Effect of La2O3 Addition on Sintering Properties of Magnesia

doi:10.19691/j.cnki.1004-4493.2020.02.005

China's Refractories ›› 2020, Vol. 29 ›› Issue (2): 25-30.DOI: 10.19691/j.cnki.1004-4493.2020.02.005

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Effect of La₂O₃ Addition on Sintering Properties of Magnesia

JIN Endong, YUAN Lei, YU Jingkun^*()

School of Metallurgy, Northeastern University, Shenyang 110819, China

Revised:2021-05-13 Online:2020-06-15 Published:2020-06-15
Contact: YU Jingkun
About author:Jin Endong, born in 1989, graduated and gained his master's degree from University of Science and Technology Liaoning in 2015. Now, he is studying for his doctor's degree at School of Metallurgy, Northeastern University. His research field is high-performance ceramics and refractories.

Abstract

Abstract:

Light burned magnesia powders with different particle sizes were obtained by calcining crystalline magnesite. Sintered magnesia was prepared from the light burned magnesia powders by adding different amounts of La₂O₃. The effect of the La₂O₃ addition on the densification of magnesia was studied. The results show that the densification of sintered magnesia can be promoted both by reducing the particle size of the light burned powder and by adding small amounts of La₂O₃. The effect of the La₂O₃ addition is more significant: the maximum bulk density of the sintered magnesia can reach 3.49 g · cm^-3 and the apparent porosity can be reduced to 0.33%. During sintering, Ca²⁺ from the impurities enters La₂O₃ lattices, causing lattice distortion of La₂O₃ thus promoting the formation of La_4.67(SiO₄)₃O phase and CaLa₄(SiO₄)₃O phase, which fill the pores between the MgO grains and promote the densification of sintered magnesia.

Key words: crystalline magnesite, sintered magnesia, lanthanum oxide, bulk density, apparent porosity

JIN Endong, YUAN Lei, YU Jingkun. Effect of La₂O₃ Addition on Sintering Properties of Magnesia[J]. China's Refractories, 2020, 29(2): 25-30.

Figures/Tables 7

Table 1 Chemical composition of crystalline magnesite /mass%

MgO	SiO₂	Al₂O₃	Fe₂O₃	CaO	I. L.
47.03	0.26	0.06	0.27	0.66	51.72

Fig. 1 Effect of La2O3 addition on densification of sintered magnesia

Fig. 2 XRD patterns of the sintered magnesia with and without La2O3 addition

Fig. 3 Plane scanning analysis of sintered magnesia sample added with La2O3 (a) 1%, (b) 2%

Table 2 EDS results of points in Fig. 3 /atomic%

Points	O	Mg	Si	Ca	La
+1	63.68	0.73	11.29	21.13	0.74
+2	61.76	3.77	7.98	19.55	7.94
+3	67.21	4.98	7.03	13.34	7.44
+4	64.26	0.94	11.53	22.66	0.62

Fig. 4 SEM micrographs of sintered MgO with 1% La2O3 prepared using MgO powder of different particle sizes (a) 11.6 μm, (b) 6.19 μm, (c) 4.85 μm and (d) 3.9 μm

Fig. 5 SEM micrographs of sintered MgO with 2% La2O3 prepared using MgO powder of different particle sizes (a) 11.6 μm, (b) 6.19 μm, (c) 4.85 μm and (d) 3.9 μm

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Effect of La₂O₃ Addition on Sintering Properties of Magnesia

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