Application of Raman Spectroscopy for Characterizing Synthetic Non-Metallic Inclusions Consisting of Calcium Sulphide and Oxides

Abstract

The presence of non-metallic inclusions (NMI) such as sulphides and oxides may be detrimental to the control of the steel casting process and product quality. The need for their identification and characterization is, therefore, urgent. This study uses time-gated Raman spectroscopy for the characterization of synthetic duplex oxide-sulphide phases that contain CaS and the oxide phases of Al2O3, CA, C12A7, C3A, and MgO·Al2O3 (MA). Binary phase samples of CaS–MA, C3A–CaS, C12A7–CaS, Al2O3–CaS, and MA–CaS were prepared with varying phase contents. The relative intensities of the Raman peaks were used to estimate the samples’ phase content. For a quantitative estimation, linear regression calibration models were used to evaluate the change in phase content in the samples. The most suitable Raman peak ratios had mean absolute error (MAE) values ranging from 3 to 7 wt. % for the external validation error, and coefficients of determination (R2) values between 0.94 and 0.98. This study demonstrated the use of Raman spectroscopy for the characterization of the calcium sulphide, magnesium aluminate spinel, Al2O3, and calcium aluminate phases of CA, C3A, and C12A7 in a duplex oxide-sulphide system, and it offers potential for inclusion characterization in steel.

Understanding the Adsorption and Desorption of Sitagliptin Phosphate Monohydrate on SS2343, Glass, and PTFE Using QCM-D and Raman Spectroscopy

“…With the preliminary result from QCM-D, Raman analysis was performed to understand the molecular interaction, structural change, and concentration of SIT on SS2343, glass, and PTFE surfaces. Raman bond vibrations revealed spectral features allowing the characterization and understanding of chemical interaction . Chemical environment changes would lead to peak position changes.…”

“…Raman bond vibrations revealed spectral features allowing the characterization and understanding of chemical interaction. 28 Chemical environment changes would lead to peak position changes. Furthermore, there is a direct correlation between the Raman peak area and concentration, allowing the quantification of SIT adsorption across the different surfaces.…”

Quantification of Synthetic Nonmetallic Inclusion Multiphase Mixtures from a CaO–Al2O3–MgO–CaS System Using Raman Spectroscopy

“…Furthermore, Jing et al [21] have shown that the route of inclusion modification and also the calcium content in the steel melt might affect the final inclusion composition. However, previous studies concerning the application of Raman spectroscopy for synthetic, [14,17,19,23] or steel samples [20] and nonmetallic inclusion studies have been limited to characterizing only the binary system between (CaO-Al 2 O 3 ) and the (CaS, Al 2 O 3 or MgAl 2 O 4 ) or MgO-CaO-Al 2 O 3 systems. Consequently, further studies regarding the use of Raman spectroscopy for characterizing a mixture of phases found in CaO-Al 2 O 3 -CaS and CaO-Al 2 O 3 -MgO-CaS systems will contribute to expanding the potential use of this technique for nonmetallic inclusions analysis.…”

“…The utilization of Raman spectroscopy performs better and requires less effort and a shorter time for the sample preparation and acquisition and analysis of the measurement results. In addition, calcium aluminate phases, [14][15][16] magnesium aluminate spinel, [17] and some sulfides such as CaS [18,19] have been demonstrated to be Raman active. Furthermore, Li and Hihara [20] have used Raman spectroscopy techniques to characterize some calcium aluminate inclusion phases such as CA2 and CA in steel samples.…”

“…The present authors previously conducted studies concerning the use of Raman spectroscopy that were focused on characterizing calcium-aluminate (CaO-Al 2 O 3 ) phases around the liquidus region in the CaO-Al 2 O 3 binary system, [14] as well as in the magnesium aluminate spinel (MgO.Al 2 O 3 )-calcium aluminate binary system, [17] and also for duplex oxide-sulfide synthetic inclusions. [19] It has been suggested [21,22] that inclusions could occur as a multicomponent system consisting of CaO-Al 2 O 3 (such as CA, C12A7, and C3A), CaS, and MgAl 2 O 4 . Figure 1 shows our most recent studies [14,17,19,23] conducted using Raman spectroscopy for characterizing the synthetic inclusions and this current study and also shows inclusion classification conducted by Thunman and Sichen.…”