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).     

高速电弧喷涂铁基Cr3C2复合涂层的显微组织

采用高速电弧喷涂技术将自制的铁基Cr3C2粉芯丝材在20钢上制备复合涂层,采用SEM、TEM、XRD等研究了涂层的显微组织和物相结构。结果表明：涂层与基体结合紧密,具有致密的层状结构,颗粒扁平细小,孔隙率低,具有较高的显微硬度;在涂层中存在着多种结构复杂的组织和化合物相,其中α-Fe为基体相,主要硬质相为（Fe,Cr）23C6、（Fe,Cr）7C3,另外还有FeCr2O4、Cr2O3等氧化物相,其中某些物相之间存在着平行的晶体学取向关系。     

等离子喷涂NiAl/Al2O3梯度陶瓷涂层的结构与组织特征

利用等离子喷涂方法制备了NiAl/Al2O3梯度陶瓷涂层,并对涂层的组织分布、相结构、硬度和孔隙率进行了研究.结果表明: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,是由α-Al2O3、γ-Al2O3、δ-Al2O3、Ni、NiO以及镍铝金属间化合物等多种相组成的复合材料;梯度涂层中NiAl合金层的孔隙最少,表面纯陶瓷层孔隙率最高;随着Al2O3含量的增加,涂层的硬度逐渐增大.     

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。     

钴基高温合金表面电弧离子镀NiCrAlY涂层的抗高温氧化性能

采用电弧离子镀在钴基高温合金K640基体上制备了NiCrAlY涂层,并进行了真空退火处理。通过X射线衍射、扫描电镜和能谱分析等技术对涂层的相结构和基体及涂层在1 000℃下的抗循环氧化行为进行了研究。结果表明:沉积态涂层主要由γ-Ni、γ′-AlNi3和β-Ni Al等物相组成,元素分布均匀;涂层真空退火后衍射峰尖锐,晶粒明显长大,主要由γ-Ni、γ′-AlNi3、β-Ni Al和α-Cr以及极少量的Cr23C6组成。涂层在循环氧化过程中形成Al2O3保护膜,经过100次循环后Al2O3氧化膜仍然完好。真空退火可使溅射涂层表面较早生成保护性能良好的α-Al2O3氧化膜,提高了涂层的抗氧化性能。     

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.     

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。     

射频/直流磁控溅射不锈钢/Al_2O_3复合薄膜组织与性能研究

利用射频 /直流磁控溅射法 ,制备了 31 6L不锈钢 /Al2 O3 陶瓷复合薄膜 ,研究了 31 6L不锈钢 /Al2 O3 陶瓷复合膜的组织形貌 ,测试了薄膜的显微硬度和耐磨性。结果表明 :直流磁控溅射 31 6L不锈钢薄膜呈柱状晶结构 ,主要有 Fe- Cr和γ- Fe相构成 ,在 Fe- Cr( 1 1 0 )晶面出现明显的择优取向 ;由于射频溅射 Al2 O3 陶瓷的掺合 ,使 31 6L不锈钢 /Al2 O3 陶瓷复合薄膜柱状晶细化 ,并出现二次柱状晶 ,在 Fe- Cr( 2 1 1 )晶面出现明显的择优取向 ,31 6L不锈钢膜硬度明显高于 31 6L块体 ,掺合了 Al2 O3 的金属 /陶瓷复合薄膜耐磨性有显著的提高。     

NiCr-CrAl涂层的高温氧化行为

采用固体粉末包埋法在高温合金K438表面制备了一种NiZr-CrAl涂层和单渗铝涂层,通过循环氧化动力学曲线分析、形貌观察及物相分析等对比研究了两种涂层在1000℃下的循环氧化行为。结果表明:单渗铝涂层和NiCr-CrAl涂层均由β-NiAl构成;在循环氧化300h后,NiCr-CrAl涂层质量增加明显低于单渗铝涂层的;单渗铝涂层表面氧化物由α-Al2O3、NiAl2O4和TiO2混合氧化物组成,涂层出现了明显的NiAl向Ni3Al退化,涂层抗氧化性能下降;而NiCrCrAl涂层表面氧化物仍由致密的α-Al2O3相构成,涂层中仅出现轻微的退化,表现出优异的抗循环氧化性能。     

CeO2加入含量对激光熔覆WC增强镍基合金涂层组织与性能的影响

以镍包碳化钨粉和CeO2粉的混合粉为原料,采用激光熔覆技术在42CrMo钢表面制备WC增强镍基合金涂层,研究原料中CeO2质量分数(0～2.0％)对涂层物相组成、显微组织、硬度和耐磨性能的影响.结果表明:添加CeO2后涂层的物相由γ-(Ni,Fe)固溶体、Ni3 Fe、WC、Cr23 C6、M7 C3(M=Fe、Cr)...     

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.     

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。     

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....     

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.