Effect of curing humidity on properties of calcium aluminate cement bonded corundum castables

doi:10.3969/j.issn.1001-1935.2021.06.002

Abstract

Abstract:

Corundum based castables were prepared using tabular corundum,α-Al₂O₃ micropowder and calcium aluminate cement as starting materials,curing at 25 ℃ in different humidities for 3 d,drying at 110 ℃ for 24 h,and firing at 800,1 100,1 450 and 1 620 ℃ for 3 h,respectively.The effects of the curing humidity (40%,70%,and 100%) on the properties,the phase composition and the microstructure of the castables were researched.The results show that,as the curing humidity decreases,the demolding strength,the drying strength and the cold modulus of rupture of the samples increase while the apparent porosity and the MOR retention ratio decrease.Moreover,with the reduction of the curing humidity,the hydration degree of the calcium aluminate cement is enhanced,and the aggregates and the matrix are bonded more closely for the castable fired at 1 620 ℃.

Key words: curing humidity, calcium aluminate cement, corundum based castables, strength

摘要：

以板状刚玉、α-Al₂O₃微粉和铝酸钙水泥为原料制备刚玉质浇注料试样。将试样于25 ℃分别在不同的湿度养护3 d,再在110 ℃烘干24 h后分别于800、1 100、1 450和1 620 ℃保温3 h进行热处理,研究了养护湿度(40%、70%和100%)对其性能、物相组成、显微结构的影响。结果表明:随着养护湿度的降低,浇注料的脱模强度、烘干强度及中高温热处理后的常温抗折强度增大,而显气孔率及热震后的抗折强度保持率逐渐降低。另外,随着养护湿度降低,铝酸钙水泥的水化程度更高,1 620 ℃热处理后浇注料的骨料与基质结合更加紧密。

关键词: 养护湿度, 铝酸钙水泥, 刚玉质浇注料, 强度

CLC Number:

TQ175

Li Ye, Lu Xinyu, Liao Guihua, Ding Dafei, Wang Qingfeng, Zhang Ju, Ye Guotian. Effect of curing humidity on properties of calcium aluminate cement bonded corundum castables[J]. Refractories, 2021, 55(6): 466-470.

李烨, 陆昕昱, 廖桂华, 丁达飞, 王青峰, 张举, 叶国田. 养护湿度对铝酸钙水泥结合刚玉质浇注料性能的影响[J]. 耐火材料, 2021, 55(6): 466-470.

Figures/Tables 6

Table 1 Formulation of specimen

原料		w/%
板状刚玉	6~3 mm	25
	3~1 mm	20
	1~0.5 mm	13
	≤0.5 mm	15
	≤0.045 mm	14
活性α-Al₂O₃微粉	d₅₀ = 2.41 μm	8
CAC	Secar 71	5
分散剂(外加)	FS10	0.15
水(外加)		4.0

Fig.1 XRD patterns of castable matrixes cured at different humidities after drying at 110 ℃ and firing at 1 100 and 1 620 ℃

Fig.2 Apparent porosity of samples cured at different humidities and fired at different temperatures

Fig.3 Cold modulus of rupture of samples cured at different humidities after demolding,drying and firing at different temperatures

Fig.4 Effect of curing humidity on the thermal shock resistance of samples fired at 1 620 ℃

Fig.5 SEM of samples cured at different humidities after firing 1 620 ℃

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