等离子喷涂Fe3Al-Al2O3陶瓷梯度涂层

用等离子喷涂方法制备了FeAl-Al2O3陶瓷梯度涂层，并对涂层的结合硬度、显微硬度及抗热震性进行了试验研究。结果表明，梯度涂层设计为成分的阶梯过滤，实现了成分和组织的连续梯度变化，没有明显的组织突变和宏观界面，梯度涂层的组织表现出宏观不均匀性和微观连续性的分布特征。其结合强度较高，涂层的显微硬度值在含75％Al2O3的区域达到最高值。基体与涂层的界面是基体-涂层体系中的薄弱环节。FeAl-Al2O3梯度涂层的800℃抗热震性优于Al2O3涂层。     

碳钢表面等离子喷涂陶瓷涂层的制备及表征

采用不同的喷涂功率,在Q235钢表面喷涂氧化铝涂层,利用X射线衍射仪、扫描电子显微镜、金相照相机和显微硬度计表征不同功率下Al2O3陶瓷涂层的成分、表面和界面形貌、金相组织以及显微硬度.结果表明,等离子喷涂能在碳钢表面形成结构致密的Al2O3陶瓷涂层,其与基体的结合主要以冶金的机械结合为主,硬度较基体有明显提高.XRD分析表明,陶瓷涂层中主要的成分是稳定的γ-Al2O3相,存在少量的α-Al2O3,同时还有极少量的其他多晶相和非晶相.     

高速电弧喷涂FeAlCrNi-Cr3C2涂层的组织与相结构研究

采用粉芯丝材高速电弧喷涂技术制备了FeAlCrNi-Cr3C2涂层,并研究了涂层的组织和相结构.结果表明:涂层具有致密的层状结构,扁平颗粒小,氧化物膜细小,硬质点相分布均匀,孔隙率低;在涂层中存在着多种结构复杂的组织和化合物相,包括单立方结构基体相FeAl、Fe3Al、AlNi,AlNi;硬质相Cr3C2、Fe3C及AlFe3C0.5;氧化物相FeO·Al2O3、Cr2O3、少量六方结构的α-Al2O3和面心立方结构的γ-Al2O3以及面心立方结构的FeO·Cr2O3;某些区域还存在面心立方结构的γ-(Fe,Ni).     

高速电弧喷涂FeAlCrNi-Cr3C2涂层的组织与相结构研究

采用粉芯丝材高速电弧喷涂技术制备了FeAlCrNi-Cr3C2涂层,并研究了涂层的组织和相结构.结果表明涂层具有致密的层状结构,扁平颗粒小,氧化物膜细小,硬质点相分布均匀,孔隙率低;在涂层中存在着多种结构复杂的组织和化合物相,包括单立方结构基体相FeAl、Fe3Al、AlNi,AlNi;硬质相Cr3C2、Fe3C及AlFe3C0.5;氧化物相FeO·Al2O3、Cr2O3、少量六方结构的α-Al2O3和面心立方结构的γ-Al2O3以及面心立方结构的FeO·Cr2O3;某些区域还存在面心立方结构的γ-(Fe,Ni).     

氧化镧掺杂对等离子喷涂Al_2O_3-40%TiO_2涂层组织和耐磨性能的影响

在45#钢基体上大气等离子喷涂制备了Al2O3-40%TiO2(AT40)以及添加不同含量La2O3稀土的陶瓷涂层,利用X射线衍射和扫描电镜对涂层的组织结构和形貌进行了研究,并分析了涂层的显微硬度和磨损性能.研究结果表明:添加稀土的AT40涂层主要是由Al2O3、Al2TiO5和LaAl11O8相组成.基体与粘结层以及陶瓷层与粘结层之间形成良好的机械结合界面.添加稀土的涂层孔隙率降低,显微硬度和断裂韧性略有增加.在相同的摩擦磨损试验条件下,稀土/AT40涂层比AT40涂层具有更好的耐磨性,磨损机制都主要是脆性剥落磨损和粘着磨损.     

陶瓷增强相对金属-陶瓷复合涂层的影响

对电弧喷涂几种不同陶瓷增强相的Fe复合涂层的特点和性能进行了研究，在20钢基体上喷涂含陶瓷TiB2／Al2O3，TiB2-Cr3C2，TiB2，Cr3C2及TiB2-Cr3C2-Al2O3的管状喷涂丝材，采用光学显微镜和XRD对涂层的微观特性进行分析，结果表明，涂层中含有TiB2，Al2O3，Cr3C2，Cr3O2等陶瓷相。通过对涂层常规性能测试表明，含TiB2／Al2O3和Cr3C2的涂层孔隙率较低、结合强度高、并具有优良的耐磨性及抗热震性能。     

等离子喷涂自反应合成陶瓷/金属复合涂层的形成机理

用Fe2O3粉、Al粉和粘结剂制备了Fe2O3-Al复合粉。等离子喷涂自制的复合粉，使其在焰流内部发生反应，在喷涂基材上形成以Al2O3陶瓷为基体，以Fe金属为第二相的陶瓷／金属复合涂层。这种工艺成功地把等离子喷涂技术和自蔓延技术结合在一起。分析了复合粉和陶瓷／金属复合涂层以及反应过程中复合粉的微观结构，研究了等离子喷涂自反应复合粉的反应过程和陶瓷／金属复合涂层的形成机理。     

化学气相沉积Ti(CN)/TiC/Al_2O_3多层涂层的结构和耐磨性能

采用化学气相沉积技术在42CrMo钢基体表面制备了Ti(CN)/TiC/Al2O3多层涂层,分析了多层涂层的断面形貌、元素分布和物相组成,并研究了多层涂层的显微硬度及其与基体的界面结合力、耐磨性能。结果表明:Ti(CN)/TiC/Al2O3多层涂层的结构较致密,主要由TiC0.2N0.8、TiC、α-Al2O3和Ti2O3组成,厚度约10μm,其显微硬度约2 654HV,涂层与基体间的界面结合力可达62N;与基体相比,多层涂层的平均摩擦因数约降低了23%,磨损量约减少了50%,其磨损机制为疲劳磨损和磨粒磨损。     

等离子喷涂纳米ZrO_2功能梯度热障涂层的孔隙结构

采用大气等离子喷涂技术制备了纳米ZrO2功能梯度热障涂层,采用定量金相分析技术分别研究了表面陶瓷层、中间层及界面处的孔隙率、孔隙尺寸和孔隙形状.结果表明:各区域的孔隙率、孔隙尺寸和孔隙形状系数服从各自相似的概率分布;界面处孔隙率最高为6.87%,表面陶瓷层和中间层孔隙率略低;涂层中尺寸在1μm以下的孔隙数量最多,约占65%;孔隙大多呈等轴状,所占比例在70%～73%之间.     

激光重熔纳米SiC复合陶瓷涂层组织和性能研究

研究了WC／Co-NiCrAl等离子复合陶瓷涂层、激光重熔等离子涂层、激光渗入纳米SiC涂层的组织结构、耐磨性能。结果证明：在所定的工艺参数下，等离子喷涂层组织呈层片状，层间为机械结合界面；经激光重熔后，激光作用区涂层组织细化，孔隙率降低，耐磨性能是原等离子涂层的1．3倍；渗入纳米SiC后，组织进一步细化，孔隙率进一步降低，SiC颗粒仍处于纳米尺度，分布在粗颗粒表面及粗颗粒之间，其耐磨性能是原等离子涂层的2．6倍。     

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...     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.     

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.