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
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摘要
本工作旨在通过向内衬材料中加入氢氧化铝来提升长水口部件的抗热震性。以氧化铝空心球、烧结刚玉为主要原料,配以不同含量的α-Al2O3微粉和干基氢氧化铝,经过预混、成型、热处理,制备了一系列长水口内衬材料。利用XRD和SEM进行显微组织分析,发现氢氧化铝含量的变化并未改变内衬材料的相组成,材料中氢氧化铝呈孤岛状分布。对内衬材料开展了若干力学及热学性能测试,结果表明,随氢氧化铝含量的增加,内衬材料体积密度降低,气孔率升高,常温抗折强度、弹性模量、热导率和热膨胀系数均降低。之后通过有限元法与回归分析,进一步建立了内衬材料热膨胀系数α、弹性模量E、热导率λ三种因素与复合长水口颈部最大热应力σmax之间的数学模型,在该模型中,σmax与α、E和λ之间呈交叉线性关系。结合力学、热学性能测试结果,借助所得数学模型,预测氢氧化铝含量与σmax呈负相关关系(即与长水口抗热震性呈正相关关系)。最后,对比了普通硅质长水口内衬与Al2O3-Al(OH)3体系内衬的实际使用效果,前者与后者的侵蚀速率分别为0. 049 mm/min和0. 032mm/min。
The purpose of the present work is to promote thermal shock resistance of long nozzles by adding aluminum hydroxide into the lining material. A series of long nozzle lining materials differing in α-Al2 O3 powder content and dried Al(OH)3 content were prepared,by using Al2 O3 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 σmaxexhibited 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 Al2 O3-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.
The purpose of the present work is to promote thermal shock resistance of long nozzles by adding aluminum hydroxide into the lining material. A series of long nozzle lining materials differing in α-Al2 O3 powder content and dried Al(OH)3 content were prepared,by using Al2 O3 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 σmaxexhibited 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 Al2 O3-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.
引文
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18 Wang Q H,Li Y B,Li S J,et al.Journal of the Ceramic Society of Japan,2017,125(6),504.
19 Jo Y M,Hutchison R B,Raper J A.Powder Technology,1997,91(1),55.
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21 Zabolotsky A V.Encyclopedia of thermal stresses,Springer,Netherlands,2014.
22zdemir I,Brekelmans W A M,Geers M G D.Journal of the European Ceramic Society,2010,30(7),1585.
2 Liu G Q,Li H X,Yan W G,et al.Advanced Materials Research,2010,129-131,348.
3 Wang Z G,Li N,Kong J Y,et al.Refractories,2004,38(2),118(in Chinese).王志刚,李楠,孔建益,等.耐火材料,2004,38(2),118.
4 Wang J,Wang L L.Continuous Casting,2002(2),41(in Chinese).王军,王立来.连铸,2002(2),41.
5 Liu H M,Li H X,Sui J L,et al.Journal of the Chinese Ceramic Society,2009,37(12),2000(in Chinese).刘辉敏,李红霞,孙加林,等.硅酸盐学报,2009,37(12),2000.
6 Liu H M.Refractories,2015,49(3),186(in Chinese).刘辉敏.耐火材料,2015,49(3),186.
7 Liu G Q,Tu S,Li H X,et al.Refractories,2015,49(Z2),327(in Chinese).刘国齐,涂闪,李红霞,等.耐火材料,2015,49(Z2),327.
8徐叶君,王志中,徐敏.中国专利,CN203695949U,2014.
9毕研虎.中国专利,CN202129424U,2012.
10刘辉敏,郭献军,李建伟,等.中国专利,CN103480833A,2014.
11 Cui X Z,Jia X L,Zhong X C.Refractories,2006,40(5),353(in Chinese).崔香枝,贾晓林,钟香崇.耐火材料,2006,40(5),353.
12 Souza A D V,Arruda C C,Fernandes L,et al.Journal of the European Ceramic Society,2015,35(2),803.
13 Salomo Rafael,Bas Mariana O C Villas,Pandolfelli Victor C.Ceramics International,2011,37(4),1393.
14 Zhenyan Deng,Takayuki Fukasawa,Motohide Ando,et al.Journal of the American Ceramic Society,2001,84(11),2638.
15 Salomo R,Ferreira V L,Oliveira I R D,et al.Journal of the European Ceramic Society,2016,36(16),4225.
16 Zhenyan Deng,Takayuki Fukasawa,Motohide Ando,et al.Journal of the American Ceramic Society,2001,84(3),485.
17 Salomo Rafael,Brandi Jamile.Ceramics International,2013,39(7),7751.
18 Wang Q H,Li Y B,Li S J,et al.Journal of the Ceramic Society of Japan,2017,125(6),504.
19 Jo Y M,Hutchison R B,Raper J A.Powder Technology,1997,91(1),55.
20 Salomo Rafael,Adriane D M Souza,Leandro Fernandes,et al.American Ceramic Society Bulletin,2013,92(7),22.
21 Zabolotsky A V.Encyclopedia of thermal stresses,Springer,Netherlands,2014.
22zdemir I,Brekelmans W A M,Geers M G D.Journal of the European Ceramic Society,2010,30(7),1585.