HQP Highlight Series: Marshall Yang
Welcome to the HQP Highlight Series: a series of interviews designed to highlight the innovative research and diverse experiences of Highly Qualified Personnel (HQP) across the Carbon to Metal Coating Institute (C2MCI) network.
Today, we welcome Dr. Marshall Yang, a Postdoctoral Associate working with Dr. Yolanda Hedberg on macro-scale research at Western University. Dr. Yang will be sharing his insights on the exciting science taking place at C2MCI and the approaches, challenges, collaborations, and career journey behind his research.
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Could you introduce yourself and briefly share what you’re currently working on at C2MCI?
My name is Marshall Yang, and my research focuses on the analysis and engineering of advanced materials interfaces. At C2MCI, I am currently investigating how interfacial surface treatments can improve the corrosion resistance, adhesion, frictional behaviour, and long-term durability of coated metallic materials.
One of my main projects examines N-heterocyclic carbene, or NHC, treatments applied to galvanized steel and other substrates before applying several types of coatings. The NHC treatment forms an extremely thin interfacial layer, so the central challenge is to understand how nanoscale changes in surface chemistry influence the macroscopic performance of the complete coating system.
To address this, we combine surface-sensitive characterization with corrosion testing, tribology, coating-property measurements, and advanced synchrotron-based techniques. The broader goal is to connect what happens at the buried metal–coating interface with how the coated material performs during service.
What first drew you to your field of research?
I was drawn to materials-interface research because interfaces strongly influence the performance of an entire coating system. A protective coating may be tens or hundreds of microns thick, but its adhesion and durability can depend on an interaction layer at the metal surface that is only a few nanometres thick.
This creates an important connection across length scales. At the nanoscale, we examine molecular bonding and surface composition. At the microscale, we study coating morphology, particle distribution, pores, defects, and localized degradation. At the macroscale, we evaluate corrosion resistance, adhesion, friction, wear, and service life.
My background in chemical engineering also motivated me to work on problems that combine fundamental mechanisms with practical manufacturing and industrial applications.
What’s the coolest analytical or synthetic technique you’ve learned recently? Why did it excite you?
One of the most exciting techniques I have recently worked with is Time-of-Flight Secondary Ion Mass Spectrometry, or ToF-SIMS. This technique can detect molecular fragments and chemical species within the outermost layers of a material surface.
It is especially valuable for the NHC project because the treatment layer is extremely thin and cannot be readily identified by conventional microscopy. ToF-SIMS enables us to detect chemical evidence of NHC-derived species and investigate their distribution across the treated substrate.
What excites me most is that it makes otherwise invisible interfacial chemistry measurable. This helps us connect molecular-scale surface modification with changes in coating adhesion, corrosion resistance, and durability.
Which of your recent projects with C2MCI are you most proud of, and what made it special?
I am particularly proud of the NHC anticorrosive coating project. The objective is to determine whether an ultra-thin surface treatment can improve the performance of coated steel.
What makes the project special is its multidisciplinary nature. It brings together surface chemistry, materials characterization, corrosion science, tribology, coating evaluation, and techniques such as ToF-SIMS and X-ray Absorption Near Edge Structure (XANES).
The project also addresses a practical industrial challenge. Conventional metal pretreatments involve multiple processing stages and chemicals, raising environmental and regulatory concerns. An NHC-based treatment could offer a more targeted approach to controlling the metal–coating interface while using only a very small amount of material.
I am especially interested in identifying the underlying mechanism. It is not enough simply to observe improved performance. We want to determine whether the improvement results from stronger interfacial bonding, modified surface chemistry, reduced under-film corrosion, better coating adhesion, or a combination of these effects.
Tell us about a paper you recently published. What was the most exciting part of the work?
A recent paper based on my previous PhD research investigated the mechanistic interplay between zinc content and film thickness in zinc-rich polyester powder coatings. We wanted to understand how these two variables work together to control corrosion protection, rather than studying either zinc loading or coating thickness in isolation.
We combined mixture-design statistical modelling with electrochemical impedance spectroscopy, polarization resistance measurements, open-circuit potential monitoring, and cross-sectional SEM–EDS analysis. This allowed us to relate coating formulation and thickness to both electrochemical performance and the physical consumption and redistribution of zinc particles during exposure.
The most exciting result was that thicker coatings were not always better. At approximately 80 weight percent zinc, a relatively thin coating of about 40 microns developed unexpectedly strong, longer-term resistance. The thinner film allowed the electrolyte to reach zinc-rich regions more readily, which accelerated localized zinc corrosion. Then, the resulting corrosion products accumulated within pores, defects, and interparticle pathways, partially blocking further electrolyte transport through the coating.
In comparison, coatings around 80 micrometres thick initially showed strong barrier behaviour due to their longer diffusion pathways, but their protection gradually became increasingly influenced by diffusion through the coating and by accumulated corrosion products. Intermediate-thickness coatings, around 55 micrometres, were less effective because they did not benefit as strongly from either corrosion-product pore blocking or the longer transport pathways present in the thickest films.
What I found most meaningful was that the study demonstrated that zinc-rich coatings are not static barriers. Their protection mechanisms evolve with time—from initial barrier and sacrificial-anode behaviour toward corrosion-product-controlled and diffusion-controlled protection. This shows that zinc loading and coating thickness need to be optimized together, with consideration of how the system changes during service rather than only how it performs immediately after exposure.
The HQP Highlight Series is made possible by the support of the Government of Canada’s New Frontiers in Research Fund (#NFRFT-2020-00573).
If you are a C2MCI HQP who might be interested in appearing in future instalments of the HQP Highlight Series, please reach out to Dr. Tetyana Levchenko to get involved.
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