稻壳制备高性能硅质多孔陶瓷的研究

发布时间：2018-06-19 01:13

  本文选题：稻壳 + 多孔陶瓷　； 参考：《安徽理工大学》2017年硕士论文

【摘要】：稻壳作为农业废弃物,主要元素为C、O、H和Si,且杂质含量低,并含有高活性的无定形SiO_2。预处理后,为低温常压下碳热还原氮化法制备高性能硅质多孔陶瓷提供硅源、碳源及成孔剂。研究了烧结温度、烧结助剂种类及掺量、稻壳掺量等对硅质多孔陶瓷(包括多孔β-Si_3N_4陶瓷、多孔α-Si_3N_4陶瓷、多孔碳化硅陶瓷及多孔氧氮化硅陶瓷)性能的影响。主要研究内容如下:以C/SiO_2为0.7的碳化稻壳和α-Si_3N_4为原料,MgO-CeO_2为烧结助剂,研究了 CeO_2掺量和烧结温度对制备多孔β-Si_3N_4陶瓷性能的影响。当CeO_2的掺量为4-5%、1500-1550℃下可制备出多孔β-Si_3N_4陶瓷,其显气孔率为45.78-42.81%,抗弯强度为49.44-82.09 MPa;当CeO_2掺量为5%、1550℃的多孔β-Si_3N_4陶瓷中,长柱状β-Si_3N_4发育良好。以C/SiO_2为0.7的碳化稻壳和α-Si_3N_4为原料,研究烧结助剂种类及掺量、稻壳掺量对稻壳制备多孔α-Si_3N_4陶瓷性能的影响。当La_2O_3.掺量为2-4%、1400℃-1450℃时,试样中主晶相为α-Si_3N_4,α-Si_3N_4相发育良好。当La_2O_3掺量为4%,烧结温度为1450℃时,所得多孔α-Si_3N_4陶瓷的综合性能最佳,抗弯强度达最大值(60.45 MPa),显气孔率为26.84%,介电常数为4.65。改变稻壳掺量可以明显提高多孔陶瓷的显气孔率;介电常数随着显气孔率的增加而急剧下降。以C/SiO_2为0.6的碳化稻壳和SiC为原料,研究烧结温度和烧结助剂种类及掺量对稻壳制备多孔碳化硅陶瓷性能的影响。当烧成温度为1550℃时,Al_2O_3掺量为6%时,成功制备出多孔碳化硅陶瓷,陶瓷断面孔洞较多,晶粒为六方状的α-SiC,当烧成温度为1550℃时,Al_2O_3掺量为4-6%时,多孔碳化硅陶瓷的宏观性能也最佳,显气孔率为27.88-30.35%,抗弯强度为40.67-42.49 MPa。以C/SiO_2为0.4的碳化稻壳为主要原料,添加少量烧结助剂,研究烧结温度和稻壳掺量对稻壳制备多孔氧氮化硅陶瓷性能的影响。在1400℃-1450℃保温2h烧成了以氧氮化硅为主相的多孔陶瓷。掺70-80%的碳化稻壳在1450-1500℃下烧成的多孔陶瓷的综合性能较好,其抗弯强度为31.84-53.76 MPa,显气孔率为42.76%-27.83%。掺70%碳化稻壳1500℃烧成试样中,Si_2N_2O晶粒呈板状,气孔分布均匀;该多孔陶瓷的抗氧化性优异,在1100℃的空气气氛中煅烧1h,氧化增重量仅为2.57%。
[Abstract]:Rice husk is a kind of agricultural waste with low impurity content and high activity amorphous SiO-2, the main elements of which are Con O O H and Si. After pretreatment, silicon source, carbon source and pore-forming agent were provided for the preparation of high performance silicon porous ceramics by carbothermal reduction nitriding under low temperature and atmospheric pressure. The effects of sintering temperature, type and amount of sintering aids and rice husk on the properties of porous silicon ceramics (including porous 尾 -Si _ 3N _ 4 ceramics, porous 伪 -Si _ 3N _ 4 ceramics, porous sic _ 3N _ 4 ceramics, porous silicon carbide ceramics and porous silicon oxynitride ceramics) were studied. The main contents of the study are as follows: the effects of CEO _ 2 content and sintering temperature on the properties of porous 尾 -Si _ 3N _ 4 ceramics were studied by using the carbonized rice husks with C / SiO _ 2 as 0.7 and 伪 -Si3N _ 4 as raw materials and MgO-CeO _ 2 as sintering auxiliaries. Porous 尾 -Si _ 3N _ 4 ceramics can be prepared when the content of CeO2 is 4-5 ~ 1500-1550 鈩，

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