Dy-黄长石固溶体的氧化行为研究

Oxidation Behavior of Dy-melilite Solid Solutions

本工作选取了四个Dy-黄长石固溶体Dy2Si3-xAlxO3＋xN4-x(Dy-M',x=0,0.3,0.6和1.0)组份；试样由热压工艺制成，并置于马弗炉中于1000℃氧化20h.随着固溶度x的增加，氧化增重的行为呈现出：即Dy－M'的抗氧化性能相对于Dy－M得到了改善．晶界相是Dy－M'的Dy-α-Sialon的试样，经热压制备，分别在1000℃和1300℃氧化20h，在第一种条件下，没有发现明显的氧化增重，显微结构观察表明样品未出现开裂。而在1300℃氧化20h时，Dy－α'-M'氧化表面层是含Si02和α-DySi2O7晶粒的硅酸盐层，其中α-Dy2Si2O7晶粒在氧化表面具有择优取向．

Four compositions of nitrogen-containing Dy-melilite solid solutions Dy2Si3-xAlxO3+xN4-x.(Dy-M', x=0, 0.3, 0.6 and 1.0) were prepared by hot-pressing and oxidized at 1000℃ for 20h in air in a TG unit. The weight gains per area of Dy-M' samples decreased with increasing the Al substitution, i.e. Dy-M'(x=0.6) Dy-M'(x=0.3) Dy-M，indicated that the oxidation resestance of Dy-M', especially for Dy-M'(x=0.6), became better compared with that of Dy-M. A composition of Dy-α-Sialon with Dy-M' as the grain boundary phase prepared by hot-pressing was exposed to air at 1000℃ and 1300℃ for 20h. No catastrophic oxidation behavior was observed in the first situation. When the sample was oxidized at 1300℃ for 20h, crystals of a-Dy2Si2O7 were observed in preferred orientation on the oxidized surface of Dy-a'-M' sample.