Abstract:

In order to adapt the demands for the lightweight, economic and functional materials, CA₂ material was prepared by two steps reaction and sintering of mixture powders method after the mixture powders of Al₂O₃ and CaCO₃ was pre-sintering at 1200℃ for 2h and sintering at 1600℃ for 1h by addition of TiO₂ micro powder, and the promoting law and mechanism of TiO₂ addition on sintering of this_{refractory was discussed.The results showed that the added Ti⁴⁺ dissolves to CA2 by substituting Al³⁺, which effectively promotes the lattice distortion of CA2 and increases the Al³⁺ vacancies, and then effectively improves the sintering activity of CA2, accelerates intercrystalline mixing and diffusion in the sintering process, thus the sintering of CA2 is effectively promoted. At the same time, the excess TiO2 reacts with the exsolution of Al2O3 to form the Al2TiO5 further fills the pores and promots the sintering densification of CA2. Based on the above factors, the sintering densification behavior of CA2 material is synergistically promoted. As a result, the dense microstructure is obtained, with the apparent porosity decreases from 12.7% to 4.7% and the bulk density increases from 2.51g/cm³ to 2.65g/cm³ after firing at 1600℃ for 1h by addition of 2%TiO2, and a texture microstructure of CA2 phases is prepared.}

Key words: CA₂, lightweight, TiO₂ addition, synthesis, sintering, activation, chemical processes

摘要：

为了适应材料轻量化、经济化以及功能化的发展需要，以Al₂O₃和CaCO₃粉末为主要原料，TiO₂为添加剂，采用固相烧结法，经1200℃预烧2h-1600℃烧结1h后，制备了CA₂材料,并考察了TiO₂促进该材料烧结规律及其机理。结果表明，添加TiO₂中的Ti⁴⁺离子在烧结过程中通过取代Al³⁺离子固溶入了CA₂相中，有效地促进了CA₂相的晶格畸变，增加了Al³⁺离子空位，提高了CA₂相的活性，加速了离子混淆与扩散，从而有效地促进了CA₂相的烧结，同时超过固溶极限过量的TiO₂与脱溶的Al₂O₃反应生成Al₂TiO₅新相，填塞气孔，进一步促进了烧结致密化。综上因素，CA₂材料的致密化被有效促进。当TiO₂的添加量为1%时，显气孔率已由未添加时的12.7%下降到4.7%，体积密度已由未添加时的2.51g/cm³上升到2.65g/cm³，可制得显微结构交织分布的致密CA₂材料。

关键词: 二铝酸钙, 轻量化, TiO₂添加, 合成, 烧结, 活化, 化学过程