负偏压对DLC薄膜结构和摩擦学性能的影响

采用离子束溅射沉积镀膜法制备了DLC薄膜,研究了偏压对薄膜性能的影响。通过原子力显微镜(AFM)和拉曼光谱对DLC薄膜的表面形貌以及内部结构进行了分析表征。并用UTM-2摩擦磨损仪对其摩擦学性能进行了测试。结果表明,利用离子束溅射沉积制备的DLC薄膜具有良好的减摩抗磨性能。随着偏压的增加薄膜的摩擦因数先减小后增加,在-150 V偏压时,薄膜的摩擦学性能最好。     

DLC薄膜的表面形貌及其摩擦学性能研究

以真空蒸发碳离子束辅助镀膜法制备了DLC薄膜，通过原子力显微镜(AFM)和扫描电子显微镜(SEM)观察了该薄膜的表面形貌，对该薄膜的表面形貌对其摩擦学行为的影响进行了研究。研究发现：用真空蒸发碳离子束辅助镀膜的方法制备的类金刚石薄膜表面光滑，颗粒均匀，粒度小，摩擦因数降低；DLC薄膜比弹簧钢片及Ti6Al4V球基体耐磨；DLC薄膜的摩擦学性能在摩擦过程中会进一步改善。     

不同温湿度下风电轴承表面防护DLC薄膜微动摩擦特性

针对湿热环境下风电绝缘轴承的微动磨损失效问题，采用等离子体增强化学气相沉积工艺在绝缘涂层Al₂O₃表面沉积类金刚石碳(DLC)薄膜，研究温湿度对其微动摩擦特性的影响。结果表明：DLC薄膜在适当高温下均具有良好的摩擦学性能，在湿度为80%RH时的平均摩擦因数较小；温湿度较高的环境有利于降低DLC薄膜的微动磨损程度，提高绝缘轴承的防护程度；对磨痕处进行拉曼光谱分析表明摩擦过程中DLC薄膜磨痕表面杂化键sp²/sp³比值均大幅上升，且薄膜发生了石墨化转变。DLC薄膜在高温下的低摩擦行为主要是由于DLC薄膜表面石墨化过渡层和磨损表面石墨化的协同作用。     

空心阴极放电制备金刚石薄膜及其性能研究

以石墨为电极，Ar气为辅助气体，利用空心阴极等离子体放电在载玻片上成功地制备了无氢类金刚石（DLC，diamond-likecarbon）薄膜。通过激光拉曼（Raman）光谱分析了所制备DLC薄膜的结构；利用扫描电子显微镜（SEM）和原子力显微镜（AFM）分析了薄膜的表面形貌；通过表面轮廓仪测量了薄膜的沉积速率；另外，试验中还利用摩擦磨损仪对薄膜的机械性能进行了研究。试验结果表明，制备的DLC薄膜比较致密均匀，粗糙度为8．1nm，有较好的耐磨性能。     

类金刚石碳基薄膜在1-乙基-3-甲基咪唑四氟硼酸盐中的摩擦学性能

利用射频等离子体增强化学气相沉积技术,以甲烷为气源,在单晶硅(P(001))衬底上制备类金刚石碳基薄膜(DLC);利用高速往复摩擦磨损试验机分别测试DLC薄膜/Al2O3球摩擦副在大气环境下和1-乙基-3-甲基咪唑四氟硼酸盐离子液润滑下的摩擦磨损性能;利用光学显微镜,X射线光电子能谱和三维轮廓仪分别对磨痕、磨痕表面元素和磨损率进行考察。实验结果表明:DLC薄膜在离子液润滑时,在低载荷下减摩作用明显,但在较高载荷下摩擦因数较无离子液润滑时高,且不随载荷增加而变化,推测是离子液形成了边界润滑膜;XPS分析表明这层边界润滑膜可能是由离子液物理吸附在摩擦接触面上形成的,并且对DLC薄膜有很强的抗磨作用。     

非平衡磁控溅射制备Cr掺杂DLC复合薄膜的高温摩擦学性能

元素掺杂是提升DLC薄膜摩擦学性能和耐温性能的重要途径。采用直流磁控溅射技术在304不锈钢基体表面沉积了含氢DLC薄膜,同时利用射频磁控溅射技术完成Cr元素的掺杂,研究Cr元素掺杂对DLC薄膜的力学性能及摩擦学性能的影响。采用纳米压痕仪测试薄膜硬度并利用划痕试验测试膜基结合力,采用拉曼光谱分析薄膜sp²和sp³键含量的变化和转移膜的生成。采用UMT多功能摩擦磨损试验机评价薄膜在常温和高温环境下的摩擦磨损性能,并利用扫描电镜观察磨损表面,分析其磨损机制。结果表明,Cr元素掺杂会显著提高薄膜的膜基结合力,但会使薄膜硬度有一定的下降。常温摩擦学性能测试显示,DLC薄膜的摩擦因数随着Cr含量的增加呈现出先下降后上升的趋势,在Cr质量分数为3.34%时达到最低;但薄膜的磨损率随Cr含量的增加略有升高。高温摩擦学性能测试表明,Cr元素掺杂显著改善了DLC薄膜的高温摩擦学性能,未掺杂的DLC在150℃以上摩擦时会失效,Cr元素掺杂使薄膜在250℃下也能保持较低的摩擦因数和较长的抗磨寿命。Cr元素的加入能够提高DLC薄膜的膜基结合力,降低摩擦因数,并提高薄膜...     

阶段离子束辅助法制备基频减反膜

在研究阶段离子束辅助制备方式对薄膜性质影响的基础上,采用电子枪蒸发及离子束辅助沉积制备了氧化铪及氧化硅单层膜,采用阶段离子束辅助沉积及全程非离子束辅助沉积制备了基频减反膜。测量了所有样品的弱吸收、残余应力和激光损伤阈值。结果发现,相对电子枪热蒸发制备的样品,离子束辅助沉积的单层膜具有大的弱吸收、低的激光损伤阈值,且张应力减小,压应力增加;阶段离子束辅助沉积制备的减反膜剩余应力变小,弱吸收稍微增加,激光损伤阈值从10.91 J/cm²增加到18 J/cm²。分析表明,离子束辅助沉积在引入提高样品激光损伤阈值有利因素的同时,也引入 了不利因素,阶段离子束辅助沉积在引入有利因素的同时,有效减少了不利因素的引入,从而提高了样品的激光损伤阈值。     

沉积温度对脉冲真空弧源沉积类金刚石薄膜性能的影响

利用脉冲真空弧源沉积技术在Cr17Ni14Cu4不锈钢和Si(100)基体上制备了类金刚石(DLC)薄膜,研究了基体沉积温度对DLC薄膜的性能和结构的影响。研究表明,随着沉积温度由100 ℃提高到400 ℃,DLC薄膜中sp3 键质量分数减少,sp2键质量分数增多,薄膜复合硬度逐渐降低。当DLC薄膜沉积温度达到400 ℃时,薄膜中C原子主要以sp2键形式存在,与沉积温度为100 ℃时制备的DLC薄膜相比,薄膜复合硬度降低50%。DLC薄膜具有优异的耐磨性,摩擦因数低,随着沉积温度由100 ℃提高到400 ℃,Cr17Ni14Cu4不锈钢表面沉积的DLC薄膜耐磨性降低。沉积温度为100 ℃时,Cr17Ni14Cu4不锈钢表面沉积的DLC薄膜后,耐磨性大幅度提高。DLC薄膜与不锈钢基体结合牢固。     

离子束辅助轰击下低能碳离子注入

材料表面经离子束辅助轰击下低能碳离子注入工艺处理后,形成由碳注入层和类金刚石碳薄膜涂层组成的改性层,其中注入层深度比DIM工艺深1倍以上。40Cr钢表面改性后显微硬度HV可提高20％－128％。     

氮化硅陶瓷表面DLC膜的制备及摩擦性能研究

利用等离子体基离子注入与沉积技术,在氮化硅陶瓷片表面制备200～400nm的类金刚石碳膜。测试薄膜的厚度、表面形貌、结构、膜基结合力,利用球盘试验机考察DLC膜的摩擦性能。结果表明:沉积薄膜均匀光滑;薄膜的硬度和弹性模量与基体差异较小,膜基结合力强;DLC膜具有较低的摩擦因数,抗磨性能优异。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.