ELASTICITY AND FRACTURE OF DLC-COATED GLASS UNDER HERTZIAN CONTACT STRESSES

Open Access
Author:
Miller, Elizabeth Christine
Area of Honors:
Materials Science and Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Carlo G Pantano, Thesis Supervisor
  • David John Green, Honors Advisor
Keywords:
  • diamond-like carbon
  • cone cracking
  • glass
  • Hertzian contact
Abstract:
Coatings are applied to substrates for a variety of reasons ranging from improving the strength of the substrate to optical property modification. However, it is often unknown how the coating will affect the mechanical properties of the combined system. The aim of this thesis is to determine the mechanical properties of the coated and uncoated sides of a commercially available diamond-like carbon (DLC) coated soda lime silica float glass. The reduced elastic modulus of the uncoated glass and the effective reduced modulus of the DLC coated glass were determined using the Hertzian direct contact method, which allows for an elastic stress analysis. Controlled-load Hertzian cone cracking was used to measure the maximum load at failure and characteristic strength. The experimental results revealed that some variability existed in the coating and its properties across the surface, which was correlated with variable thickness as confirmed by characterization techniques such as Raman spectroscopy and scanning electron microscopy. However, this variability was not substantial enough to affect the ability of the coating to improve the mechanical properties of the glass. The DLC coated glass effectively exhibited higher strength, higher elastic modulus, and higher mean and median load at cone cracking than the uncoated glass.