添加剂对合成CA_6性能和显微结构的影响

Effects of additives on properties and microstructure of synthesized CA_6

为了合成更致密的六铝酸钙材料,以86%(w)的α-Al_2O_3微粉(d_(50)=3.64μm,分析纯)和14%(w)的碳酸钙(d_(50)=5.24μm,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TiO_2、Y_2O_3、ZrO_2为添加剂,经配料、混练、成型、烘干后,于1 550℃保温3 h煅烧,研究了不同添加剂对合成CA_6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CA_6时加入TiO_2添加剂,生成新物相CaTiO_3,有α-Al_2O_3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CA_6时加入Y_2O_3添加剂,烧后试样的主要物相为CA_6和Al_5Y_3O_(12)。Al_5Y_3O_(12)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CA_6时加入ZrO_2添加剂,烧后试样主要物相为CA_6和ZrO_2相,ZrO_2并没有提高试样的致密性。

This work aims at synthesizingdenser calcium hexaluminate(CA6)materials.CA6 materials were preparedusing 86 mass%ofα-AI2O3 powder(G5=3.64μm,analytically pure)and 14 mass%of calcium carbonate(G5=5.24μm,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 1550℃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 resuits shows that:(1)adding TiO2 additive generates anew phase CaTiO3,andα-AI2O3 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 Al2Y3O1;although yttrium aluminate is a high melting point phase,has no influence on the physical properties of the material at room temperature;(3)the specimen addedwith ZrO2 additive has the main phases of CA6 and ZrO2;ZrO2 does not densify the specimen.