Rice Engineers Demonstrate Lab-Grown Diamond Films Can Prevent Mineral Buildup in Pipes
Mineral scaling in industrial pipes is a significant issue, much like the limescale that builds up in kettles, but it’s on a much larger and more expensive scale. This buildup can hinder water flow, put a strain on equipment, and drive up operational costs.
A recent study from engineers at Rice University has uncovered a promising solution: lab-grown diamond coatings. These coatings offer a robust alternative to traditional chemical additives and mechanical cleaning methods, which often provide only temporary fixes and come with their own environmental or operational challenges.
“Given these limitations, there’s a growing interest in materials that can naturally resist scale formation without needing constant maintenance,” explained Xiang Zhang, an assistant research professor of materials science and nanoengineering, who co-authored the study with Rice postdoctoral researcher Yifan Zhu. “Our research aims to meet this pressing need by identifying a coating material that can essentially ‘stay clean’ on its own.”
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Diamonds are prized for their hardness, chemical stability, and ability to endure high temperatures, making them ideal for tough industrial settings. While previous studies have shown that diamonds resist biological fouling and bacterial growth, their potential to combat mineral scaling hadn’t been thoroughly investigated until now.
The research team used microwave plasma chemical vapor deposition (MPCVD) to grow diamond films. This process involves energizing methane and hydrogen gases into a hot plasma, allowing freed carbon atoms to settle onto silicon wafers and form diamond’s tightly packed crystalline structure. After growth, the researchers treated the diamond films to customize their surface chemistry.
Their tests showed that nitrogen-terminated diamond surfaces significantly outperformed other treatments. These surfaces accumulated over ten times less scale than those treated with oxygen, hydrogen, or fluorine, with microscopy revealing only scattered crystal clusters compared to the dense layers found on other surfaces.
Molecular simulations have shown that nitrogen helps create a tightly bound layer of water on diamond surfaces. This layer acts as a barrier, stopping mineral ions from sticking and starting the scale formation process.
When this same surface chemistry was applied to boron-doped diamond electrodes in electrochemical systems, it resulted in about one-seventh of the mineral scaling, all without sacrificing performance. A combination of microscopy, chemical analysis, and adhesion tests confirmed both the reduced scale buildup and weaker adhesion, showcasing the effectiveness of the coating.
“Such a comprehensive study was previously limited by the high costs and availability of quality diamond films, as well as reliable surface treatment methods, which technology has only recently made feasible,” Zhang noted.
“These findings highlight vapor-grown, cost-effective, polycrystalline diamond films as a robust, long-lasting solution against scaling, with significant potential in water desalination, energy systems, and other industries plagued by mineral buildup,” said Pulickel Ajayan, the Benjamin M. and Mary Greenwood Anderson Professor of Engineering and a professor of materials science and nanoengineering.
“The scalable and adaptable deposition process of the coating also makes it very appealing for various industry sectors,” Jun Lou, the Karl F. Hasselmann Professor of Materials Science and Nanoengineering, added.
Ajayan, Lou, and Zhang are the corresponding authors of this study.
The research received support from the National Science Foundation (1449500, 1539999), the Welch Foundation (C-2248), the São Paulo Research Foundation (2023/08122-0), São Paulo State University, the National Council for Scientific and Technological Development-Brazil (304957/2023-2), and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior-Brasil. The content of this release is solely the responsibility of the authors and does not necessarily reflect the official views of the funding organizations.
