热压烧结制备BN-MgAlON复合材料及其力学性能研究

Mechanical Properties of BN-MgAlON Composites Prepared by Hot-pressing Sintering

以BN-MgAlON复合粉体为原料,Y2O3为烧结助剂,在N2气氛下热压烧结制备了BN-MgAlON复合材料,用X射线衍射和扫描电镜对材料的物相组成和显微结构进行了表征,研究了烧结温度对材料的物相组成、烧结性能和力学性能的影响。结果表明,在1650~1750℃可制备出致密的BN-MgAlON复合材料。材料主要成分为MgAlON、Sialon、BN和Ca YAl3O7,随烧结温度的提高,MgAlON的衍射峰逐渐增强。1750℃下所得材料结构均匀致密,材料中Al、Mg、O、N分布比较均匀。材料的抗弯强度、断裂韧性和显微硬度均随着烧结温度的升高而提高。1750℃下的材料性能最好,其体积密度为2.79 g·cm-3,显气孔率为0.3%,抗弯强度为283 MPa,断裂韧性为3.85 MPa·m1/2,硬度为15.33 GPa。并且1750℃,恒温1 h条件下烧结的得到的BN-MgAlON复合材料的抗冲刷性和耐磨性均远远优于耐磨钢B-hard-450。

BN-MgAlON composites were prepared by hot-pressing sintering under nitrogen atmosphere using BN-MgAlON composite powders as raw material and Y2O3 as sintering additive. The phase composition and microstructure of the samples were characterized by X-ray diffraction and scanning electron microscope. The effects of sintering temperature on phase composition,sintering performance and mechanical property were investigated. The dense BN-MgAlON composites can be prepared at 1650-1750 ℃. The main components of the material are MgAlON,Sialon,BN and CaYAl3O7 at 1650-1750℃,and the peaks of MgAlON phase became stronger as the sintering temperature increasing. The BNMgAlON composites prepared at 1750 ℃ are uniform and compact with the distributions of Al,Mg,O,N. Bending strength,fracture toughness and Vickers ＇ hardness of hot-pressed materials at different temperatures increase as the sintering temperature increases,therefore,the materials sintered at 1750 ℃with the bulk density of 2. 79 g · cm-3,apparent porosity of 0. 3%,bending strength of 283 MPa,fracture toughness of 3. 85 MPa·m1 /2and Vickers＇ hardness of 15. 33 GPa. Compared with 45 HB gradewear-resistance steel,the BN-MgAlON composites sintered at 1750 ℃ for 1 h have very good scouring resistance and abrasion resistance.