Preparation of AgSnO₂ composite powders by hydrothermal process

Abstract

Silver-tin oxide powders were synthesized by the hydrothermal method with Ag(NH₃)₂⁺ solution and Na₂SnO₃ solution as raw materials and Na₂SO₃ as reductant. The precipitation conditions of Na₂SnO₃ solution and the reduction conditions of Ag(NH₃)₂⁺ were also investigated. The powders prepared were characterized by differential thermal analysis (DTA), X-ray diffraction analysis (XRD), scanning electron microscope (SEM) and energy spectrum analysis. The results show that pH value of the solution is a key parameter in the formation of Sn(OH)₄ precipitate and the reduction reaction of Ag(NH₃)₂⁺ can release H⁺ ions, which results in synchronous precipitation of Sn(OH)₆²⁻ as Sn(OH)₄. The reduction of Ag(NH₃)₂⁺ and precipitation of Na₂SnO₃ occur simultaneously and the coprecipitation of silver and tin oxide is reached by the hydrothermal method. The silver-tin oxide composite powders have mainly flake shape of about 0.3 μm in thickness and there exists homogeneous distribution of tin oxide and silver in the powder synthesized.

Keywords

silver-tin oxide powder / hydrothermal method / flake structure / coprecipitation

References

[1] ZHANG Wang-sheng. Basic conditions of electrical contacts abroad[J]. Electrical Alloys, 1995 (1): 10–13. (in Chinese)

[2] CHANG H. Novel method for preparation of silver-tin oxide electrical contacts[J]. Journal of Materials Engineering and Performance, 1992(1): 255–260.

[3] RolandM.. Metallurgical aspects of silver-based contact materials for air-break switching devices for power engineering[J]. IEEE Trans on Comp Hybrids and Manuf Tech, 1989, 12(1): 71-81

[4] LiuH.-y., WangY.-p., DingB.-j., et al.. Preparation and microstructure analysis of nanostructured silver-tin oxide contact materials[J]. Rare Metal Materials and Engineering, 2002, 31(2): 122-124

[5] BEHRENS V, HONIG TH, KRAUS A, et al. Advanced silver/tin oxide contact material[C]// Proceedings of the Annual Holm Conference on Electrical Contacts. Pittsburg, 1993: 19–25.

[6] JOST E M, KIRK M. Electrically Conductive Material and Method for Making[P]. America Patent: US5846288. 1998-12-18.

[7] ROGER W, MECHTHILD M, FRANK H, et al. Method for Producing Composite Powders Based on Silver-Tin Oxide, the Composite Powders so Produced, and the Use of Such Powders to Produce Electrical Contact Materials by Powder Metallurgy Techniques[P]. America Patent: US0051102. 2001-12-12

[8] ZhengY., LiS.-l., GaoH.-x., et al.. Study on Ag/SnO₂ nanocrystalline powder for electric contact material[J]. Rare Metal Materials and Engineering, 2003, 32(10): 829-831

[9] ChenJ.-c., SunJ.-l., DuY., et al.. Investigation of electrical conductivity of silver tin oxide electrical contact materials fabricated by reactive synthesis[J]. Rare Metal Materials and Engineering, 2003, 32(12): 1053-1056

[10] ZozH., RenH., SpäthN.. Improved Ag-SnO₂ electrical contact material produced by mechanical alloying[J]. Metall, 1999, 53(8): 423-428

[11] LorrainN., ChaffronL., CarryC., et al.. Kinetics and formation mechanisms of the nanocomposite powder Ag-SnO₂ prepared by reactive milling[J]. Materials Science and Engineering A, 2004, 367: 1-8

[12] DuZ.-j., YangT.-z., GuY.-y., et al.. The advances of preparing methods and application of AgSnO₂ contact material[J]. Materials Review, 2005, 19(2): 39-42

[13] LiW.-j., ShiE.-w., ZhongW.-z., et al.. Growth unit model of anion coordination polyhedron and the particle size of powders in the hydrothermal formation[J]. Journal of the Chinese Ceramic Society, 1999, 27(2): 164-171

[14] Zhouzhou Smelting Plant.Separation and Determination of Elements in Nonferrous Metallurgy[M], 1979, Changsha, Metallurgical Industry Press

[15] Mechanical Industry Standards of the People’s Republic of China[JB/T7777.1-1995]. Chemical Analysis Procedures for Silver Tin Oxide, Indium Oxide Electrical Contact Materials: Determination of Tin by Iodimetry.

[16] BaikN. S., SakaiG., ShimanoeK., et al.. Hydrothermal treatment of tin oxide sol solution for preparation of thin-film sensor with enhanced thermal stability and gas sensitivity[J]. Sensor and Actuators B, 2000, 65: 97-100

[17] CHEN Jing-chao, SHEN Jia-ling, DU Yan, et al. Investigation in properties and microstructure of silver-tin oxide electrical contact materials fabricated by reactive synthesis[J]. Electrical Material, 2003(3): 3–11. (in Chinese)

[18] JiangM.-x., YangT.-z., ChuG., et al.. Synthesis of antimony-doped tin oxide nanoparticles by complexing-hydrothermal oxidation method[J]. Journal of Central South University: Science and Technology, 2006, 37(2): 247-251

[19] HeQ.-x., YuW.-p., HuJ.-qing.. Synthesis and characterization of bismuth-doped tin dioxide nanometer powders[J]. Journal of Central South University: Science and Technology, 2006, 13(5): 519-524