Improving Thermal Shock Resistance of Long Nozzle by Adding Aluminum Hydroxide into Lining Material: Microstructure, Properties of Lining Material, and Mathematical Model for Maximum Thermal Stress of Long Nozzle Neck Portion
TIAN Xiangyu1,2, SHANG Xinlian1, LI Hongxia1, WANG Xinfu1, LIU Guoqi1, YANG Wengang1,YU Jianbin1
1 State Key Laboratory of Advanced Refractories, Sinosteel Luoyang Institute of Refractories Research Co. Ltd., Luoyang 471039; 2 AVIC Manufacturing Technology Institute, Beijing 100024
Abstract: The purpose of the present work is to promote thermal shock resistance of long nozzles by adding aluminum hydroxide into the lining mate-rial. A series of long nozzle lining materials differing in α-Al2O3 powder content and dried Al(OH)3 content were prepared, by using Al2O3 hollow spheres and sintered corundum as main raw materials, and through the processes of preblending, forming and heat treatment (at 950 ℃). Microstructure analyses based on XRD and SEM confirmed the same phase composition of the lining materials despite the variation of Al-(OH)3 content, as well as a discontinuous distribution of Al(OH)3 within the material. The mechanical and thermal properties tests showed that, the increase of Al(OH)3 could lead to the declines of bulk density (higher pore ratio), room temperature flexural strength, elastic modulus, and thermal conductivity and expansion coefficient, with respect to the lining materials. Furthermore, by applying finite element analysis and linear regression, we established a mathematical model for the maximum thermal stress of the neck portion of long nozzle (σmax), in which σmax exhibited a ‘cross linear relationship’ with thermal expansion coefficient (α), elastic modulus (E) and thermal conductivity (λ) of lining material. Then combined the obtained mechanical & thermal properties and the proposed model, and as a result the inverse correlation between Al(OH)3 content and σmax (i.e. positive correlation between Al(OH)3 content and thermal shock resistance) could be revealed. Finally we fabricated long nozzles with the Al2O3-Al(OH)3 lining and the ordinary silica lining, respectively, and compared their practical operation performances. The erosion rate results of the former and the latter were 0.032 mm/min and 0.049 mm/min, which supported the proposed mathematical model.
田响宇, 尚心莲, 李红霞, 王新福, 刘国齐, 杨文刚, 于建宾. 在内衬材料中添加氢氧化铝提升长水口的抗热震性:内衬材料显微组织与性能及长水口颈部最大热应力数学模型[J]. 材料导报, 2019, 33(4): 611-616.
TIAN Xiangyu, SHANG Xinlian, LI Hongxia, WANG Xinfu, LIU Guoqi, YANG Wengang, YU Jianbin. Improving Thermal Shock Resistance of Long Nozzle by Adding Aluminum Hydroxide into Lining Material: Microstructure, Properties of Lining Material, and Mathematical Model for Maximum Thermal Stress of Long Nozzle Neck Portion. Materials Reports, 2019, 33(4): 611-616.