Modification of nano-TiO₂ by Al₂O₃ in-situ coating

Abstract

A novel technology of in-situ coating Al₂O₃ on the surface of H₄TiO₄ was developed to prevent the aggregation of nano-TiO₂ powders and improve the dispersibility and thermal stability in the way of forming a uniform coating layer. The heterogeneous nucleation was conducted to prepare the precursor of nano-TiO₂ and then Al₂O₃ was coated on the surface of precursor. The effects of Al₂O₃ in-situ coating on the properties of nano-TiO₂ were investigated. The results show that H₄TiO₄ can be dispersed well under alkaline condition (pH 8.5) and the heterogeneous nucleation can be controlled easily. The optimized uniform coating layer is obtained by adding 5% (mass fraction) and 10% of Al₂O₃ and the aggregation of nano-TiO₂ powders is effectively inhibited and the dispersibility is obviously improved. The crystal sizes of TiO₂ powders are 12.3, 11.4 and 8.7 nm after coating 0,5% and 10% of Al₂O₃ respectively. Al₂O₃ on the surface of particulates in amorphous phase could increase the thermal stability of nano-particles after calcined at 550 °C.

Keywords

in-situ coating / nano-TiO₂ / aggregation / dispersibility / thermal stability

References

[1] ZhangJu-xian, HouYao-yong, GaoLong-qiao, et al.. Surface modification of nano-sic powder by coating with heterogeneous nucleation process[J]. Journal of the Chinese Ceramic Society, 1998, 26(6): 762-766(in Chinese)

[2] YoshinariM, OdaY, KatoT, et al.. Influence of surface modifications to titanium on antibacterial activity in vitro[J]. Biomaterials, 2001, 22(2): 2043-2048

[3] ZhangFeng, WolfG K, WangXiang-hui, et al.. Surface properties of silver doped titanium oxide films [J]. Surface and Coatings Technology, 2001, 148(3): 65-70

[4] ZhangXin-tong, SutantoI, TaguchiT, et al.. Al₂O₃-coated nanoporous TiO₂ electrode for solid-state dye-sensitized solar cell[J]. Solar Energy Materials and Solar Cells, 2003, 80(3): 315-326

[5] ZhengZi-shan, TangZi-long, ZhangZhong-tai, et al.. Surface modification of Li_1.03Mn_1.97O₄ spinel for improved capacity retention[J]. Solid State Ionics, 2002, 148(3): 317-321

[6] ParkK S, SonJ T, ChungH T, et al.. Surface modification by silver coating for improving electrochemical properties of LiFePO₄ [J]. Solid State Communications, 2004, 129(5): 311-314

[7] FukumotoS, TsubakinoH, InoueS, et al.. Surface modification of titanium by nitrogen ion implantation [J]. Materials Science and Engineering A, 1999, 263(2): 205-209

[8] YangYong-lai, NingGui-ling, LuBing-ling. Agglomeration prevention of particles of nanometer powders prepared by liquid-phase method[J]. Materials Review, 1998, 12(2): 11-13(in Chinese)

[9] HarmerM A, BergnaH, SaltzbergM, et al.. Preparation and properties of borosilicate-coated alumina particles from alkoxides[J]. J Am Ceram Soc, 1996, 79(6): 1546-1552

[10] CuiAi-li, WangTing-jie, JinYong, et al.. Mechanism and structure analysis of TiO₂ surface coated with SiO₂ and Al₂O₃[J]. Chemical Journal of Chinese Universities, 1998, 19(11): 1727-1729(in Chinese)

[11] MitchellT D, de JongL C. Processing and properties of particulate composites from coated powders [J]. J Am Ceram Soc, 1995, 78(1): 199-204

[12] LutherE P, LangeF E, PersonD S. “Alumina” surface modification of silicon nitride for colloidal processing[J]. J Am Ceram Soc, 1995, 78(8): 2009-2014

[13] HanK R, LimC S, HongM J, et al.. Surface modification of silicon nitride powder with alumina[J]. J Am Ceram Soc, 1996, 79(2): 574-576

[14] DaugerA. Ceramic nano-composites made from submicron powders coated by a sol-gel method[J]. Metal Powder Report, 2002, 57(4): 40-41

[15] GarinoT. Heterocoagulation as an inclusion coating technique for ceramic composite processing[J]. J Am Ceram Soc, 1992, 75(3): 514-518

[16] ZhangJu-xian, YangJing-yi, GaoLong-qiao. Preparation of Al₂O₃ and Y₂O₃-coated SiC composite particles[J]. Journal of Inorganic Materials, 1999, 14(3): 380-385(in Chinese)

[17] DingMing, DongQiang, FanGuang-neng, et al.. Study on coating nanometer TiO₂ on mica microflake by two step method[J]. Journal of Hefei University of Technology, 1998, 21(1): 74-76(in Chinese)

[18] CuiAi-li, WangTing-jie, JinYong. TiO₂ particle coating and structure analysis of surface coated with SiO₂ and Al₂O₃[J]. Engineering Chemistry & Metallurgy, 1999, 20(2): 178-181(in Chinese)

[19] CuiAi-li, WangTing-jie, JinYong, et al.. Thermodynamic research on the coating process of silica nano film on titanate particles surface[J]. Chemical Journal of Chinese Universities, 2001, 22(9): 1543-1545(in Chinese)

[20] ZhangJu-xian, YangJing-yi, YuXin, et al.. Preparation of coated ZrO₂ (3Y) powder[J]. Journal of Inorganic Materials, 1998, 13(6): 882-886(in Chinese)

[21] YinChun-lei, YuanFang-li, HuangShu-lan. Preparation of Al₂O₃-coated nano-ZnO composite for reducing photocatalytic activity [J]. The Chinese Journal of Process Engineering, 2003, 3(4): 346-350(in Chinese)

[22] KangChun-lei, LiChun-zhong, WangZhi-ting, et al.. Morphology and mechanism of rutile titanium dioxide powder coated by aluminium oxide[J]. Journal of East China University of Science and Technology, 2001, 27(6): 631-635(in Chinese)

[23] ZouJian, GaoJia-cheng, WangYong, et al.. Characterization and surface modification nano-TiO₂ by alumina[J]. Ordnance Material Science and Engineering, 2004, 27(3): 46-49(in Chinese)

[24] KimJ, SongK C, FoncillasS, et al.. Dopants for synthesis of stable bimodally porous titania[J]. J Euro Ceram Soc, 2001, 21(1): 2863-2872