Design, fabrication, and testing of CVI-SiC/SiC turbine blisk under different load spectrums at elevated temperature

Abstract

In this article, design, fabrication, and testing of SiC/SiC turbine blisk with the fiber’s preform of Spider Web Structure (SWS) subjected to different load spectrums at elevated temperature are conducted. Micro-CT scans are conducted to show the fibers preform and defects inside the SWS-SiC/SiC turbine blisk. For 2D plain-woven SiC/SiC composite under monotonic tensile loading at an elevated temperature of T = 900°C in air atmosphere, the composite ultimate tensile strength is σ uts = 200 MPa with the fracture strain ε f = 0.36%. For SWS-SiC/SiC turbine blisk under the rotation testing, the first and second order natural frequency of the SWS-SiC/SiC turbine blisk are tested using the laser vibration meter. Relationships between the rotation speed, internal damage, and the natural frequency degradation of the SWS-SiC/SiC turbine blisk are established. Under the maximum rotation speed of n = 17,000 rpm at the exhaust temperature of T = 930°C, no damage occurred in the SWS-SiC/SiC turbine blisk. However, multiple coating spalling occurred due to the thermal-chemical coupling failure of the coating under flame impingement. The first natural frequency of the SWS-SiC/SiC turbine blisk decreases by 5% with the increase in the rotating speed from n max = 85,000 rpm to n max = 105,000 rpm, which indicates that there is an internal damage in the SWS-SiC/SiC turbine blisk, which leads to the decrease in the stiffness of the blisk.

Keywords

• ceramic-matrix composites
• turbine blisk
• high temperature
• damage
• natural frequency