CVD金刚石涂层拉丝模温度场数值分析

衬底温度是热丝化学气相沉积(HFCVD)制备金刚石薄膜的重要参数之一,在拉丝模表面沉积CVD金刚石涂层时,均匀的衬底温度场显得尤为重要.对HFCVD系统中制备CVD金刚石涂层时拉丝模衬底温度场进行数值分析,得到了拉丝模温度场的分布和热丝参数对衬底温度场的影响规律,为CVD金刚石涂层拉丝模的制备提供重要指导.     

CVD金刚石薄膜涂层轴承支撑器的制备和应用

轴承支撑器是轴承精密加工中的关键部件。本文采用热丝化学气相沉积(简称CVD)法,以丙酮和氢气为碳源,在WC-Co硬质合金轴承支撑器衬底上沉积金刚石薄膜,制备CVD金刚石薄膜涂层轴承支撑器,并应用于轴承的精密磨削加工。结果表明,合理控制衬底材料的预处理和CVD沉积工艺对金刚石薄膜质量、形貌、粗糙度和薄膜与衬底间的附着力有显著影响。与传统硬质合金轴承支撑器相比,CVD金刚石涂层轴承支撑器的耐用度和使用性能显著提高。     

复杂曲面金刚石涂层刀具的制备与试验研究

以氢气和丙酮为原料,采用电子增强化学气相沉积(EACVD)法,利用改进了的化学气相沉积(CVD)装置在复杂曲面硬质合金(WCCo)钻头表面涂覆一层金刚石涂层.研究了适用于复杂曲面金刚石涂层刀具衬底预处理新方法和CVD涂层新工艺,并对碳化硅颗粒增强铝基复合材料进行了试验研究,研究结果表明,所制备的复杂曲面金刚石涂层刀具的耐用度和切削性能得到了显著提高.     

CVD金刚石厚膜刀具的制造及应用

随着汽车、宇航、电子工业的发展,大量有色金属和新型材料的广泛应用,使金刚石切削刀具的需求量迅速增长。化学气相沉积(CVD)金刚石作为一种新型超硬刀具的材料,为金刚石刀具的应用开辟了新的途径。CVD金刚石刀具主要有两种类型:CVD金刚石薄膜涂层刀具和CVD金刚石厚膜焊接刀具。金刚石薄膜涂层与刀具衬底材料之间的     

HFCVD衬底三维温度场有限元法模拟

热丝化学气相沉积(Hot filament chemical vapor deposition,HFCVD)方法制备金刚石薄膜设备简单,成本低廉,适合大面积金刚石膜的产业化生产,其中衬底温度是沉积高质量CVD金刚石膜的重要参数之一.基于此,首先分析大面积HFCVD系统的热交换过程,建立大面积HFCVD系统衬底温度场的三维有限元模型.与传统纯热辐射模型相比,本模型更加接近实际系统,并较好符合试验测定的结果.根据三维有限元模型开展对大面积HFCVD系统衬底温度场的有限元仿真研究,得到HFCVD系统衬底温度场的三维分布规律,并讨论热丝直径、热丝温度、热丝根数、热丝-衬底距离和水冷散热系数等对衬底温度大小及均匀性的影响.仿真结果表明,在适宜金刚石膜生长的参数范围内,热丝参数和衬底接触热阻对衬底温度大小有显著影响,由于衬底内部的三维热传导使得衬底温度场更加均匀,各参数对衬底温度场的均匀性影响不大.研究结果为高质量制备金刚石膜提供理论基础.     

沉积压力对金刚石涂层组织结构及铣削性能的影响

研究不同沉积压力对化学气相沉积CVD金刚石涂层的组织结构及切削性能的影响.采用热丝化学气相沉积(HFCVD)方法,在不同的沉积压力下于WC-Co基硬质合金基体表面制备金刚石涂层.通过X射线衍射分析(XRD)和扫描电子显微镜(SEM)分析涂层的微观组织结构,利用拉曼光谱(Raman Spectroscopy)分析金刚石涂...     

CVD金刚石厚膜焊接刀具的试验研究

提出一种制作CVD金刚石厚膜焊接刀具的新工艺。采用电子辅助化学气相沉积法 (EACVD)制备直径10 0mm、厚度 0 8～ 1mm的金刚石厚膜 ;通过对金刚石刀头表面进行金属化处理 (化学气相沉积W膜 ) ,改善了金刚石的耐高温性及与低熔点合金焊料的浸润性 ,可在大气环境下实现金刚石刀头与刀架的焊接。车削试验结果表明 :用新工艺制作的金刚石刀具适用于精密加工     

焕发刀具潜能的金刚石涂层

通过化学气相沉积（CVD）工艺在钨硬质合金刀具上涂覆金刚石涂层,可以产生元与伦比的优势。 化学气相沉积金刚石保留了天然金刚石的属性。其超高硬度和弹性模量保障了非常高的尺寸稳定性及耐磨性。和天然金刚石一样,化学气相沉积金刚石的摩擦系数很低,因此切削力和功耗很低,摩擦发热很低,切割时可以防止积屑瘤的形成。     

改善CVD金刚石薄膜涂层刀具性能的工艺研究

用热丝CVD法,以丙酮和氢气为碳源,在WC-Co硬质合金衬底上沉积金刚石薄膜,在分析了工艺条件(衬底温度、碳源浓度、反应压力)对金刚石薄膜性能的影响的基础上,提出了分步沉积法改善金刚石薄膜涂层刀具性能的新工艺.结果表明,合理控制工艺条件的新工艺对涂层薄膜质量、形貌和粗糙度、薄膜与衬底间的附着力、刀具的耐用度及切削性能有显著影响,对获取实用化的在硬质合金刀具基体上沉积高附着强度、低粗糙度金刚石薄膜的新技术具有重要的意义.     

大尺寸单晶金刚石衬底抛光技术研究现状与展望

近些年来,化学气相沉积（Chemical vapor deposition,CVD）单晶金刚石在电子学领域的应用令人瞩目,这得益于CVD单晶金刚石在生长技术和半导体掺杂技术上的进展。一直以来,成熟的衬底加工技术是半导体材料得以应用的基础,其中超精密抛光作为晶圆衬底加工的最后一道工序,直接决定了晶圆表面粗糙度和亚表面损伤程度。可以预见,超精密抛光技术将会在制备大尺寸高质量金刚石衬底中发挥重要作用。对目前国内外现有的单晶金刚石抛光方法进行综述,以制备大尺寸高质量单晶金刚石衬底为目标,从加工设备、工艺参数、加工精度、加工效率和材料去除机理等方面进行分析,总结各种抛光方法的优势和缺点,展望未来大尺寸单晶金刚石衬底抛光技术的发展趋势。目前鲜有针对大尺寸单晶金刚石抛光技术的综述,本文为国内学者展开单晶金刚石抛光相关工作的研究提供综述资料。     

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.