Analysis of Bimetallic Adhesion and Interfacial Toughness of Kinetic Metallization Coatings

<p>Due to their ability to confer enhanced surface properties without compromising the properties of the substrate, coatings have become ubiquitous in heavy industrial applications for corrosion, wear, and thermal protection, among others. Kinetic Metallization (KM), a solid-state impact consolidation and coating process, is well-suited for depositing industrial coatings due to its versatility, low substrate heat input, and low cost. The ability of KM coatings to adhere to the substrate is determined by the quality of the interface. The purpose of this study is to develop a model to predict the interfacial quality of KM coatings using known coating and substrate properties. Of the various contributions to adhesion of KM coatings, research suggests that the thermodynamic Work of Adhesion (W_AD) is the most fundamental. It is useful to define interfacial quality in terms of the critical strain energy release rate (G_C) at which coating delamination occurs. Studies show that G_C for a given interface is related to W_AD. This study attempts to develop a theoretical model for calculating W_AD and understand the relationship between G_C and W_AD. For a bimetallic interface between two transition metals, W_AD can be theoretically calculated using known electronic and physical properties of each metal: the molar volume, V, the surface energy, γ, and the enthalpy of alloy formation, ΔH^interface; ΔH^interface is a function of the molar volume, V, the work function, φ, and the electron density at the boundary of the Wigner-Seitz cell, n_WS.W_AD for Ni-Cu and Ni-Ti interfaces were 3.51 J/m² and 4.55 J/m², respectively. A modified Four-point bend testing technique was used to experimentally measure G_C for Ni-Cu and Ni-Ti specimens produced by KM. These tests yielded mean G­_C values of 50.92 J/m² and 132.68 J/m² for Ni-Cu and Ni-Ti specimens, respectively. Plastic deformation and surface roughness are likely the main reasons for the large discrepancy between G_C and W_AD. At the 95% confidence level, the mean G_C of the Ni-Ti interface is significantly higher than that of the Ni-Cu interface. Further testing is recommended to better understand the relationship between W_AD and G_C.</p>

Name thesis:degree_name

MS in Engineering - Materials Engineering

Discipline thesis:degree_discipline

Materials Engineering

Year dc:date.available

2013

Author dc:creator

• Guraydin, Alec D

Contributors dc:contributor

• Trevor S. Harding

• Thermal Spray
• Kinetic Metallization
• Work of Adhesion
• Critical Strain Energy Release Rate
• Interfacial Toughness
• solid-state wetting
• Metallurgy
• Other Materials Science and Engineering
• Structural Materials

Identifier

10.15368/theses.2013.38

OAI identifier oai:identifier

oai:digitalcommons.calpoly.edu:theses-1989