Thin Film-Residual Stress Assessment.
Abstract
That residual stresses exist in thin-film coated structures has been known for decades. Their existence plays an important role in the ability of coated structures to withstand external loads which might arise from mechanical, thermal, electrical and optical environments. Magnitudes of the residual stresses are influenced by many factors. These include mechanical properties of the films and substrates, mismatch of the thermal expansion between films and substrates, processing parameters such as deposition rate, film thickness, substrate temperature and chamber pressure during deposition, and coating/substrate adhesion characteristics. A successful prediction of residual stresses relies on; (1) valid mathematical modeling, (2) accurate measurement of deformation of thin film coated structures, (3) detailed understanding of the mechanical and thermophysical properties of the films and substrate materials. This report documents the result, findings, progress and status of the residual stress assessment activities in the following categories: (1) Analytical, derivation of stress behavior in the film coated substrates, (2) development of viable measuring techniques to determine the deformation of the thin film coated structures, (3) establishment of a testing methodology to quantify the coating material properties in thin film configurations, and (4) identification of failure modes and failure mechanisms to provide information toward the establishment of failure criteria of thin film coated structures. Keywords: Laser interferometry, Stress behavior, Young's modulus, Shear modulus, Thermal stress, Intrinsic stress.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 12, 1988
- Accession Number
- ADA193205
Entities
People
- C. Tseng
- D. J. Chang
- K. W. Paschen
- P. M. Adams
- R. Muki
Organizations
- The Aerospace Corporation