添加剂对合成CA6性能和显微结构的影响

摘要

为了合成更致密的六铝酸钙材料,以86％(w)的α-Al2O3微粉(ds0=3.64 μm,分析纯)和14％(w)的碳酸钙(d50=5.24 μm,分析纯)为原料,聚乙烯醇(PVA)为结合剂,分别外加5％(w)的化学纯TiO2、Y2O3、ZrO2为添加剂,经配料、混练、成型、烘干后,于1 550℃保温3h煅烧,研究了不同添加剂对合成CA6材料体积密度、显气孔率、常温耐压强度、物相组成和显微结构的影响.结果表明:1)在合成CA6时加入TiO2添加剂,生成新物相CaTiO3,有α-Al2O3相剩余,能够明显地促进试样的烧结,降低显气孔率,增加体积密度,并且显著增加试样的常温耐压强度;2)在合成CA6时加入Y2O3添加剂,烧后试样的主要物相为CA6和Al5Y3O12.Al5Y3O12虽然是高熔点相,但是其对材料的常温物理性能并没有影响.3)在合成CA6时加入ZrO2添加剂,烧后试样主要物相为CA6和ZrO2相,ZrO2并没有提高试样的致密性.%This work aims at synthesizing denser calcium hexaluminate (CA6) materials.CA6 materials were prepared using 86 mass％ of α-Al2O3 powder (d50 =3.64 μm,analytically pure) and 14 mass％ of calcium carbonate (d50 =5.24 μm,analytically pure) as the starting materials,polyvinyl alcohol (PVA) as the binder,extra-adding 5 mass％ of chemically pure TiO2,Y2O3,or ZrO2 as additive,batching,mixing,shaping,drying and firing at 1 550 C for 3 h.The effects of different additives on bulk density,apparent porosity,cold compressive strength,phase composition and microstructure of CA6 materials were investigated.The results shows that:(1)adding TiO2 additive generates a new phase CaTiO3,and α-Al2O3 phase remains;it can significantly promote the sintering,reduce apparent porosity,increase the bulk density,and significantly increase the cold compressive strength of specimens;(2)the specimen added with Y2O3 additive has the main phases of CA6 and Al5Y3O12;although yttrium aluminate is a high melting point phase,it has no influence on the physical properties of the material at room temperature;(3)the specimen added with ZrO2 additive has the main phases of CA6 and ZrO2;ZrO2 does not densify the specimen.