纳米氧化锆增韧刚玉质陶瓷蓄热体的性能研究

Properties of nano zirconia toughening corundum ceramic regenerator

以板状刚玉细粉、活性α-Al2O3微粉为主要原料,脱硅锆或不同Y2O3含量的纳米ZrO2为添加剂,CMC为结合剂,在200 MPa液压压力下半干法压制成型,经1550℃2 h烧成,制备了刚玉质陶瓷蓄热体试样,检测烧后试样的常温抗折强度、常温耐压强度、抗热震性,并借助SEM分析了其显微结构。结果表明:引入纳米ZrO2与引入脱硅锆相比,纳米ZrO2作为第二相粒子弥散分布于刚玉质陶瓷蓄热体的内部,提高了其强度和抗热震性;纳米ZrO2的增韧效果与其引入时的晶型有关,引入的ZrO2全部为立方晶型时不能发生相变增韧,仅发生微裂纹增韧,增韧效果小,而引入的ZrO2存在适量四方和单斜晶型时通过相变增韧和微裂纹增韧的共同作用提高了刚玉质陶瓷蓄热体的韧性。

The corundum ceramic regenerator were prepared using tabular corundum fine powder and active α-Al2O3 micro powder as main starting materials,desilicated zirconia or various nano zirconia with different Y2O3 content as additive,and CMC as binder.Specimens were formed by half dry method under 200 MPa hydraulic pressure and fired at 1 550 ℃ for 2 h.The cold modulus of rupture,cold crushing strength and thermal shock resistance of the fired specimens were researched.The microstructure of the specimens was observed by SEM.The results indicate that the strength and thermal shock resistance of the specimens with nano ZrO2 are improved compared with the specimen with desilicated zirconia for nano ZrO2 dispersedly distributes in the corundum ceramic regenerator as the second phase particle;the toughening effect of nano ZrO2 is related with the crystal pattern;the toughening effect of cubic zirconia is minor for only micro crack toughing but no phase transformation toughing occurs.The toughening effect becomes obvious when tetragonal and monoclinic zirconia coexist resulting from the combination of micro crack toughing and phase transformation toughing.