高压过热蒸汽管道失效分析

本文对在540℃、100个大气压条件下使用的高压过热蒸汽管道进行了研究。样品取自运行23年的12CrlMoV过热蒸汽管。由断口分析看出:管子内外表面都存在一个Fe_3O_4氧化层,厚度300μm左右。氧化层与基体交界面之间为沿晶氧化区,厚度为20～40μm。断口呈现沿晶断裂,晶界面上大量分布含有铬的粒状析出物(照片1、2)。再向内是50μm左右厚的含有极少量的沿晶断裂区。内部基体组织珠光体基本消失。使用过的管子碳化物晶格常数明显变小,而且还出现M_2C、MC相。文章还讨论了表面氧化,组织变化和使用寿命等问题。通过计算:φ325壁厚26mm的管子内表承受最大     

深井管道断裂失效分析

某饮用水井在使用 10余天时发生故障 ,位于地下管道 2 30ｍ处末级钢管与法兰焊缝连接处断裂 ,末级法兰及吸水电机掉入水中。本文应用进口直读光谱仪、扫描电子显微镜、金相显微镜等对断裂管道的断口、钢管材质、焊接质量、显微组织进行检测、分析 ,确定其断裂失效的原因。检测结果分析管道断裂位于末级钢管与法兰焊接处 ,断口无明显塑性变形 ,断口中人字纹花样显示断裂系由内向外、多源、脆性断裂。可排除安装、使用不当过载断裂的可能性。将断口切割成 6块 ,分别从截面进行显微组织检测 ,发现在焊缝中存在多条裂纹 ,裂纹较粗、曲折、断续小…     

高压热水泵的密封结构设计分析

目前,我国使用的高压热水泵,其内部结构大多数是采用密封性的设计。但由于密封的方式过多,并且不同方式所表现出来的作用也存在差异性,这就增加了高压热水泵的密封结构设计的难度。本篇文章对该设计做出了相应的研究讨论,并提出了在进行密封设计时加以运用一些辅助系统会有更好的作用效果。     

Reliability test and failure analysis of high power LED packages

A new type application specific light emitting diode (LED) package (ASLP) with freeform polycarbonate lens for street lighting is developed, whose manufacturing processes are compatible with a typical LED packaging process. The reliability test methods and failure criterions from different vendors are reviewed and compared. It is found that test methods and failure criterions are quite different. The rapid reliability assessment standards are urgently needed for the LED industry. 85 ℃/85 RH with 700 mA is used to test our LED modules with three other vendors for 1000 h, showing no visible degradation in optical performance for our modules, with two other vendors showing significant degradation. Some failure analysis methods such as C-SAM, Nano X-ray CT and optical microscope are used for LED packages. Some failure mechanisms such as delaminations and cracks are detected in the LED packages after the accelerated reliability testing. The finite element simulation method is helpful for the failure analysis and design of the reliability of the LED packaging. One example is used to show one currently used module in industry is vulnerable and may not easily pass the harsh thermal cycle testing.     

Reliability test and failure analysis of high power LED packages

A new type application specific light emitting diode(LED) package(ASLP) with freeform polycarbonate lens for street lighting is developed,whose manufacturing processes are compatible with a typical LED packaging process.The reliability test methods and failure criterions from different vendors are reviewed and compared.It is found that test methods and failure criterions are quite different.The rapid reliability assessment standards are urgently needed for the LED industry.85℃/85 RH with 700 mA is used to test our LED modules with three other vendors for 1000 h,showing no visible degradation in optical performance for our modules,with two other vendors showing significant degradation.Some failure analysis methods such as C-SAM,Nano X-ray CT and optical microscope are used for LED packages.Some failure mechanisms such as delaminations and cracks are detected in the LED packages after the accelerated reliability testing.The finite element simulation method is helpful for the failure analysis and design of the reliability of the LED packaging.One example is used to show one currently used module in industry is vulnerable and may not easily pass the harsh thermal cycle testing.     

Recent progress of physical failure analysis of GaN HEMTs

Gallium nitride (GaN)-based high-electron mobility transistors (HEMTs) are widely used in high power and high frequency application fields,due to the outstanding physical and chemical properties of the GaN material.However,GaN HEMTs suffer from degradations and even failures during practical applications,making physical analyses of post-failure devices extremely significant for reliability improvements and further device optimizations.In this paper,common physical characterization techniques for post failure analyses are introduced,several failure mechanisms and corresponding failure phenomena are reviewed and summarized,and finally device optimization methods are discussed.     

分析大功率MOSFET管在调频电视全固态发射机中的应用

无线电领域是发展的重点,而其发展必须要有MOSFET的支持,因为其是取代电子管的最佳器件,无需高压支持,且耗电量不高,完全可以确保电视节目或者其他电台的正常输出。     

薄壁应变筒式光纤光栅压力传感器的研究

设计并制备了一种金属薄壁应变弹性筒式光纤光栅压力传感器,将FBG1和FBG2分别沿着轴向和周向粘贴在该结构内筒外壁上,FBG2用来测量压力,FBG1是温度补偿光栅.通过择优选取不锈钢(Cr18Ni9)材料作为基材,优化结构内筒径与内筒壁厚的比例,测得压强达到40 MPa,压力响应度达到0.033 nm/MPa,与普通的裸光纤光栅压力传感器相比较,增大了测量范嗣,提高厂响应度达11倍.实验结果表明,通过凋整传感器结构的参数,如基材和几何尺寸等,可以使该结构压力传感器满足不同的测量范围和响应度.     

集成电路失效分析新技术

通过实例综述了目前国内集成电路失效分析技术的现状和发展方向。包括：无损失效分析技术、信号寻迹技术、二次效应技术、样品制备技术和背面失效定位技术,为进一步开展这方面的工作提供参考。     

肥大性扁桃体对咽鼓管气压平衡功能的影响

应用丹麦生产的AZ-26型声阻抗仪，对反笔发作的慢性扁桃体炎所致的扁桃体肥大进行咽鼓管气压平衡功能的测定。通过术前、术后鼓室压力曲线测定的对照、了解其影响程度。结果表明：肥大性扁桃体对咽鼓管气压平衡的功能具有一定的影响。大多数属于轻度和中度，一般不诱发鼓室积液。肥大性扁桃体摘除后，咽鼓管的气压平衡功能逐渐恢复正常。因此，对于反复发作的扁桃体炎扁桃体肥大，应早期给予手术治疗，减少或避免其他疾病的产生，有利于患儿的身体健康、生长和发育。     

一种用于标记蓝宝石盘的高压冷冻制样辅助装置

高压冷冻技术(high pressure freezing,HPF)是近年来出现的一种可以更有效保存样品原始结构的制样方法.本文介绍了针对高压冷冻制样过程中,无法区分用于培养细胞的蓝宝石盘正反两面的问题,使用3D打印技术制作模具进行喷涂特殊样式的碳膜标记,从而得以区分蓝宝石盘正反面,提高制样成功率.     

高压冷冻技术及其在植物细胞超微结构中的应用

冷冻固定技术可以将生物组织和细胞内所有结构和成分同时固定。因此避免了因化学渗透固定而引起的各种假象。通常,在常压下冷冻技术仅能使生物样品表面１０～３０μｍ厚度得以充分固定,而高压冷冻技术则能使样品有效固定厚度增加至６００μｍ。尽管植物组织细胞具有特殊的结构－厚壁和含大量水分的液泡,使冷冻固定较为困难,但利用高冷冻技术仍能使２００μｍ厚度的样品得到充分固定,而且能够捕获近似自然状态的细胞超微结构。本