纳米粒子对Ni-Ti复合镀层摩擦学特性的影响

用化学复合镀方法制备含碳纳米管(CNTs)和纳米稀土氧化物Ni-Ti纳米复合镀层,研究纳米粒子含量对纳米复合镀层摩擦磨损性能的影响,并用扫描电子显微镜SEM对纳米镀层进行分析,并测定纳米复合镀层的显微硬度,利用AES能谱分析其磨损机制。结果表明:随着纳米粒子含量的增加,纳米复合镀层的显微硬度增加,摩擦因数降低,耐磨性能提高;质量分数为1.5%的纳米复合镀层的摩擦因数最低,并显示优良的耐磨性能。     

Ni-P/n-MoS2复合镀层制备与摩擦学性能研究

以纳米MoS2颗粒为分散相,用化学复合镀的方法制备出Ni-P/n-MoS2复合镀层,并研究纳米MoS2颗粒在镀液中的添加量对镀层组织结构、显微硬度、纳米MoS2复合量和摩擦学性能的影响.结果发现:镀液中纳米二硫化钼的加入量为2.0 s/L时,得到的复合镀层中二硫化钼的分散效果最好,纳米MoS2复合量最大值为3.18%(质量分数),硬度最大值为HV653;磨损试验后,磨痕表面的二硫化钼质量分数最高可达7.8%,表明复合在镀层中的纳米二硫化钼在摩擦过程中被缓慢释放到表面,因而复合镀层表现出优异的自润滑和减磨性能.     

CeO2对Ni/α-Al2O3纳米复合镀层微观组织和摩擦学性能的影响

采用纳米复合电镀技术,通过向Ni/α-Al2O3纳米复合镀溶液中添加CeO2方法在45#钢上制备了Ni/α-Al2O3-CeO2纳米复合镀层;研究了CeO2对镀层微观组织、显微硬度及摩擦学性能的影响;用分析型扫描电镜、显微硬度计及摩擦磨损试验机对复合镀层组成、微观组织、显微硬度及摩擦学性能进行了分析。结果表明,适量CeO2的加入促进了纳米α-Al2O3的沉积量,使纳米α-Al2O3在镀层中的分布更加均匀,添加过多的CeO2对纳米α-Al2O3分布不利;CeO2添加量为40g/L时,平均显微硬度比未添加CeO2的提高近30%,磨痕宽度减少近40%;CeO2能改善复合镀层的耐磨性能,有效防止镀层片状脱落。     

Ni-P-SiC(纳米)化学复合镀工艺试验研究

在传统的镍磷化学复合镀液中加入纳米SiC粒子,即Ni-P-SiC(纳米)化学复合镀工艺是一项新型的、很有前景的模具表面处理技术。这种方法能进一步提高镀层表面的硬度和耐磨性。采用正交试验方案对45号钢板进行Ni-P-SiC(纳米)化学复合镀工艺试验,归纳和分析了纳米SiC粒子浓度、施镀温度、搅拌速度、镀液PH值4个工艺参数对镀层硬度的影响规律,由正交工艺试验结果推导出最优工艺参数组合。工艺试验得到的镀层硬度值表明优化结果正确。     

Fe-W-Al2O3纳米复合镀层的结构及其耐磨性

利用复合电沉积工艺制备了Fe-W-Al2Q3纳米复合镀层，采用扫描电镜及附带的能谱仪、X射线衍射仪和显微硬度计等研究了复合镀层的表面形貌、成分、结构、显微硬度和耐磨性能。结果表明：Fe-W-Al2O3纳米复合镀层仍呈非晶态，Al2O3纳米粒子在复合镀层中分布均匀，镀层组织致密；Al2O3纳米粒子的添加提高了复合镀层的显微硬度，室温下该复合镀层的耐磨性是Fe-W合金镀层的2倍，并且有效减轻了镀层的内应力，避免了镀层裂纹的出现。     

复合镀液中Al2O3掺杂量对Ni-P-Al2O3-PTFE复合镀层性能的影响

在复合镀液中添加不同含量的Al2 O3,采用化学镀方法制备Ni-P-Al2 O3-PTFE(聚四氟乙烯)复合镀层,研究了复合镀液中Al2 O3质量浓度(0～3.0 g·L-1)对复合镀层显微组织、硬度、耐磨性能的影响.结果表明:随着复合镀液中Al2 O3掺杂量的增加,化学镀Ni-P-Al2 O3-PTFE复合镀层中Al2 O3含量先升高后降低,Ni-P基质的结晶性先增强后减弱,硬度先升高后降低,磨损质量损失先减小后增加;当Al2 O3质量浓度为2.0 g·L-1时,Ni-P基质结晶性优良,Ni-P-Al2 O3-PTFE层与Ni-P过渡层结合良好,复合镀层中Al2 O3的含量最高,PTFE、Al2 O3粒子均匀弥散地镶嵌在Ni-P基质中,复合镀层的硬度最高,为7.6 GPa,磨损质量损失最低,复合镀层具有优异的耐磨性能.     

Al2O3增强镍-磷-钨复合镀层的制备及性能

为了提高镍-磷-钨合金镀层性能,制备了Al2O3增强的镍-磷-钨复合镀层;探讨了镀液中Al2O3颗粒尺寸、搅拌方式、电流密度、镀液中Al2O3、Na2WO4的含量和pH值等对镀速、镀层中Al2O3的质量分数及镀层外观质量的影响;确定了复合电沉积最佳工艺条件;并对镀层的硬度、耐磨性能、抗高温氧化性能、耐腐蚀性能、表面形貌、相结构和化学成分等进行了测试.结果表明:在超声波振荡搅拌下,加入纳米Al2O3,控制电流密度为2A·cm-2,镀液中Al2O3和Na2WO4的含量分别为50g·L-1和6g·L-1,pH值为5.0时,镀速和镀层中的Al2O3质量分数最大,镀层质量最佳;加入微米和纳米Al2O3镀层的综合性能均高于未加入Al2O3的镀层.     

脉冲电沉积Ni/纳米Al_2O_3复合镀层的组织结构与性能

采用脉冲电沉积方法制备Ni/纳米Al2O3复合镀层。利用扫描电镜(SEM)观察分析Ni/纳米Al2O3复合镀层的组织结构,对Ni/纳米Al2O3复合镀层的硬度、摩擦磨损性能和铝液在复合镀层表面的铺展性能进行测试。结果表明:复合镀层的硬度随镀液中Al2O3悬浮量的增加而升高;纳米Al2O3悬浮量为20g/L的Ni/纳米Al2O3复合镀层的摩擦因数为0.459;铝液在Ni/纳米Al2O3复合镀层表面的亲润性比淬火45#钢差,具有良好的耐铝液侵蚀性能。     

多层复合镀层工艺与性能的研究

利用改进的电刷镀技术研制具有层状结构的复合镀层，探索了利用多种固体粒子（Cr2O3、SiC、ZrO、Al2O3等）构成多层复合镀层的可能性与工艺上的可行性。此外，还研究了多层复合镀层的组织、结构、显微硬度以及耐磨性等性能。     

高碳钢表面Ni-P/纳米Ti(C,N)化学复合镀研究

研究了高碳钢表面Ni-P/纳米Ti(C,N)化学复合镀工艺以及热处理对复合镀层性能的影响。结果表明:施镀工艺中各因素对镀速影响的显著性顺序是pH值>镍磷比>施镀温度>纳米Ti(C,N)加入量;较好的施镀工艺为硫酸镍为25g/L、次亚磷酸钠为29.9g/L、乳酸为34g/L、乙酸钠为4g/L、PbCl2为0.001g/L、Ti(C,N)为6g/L、pH值为4、施镀温度为80℃;复合镀层较佳的热处理工艺为400℃保温45min,空冷。在最佳工艺下,得到的Ni-P/纳米Ti(C,N)复合镀层的硬度为975.2HV,是高碳钢基体硬度的3.8倍,且镀层与基体的结合力强。     

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.