The Color Change of Natural Green Sapphires by Heat Treatment

Mungchamnankit, Araya; Kittiauchawal, T.; Kaewkhao, J.; Limsuwan, Pichet

doi:10.1016/j.proeng.2012.02.037

Cited by 6 publications

(2 citation statements)

References 3 publications

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“…Oxygen presented in each formed zone. Specifically, Fe and Al and other metallic elements found in the concrete influence the formation of a different color when exposed to high temperatures found in cement-based material 34 , 41 . Thus, the colored surface forming inside the glassy layer is due to the presence of various metallic oxides.…”

Section: Resultsmentioning

confidence: 99%

An experimental investigation of laser scabbling on cement-based materials using nanosecond fiber laser

Huynh

Mondal

Lee

2022

Sci Rep

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In this study, the influence of a pulsed fiber laser of 250 W power with a spot size of 40 µm was successfully analyzed during scabbling of six types of cement mortar and three types of ultra-high-performance concrete (UHPC). Confocal microscopy on the surface of the scabbled samples elucidated the formation of three distinct zones: glassy layer (GL), partially melted zone (PMZ), and heat-affected zone (HAZ) with unique morphological appearances. The glassy layer exhibited bubble formation, whereas cracks were spotted alongside the scabbled area. The difference in scabbling depth between the beginning and end of the process was revealed by using 3D topography images. Moreover, the development of pores and the changes in the microstructure of each zone were observed by using scanning electron microscopy (SEM). Further energy dispersive X-ray (EDX) analysis also revealed significant changes in the percentage of silicon and calcium inside the glassy layer and non-processed zone (NPZ).

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Section: Resultsmentioning

confidence: 99%

An experimental investigation of laser scabbling on cement-based materials using nanosecond fiber laser

Huynh

Mondal

Lee

2022

Sci Rep

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“…One explanation for this phenomenon could be the presence of metal transition ions in oxidation states, especially ferric ions in the Al 3+ and Fe 2+ oxidation states. At high temperatures, the Al 3+ and Fe 2+ exposed green and blue, respectively [17]. Furthermore, Wignarajah et al [18] reported that the presence of metallic oxides in cement samples contributed to color changes on the processed zone impacted by the laser.…”

Section: Morphological Analysismentioning

confidence: 99%

The Effect of Silica Sand Proportion in Laser Scabbling Process on Cement Mortar

Huynh

Seo

Lee

2021

Metals

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Cement mortar composite has a wide range of applications on construction sites, including masonry, plastering and concrete repair. In construction sites, scabbling process is a method to remove from a few millimeters to several centimeters of defect concrete surfaces. As a result, it is essential to investigate the scabbling characteristics for cement mortar with different silica sand proportion in laser scabbling process. In this study, 5 types of cement mortar with different silica sand proportions in mixing were fabricated and scabbled by using a high-density power laser beam. The effects of silica sand proportion in color changing and penetration depth of the samples after laser scabbling process were studied. Furthermore, the generation of micro-cracks and pores were observed by using scanning electron microscopy (SEM). In addition, chemical composition changes between processed zone and non-processed zone were also evaluated by Energy Dispersive X-ray (EDX) analysis. The results of this study are expected to provide valuable knowledge in understanding of the laser scabbling process for cement-based materials.

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