硼砂对自蔓延高温合成ZrB_2粉体的影响
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摘要
以ZrO_2、Mg、B_2O_3及Na_2B4O_7为原料,采用自蔓延高温合成技术制备ZrB2粉体。通过FactSage7.0软件计算,从热力学角度研究了该反应体系发生自蔓延反应的可能性。采用X射线粉末衍射物相分析仪、场发射电子扫描电镜-能谱分析对最终产物的物相组成及显微形貌进行检测。分析结果显示,过量的Mg、B_2O_3可有效提高产物中ZrB_2的含量,Mg和B_2O_3分别过量40%(质量分数)、30%(质量分数)为Mg-ZrO_2-B_2O_3体系的较佳配比。基于上述优化配比,研究了用无水硼砂(Na_2B_4O_7)替换原料中B_2O_3对产物ZrB_2含量及晶粒尺寸的影响,当替换量达到15%(质量分数)时,ZrB_2的含量最高,并且随着Na_2B_4O_7替换量的增加,产物的晶粒尺寸由2μm减小至不足0.5μm。
ZrB_2 powders were prepared by the self-propagating high-temperature synthesis(SHS)using ZrO_2,Mg,B_2O_3 and Na2 B4 O7 as main raw materials.Based on thermodynamic calculation,the feasibility of the SHS was studied by FactSage7.0.The phase composition and microstructure of the final product were characterized with X-ray diffraction(XRD)and field-emission scanning electron microscopy(FESEM)with energy dispersive spectrometer(EDS).The ZrB_2 purity of the final product could be improved when the raw materials were mixed with extra amount of Mg and B_2O_3,it was found that the optimum extra amounts of Mg and B_2O_3 were 40 wt%and 30 wt%,respectively.Based on the optimum ratio,the effect of replacing B_2O_3 by Na_2B_4O_7 on purity and microstructure of ZrB_2 was studied.When the replacement ratio was 15%,the purity of ZrB_2 was the best,the grain size of ZrB_2 decreased from 2μm to less than 0.5μm with the increasing Na_2B_4O_7 replacement ratio.
ZrB_2 powders were prepared by the self-propagating high-temperature synthesis(SHS)using ZrO_2,Mg,B_2O_3 and Na2 B4 O7 as main raw materials.Based on thermodynamic calculation,the feasibility of the SHS was studied by FactSage7.0.The phase composition and microstructure of the final product were characterized with X-ray diffraction(XRD)and field-emission scanning electron microscopy(FESEM)with energy dispersive spectrometer(EDS).The ZrB_2 purity of the final product could be improved when the raw materials were mixed with extra amount of Mg and B_2O_3,it was found that the optimum extra amounts of Mg and B_2O_3 were 40 wt%and 30 wt%,respectively.Based on the optimum ratio,the effect of replacing B_2O_3 by Na_2B_4O_7 on purity and microstructure of ZrB_2 was studied.When the replacement ratio was 15%,the purity of ZrB_2 was the best,the grain size of ZrB_2 decreased from 2μm to less than 0.5μm with the increasing Na_2B_4O_7 replacement ratio.
引文
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7 Khanra A K,Pathak L C,Godkhindi M M.Double SHS of ZrB2powder[J].J Mater Process Technol,2008,202:386.
8 Zhang Shaowei,Matthana Khangkhamano,Zhang Haijun,et al.Novel synthesis of ZrB2 powder via molten-salt-mediated magnesioth-ermic reduction[J].J Am Ceram Soc,2014,97(6):1686.
9 Merzhanov A G,Borovinskaya I P.A new class of combustion processes[J].Combust Sci Technol,1975,10:195.
10 La Peiqing,Han Shaobo,Lu Xuefeng.Effect of the amount of Mg on size and purity of ZrB2 prepared by combustion synthesis[J].Powder Metallurgy Technology,2013,31(1):3(in Chinese).喇培清,韩少博,卢学峰.合成原料中Mg配比对燃烧合成制备的ZrB2粉体粒度与纯度的影响研究[J].粉末冶金技术,2013,31(1):3.
2 Zhang Tianmei.Preparation of high purity ZrB2 micropowder by self-propagating high-temperature synthesis[D].Harbin:Harbin Institute of Technology,2006(in Chinese).张田梅.自蔓延镁热还原合成高纯ZrB2微粉[D].哈尔滨:哈尔滨工业大学,2006.
3 Mishra S K,Das S K,Ramachandrarao P,et al.Synthesis of zirconium diboride-alumina composite by the self-propagating hightemperature synthesis process[J].Metall Mater Trans A,2003,34(9):1979.
4 Fan Zhou,Wang Hao,Fu Zhengyi,Composition of ZrB2 ceramic powder via Zr-B system by self-propagating high-temperature synthesis[J].J Chin Ceram Soc,2004,32(8):1016(in Chinese).方舟,王皓,傅正义.Zr-B体系自蔓延高温合成ZrB2陶瓷粉末[J].硅酸盐学报,2004,32(8):1016.
5 Camurlu H E,Filippo Maglia.Preparation of nano-size ZrB2powder by self-propagating high-temperature synthesis[J].J Eur Ceram Soc,2009,29:1501.
6 La Peiqing,Han Shaobo,Lu Xuefeng.Effect of the amount of diluent on microstructure of submicron ZrB2prepared by combustion synthesis[J].J Inorg Mater,2014,29(2):191(in Chinese).喇培清,韩少博,卢学峰.稀释剂添加量对燃烧合成亚微米级ZrB2微观组织的影响[J].无机材料学报,2014,29(2):191.
7 Khanra A K,Pathak L C,Godkhindi M M.Double SHS of ZrB2powder[J].J Mater Process Technol,2008,202:386.
8 Zhang Shaowei,Matthana Khangkhamano,Zhang Haijun,et al.Novel synthesis of ZrB2 powder via molten-salt-mediated magnesioth-ermic reduction[J].J Am Ceram Soc,2014,97(6):1686.
9 Merzhanov A G,Borovinskaya I P.A new class of combustion processes[J].Combust Sci Technol,1975,10:195.
10 La Peiqing,Han Shaobo,Lu Xuefeng.Effect of the amount of Mg on size and purity of ZrB2 prepared by combustion synthesis[J].Powder Metallurgy Technology,2013,31(1):3(in Chinese).喇培清,韩少博,卢学峰.合成原料中Mg配比对燃烧合成制备的ZrB2粉体粒度与纯度的影响研究[J].粉末冶金技术,2013,31(1):3.