X-Ray Excited Optical Luminescence and Portable Electron Probe Microanalyzer–Cathodoluminescence (EPMA–CL) Analyzers for On-Line and On-Site Analysis of Nonmetallic Inclusions in Steel

Abstract

The potential of the application of an X-ray excited optical luminescence (XEOL) analyzer and portable analyzers, composed of a cathodoluminescence (CL) spectrometer and electron probe microanalyzer (EPMA), to the on-line and on-site analysis of nonmetallic inclusions in steel is investigated as the first step leading to their practical use. MgAl2O4 spinel and Al2O3 particles were identified by capturing the luminescence as a result of irradiating X-rays in air on a model sample containing MgAl2O4 spinel and Al2O3 particles in the size range from 20 to 50 μm. We were able to identify the MgAl2O4 spinel and Al2O3 particles in the same sample using the portable CL spectrometer. In both cases, not all of the particles in the sample were identified because the luminescence intensities of the smaller Al2O3 in particular were too low to detect. These problems could be solved by using an X-ray tube with a higher power and increasing the beam current of the portable CL spectrometer. The portable EPMA distinguished between the MgAl2O4 spinel and Al2O3 particles whose luminescent colors were detected using the portable CL spectrometer. Therefore, XEOL analysis has potential for the on-line analysis of nonmetallic inclusions in steel if we have information on the luminescence colors of the nonmetallic inclusions. In addition, a portable EPMA-CL analyzer would be able to perform on-site analysis of nonmetallic inclusions in steel.

Simple identification of Al2O3 and MgO·Al2O3 spinel inclusions in steel using X‐ray‐excited optical luminescence

“…Therefore, the XEOL analysis is a promising approach for an online analysis of nonmetallic inclusions in steel. In our previous paper, Al 2 O 3 reagent particles emitted blue luminescence . In contrast, we have also reported that Al 2 O 3 inclusions in steels emit red or blue luminescence owing to the difference in the concentrations of impurities in the Al 2 O 3 inclusions, observed by a cathodoluminescence (CL) analysis, where the same phenomenon as that in the XEOL analysis is observed with an incident electron beam instead of an X‐ray.…”

“…In our previous paper, Al 2 O 3 reagent particles emitted blue luminescence. [16] In contrast, we have also reported that Al 2 O 3 inclusions in steels emit red or blue luminescence owing to the difference in the concentrations of impurities in the Al 2 O 3 inclusions, observed by a cathodoluminescence (CL) analysis, [17] where the same phenomenon as that in the XEOL analysis is observed with an incident electron beam instead of an X-ray. Therefore, it is necessary to perform an XEOL analysis for samples prepared under conditions similar to those in the industrial steel production.…”

“…We have recently demonstrated that it is possible to identify Al 2 O 3 and MgO·Al 2 O 3 spinel reagent particles using X‐ray‐excited optical luminescence (XEOL) analysis that is used to obtain images and spectra based on the phenomenon of light emission from materials induced by X‐ray irradiation. XEOL images can be utilized to simultaneously identify the sizes, shapes, and compositions of nonmetallic inclusions in steel.…”

Effect of Reheating and Quenching on the Cathodoluminescence Intensity of Free Lime in Steelmaking Slag

“…The acceleration voltage of the STEM was set to 200 kV. The CL images and spectra were acquired using a custom SEM-CL system, whose details have been previously reported (Imashuku et al, 2017a(Imashuku et al, , 2017b(Imashuku et al, , 2017cImashuku & Wagatsuma, 2018, 2019a, 2019b, 2019c, 2020c, 2020dTsuneda et al, 2019). In brief, the CL images were captured through a quartz viewport attached to the SEM (Mighty-8DXL, TECHNEX, Tokyo, Japan) by a digital mirrorless camera (α7RII, Sony Corp., Tokyo, Japan) equipped with a zoom lens (LZH-10A-05T, Seimitu Wave Inc., Kyoto, Japan).…”

Cathodoluminescence analysis of nonmetallic inclusions of nitrides in steel

“…However, these methods cannot simultaneously identify the composition, size, shape, and amount of inclusions. We have recently demonstrated that capturing cathodoluminescence (CL) images enables MgAl 2 O 4 spinel and Al 2 O 3 inclusions in steels to be distinguished more rapidly than by the conventional method . CL analysis is obtaining images and spectra based on the phenomenon of light emission from materials as a result of electron bombardment and can simultaneously identify the amount, size distribution, shape, and occasionally, composition of non‐metallic inclusions in steel …”