CaO对MgAl_(2)O_(4)材料和ZrO_(2)-MgAl_(2)O_(4)材料侵蚀机制研究

Corrosion mechanisms of CaO to MgAl_(2)O_(4)materials and ZrO_(2)-MgAl_(2)O_(4)materials

为了研究CaO对MgAl_(2)O_(4)材料和ZrO_(2)-MgAl_(2)O_(4)材料的侵蚀机制,以MgAl_(2)O_(4)微粉、脱硅锆微粉和分析纯碳酸钙为原料,将碳酸钙煅烧、粉碎后得CaO微粉,以MgAl_(2)O_(4)粉和CaO粉质量比为4∶1制备了MgAl_(2)O_(4)材料,以脱硅锆粉、MgAl_(2)O_(4)粉、CaO粉质量比为3∶4∶1制备了ZrO_(2)-MgAl_(2)O_(4)材料,并分别于1500、1600、1700℃保温3 h煅烧。利用相图和热力学计算分析了体系中可能发生的反应,利用XRD和SEM分析了烧后试样的物相组成和显微结构。结果表明:对于MgAl_(2)O_(4)材料,CaO与MgAl_(2)O_(4)会反应生成低熔点CaO·Al_(2)O_(3)和12CaO·7Al_(2)O_(3)。对于ZrO_(2)-MgAl_(2)O_(4)材料,大量CaO与ZrO_(2)反应生成高熔点c-ZrO_(2)和CaZrO_(3),而剩余少量CaO与MgAl_(2)O_(4)反应生成CaO·Al_(2)O_(3),减少了低熔点相的生成。

This work aims to study the corrosion mechanisms of CaO to MgAl_(2)O_(4)materials and ZrO_(2)·MgAl_(2)O_(4)materials.MgAl_(2)O_(4)micropowder,desilicated zirconia micropowder,and analytically pure calcium carbonate were used as raw materials.CaO micropowder was obtained by calcining the calcium carbonate and crushing,and then the MgAl_(2)O_(4)material was prepared with the mass ratio of MgAl_(2)O_(4)micropowder to CaO micropowder of 4∶1 and the ZrO_(2)-MgAl_(2)O_(4)material was prepared with the mass ratio of desilicated zirconium powder,MgAl_(2)O_(4)micropowder and CaO micropowder of 3∶4∶1.Both the materials were heat treated at 1500,1600 and 1700℃for 3 h,respectively.The possible reactions in the system were analyzed using phase diagrams and thermodynamic calculations.The phase composition and microstructure of the fired samples were analyzed by XRD and SEM.The results show that:for the MgAl_(2)O_(4)material,CaO reacts with MgAl_(2)O_(4)to form low-melting-point CaO·Al_(2)O_(3)and 12CaO·7Al_(2)O_(3);for the ZrO_(2)-MgAl_(2)O_(4)material,a large amount of CaO reacts with ZrO_(2)to generate high-melting-point c-ZrO_(2)and CaZrO_(3),while the remaining small amount of CaO reacts with MgAl_(2)O_(4)to form CaO·Al_(2)O_(3),which reduces the formation of low-melting-point phases.