Si粉过渡塑性相对锆刚玉材料结构和性能的影响

摘要

SiC-SiAlON bonded corundum-zirconia materials were prepared via the transient plastic phase,buried in carbon at 1500 ℃ for 3 h.Corundum-zirconia powder,added with Si powder of different mass fractions(4%,6%,8% and 10%),was used as starting material.The results showed that Si powder not only played a role in plastic phase molding,but also promoted the sintering process and improved the modulus of rupture and thermal shock resistance of corundum-zirconia material. When 1 0% Si powder was added,the values of cold modulus of rupture and residual strength ratio were 33 MPa and 85%,respectively.Compared with the sample without Si powder addition,they were increased by 24 MPa and 16%.And the maximum hot modulus of rupture was obtained at 8% Si powder,which was 8 MPa,about 2.3 times compared with that of the sample without Si powder addition.The improvement of modulus of rupture and thermal shock resistance of corundum-zirconia materials was attributed to SiC and SiAlON,which were interspersed in corundum-zirconia skeleton structure leading the strengthening. In addition, when cracks met SiC fibres, which resulted in strengthening and toughening effects by the bridging traction and the deflection,then improved the modulus of rupture and thermal shock resistance of corundum-zirconia materials.%将质量分数4%、6%、8%和10%的 Si 粉引入到锆刚玉材料中,采用过渡塑性相工艺,并在埋炭条件下于1500℃保温3 h烧成,制备出了SiC-SiAlON结合锆刚玉材料。研究表明：Si 粉不仅起塑性相成型的作用,并可促进烧结,改善锆刚玉材料的强度和抗热震性。质量分数10% Si粉试样的常温抗折强度和残余强度保持率分别为33 MPa和85%,较未添加Si粉的试样分别提高了24 MPa和16%。高温抗折强度则在Si粉质量分数为8%时最大,为8 MPa,为未添加 Si 粉试样的2.3倍。锆刚玉材料强度和抗热震性的提高归因于原位反应生成的纤维状β-SiC 和少量粒状的 O'-SiAlON 填充在锆刚玉骨架中所起的强化作用,及裂纹遇到SiC纤维时通过桥联和偏转等所起的增强增韧作用。