Date of Award

8-2-2025

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Systems Engineering

First Advisor

Sujan Ghosh

Abstract

Nickel-Chromium (Ni-Cr) coatings are widely used in industrial applications due to their resistance to oxidation, thermal stability, and adjustable electrical and mechanical properties. However, achieving improved multifunctional performance across various use cases ranging from extreme tribological environments to microscale device integration remains a significant challenge. This thesis explores two complementary strategies for enhancing the performance of Ni-Cr coatings in both thick and thin film configurations, aiming to address limitations in wear resistance, durability, adhesion, and electrical conductivity. For thick coatings, Ni-Cr was reinforced with Ti3SiC2 MAX phase particles and processed using selective laser sintering (SLS) with optimized parameters. The addition of 10% MAX phase significantly improved the tribological performance, resulting in a stable coefficient of friction (CoF) of 0.47 and durability of 78,190 seconds under reciprocating wear testing. These enhancements were attributed to improved particle dispersion, reduced porosity, and the formation of lubricating and oxidation-resistant tribofilms, demonstrating the suitability of MAX-reinforced Ni-Cr for applications in aerospace and thermal protection systems. Ni-Cr thin films were deposited using DC magnetron sputtering onto glass and silicon substrates, incorporating metallic underlayers of Ti and Cr to improve mechanical strength and electrical performance. The films were characterized through SEM, AFM, nanoindentation, scratch testing, wear analysis, and four-point probe measurements. The Ni-Cr/Ti film on silicon exhibited the most balanced properties, featuring a hardness of 7 GPa, an elastic modulus of 145 GPa, a creep strain of 0.0175, a low CoF of 0.11, and electrical conductivity of 225 kS/m. Although Cr underlayers provided superior conductivity of up to 460 kS/m, they compromised wear resistance and mechanical integrity. The study demonstrates that integrating reinforcement strategies, such as MAX phase addition and tailored underlayers, allows for systematic tuning of Ni-Cr coatings to meet the demands of specific applications. The findings support the application of these engineered coatings in areas such as MEMS-based gas sensing microheaters, microelectronic interconnects, and high-temperature tribological systems, thereby expanding the utility of Ni-Cr across both macroscale and nanoscale domains.

Download

Share

COinS