Mechanical Properties of Epoxy/Clay Composite Coatings on an X65 Steel Substrate
Date
2021
Journal Title
Journal ISSN
Volume Title
Publisher
Taylor & Francis Group
Abstract
This paper presents the results of a combined experimental and theoretical study of the interfacial and mechanical properties of epoxy/clay composites
coatings on a mild steel substrate. This was studied using nano-indentation and
Brazil Disk techniques to determine the Young’s moduli, hardness values and mode
mixity characteristics of the composite coatings. The Young’s moduli of the rein forced composites comprising 1, 3, and 5 wt. % of montmorillonite clay particles are
shown to improve, respectively, by about 23%, 58%, and 50% while the respective
hardness values increased by about 46%, 80%, and 88%, relative to those of pristine
epoxy. The measured mechanical properties have also shown to compare favorably
with predictions from composite theories (rule-of-mixture and shear lag theories).
The interfacial toughness between X65 steel and the epoxy/clay coatings increases
with increasing mode mixity. This is associated with crack-tip shielding by crack
deflection and crack bridging. The trends in the measured mode-mixity dependence
of the interfacial fracture toughness values are consistent with predictions from the
simplified zone, normal zone, and row models (at lower mode mixity). The insights
from the observations and the measured crack profiles are incorporated into zone
and row models for the estimation of crack-tip shielding. The implications of the results are discussed for the design of epoxy/clay composites with attractive combinations of mechanical properties.
Description
Research Article
Keywords
Mechanical properties, interfacial fracture, toughening mechanisms, epoxy/clay composites, coating/interfacial design