度为0.033X RMS(λ=632.8 nm),表面粗糙度优于0.5mmRMS.结果表明,本方法不仅可以很大程度提高元件表面质量,还可以进一步精修面形,为超光滑,低散射RB-Sic反射镜的加工提供了一条可行途径.  相似文献   

10.
镁合金表面处理研究的进展   总被引:7,自引:3,他引:7  
论述了镁合金表面处理,包括化学表面转化处理、机械表面硬化处理、强束流表面改性3方面的研究现状.着重叙述了铬化、磷化处理、阳极氧化、微弧氧化等表面处理工艺。同时,还论述了机械表面硬化处理的表面喷丸强化和滚压强化。强束流表面改性代表现代先进表面改性技术,包括离子束、激光束、电子束表面改性,国外研究较多,而国内研究相对较少,应该引起足够的重视。  相似文献   

11.
镯面和一般复曲率面的光线追迹   总被引:1,自引:0,他引:1  
王永仲 《光电工程》1993,20(5):7-12
本文讨论镯面和一般复曲率面的光线追迹;指出一般文献的疏漏;提出解决办法。  相似文献   

12.
分形理论在表面计量学中的应用   总被引:2,自引:0,他引:2  
分形几何理论已被广泛用于工程表面的研究,文中首先研究了粗糙表面的分形模型,叙述了分形几何在工程表面的机械加工、接触机理、摩擦的磨损等方面的应用;最后指出了制约分形理论应用的几个问题和发展方向。  相似文献   

13.
水镁石粉体是聚合物的常用填料,但水镁石极性较大,与基材的相容性也较差,因此必须通过表面改性,降低水镁石粉体表面能,增强亲油疏水性,从而增加与聚合物之间的相容性,而阴离子表面活性剂是合适的改性剂之一。水镁石粉体改性后的表面性能,可以用固体表面能数值的变化来表征,本文选择丙三醇、水、1-溴代萘为探针液体,用直接测定法与Washburn方程间接计算法获得了改性前后水镁石的接触角,通过Lifshitz-van der Waals acid base三参数法计算其表面能。研究结果表明,不同的阴离子基团中,羧酸类、磷酸较之磺酸类硫酸类改性效果有明显优势,表面能的碱分量γ-S和酸分量γ+S降为0;随着改性剂中非极性链烃的碳原子个数增加,表面能非极性分量γLSW下降很多,最终导致总表面能下降,接触角增加,疏水性增强。  相似文献   

14.
通过解析公式计算得到面源和面偶的诱导速度,在面偶附近区域,用涡环代替面偶,计算得到螺旋桨的速度场,根据尾涡面必须和当地流体流速相切的原则,修正原来尾涡面的形状,逐步迭代直至尾涡形状收敛,用这种方法预报了三维水翼和螺旋桨的尾涡面的形状和梢涡卷起,与试验结果有较好的一致性。  相似文献   

15.
聚酰亚胺薄膜因表面光滑和亲水性差,导致其粘接性能低,有必要对其进行表面改性.从聚酰亚胺薄膜表面性质出发,详细介绍了酸碱处理、等离子处理、离子束和表面接枝等几种不同的聚酰亚胺薄膜表面改性方法及其研究进展.通过这些改性方法,聚酰亚胺薄膜表面与其他材料的粘接性能得到显著提高.  相似文献   

16.
膜污染被公认为是限制膜技术在环保、生物、医药、食品以及废水处理等工业领域广泛应用的最大瓶颈.主要综述了目前应用广泛的抗污染表面的构建方法,其中包括表面涂覆法,表面接枝法及表面偏析法.重点介绍了此三种方法的基本原理、研究现状以及存在的问题,在此基础上对抗污染表面构建方法的发展前景进行了分析.  相似文献   

17.
复合材料的切削加工表面结构与表面粗糙度   总被引:15,自引:1,他引:15       下载免费PDF全文
普通金属材料的切削加工理论表面粗糙度可以用公式计算。复合材料经切削加工后其表面留有各种凹凸缺陷,这些谷峰轮廓并非由刀刃直接切出,故不宜用现有普通材料的公式计算其理论表面粗糙度。纤维增强复合材料的切削加工表面结构和粗糙度与切削方向密切相关。颗粒增强复合材料无方向性,其已加工表面结构和粗糙度主要受增强颗粒硬度和粒度以及含量控制。增强体与基体的界面强度及切削刀具和工艺条件对复合材料加工表面粗糙度有很大影响。   相似文献   

18.
介绍了一种高温表面温度计校验仪,适应于50~700℃较高温度范围内的表面温度计校准。对校验仪的温度均匀度和稳定性进行了测试。该校验仪表面热板具有ф50mm的均匀温度场,在最高使用温度时表面温度均匀度小于2℃,温场稳定性小于1℃/10min。对高温状态下表面温度校验仪的不确定度进行了评估,校准数据表明该校验仪可用于高温表面温度计的校准。  相似文献   

19.
As a simulation of surface solidification of materials,quasi-two dimensional dendritic deposition ofammonium chloride(NH_4Cl)crystals from an aqueous solution film with free surface byvapourization was investigated by the in- situ observation technique.The depositing morphologiesof NH_4Cl crystals are faceted and of growth laws differing from the three-dimensional case.Underlow supersaturation,faceted dendrites formed,whereas the anisotropy in growth kinetics decreaseswith the increase of supersaturation.When vapourizing rate(supersaturation)is not very low,oscillations of growth rate.tip-radius and second arm spacing of the dendrites were observed.It issuggested that this dynamic phenomenon is attributed to the correlation between theconvection-transfer effect induced by the surface tension gradient of solution film.and the drivingforce for deposition.  相似文献   

20.
The spontaneous emission of metallic electrons embedded in a high-intensity enhanced surface plasmon field is considered analytically. The electrons are described by dressed quantum states which contain the interaction with the plasmon field non-perturbatively. Considerable deviations from the perturbative behaviour have been found in the intensity dependence of the emitted fundamental and the second harmonic signals, even at moderate incoming laser intensities. The theoretical predictions deduced from the formalism are in good qualitative agreement with the experimental results.  相似文献   

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