Creep Behavior of Nextel™ 610/Monazite/Alumina Composite at Elevated Temperatures

Abstract

Aerospace components require structural materials that have superior mechanical properties and can withstand severe environmental conditions, such as ultra-high temperature, high pressure, or water vapor. Ceramic-matrix composites (CMCs), capable of maintaining excellent strength and fracture toughness at high temperatures are prime candidate materials for aerospace applications. This research effort investigates creep behavior of N610/LaPO4/Al2O3 composite consisting of a porous alumina matrix reinforced with Nextel 610 fibers coated with monazite in a symmetric cross-ply (0°/90°/0°/90°)s orientation. Tensile creep was examined at temperatures in the 900-1100°C range for creep stresses ranging from 40 to 150 MPa. At 900°C primary and secondary creep regimes were observed. At temperatures above 900°C, the composite exhibited primary, secondary and tertiary creep. Minimum creep rate was reached in all tests. Creep rates accelerated with increasing temperature and creep stress. Creep run-out was defined as 100 h at creep stress. At 900°C the run-out stress was 120 MPa. Monazite coating resulted in improved creep resistance at 900°C. Creep performance deteriorated rapidly at temperatures above 900°C.