Effects of coating thickness and residual stresses on bond strength of C633-79 thermal spray coating test specimens

Book · Sat Dec 31 04:00:00 EST 1994

OSTI ID:160514

Greving, D J; Shadley, J R; Rybicki, E F ^[1]

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1. Univ. of Tulsa, OK (United States)

Wire arc sprayed nickel-aluminum is widely used in the aircraft industry for dimensional restoration of worn parts and as a bond coat for thermal barrier coatings and other top coats. There is an interest in making nickel-aluminum coatings thicker to increase the limits of thermal spray repairs. The wire arc thermal spray process typically provides thick nickel-aluminum coatings with high bond strengths. However, nickel-aluminum coatings are found to have decreased bond strength with increasing coating thickness. Residual stresses and free edge effects depend on coating thickness and play a role in the reduced bond strength of thicker coatings. The goal of this work is to provide insight and possible explanations for the observed effects of decreased bond strength with increased coating thickness. The approach to accomplishing this goal is to extend the fracture mechanics analysis for debonding thermal spray coatings to include residual stresses. The layer removal method was used to experimentally determine the residual stresses in wire arc sprayed nickel-aluminum coatings of different thicknesses. Bond strength evaluations were performed using an improved ASTM C633-79 test specimen for a range of coating thicknesses. Based on the data obtained in this study, a finite element analysis and fracture mechanics approach were used to investigate the effects of coating thickness and residual stress on coating bond strength.

• OSTI ID: 160514
• Report Number(s): CONF-940684--; ISBN 0-87170-509-5
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
36 MATERIALS SCIENCE
AEROSPACE INDUSTRY
AIR
ALUMINIUM ALLOYS
BONDING
EXPERIMENTAL DATA
FRACTURE MECHANICS
MATERIALS
NICKEL BASE ALLOYS
RESIDUAL STRESSES
SPRAY COATING
STEELS
STRAIN GAGES
THICKNESS
YOUNG MODULUS