Influence of High-Temperature Liquid on Phase Composition and Morphology of Carbothermal Reduction-Nitridation Products from Coal Gasification Slag

• Published in: Materials Vol. 13; no. 6; p. 1346
• Main Authors: Yuan, Hudie, Yin, Hongfeng, Tang, Yun, Shuai, Hang, Xin, Yalou, Pu, Xilou
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 16-03-2020; MDPI
• Subjects: Aspect ratio; ca-α-sialon; Carbon black; carbothermal reduction–nitridation; Coal gasification; coal gasification slag; Experiments; Grain growth; High temperature; high-temperature liquid; Liquid phases; Morphology; Nitrogen; Phase composition; Phase transitions; Quantitative analysis; Reduction; Slag; Temperature; Viscosity; carbothermal reduction–nitridation; high-temperature liquid; Ca-α-SiAlON; coal gasification slag
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma13061346

In this paper, the products using three kinds of coal gasification slags as starting materials were obtained via carbothermal reduction-nitridation at 1450 °C. The effects of high-temperature liquid on the phase composition and morphology of the samples were investigated by XRD and SEM, while the content of high-temperature liquid was calculated by the computer software package FactSage. The results show that: (1) the existence of high-temperature liquid phase is beneficial to the formation and growth of Ca-α-SiAlON phase; (2) The formation of long-columnar Ca-α-SiAlON were greatly affected by the content and viscosity of liquid phase, which is in non-linear relationship with aspect ratios of Ca-α-SiAlON. Among the three kinds of slags, the HT slag with relatively high liquid phase content and the lowest viscosity is the most favorable to the growth of elongated Ca-α-SiAlON grain; the aspect ratio of the formed Ca-α-SiAlON is the largest; Compared to the SH slag with the highest liquid phase content and viscosity, Ca-α-SiAlON prepared from TE slag possesses the smallest aspect ratio, which exhibits equiaxed grain morphology.