【作者】 李旭；

【导师】 陆继东； 唐贤文；

【作者基本信息】 华南理工大学 ， 动力工程（专业学位）， 2016， 硕士

【摘要】 随着我国能源压力的增大,近年来火电厂机组建设向着高蒸汽参数、大装机容量发展,高温高压、冲刷腐蚀恶劣环境的长期运行会导致受热面金属材料的微观结构和机械性能发生改变,逐渐发生老化和损伤,产生裂纹和内伤,大大增加了锅炉的爆管几率。为了保证电站长期高效的稳定运行,必须增加对受热面材料安全的关注。激光诱导击穿光谱(Laser Induced Breakdown Spectroscopy,简称LIBS)是一种新型原子发射光谱分析技术,因其烧蚀量小被视为一种无损检测技术。LIBS技术具有传统金属受热面检测所无法具备的优点——快速、无损检测。本文利用LIBS光谱分析技术的基体效应,讨论元素分布对光谱特性造成的影响,研究LIBS光谱与金相组织形貌的关联性,并利用光谱特性区分不同金相组织形貌的12Cr1MoV样品。论文首先阐述了本文的研究背景和意义,介绍了传统受热面材料失效分析技术的优劣,分析总结了激光诱导击穿光谱的原理及研究现状。实验采用高功率聚焦物镜,调节聚焦光斑尽量小,考察了激光在样品表面作用的光谱数据变化趋势,分析了表面特征光谱分布的不均匀性,对比了不同含量元素的分布差异,结果表明元素含量越低,光谱分布越不均匀,表明单点LIBS光谱数据对样品特性的描述没有代表性。进一步调整实验台架及参数,描述对比了不同金相组织形貌样品表面谱线强度的分布,包括单次光谱数据分布随激光脉冲击打次数的变化以及不同元素的谱线均值分布,分析了平均方式对数据均匀性的影响,得出合理的数据平均处理方式,使LIBS光谱特性能准确描述受热面材料特性。研究不同金相组织形貌12Cr1MoV样品的光谱特性,包括光谱强度、等离子体温度、电子密度以及谱线强度比值,利用光谱特性存在的规律性差异加以区分不同金相组织样品,并将光谱特性与样品硬度关联,预测受热面材料失效状态。最后,对全文研究结论进行总结陈述,提出了论文创新点,并对LIBS应用于元素分布与金相组织形貌关联性的研究工作提出了展望。更多还原

【Abstract】 Recently, with the problem of energy pinch, thermal power plant units develop to be high-capacity and high-parameters. Heating surface is facing a bigger challenge due to the high temperature and high pressure and the erosion-corrosion. The macroscopic properties and microstructure of the metal material will transform because of the long-time serving in the harsh environment. Aging and damage brings cracks, which increases the chance of tube burst. To ensure the stable and safe operation of power plants, we should pay more attention to heating material safety.Laser Induced Breakdown Spectroscopy(LIBS) is a new type atomic emission spectroscopy analysis technique with little ablation, which is deemed as a non-destructive testing technology. Comparing to the traditional testing methods, LIBS has lots of advantages, such as rapid detection, nondestructive testing, etc. In this paper, we take advantages of matrix effects of LIBS to analyze the spectral characteristics, as well as the influence of element distribution and relationship with metallographic structure, and distinguish different 12Cr1 MoV samples with the results.First we introduced the background and significance of the paper and summarized the strengths and weaknesses of traditional testing methods. We took a brief introduction of Laser Induced Breakdown Spectroscopy technology and the research status of the world wild.Secondly, we use MicroSpot focusing lens to get smaller laser spot and observed the variation of spectral characteristics. With the analysis of the nonuniformity of surface spectral intensity distribution and the comparison of different elements, we found the element with less content is more nonuniform. Which indicates there is no connection between single-point LIBS spectroscopic data and the sample characteristic.After that we adjusted the experiment bench and parameter, and compared the intensity distribution of different metallographic structure 12Cr1 MoV samples. After the comparison and analysis of average methods, we obtained the reasonable data average method. In order to make the LIBS spectral characteristics can accurately describe the characteristic of heating surface material.Then we compared the spectral characteristics of different metallographic structure12Cr1 MoV samples, including intensities, plasma temperature, electron concentration and intensity ratio. We used the difference to distinguish the different metallographic structure12Cr1 MoV samples. We associated the spectral characteristics with the hardness of the samples to predict the failure of heating surface material.At last, we made a conclusion of the research and summarize the innovative point of this paper and make a suggestion of the further work.更多还原