航空发动机模拟环境对Hi-Nicalon纤维力学性能及微结构的影响

Abstract

[中文文摘]将Hi-Nicalon纤维在H_2O 14 kPa;O_28 kPa;Ar 78 kPa的模拟气氛环境中,分别加热到1300、1400、1500、1600℃,保温1h。测试各处理温度样品的断裂强度,通过扫描电子显微镜(SEM)观察纤维断口表面随温度的变化情况,并利用透射电子显微镜(TEM)观察随温度升高纤维的微结构变化。结果显示,随热处理温度的升高,纤维强度有所增加,纤维表面的钝化膜厚度增大,内部晶粒长大,层错等缺陷增多。氧化膜的存在和厚度的增加有利于阻止纤维活性氧化,从而保持了强度;而缺陷的增多则有利于松弛因温度升高而带来的各种内应力,协调纤维因受外力而产生的变形,使纤维能够承受更高强度的拉伸和冲击。[英文摘要]For the purpose of studying the mechanical property and microstructure of the Hi-Nicalon fiber under aircraft engine simulated environment,Hi-Nicalon fibers were subjected to exposure test at 1 300,1 400,1 500,1 600℃in an gas mixture with an oxygen partial pressure of 8 kPa,argon partial pressure of 78 kPa and H_2O partial pressure of 14 kPa for 1 h,respectively. Tensile strength was evaluated by tensile test.The changs of the fracture surfaces and the microstructure were observed by Scanning Electron Microscope (SEM） and Transmission Electoron Microscope (TEM）.The result indicated that tensile strength, the thickness of the passive film, the grain size of -SiC and the amount of the stacking fault increased with the heat treatment temperature increasing.