Date of Award

2019-01-01

Degree Name

Master of Science

Department

Mechanical Engineering

Advisor(s)

Ramana Chintalapalle

Abstract

Nitride nanocomposite thin films have generated significant attention as a result of their robust mechanical properties, excellent triobology, and good chemical (corrosion) stability. Due to their excellent hardness and high wear resistance NbN coatings have found use in a wide variety of applications such as the coating of cutting tools and to strengthen the surface mechanical properties of superconducting cavities. The mechanical properties of NbN can be further improved through mixing with Si3N4, leading to the formation of a nanocomposite structure. NbN-Si3N4 nanocomposite coatings have been actively studied due to their high hardness, high elastic modulus, and high resistance to oxidation.

The present work focus towards the synthesis and characterization of Nb-Si-N nanocomposite films with variable Nb-N and establish a correlation between mechanical, chemical, and optical properties. The Nb-Si-N films were deposited by pulsed DC and DC magnetron sputtering onto silicon substrates. Pulsed DC was used to ensure the stability for dielectric Si3N4 and remained at a constant power of 150 W concurrent with variable power DC sputtering (0-150 W) for NbN. The nitrogen (N2) flow rate was selected via hysteresis monitoring with the co-deposition at 150 W Si and 150 Nb related to maximum nitrogen uptake and seeing the metallic, transition, and poisoned modes. X-ray diffraction (XRD) studies indicate that all the films were amorphous. Chemical analyses using X-ray photoelectron spectroscopy (XPS) indicate a progressive reduction in Si content with increasing Nb. The studies show a strong correlation with chemical composition to the structural, optical, and mechanical characteristics for the Si-Nb-N films. The implications of chemical composition in the structure-property relationship of Si-Nb-N films are presented in detail.

Language

en

Provenance

Received from ProQuest

File Size

56 pages

File Format

application/pdf

Rights Holder

Cristian Orozco

Download

Share

COinS