不同温度火烧驱油工况下油套管用钢的腐蚀行为

通过模拟火烧驱油工况,研究了油套管用N80钢、BG80-3Cr钢、P110钢、BG90H钢、BG90H-9Cr钢和BG90H-13Cr钢在不同温度下的腐蚀行为,分析了其腐蚀机制。结果表明:在较低温度(50℃)下,试验钢主要发生CO_2和氧腐蚀,腐蚀产物为FeCO_3,腐蚀产物膜的保护性较差,均匀腐蚀速率较高;在较高(150℃)温度下,氧腐蚀占主导作用,腐蚀产物为Fe_3O_4和FeCO_3,腐蚀产物膜的保护性下降,均匀腐蚀速率增大;在高温(250℃)条件下,腐蚀机制为氧腐蚀,腐蚀产物为Fe_3O_4,Fe_3O_4水化物膜的保护性较强,均匀腐蚀速率降低;N80钢、BG80-3Cr钢、P110钢、BG90H钢的均匀腐蚀速率均明显高于BG90H-9Cr钢和BG90H-13Cr钢的,且在50,150℃时的均高于0.2 mm·a~(-1);BG90H-9Cr钢和BG90H-13Cr钢在试验条件下的均匀腐蚀速率都低于0.2mm·a~(-1),在火烧驱油工况下具有良好的耐均匀腐蚀性能。     

TP347H耐热钢管在超临界条件下的氧化膜结构及形成机理

研究了发生堵塞爆管事故的TP347H耐热钢管氧化膜的结构和形成机理。结果表明:TP347H耐热钢的氧化膜分为三层,最外层主要为Fe2O3,中间层主要是Fe3O4,还含有少量尖晶石(FeCr2O4、NiFe2O4),最内层由富铬层(FeCr2O4和Cr2O3)和富镍金属层组成;最外层的Fe2O3和中间层的Fe3O4是由铁离子向外传输与氧反应形成的;最内层的富铬层和富镍金属层的形成与铬、镍与氧的亲和力大小不同而导致的选择性氧化有关。     

Inconel 740H合金在纯水蒸气环境中的高温氧化行为

通过高温氧化试验研究了Inconel 740H合金在750℃的动态纯水蒸气环境中的氧化行为。结果表明:Inconel 740H合金的氧化增重近似遵循抛物线规律,随氧化时间的延长氧化产物粗大;氧化膜形貌与在干燥空气中氧化的明显不同,但未发现明显的氧化膜开裂和剥落现象;合金氧化100h后形成连续的Cr2O3氧化膜,氧化膜厚度随着氧化时间的增加而增大;氧化1 000h后形成的氧化膜主要由Cr2O3和少量的(Mn,Ni)Cr2O4尖晶石组成,靠近氧化膜的合金内部出现明显的贫铬区,并伴生少量的Al2O3和TiO2内氧化产物。     

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。     

金属-玻璃封接中4J29可伐合金的氧化研究

计算了4J29可伐合金氧化生成不同产物的热力学上的氧化气氛条件。根据所计算的临界H2／H2O比值，在可控制的N2／H2／H2O混合气氛下，对4J29可伐合金进行氧化实验。氧化膜层的X射线衍射分析表明，通过加入H2，调整混合气氛的成分(H2／H2O比)，4J29可伐合金氧化可以得到以致密封接所需的Fe3O4为主要成分的氧化物。同时氧化气氛的调整能够控制氧化物的生长，在1000℃下4J29可伐合金氧化15min得到的氧化膜厚度约为0．5μm。     

0Cr18Ni9、1Cr13和1Cr17不锈钢在熔融LiCl-5%Li2O中的腐蚀行为

采用浸没法分别研究了0Cr18Ni9、1Cr13和1Cr17三种不锈钢材料在700℃LiCl-5%Li2O(质量分数)熔融盐中的腐蚀行为.结果表明:0Cr18Ni9和1Cr13不锈钢的腐蚀产物主要为LiFeO2和LiCrO2,1Cr17的腐蚀产物主要由LiFeO2、LiFe5O8和LiCrO2组成;三种钢的腐蚀速率均随时间的延长而增大,并且1Cr13的腐蚀速率明显大于1Cr17和0Cr18Ni9的;在试验条件下,1Cr17铁素体钢和0Cr18Ni9奥氏体钢的耐蚀性能相当,均优于1Cr13马氏体钢.     

12Cr1MoV锅炉过热器管长期过热开裂原因分析

某厂的12Cr1MoV锅炉过热器管运行39 840 h后发生开裂。宏观检测发现有堵管现象,断口呈厚唇状,表面覆盖着氧化物。采用光学显微镜、X射线衍射、扫描电镜、能谱仪、透射电子显微镜等测试方法对失效管进行检测。研究表明,堵管物的成分是Na3PO4、Fe2O3和NaFeO2;内壁氧化物在未堵管位置是Fe3O4,在堵管位置是Fe2O3。断口呈沿晶形貌,有沿晶界的二次裂纹和晶界孔洞。靠近裂纹和远离裂纹的金相组织相同,原始态的片状珠光体消失,碳化物在晶界聚集长大,组织发生了严重球化,晶界碳化物是M23C6型碳化物;根据电力行业标准评定材料球化级别为5级。由球化级别和运行时间估算壁温,得知过热器管超温运行。靠近裂纹和远离裂纹的试样的硬度值相近,数值较低,约为135 HV。12Cr1MoV锅炉过热器管的失效模式是高温蠕变开裂,失效主要是由内壁氧化层和堵管物造成的长期过热引起。     

电子束物理气相沉积制备NiCrCoAl合金在1000℃的氧化行为

对物理气相沉积制备的微晶材料Ni-11.5Cr-4.5Co-0.5Al高温合金薄板在1 000℃空气中恒温氧化进行了研究,用扫描电镜对氧化试样的表面和截面形貌进行观察,用X射线衍射仪与能谱仪对其相和成分分布进行了分析.结果表明:微晶材料高温合金板在初始氧化阶段遵循抛物线规律,长时间氧化时遵循四次方规律;氧化时表面形成细小、致密的氧化物层,随着时间的延长氧化物颗粒逐渐长大,外表面形成NiO、CoCr2O4和Cr2O3混合氧化物;氧化96 h的截面有一连续Al2O3层在氧化物和基体界面形成.     

几种耐热钢在超(超)临界水中抗氧化性能的比较

采用电化学阻抗试验、氧化增重法分析了Super304H、P92、15CrMo钢在554,645℃及24MPa超(超)临界水中氧化44h后的电化学性能和抗氧化性能,并用SEM和XRD对氧化膜的表面形貌及物相组成进行了分析。结果表明:Super304H钢氧化后没有明显的质量变化,P92钢和15CrMo钢有氧化增重现象,但氧化增重的差异不明显;Super304H钢表面由细小的针状或颗粒状的含铁和铬的氧化物组成,P92钢和15CrMo钢表面为相对较大的颗粒状Fe3O4组成;554℃超临界水氧化后在NaCl溶液中的阻抗由小至大顺序为P92、Super304H、15CrMo钢,随温度升高阻抗增大;电化学阻抗可在短时氧化条件下有效分析耐热钢的抗氧化特性。     

单晶高温合金溅射NiCrAlY微晶涂层的循环氧化行为

采用磁控溅射方法在镍基单晶高温合金基体上制备日 粒平均尺寸小于100nm的Ni-30Cr-12Al-0.3Y微晶涂层;并对基体和涂层在1050℃下的抗循环氧化行为进行了研究。结果表明：基体经过2次循环后,氧化膜即出现剥落,基体表面形成的氧化物主要是NiO和Cr2O3,保护性能不及Al2O3;而微晶涂层在循环氧化过程中形成Al2O3保护膜,经过100次循环后Al2O3氧化膜仍完好无损,真空热处理提高了涂层氧化膜形成的均匀性。     

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.     

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....     

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。     

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.