Accession Number:

AD1076360

Title:

Creep of Nextel 720/Alumina Ceramic Matrix Composite with Diamond-Drilled Effusion Holes at 1200 deg C in Air and in Steam

Descriptive Note:

[Technical Report, Master's Thesis]

Corporate Author:

AIR FORCE INSTITUTE OF TECHNOLOGY WRIGHT-PATTERSON AFB OH

Personal Author(s):

• Harkins, Megan L

Report Date:

2019-03-21

Pagination or Media Count:

175

Abstract:

This effort evaluated the tensile creep behavior of Nextel720alumina with diamond-drilled DD effusion holes at 1200C. Tensile properties at 1200C in laboratory air were unaffected by the presence of an array of 17 DD holes. Notably, examination of the composite microstructure did not reveal any damage caused by the drilling process. The DD specimens exhibited similar degradation to creep lifetimes as laser-drilled LD specimens for creep tests between 46-150 MPa in air, but contrary to unnotched and LD specimens, saw minimal degradation due to steam. These results were attributed to a change in dominant damage mechanism that caused minimum creep rates in air to exceed those in steam.

Descriptors:

• ceramic matrix composites
• mechanical working
• materials science
• mechanics
• composite materials
• tensile strength
• tensile properties
• failure mode and effect analysis
• mechanical properties
• modulus of elasticity
• x-ray computed tomography
• air force
• creep
• materials
• materials laboratories
• notch sensitivity
• physical properties
• creep tests
• materials processing
• microscopy

Subject Categories:

• Mechanics
• Ceramics, Refractories and Glass
• Laminates and Composite Materials

Distribution Statement:

[A, Approved For Public Release]