Porous Alumina Ceramic Prepared by HEMA-TBA Gelcasting System

doi:10.15541/jim20160550

Abstract

Abstract:

Porous alumina ceramics with high porosity and high strength were successfully fabricated by HEMA-TBA gelcasting system. Fabrication processes of slurries and ceramic were studied, effects of solid loading and dispersant contents on viscosity and stability of slurries, effects of drying and monomer content on green bodies, and effects of solid loading and sintering temperature on sintered bodies were investigated. The results show that optimum addition of citric acid of 2wt% decreases the viscosity and increases the stability of slurry. The viscosity and stability of the slurries increase with the increase of the solid loading of slurries. Green bodies with low solid loading can be dried with relatively small shrinkage less than 10% and its drying time is also relatively shorter than water based gelcasting system. The amount of monomer has great influence on green body and the strength of green body achieve high value at monomer content of 25%. By choosing the solid loading of slurries and sintering temperatures, ceramic microstructures and the porosity ranging from 40%-65% can be effectively controlled and strength of porous ceramics changes in the range of 5.7-91.2 MPa.

Key words: porous ceramic, gelcasting, slurry, rheological properties

CLC Number:

TQ174

XIE Yu-Zhou, PENG Chao-Qun, WANG Xiao-Feng, WANG Ri-Chu, LUO Feng. Porous Alumina Ceramic Prepared by HEMA-TBA Gelcasting System[J]. Journal of Inorganic Materials, 2017, 32(7): 731-738.

Figures/Tables 14

Table 1 Manufacture and purity of the raw materials

Name	Abbreviation	Purity	Manufacture
Tert-butanol	TBA	AR	Shanghai Chemical Reagent Co.
2-hydroxyethyl methacrylate	HEMA	AR	Shanghai Chemical Reagent Co.
Methylene-bis-acrylamide	MBAM	AR	Shanghai Chemical Reagent Co.
Benzoyl peroxide	BPO	AR	Shanghai Chemical Reagent Co.
N, N-dimethylaniline	DMA	AR	Shanghai Chemical Reagent Co.
Citric acid	C₆H₆O₇	AR	Shanghai Chemical Reagent Co.
Acetic acid	C₂H₄O₂	AR	Shanghai Chemical Reagent Co.
Alumina	α-Al₂O₃	99.8%	Henan Jiyuan Brother Material Co.

Fig. 1 Relationship between dispersant amount and viscosity of slurry Solid loading: 10%; O.pH=3

Fig. 2 Relationship between dispersant amount and sedimentation height of slurrySolid loading: 10%; O. pH=3

Fig. 3 Relationship between viscosity and solid loading of slurryAmount of citric acid: 2%, O. pH=3

Fig. 4 Relationship between sedimentation height and solid loading of slurryAmount of citric acid: 2%, O. pH=3

Fig. 5 Mass loss of green body with different solid loadings during the drying process

Table 2 Shrinkage in green body with different solid loadings after drying

Solid loading	Shrinkage
5%	9.2%-10.1%
10%	5.1%-6.3%
15%	0.9%-1.2%
20%	0.8%-1.0%

Fig. 6 Storage modulus of slurry with different monomer amount as a function of time Solid loading: 10%

Fig. 7 Microstructures of green body after drying with different monomer amounts(a) 15%; (b) 25%; (c) 35%, solid loading: 10%

Table 3 Flexural strength of green body after drying with different monomer amounts

Monomer amount	Flexural strength/MPa
15%	3.2±0.2
25%	6.1±0.2
35%	4.2±0.2

Fig. 8 Microstructures of porous alumina ceramic with different solid loadings sintered at 1500℃(a) 5% ; (b) 10%; (c) 15%; (d) 20%

Table 4 Porosity and flexural strength of porous alumina ceramic with different solid loadings sintered at 1500℃

Solid loading	Porosity	Flexural strength/MPa
5%	61-65%	5.7±0.2
10%	55-58%	8.3±0.2
15%	47-49%	27.6±1.5
20%	43-46%	48.5±2.1

Fig. 9 Microstructures of porous alumina ceramic sintered at different temperatures(a) 1400℃; (b) 1500℃; (c) and (d) 1600℃

Table 5 Porosity and flexural strength of porous alumina ceramic sintered at different temperatures

Sintering temperature/℃	Porosity	Flexural strength/MPa
1400	49%-50%	23.7±1.3
1500	43%-46%	48.5±2.1
1600	40%-42%	91.2±4.5

References 30

[1]	OHJI T, FUKUSHIMA M.Macro-porous ceramic: processing and properties.International Materials Reviews, 2012, 57(2): 115-131.
[2]	SU C H, XU Y Q, ZHANG W, et al.Porous ceramic membrane with superhydrophobic and superoleophilic surface for reclaiming oil from oily water.Applied Surface Science, 2012, 258(7): 2319-2323.
[3]	HAUGEN H J, MONJO M, RUBERT M, et al.Porous ceramic titanium dioxide scaffolds promote bone formation in rabbit peri-implant cortical defect model.Acta Biomaterialia, 2013, 9(2): 5390-5399.
[4]	YOUNG A C, OMATETE O O, JANNEY M A, et al.Gelcasting of alumina.Journal of the American Ceramic Society, 1991, 74(3): 612-618.
[5]	WANG X F, WANG R C, PENG C Q, et al.Research and development of gelcasting.The Chinese Journal of Nonferrous Metal, 2010, 20(3): 496-509.
[6]	WU J M, ZHANG X Y, YANG J L.Novel porous Si3N4 ceramic prepared by aqueous gelcasting using Si3N4 poly-hollow microspheres as pore-forming agent.Journal of the European Ceramic Society, 2014, 34(5): 1089-1096.
[7]	LIU Y F, LIU X Q, WEI H, et al.Porous mullite ceramic from national clay produced by gelcasting.Ceramic International, 2001, 27(1): 1-7.
[8]	ZHANG F Z, KATO T, FUJI M, et al.Gelcasting fabrication of porous ceramics using a continuous process.Journal of the European Ceramic Society, 2006, 26(4): 667-671.
[9]	CHEN R F, HUANG Y, WANG C A, et al.Ceramics with ultra- low density fabricated by gelcasting: An unconventional view.Journal of the American Ceramic Society, 2007, 90(11): 3424-3429.
[10]	彭俊. 醇水基浆料凝胶注模成型氧化铝多孔陶瓷. 长沙: 中南大学硕士学位论文, 2013.
[11]	刘伟渊. 高气孔率、高强度多孔氧化铝陶瓷的制备及表征. 北京: 清华大学硕士学位论文, 2009.
[12]	高濂, 孙静, 刘阳桥. 纳米粉体的分散及表面改性. 北京: 化学工业出版社, 2003.
[13]	LEWIS J A.Colloidal processing of ceramic.Journal of the American Ceramic Society, 2000, 83(10): 2341-2359.
[14]	HOU Z G, DU H Y, LIU J C, et al.Fabrication and properties of mullite fiber matrix porous ceramics by a TBA-based gelcasting process.Journal of the European Ceramic Society, 2013, 33(4): 717-725.
[15]	WANG X F, WANG R C, PENG C Q, et al.Reology of aqueous BeO suspension with NH4PAA as a dispersant.Progress in Natural Science, 2012, 22(4): 347-353.
[16]	YANG J L, XIE Z P, TANG Q, et al.Studies on rheological behavior and gelcasting of α-Al2O3 suspension.Journal of the Chinese Ceramic Society, 1998, 26(1): 41-46.
[17]	MENON M, DECOURCELLE S, RAMOUSSE S, et al.Stabilization of ethanol-based alumina suspensions. Journal of the American Ceramic Society, 2006, 89(2): 457-464.
[18]	HIIDBER P C, GRAULE T J, GAUCKLER L J.Citric acid-a dispersant for aqueous alumina suspensions.Journal of the American Ceramic Society, 1996, 79(7): 1857-1867.
[19]	LIU B, PENG C Q, WANG R C, et al.Influence factors for stability behavior of Al2O3 suspension.The Chinese Journal of Nonferrous Metals, 2012, 22(10): 2833-2838.
[20]	YANG J L, YU J L, HUANG Y.Recent developments in gelcasting of ceramics.Journal of the European Ceramic Society, 2011, 31(14): 2569-2591.
[21]	WANG X F, PENG C Q, WANG R C, et al.Liquid drying of BeO gelcast green bodies using ethanol as liquid desiccant.Transactions of Nonferrous Metals Society of China, 2015, 25(7): 2466-2472.
[22]	WANG X F, WANG R C, PENG C Q, et al.Rheological property and drying mechanism of thermoresponsive gelcasting of ZnO.Transactions of Nonferrous Metals Society of China, 2015, 25(8): 2789-2796.
[23]	WANG X F, WANG R C, PENG C Q, et al.Thermoresponsive gelcasting: improved drying of gelcast bodies.Journal of the American Ceramic Society, 2011, 94(6): 1679-1682.
[24]	XU K H, SUN Y, HUANG Y, et al.Preparation of porous alumina ceramics by TBA gelcasting process.Refractories, 2011, 45(2): 93-95.
[25]	LI Y G, WANG Z Y.Influences of different drying methods on the dehydration process of alumina green body fabricated by gelcasting.Shandong Ceramics, 2011, 34(6): 26-28.
[26]	潘祖仁. 高分子化学(增强版). 北京: 化学工业出版社, 2007.
[27]	WANG X F, WANG R C, PENG C Q, et al.Gelation kinetics uniformity of gelcasting.Journal of Central South University (Science and Technology), 2012, 43(4): 1281-1289.
[28]	WANG X F, WANG R C, PENG C Q, et al.Effect of process conditions on strength of BeO green body prepared by gelcasting.Journal of Functional Materials, 2011, 42(7): 1197-1202.
[29]	JIN X, CAI K, LIU W, et al.Effects of monomer content on internal stresses during solidification process and properties of green bodies by gelcasting.Journal of the Chinese Ceramic Society, 2011, 39(5): 794-798.
[30]	ZHOU L Z, WANG C A, LIU W Y, et al.Fabrication of low density high strength porous mullite ceramics by tert-buty alcohol- based gelcasting process.Journal of Inorganic Materials, 2009, 24(6): 1173-1177.