热处理温度对硬铬镀层性能的影响

研究了热处理温度对硬铬镀层性能的影响.发现经过200～300℃1*#h热处理,镀层硬度明显提高,耐磨性得到改善,但硬度和耐磨性的最优点对应不同的热处理温度.对镀层XPS分析表明,热处理过的镀层中有有机碳化物析出.对镀层的EDAX分析表明,热处理使镀层表面氧含量增高,但对镀层微裂纹数量和宽度没有明显影响.对镀层的XRD实验结果表明,热处理后镀层的晶体结构未发生改变.     

纳米TiC粉末改性钎料钎焊CBN磨粒的结合界面和磨损特性

采用了Ag-Cu-Ti 合金和纳米 TiC 粉末组成的新型复合钎料钎焊立方氮化硼(CBN)磨粒和工具基体,运用了三维体式显微镜和扫描电镜,研究了CBN磨粒与改性钎料之间的结合体系,包括界面微结构和反应产物,并进行了钎焊磨粒耐磨性试验.试验结果表明:加入的纳米TiC粉末均匀分布在钎料层内,细化了Ag-Cu-Ti合金钎料层的显微组织,有效控制了CBN磨粒与钎料的剧烈反应;磨粒表面化合物均匀致密,确保了CBN磨粒、纳米改性钎料和基体之间的结合强度;钎焊CBN磨粒的磨损形式以磨耗磨损为主,后期出现微小破碎,无磨粒脱落.     

基于光谱分析技术的磨损故障监测

采用转盘电极式原子发射光谱分析技术,监测某型燃气轮机传动润滑系统磨损状况的发展变化趋势,及时诊断早期磨损故障.为确保光谱分析技术监测的准确性,着重研究了环境温度波动、标准曲线细化、样品黏度以及磨损颗粒尺寸等主要因素对测量结果的影响,并简要阐述了光谱分析技术的基本原理.经大量研究试验表明:光谱分析技术能够提前预报燃气轮机传动润滑系统可能发生的磨损故障,是油液状态监控的1种有效手段.     

基于神经网络规则提取的航空发动机磨损故障诊断知识获取

针对神经网络智能诊断与专家系统中知识难于理解和诊断解释能力差等问题,研究了一种新的基于功能性观点的神经网络规则提取方法,介绍了方法流程及关键算法.并用UCI(加利福尼亚大学埃尔文分校)机器学习数据对方法进行了分析和验证.最后,将方法应用于实际航空发动机磨损故障诊断中,采集了某型航空发动机实测油样光谱数据237个样本,利用神经网络规则提取方法提取了发动机磨损故障诊断知识规则,并对其进行了解释,结果表明了方法的正确有效性.      

磨粒分析技术及其在发动机故障诊断中的应用

基于显微形态学方法的磨损微粒显微分析技术是近年来出现的解决发动机磨损故障诊断问题的新方法之一。应用形态学分析方法建立一套磨粒显微特征描述体系提取磨粒特征信息,作为磨粒识别的信息基础,可以准确地完成磨粒自动识别。基于发动机润滑系统磨粒分析的结果和颗粒摩擦学理论,比较准确地评估出发动机接触磨损部件的磨损状态,进而诊断或预测此类磨损故障;另外,此项分析诊断技术在发动机气路磨损故障诊断中也具有潜在的应用前景。      

Laser-induced oxidation assisted micro milling of high aspect ratio microgroove on WC-Co cemented carbide

Severe tool wear and poor surface quality are the main problems during micro machining of cemented carbide. In this work, an innovative hybrid process of laser-induced oxidation assisted micro milling (LOMM) was proposed to solve the problems. A nanosecond laser was utilized to induce oxidation of the WC-20%Co material, producing loose oxide which was easy to remove. The micro machinability of the material was improved by laser-induced oxidation. The oxidation mechanisms of cemented carbide were studied. A microgroove with a depth of 2.5 mm and aspect ratio of 5 was fabricated successfully. The milling force, surface quality and tool wear mechanisms were investigated. For comparison, a microgroove was also fabricated with conventional micro milling (COMM) using identical milling parameters. Results revealed that in LOMM the milling force and tool wear rate were extremely low during removing the oxide. The machined surface quality and dimensional accuracy achieved by LOMM were superior to those obtained by COMM. The surface roughness S_a of the microgroove bottom reached 88 nm in LOMM, while the cross-sectional geometry of the microgroove was a trapezoid. Perpendicularity of the microgroove sidewall machined by LOMM was better than that by COMM. The tool wear forms in LOMM were coating spalling and slight tool nose breakage. Compared with COMM, the tool life in LOMM was prolonged significantly. It indicates that the proposed hybrid process is an effective and efficient way to fabricate high aspect ratio micro-features with high dimensional accuracy.     

基于接触状态的叶冠预扭设计

针对某工程的实际问题,建立了叶片三维分析模型,应用谐波平衡法和时频转换法,分析了叶冠结构参数与安装状态下叶冠力学性能的关系,总结了叶冠几何参数对接触状态的影响规律;就叶冠接触状态与叶冠磨损之间的关系进行了讨论;基于接触状态的设计理论,提出了叶冠预扭设计基本思想和工程方法.     

Morphology and Frictional Characteristics Under Electrical Currents of Al203/Cu Composites Prepared by Internal Oxidation

Two AhO3/Cu composites containing 0.24 wt.% A1203 and 0.60 wt.% A1203 separately are prepared by internal oxidation.Effectsof sliding speed and pressure on the fi-ictional characteristics of the composites and copper against brass are investigated and compared.The changes in morphology of the sliding surface and subsurface are examined with scanning electron microscope (SEM) and energy dispersive X-ray spectrum (EDS).The results show that the wear resistance of the AI203/Cu composites is superior to that of copperunder the same conditions.Under a given electrical current,the wear rate of AI203/Cu composites decreases as the AleO3-content increases.However,the wear rates of the Al203/Cu composites and copper increase as the sliding speed and pressure increase under drysliding condition.The main wear mechanisms for AleO3/Cu composites are of abrasion and adhesion;for copper,it is adhesion,although wear by oxidation and electrical erosion can also be observed as the speed and pressure rise.     

金属基高功率CO2激光沉积超硬Si3N4膜层性能研究

本文采用高功率ＣＯ２激光在金属基材汽相沉积出厚度－３０μｍ标准化学计量配比、平均硬度达２２００ＨＫ的ａ－Ｓｉ３Ｎ４膜层，与基材有良好的结合界面，实验分析表明所沉积膜具有超硬和良好的耐磨抗蚀等性能。     

磨粒监测与分析系统在航空发动机状态监控中的应用(英文)

磨损颗粒是研究机器磨损状态时最直接、最重要的信息元 ,通过对滑油中的磨粒进行监测与分析以判断机械设备的磨损状况 ,可以监测并预防机械设备的磨损故障。本文介绍的磨粒监测与分析系统 ( DMAS)具有制谱简单、自动化程度高、能及时准确预报及诊断机器的各种磨损类故障等特点 ,可以有效地保障机器安全可靠地运行。本文详细地阐述了这套系统的基本原理、软硬件组成 ,以及在航空发动机磨损状态监测中的应用