Research On The Effect Of Environmental Factors On The Composition Of Alloys Detected By DP-LIBS

Laser Induced Breakdown Spectroscopy?LIBS?as a new method of material element analysis has developed rapidly and has been paid more and more attention by people.The principle is to use a high-energy-density pulsed laser beam to bombard the surface of the sample to generate a plasma,and then analyze the plasma spectrum to qualitatively and quantitatively analyze the composition of matter.However,the interaction between laser and matter is an extremely complex nonlinear process.LIBS detection technology still has many deficiencies,such as low spectral intensity and signal-to-back ratio,unsatisfactory spectral quality,high detection limit,low precision and repeatability of quantitative analysis,These greatly limits its application in real life.In order to increase the LIBS spectral line intensity and signal-background ratio,reduce the detection limit and improve the precision and reliability of quantitative analysis,this paper discussed the influence of two environmental factors on the DP-LIBS detection of metal plasma spectrum,which are gas atmosphere and sample temperature.The paper consists of six chapters.The first chapter gives a brief overview of LIBS,introduces the purpose and significance of this study as well as the research status at home and abroad,and finally gives a brief overview of the content and structure of the paper.The second chapter introduces laser-induced plasma characteristics and spectral quantitative analysis methods.It focuses on the diagnosis of plasma plasma characteristic parameters and the commonly used quantitative analysis methods.The third and fourth chapters discuss the effect of Ar,Air,and N₂ on the plasma characteristics and quantitative analysis of alloy steels by DP-LIBS based on the measured spectral data.The experimental results show that under the Ar environment,by increasing the electron temperature and electron density of the plasma,the excitation conditions of the laser-induced sample particles are effectively improved,and the spectral line intensity and the signal-background ratio are increased.At the same time,the R² of the calibration curve is improved,and the RSD and the LOD are reduced.The precision and reliability of quantitative analysis are effectively improved.The fifth chapter discusses the influence of sample temperature on DP-LIBS detection of metal Al plasma characteristics,and measures the change of characteristic parameters such as plasma electron temperature and electron density during the temperature increase of the sample.the experimental results show that the morphology of plasma plume collected by the CCD camera can be used as a direct reflection of the change of its characteristic parameters;with the sample temperature rise,the spectral line intensity,FWHM,electron temperature and electron density are increased to saturation;For ionic and atomic lines,the sample temperature has different enhancement effect on spectrum intensity and the FWHM.The sixth chapter summarizes the experimental results of this thesis,and puts forward some opinions and suggestions on the later research direction in this field.