二氧化硅对锆酸钙材料结构及性能的影响

Effect of SiO_2 on Structure and Properties of CaZrO_3 Material

以分析纯氧化锆和碳酸钙为原料，成本相对低廉的二氧化硅为添加剂，利用固相反应烧结制备锆酸钙材料。研究了二氧化硅对锆酸钙材料相组成、晶胞参数、微观结构及常温性能的影响。用X射线衍射、扫描电镜及X＇pert plus分析软件分别对烧后锆酸钙试样的l锅相组成、显微结构和品胞参数进行表征和计算，并对试样的体积密度和显气孔率进行了测定。结果表明：利用碳酸钙和氧化锆住1600℃下保温3h，制备出的锆酸钙材料致密度较低；引入二氧化硅可以促进锆酸钙材料的烧结，当二氧化硅的加入量小于0．5mol％时，二氧化硅主要是通过在锆酸钙材料中形成间隙固溶体，产生品格缺陷而促进材料的烧结；同时二氧化硅在锆酸钙材料中形成固溶体后，还导致锆酸钙相晶胞参数和晶胞体积的增大；由于O2-半径较大，难以进人间隙位置，使得二氧化硅在锆酸钙材料中的固溶量很小。当二氧化硅的加入量大于或等于0．5mol％时，锆酸钙的品胞参数和晶包体积将几乎不发生变化，但是在锆酸钙材料中会有硅酸二钙相的出现和增加；二氧化硅最佳加入摩尔百分含量为0．25％～0．5％。

CaZrO3 was synthesized by solid reaction using analytical ZrO2 and CaCO3 as raw materials, relatively cheap SiO2 as additive. The effects of SiO2 on composition, microstructure and lattice parameters of crystalline phases were studied. Crystalline phases, lattice parameters and microstructure were respectively determined by XRD, SEM and X Pert plus software. Bulk density and apparent porosity of the CaZrO3 were measured. The results show that CaZrO3 can be synthesized from ZrO2 and CaCO3 at 1600 ~C heat preservation for 3 h, but the density of CaZrO3 is low. When SiO2 is added into starting materials, it can promote CaZrO3 material sintering. When the addition of SiO2 is less than 0.5mo1%. SiO2 mainly forms interstitial solid solution in CaZrO3 material, generates lattice defects and promotes the materials sintering. When the SiO2 forms solid solution in CaZrO3, the lattice parameters and unit cell volume of CaZrO3 are increased. Due to O2- radius is large, it is difficult to enter the interstitial position, which making that the solution quantity of SiO2 in CaZrO3 material is limited. When the addition of SiOz quantity is greater than or equal to 0.5mo1%, the lattice parameters and unit cell volume of CaZrO3 will hardly change, but results in the formation and increasing of CazSiO4 in CaZrO3 materials. The appropriate addition of SiOz in the CaZrO3 should be 0. 25% -0.5% in molar fraction.