含磷极压抗磨剂抗微点蚀性能评价和机理分析

目的 评价三种含磷极压抗磨剂的抗微点性能并分析其作用机理。方法 使用MPR模拟微点蚀试验机考察三种含磷极压抗磨剂（磷型P-1、硫磷型P-2、分散型P-3）的抗微点蚀性能。使用四球试验机、铜片腐蚀试验仪、烘箱、油膜厚度测试仪等，评价添加剂的摩擦、抗腐蚀、抗氧化性能及油膜形成能力，分析添加剂抗微点蚀性能与上述性能之间的关系。借助SEM测试分析不同添加剂的抗微点蚀机理。结果 添加P-3的润滑油GO-3的综合性能最好，GO-3具有良好的抗微点蚀性能，9 h MPR试验的辊子轨道宽度变化率为35.87%。GO-3具有良好的极压抗磨减摩性能，四球机试验测得其最大无卡咬负荷为1441.6 N，磨斑直径为0.38 mm，在试验载荷大于294 N时，其摩擦系数最低。GO-3的抗腐蚀性能良好，铜片腐蚀试验级别为1b。GO-3的氧化腐蚀性低，烘箱氧化试验中钢片评分为1分，且无油泥产生。GO-3的油膜形成能力强，60~120 ℃时弹性流体润滑油膜的厚度为371.2~153.6 nm。结论 分散型磷氮极压抗磨剂P-3化学活性适中，可以避免在摩擦表面发生严重腐蚀或剧烈摩擦化学反应，具有良好的承载、减摩、抗磨和抗微点蚀性能。     

水性环氧硅溶胶复合防腐涂料的制备及其性能

以水性环氧树脂乳液和水性硅溶胶作为成膜基料,添加防锈颜填料,制备了一种有机-无机水性复合防腐涂料。研究了防腐涂料的腐蚀速率以及水性硅溶胶用量对涂层在不同腐蚀介质中的耐蚀性,及其表干时间、实干时间、硬度、附着力和耐盐雾性的影响,通过电化学方法确定了涂层的最佳厚度。结果表明:当防闪锈剂添加量为1%(w)、颜基比为20%(w)、水性硅溶胶的质量占水性环氧树脂质量的15%、漆膜厚度为180μm时,所制复合水性防腐涂料具备良好的耐水、耐碱、耐盐雾性。     

基于双向耦合的东安513型发动机整机多物理场研究

以东安513型汽油发动机整机为例,基于ANSYS有限元分析软件对其进行流体场、瞬态温度场以及瞬态结构场的多物理场双向耦合研究,实现了对发动机实际工况下的有限元分析。研究了发动机整机在实际工况下的受力以及密封情况,并对现有发动机组合结构存在的密封缺陷进行优化调整。文中详细阐述了在分析过程中涉及到的关键技术和要点,并最终获得了发动机整机实际工作状态下的多个结果云图。根据分析结果云图可以发现,发动机在热载荷、螺栓预紧力以及爆破压力的共同影响下,会使整机发生一定的形变,这种变形会影响其工作状况下的密封性能。通过对分析结果的研究,最终选择调整螺栓预紧力的大小和分布来提高发动机密封性能。     

云制造平台资源需求的高效匹配策略研究

为快速、精确地从云制造平台资源池中搜索到满足用户需求的资源,实现资源与需求的高效匹配,提出了一种资源需求高效匹配策略。首先,建立了资源与需求的形式化描述模型,在此基础上,采用改进的K-means聚类算法按基本信息进行聚类,对云服务池中的资源进行预处理,形成多个资源簇;其次,计算用户需求与各资源簇聚类中心基本信息的相似度,确立备选资源簇;最后,再分别从资源的状态信息、功能信息和服务信息3个方面对备选资源簇中的备选资源进行筛选匹配。实例分析和研究结果表明:与已有的匹配方法相比,该方法在保持较高匹配精度的同时具有更高的匹配效率。     

地质统计学反演在薄煤层预测中的应用

曙光煤矿煤层多为薄煤层,利用地震数据常规反演技术预测开采区域煤层厚度的分辨能力有限,远低于煤层开采的需要。引入基于MCMC算法的地质统计学反演技术对曙光煤矿采区内薄煤层进行厚度预测。预测结果与常规解释结果进行对比,并利用已有钻孔资料进行验证,发现该方法的分辨率可达到1 m,对煤层厚度、煤中夹矸厚度的预测误差分别控制在0.5、0.1 m以内。有效解决了曙光煤矿薄煤层预测问题。     

基于变权与正态云理论的煤矿安全评价及应用

为准确对煤矿安全状态作出客观评价,综合考虑评估过程中指标的模糊性和状态随机性,构建基于变权与正态云理论的煤矿安全状态评估模型。结合正态云的数字特征量期望、熵、超熵组成的特定结构函数确定安全状态评判矩阵,得出各评价指标隶属于不同等级的确定度。同时为了避免常权方法确定权重的局限性及突出关键指标对综合评判结果的影响,引入变权理论对常权权重进行处理得到变权。结合实例研究,发现基于变权云理论评判方法对取值较差的指标作用不会被其他指标作用中和,可以有效地反映煤矿的真实安全状态,能够为煤矿的安全风险预测提供了一种技术途径。     

Evolution of internal cracks and residual stress during deposition of TBC

Thermal barrier coating (TBCs) are ceramic coatings that are deposited on metallic substrates to provide high thermal resistance. Residual stress is among the critical factors that affect the performance of TBCs. It evolves during the process of coating deposition and in-service loading. High residual stresses result in significant cracking and premature delamination of the TBC layer. In the present study, a hybrid computational approach is used to predict the evolution of internal cracks and residual stress in TBC. Smooth particle hydrodynamics (SPH) is first used to model the deposition of yttria-stabilized zirconia (YSZ) layer that contains various interfaces and micropores on a steel substrate. Then, three-dimensional (3D) finite element analysis is utilized to predict the evolution of internal cracks and residual stress in the ceramic coating layer. It is found that multiple cracks emerge during the solidification of the coating layer due to the development of high tensile (quenching) stresses. The cracking density is higher at regions near the coating interface. It is also found that compressive (residual) stresses are developed when the deposited coating is cooled to room temperature. The residual stress state is equibiaxial and nonlinear across the thickness/width of the TBC layer. The residual stress profile predicted compares well with that of hole drilling experiments.     

Effect of slot-die configurations on coating gap dependence of maximum and minimum wet thicknesses

The dependence of the maximum and minimum wet thicknesses on the coating gap is derived for the slot-die coating process, under different slot-die configurations. Analytical expressions for the wet thickness and its derivative with respect to the coating gap are obtained using a simple flow model. The results indicate that, as expected, the minimum wet thickness increases linearly with the coating gap; however, the maximum wet thickness demonstrates a counterintuitive trend of decreasing as the coating gap increases, when a specific slot-die configuration is assumed. Moreover, the results are also validated by numerically solving the complete two-dimensional (2D) Navier–Stokes equation.     

Excitonic Properties of Chemically Synthesized 2D Organic–Inorganic Hybrid Perovskite Nanosheets

2D organic–inorganic hybrid perovskites (OIHPs) represent a unique class of materials with a natural quantum‐well structure and quasi‐2D electronic properties. Here, a versatile direct solution‐based synthesis of mono‐ and few‐layer OIHP nanosheets and a systematic study of their electronic structure as a function of the number of monolayers by photoluminescence and absorption spectroscopy are reported. The monolayers of various OIHPs are found to exhibit high electronic quality as evidenced by high quantum yield and negligible Stokes shift. It is shown that the ground exciton peak blueshifts by ≈40 meV when the layer thickness reduces from bulk to monolayer. It is also shown that the exciton binding energy remains effectively unchanged for (C₆H₅(CH₂)₂NH₃)₂PbI₄ with the number of layers. Similar trends are observed for (C₄H₉NH₃)₂PbI₄ in contrast to the previous report. Further, the photoluminescence lifetime is found to decrease with the number of monolayers, indicating the dominant role of surface trap states in nonradiative recombination of the electron–hole pairs.