Determination Of Iron Content In The Coating Of Alloying Galvanized Sheet By Laser-Induced Breakdown Spectroscopy

The iron content in the coating is very important in the production of the alloy coated steel plate,it is very helpful in estimating the properties of the coating material.The common detection techniques,such as X-ray fluorescence spectroscopy,Inductively coupled plasma atomic emission spectrometry,chromatographic analysis and Chemical experiment,need strict sample preparation processes that consume a lot of analysis time.The information of the production processes,therefore,cannot be obtained in time,which delays the quality control,induces a great waste of energy and materials,destroys the protective effect of coating.Laser-induced breakdown spectroscopy(LIBS)is a new spectroanalysis technique,and is appealing for its good prospects of the in-situ,on-line,quick and long-distance applications.The purpose of this dissertation is to aim at the main body analysis of the chemical compositions of multielemental alloys,improve the quantitative analysis performance,and quicken the on-line applications of LIBS.The contents of the dissertation include the design of the LIBS experimental systems simulating the frame of the on-line analytical equipment,optimization of some key system parameters,experimental data acquisition and processing,Quantitative analysis of iron content in coating.The specific contents can be summarized as follows:(1)This paper analyzed and introduced the main methods of measuring the iron content in the coating of alloying galvanized sheet.The application status and development of laser induced breakdown spectroscopy in the analysis of coatings are summarized,and the problems are evaluated.(2)The theory of laser induced breakdown spectroscopy were reviewed,including the mechanism of plasma and the basic model,introduced the basic knowledge of the qualitative and quantitative analysis of substances,studied the commonly components of LIBS experimental system.The LIBS experimental system is designed for the analysis of the coating of alloying galvanized sheet.The system adopts the electric three dimensional translation platform to ensure the striking difference.The performance,parameters and indexes of the experimental equipment were analyzed,and the setting up steps of the experimental device were summarized,which laid the foundation for the experiment.(3)Optimized the key parameters of the system,studied the influence of laser energy density,and select the appropriate energy density.The depth of the impact of the laser is deep enough,and the area of the ablation crater is small enough.The characteristics of the depth distribution of the elements in the alloy galvanized sheet are studied by analyzing the spectral intensity of the iron and zinc in the coating.In the coating,the more close to the coating surface,the less iron content,the more zinc content.The data acquisition and processing methods were optimized.(4)The quantitative analysis methods and their performance indexes are introduced,then using the standard linear calibration curve method,internal standard method to calibrate the content in the coating of alloying galvanized,and the iron content was predicted,the analytical performance of the different methods were compared systematically.