Effect of nano lanthanum oxide on the high-temperature performance of phosphate material and alumina fiber reinforced phosphate composites
Haoyan Zhang, Jie Ding, Wanxin Li, Fangyi Wu, David Hui, Yuzhe Ma, Mengyuan Du, Kang YangAbstract
This study utilized phosphate composites modified with nano-La 2 O 3 . The influences of nano-La 2 O 3 on the thermal stability, phase evolution, and high-temperature load-bearing capacity of phosphate materials were investigated, as well as the high-temperature resistance and flexural strength of alumina/phosphate composites based on nano-La 2 O 3 . The results indicate that the incorporation of nano-La 2 O 3 effectively enhances the mass retention of phosphate materials, with the material exhibiting optimal overall performance at a nano-La 2 O 3 loading of 20 wt%. After heat treatment at 1,200 °C, the modified composite material retained a flexural strength of 28.1 MPa, which was significantly higher than that of the unmodified composite material. Microstructural characterization confirms that the composite undergoes a phase transformation at high temperatures, yielding a densified structure. This transformation promoted the formation of an effective thermal protection barrier composed of AlPO 4 and LaPO 4 phases. The formation of this protective layer plays a critical role in significantly improving the high-temperature load-bearing capacity and ablation performance of composite materials.