喷涂法制备PTFE基减摩耐磨涂层工艺参数的优化

以环氧树脂为黏结剂,聚四氟乙烯(PTFE)为固体润滑剂,MoS_2为填料,采用空气喷涂法在GCr15钢基体上制备PTFE基减摩耐磨涂层,利用往复式摩擦磨损试验机测试了涂层的摩擦磨损性能,并采用正交试验法对固化温度、固化时间、喷枪压力等喷涂工艺参数进行了优化。结果表明:影响PTFE基减摩耐磨涂层摩擦学性能的喷涂工艺参数的主次顺序为喷枪压力、固化时间、固化温度;当固化温度为120℃、固化时间为60 min、喷枪压力为0.3 MPa时,涂层的平均摩擦因数为0.106,磨损体积为0.001 5mm~3,此时摩擦学性能最优。     

MoS_2对PTFE基粘结固体润滑涂层摩擦学和附着性能的影响

以聚四氟乙烯(PTFE)作为固体润滑剂,以MoS2粉作为填料,配制了PTFE和MoS2粉质量比分别为1…2,3…2和5…2的三种涂料(环氧树酯作为粘结剂),利用压缩空气喷涂法在GCr15钢基体上进行喷涂,然后分别在80,120,160℃固化制得了PTFE基粘结固体润滑涂层,研究了MoS2对涂层摩擦学性能和附着性能的影响。结果表明:涂料中PTFE和MoS2的质量比为5…2时,填料与固体润滑剂的协同达到最优,且当固化温度为120℃时,该配方涂层的摩擦学性能和附着性能最优,摩擦因数为0.125,磨损量约为0.008 3mm3,附着力为16.73N。     

环氧基耐热耐磨自润滑涂料的制备及性能研究

以环氧树脂TGDDM和固化剂A及固化剂B为基体,添加聚四氟乙烯(PTFE)、石墨和碳纤维作为固体润滑剂,制备了一种环氧基耐热耐磨自润滑涂料。涂料在150℃×1h的条件下固化,研究了3种填料对涂膜性能的影响。结果表明,石墨能有效降低涂膜的摩擦因数和磨损量,但会降低涂膜的力学性能;过多的PTFE对涂膜的摩擦因数影响不大,但会急剧降低涂膜的耐磨性和力学性能;碳纤维使涂膜的摩擦因数增大,但对降低涂膜的磨损量和提高力学性能却十分有效。石墨、PTFE和碳纤维的最佳用量分别为20份、40份和30份。     

PTFE基耐磨涂层往复滑动摩擦学性能研究

采用CETR多功能磨损试验机,考察PTFE基耐磨涂层在往复滑动条件下的摩擦磨损性能;利用了扫描电子显微镜、三维形貌轮廓仪和电子能谱对磨痕表面进行微观分析,探讨PTFE涂层的摩擦磨损机制。结果表明:PTFE涂层的摩擦学性能与涂层的特性密切相关,较低的摩擦因数对应着较好的耐磨性;涂层的往复滑动磨损表现为磨粒磨损和氧化磨损共同作用的机制。     

波箔气体轴承MoS2基润滑涂层的制备和性能研究

为了提高波箔轴承的耐磨减摩性能,采用喷涂法在平箔片和圆盘试样上制备MoS_2固体润滑涂层,并对圆盘试样涂层结合强度进行分析;采用自制球盘摩擦磨损试验机研究涂层圆盘试样的摩擦磨损性能,通过扫描电镜(SEM)测试涂层圆盘试样摩擦磨损前后表面、截面形貌,利用波箔轴承性能测试实验台探究涂层在实际工作中的耐磨减摩性能。研究结果表明:基体表面的粗糙度影响MoS_2涂层的结合强度,其中试样表面进行喷砂处理后与MoS_2涂层结合力最好;制备的MoS_2固体润滑涂层中各成分均匀分布,涂层的结合方式以机械结合为主;球盘摩擦磨损试验表明,制备的MoS_2涂层的耐磨减摩性能较好,其平均摩擦因数相比不锈钢基体降低了54.5%左右,磨损量相对减小了40.7%;波箔轴承台架试验表明,制备的MoS_2涂层减摩性能已接近商用PTFE涂层,但其耐磨性能较差。     

高载荷条件下环氧树脂涂层摩擦学性能研究

以45#钢为基体制备了环氧树脂(EP)涂层,并用自制的摩擦因数测试装置研究了该涂层在不同润滑条件下的摩擦学性能.结果表明:加载力在500～2 500 N时,EP涂层具有优良的减摩性能,并随着载荷增加,摩擦因数呈下降趋势;添加润滑剂后,可进一步降低涂层摩擦因数,其中固体润滑脂润滑效果最好,最低动摩擦因数达到0.048.     

PTFE基固体润滑涂层的摩擦学和力学性能试验

为了探讨PTFE基固体润滑涂层的摩擦学和力学性能,采用HSR-2M型高速往复式摩擦磨损试验机、INSTRON5944拉压试验机和DDL-300电子万能试验机分别对PTTE基固体润滑涂层的摩擦学性能、粘结性能和抗压性能进行研究.结果表明:A配方涂层的粘结性能较优,其粘结强度是B配方和C配方涂层的4倍左右;B涂层的力学性能最差;C涂层的摩擦学性能和抗压性能最优,其抗压强度是A和B涂层的2倍左右,并且其韧性也较好.     

不同气氛环境中纳米Al2O3／PTFE复合材料摩擦磨损特性研究

利用QG-700高温气氛摩擦磨损试验机, 考察了PTFE及其纳米Al2O3复合材料在干摩擦条件下,在氧气、50%氧气/50%氮气、空气及氮气等气氛环境中的摩擦磨损特性.采用JSM-5610LV型扫描电子显微镜对摩擦表面进行观察,采用EDAX能谱分析仪分析表面成分,研究了干摩擦条件下气氛对复合材料摩擦学性能影响的机制.结果表明:在试验研究范围内,纳米Al2O3的加入可减小PTFE复合材料的磨损量,提高材料的抗磨性能;PTFE和3%Al2O3/PTFE复合材料在氧气环境气氛下的摩擦因数最小,而在氧气和氮气环境气氛下的摩擦因数最大,但磨损量最小;氧气气氛环境最有利于提高PTFE及其复合材料的摩擦学综合性能,氮气环境次之,氧气和氮气环境则有利于增强材料的抗磨性.     

聚酰亚胺填充三层复合材料摩擦磨损影响因素分析

考察了两种不同类型PI树脂填充PTFE基体三层复合材料的摩擦学特性,分析了PI配方与含铅配方的性能差异及其微观作用机理,并探讨了固体润滑剂对该类复合材料摩擦磨损性能的影响。研究表明,一般情况下双马来型PI填充复合材料在油润滑时的摩擦因数和磨损量最小,但在大载荷下含MS10配方材料的减摩性能更为突出。     

TiN/Ti涂层在波箔轴承中的摩擦磨损性能

采用真空离子镀的方法在304不锈钢基体上喷涂厚度为3μm的TiN/Ti薄层,利用硬度计、三维形貌仪、划痕试验仪对涂层基本力学性能进行分析,通过球盘试验机分析涂层试样的摩擦磨损性能,根据波箔轴承性能测试实验台的测试结果:研究TiN/Ti涂层对基体表面耐磨减摩性能的影响。研究结果表明:TiN涂层硬度可达HV1 500,是基材硬度的5.5倍;TiN/Ti涂层平均摩擦因数为0.23,相对不锈钢304基材的平均摩擦因数0.71,降低了68%,磨损量也仅为基材的18.75%;GCr15与PTFE对磨的最大摩擦力矩可达2.4 N·mm,而TiN/Ti与PTFE对磨的最大摩擦力矩仅为1 N·mm,仅为GCr15的41.7%。TiN/Ti涂层表现出了优异的承载能力和耐磨减摩性能。     

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.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.