"High-Throughput Design of Co-free Wear Coatings" 

Murtaza Siddiqui, MSE PhD Candidate 

Advisor(s): Professor Kenneth Sandhage and Michael Titus

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ABSTRACT

Ceramic-metal composites (or cermets) are a class of materials that are widely used in industry. Applications like wear coatings and industrial equipment utilize the attractive mechanical and wear properties of cermets. In particular, the cermet tungsten carbide-cobalt (WC-Co) is widely utilized due to its exceptional mechanical properties (especially wear resistance) and finds its use in thermal spray applications. However, health, economic, and social concerns related to cobalt, including its potential carcinogenicity and price volatility, have spurred a significant search for cobalt-free alternatives in the industry. To address these concerns and explore potential alternatives, this work utilizes high-throughput methodologies to identify high-performance, Co-free cermets. The research aims to develop a high-throughput calculation methodology to efficiently and objectively down-select from a large set of ceramic and ferrous metal combinations, considering alternative binders such as Fe, Mn, and Cu. These combinations were investigated, and calculations were made to refine the initial dataset of ~4 million compositions down to a small set of exceptional performers. The composition data was used to filter, categorize, and rank top performers with a modified MCDA method. Alloys with exceptional computed properties were selected for fabrication, to be fabricated with liquid phase sintering (LPS) and melt infiltration (MI). The optimized set of compositions were fabricated and tested in a high-throughput manner through various experimental techniques to evaluate their mechanical and tribological properties, including hardness, toughness, and density. Hardness and toughness measurements were made using microhardness indentations and relative density measurements were made using a combination of Archimedes, geometric, and image analysis.