| As a pillar industry of national economy,metallurgical industry has always been an important symbol of national strength and the industrial development level.As modern metallurgical production is becoming more and more large-scale,high-speed and integrated,on-line analysis of smelting process becomes the focus of metallurgical analysis and research,and then,realizing the real-time and closed-loop control of the whole smelting process becomes the development direction of on-line analysis of metallurgy.Component analysis is an indispensable part of metallurgical analysis.Laser induced breakdown spectroscopy(LIBS)is a kind of quantitative analysis technology,which is based on the interaction between laser and material to produce emission spectrum.In recent years,it has been widely used in the field of metallurgical analysis for its advantages of rapid analysis of full elements online and remotely without sample preparation.Temperature is another important parameter to be controlled in metallurgical process.It affects the material equilibrium state and thermodynamic process of smelting process directly,and affects the quality and performance of final products.Infrared thermometry(IR thermometry)is a kind of non-contact thermometry technology based on Planck’s law of blackbody radiation,which is especially suitable for online temperature monitoring in the field of metallurgy.This dissertation is devoted to the research of the hyphenated techniques of LIBS and infrared thermometry,basing on the same optical system to realize on-line measurement of element composition and smelting temperature in metallurgy process,and provides theoretical basis and development experience for industry practice of on-line metallurgy analysis.The specific contents of this dissertation are as follows:1.Based on the same the optical system,an experimental LIBS-IR thermometry system was designed and built,and a radiation efficiency calibration system was built to calibrate the experimenta system.Via the experimental system,the composition and temperature of a series of standard molten steel samples were measured in real time.The relative error of components measurement was less than 10%,the relative error of temperature measurement was less than 1%.The obtained results demonstrated the practicability of LIBS-IR thermometry.Then,we applid the experimental system for the study of the corrosion process of molten metal under a fixed smelting temperature(1000℃).The concentration variation of Fe,Mn and Cr dissolved in liquid aluminum were measured by absolute intensity methord.And the off-line measurement methods were compared with LIBS-IR thermometry.This application fully demonstrated the advantages of LIBS-IR thermometry for online measurement.2.A LIBS-IR thermometry probe based on Schwarzschild telescope was constructed for industrial application.With optical design,structure optimization and thermal simulation,a contact-type probe was constructed for the smelting furnace,and the probe was applicable at a smelting temperature of 1200 ℃.Then,we calibrated the probe with a startand light source to obtain the original infrared radiation spectrum and the original radiation spectrum of the plasma,which contributed to the improvement of measurement accuracy.For industrial application,a supporting platform and a control software were developed to realize an automatic measurement.3.The constructed probe was applied in the plant of aluminum casting,and the components and the smelting temperature of the molten aluminum alloy were obtained online.The relative error of composition measurement obtained by internal standard method was lower that 6.25%.And the measurement precision obtained by CF-LIBS was comparable with that obtained by internal standard method.The relative error of temperature measurement was lower that 7.2%,with a RSD of 0.8%.The obtained measurement results generally meet the needs of industrial measurement,which provided practical experiment for industrial application of LIBS-IR thermometry. |
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