Industrial pipes carrying water or chemicals invariably get gunked up as deposits accumulate on their internal surfaces. That slows flow, and slowly damages the equipment, leading to the need for periodic maintenance and higher operational costs.

There are many ways to tackle this, including water softeners, chemical-based scale inhibitors that aim to prevent mineral buildup, and using specialized pipe materials and pipe lining. But they all come with one drawback or another. Now, researchers at Rice University in Houston, Texas, have hit upon a more effective solution to resisting scale formation: coatings made with lab-grown diamonds.

The material scientists note their chosen coating material can stay clean without regular intervention. Their work builds on previous studies which found that diamond, besides being incredibly hard and chemically stable, can also stave off bacterial growth.

To evaluate this, the team first grew diamond films through a process called microwave plasma chemical vapor deposition, or MPCVD, which you can see demonstrated in the video clip below. MPCVD is the most common method for making synthetic diamonds.

For this film coating, methane and hydrogen gases were fed into a reactor chamber that contained silicon wafers spin-coated with a nanodiamond solution. High-power microwave radiation energized the atoms of the gases into a hot plasma state, which freed up carbon atoms to settle on the wafers, and linked into the diamond structure over the course of several hours. The film was also terminated with different gases to achieve subtle changes to its surface, and test how they'd perform.

Samples of the film were then immersed in a supersaturated calcium sulfate solution for 20 hours at room temperature, to allow the mineral scale to deposit. The nitrogen-terminated diamond film accumulated more than an order of magnitude less scale than the other versions of film terminated with oxygen, hydrogen or fluorine. Plus, the buildup appeared only in scattered crystal clusters, as opposed to dense layers that would be hard to break down and remove.

When this approach was applied to boron-doped diamonds electrodes, the buildup was approximately seven times lower compared to untreated electrodes.

"These findings identify vapor-grown, cost-effective, polycrystalline diamond films as a powerful, long-lasting anti-scaling material with broad potential across water desalination, energy systems and other industries where mineral buildup is a problem," said Pulickel Ajayan, professor of materials science and nanoengineering at Rice University and an author of the study that appeared in ACS Nano earlier this month.

Ajayan and his team have been involved in work on diamond films before, including in a study from earlier this year that showed its potential in enabling the production of faster and more efficient electronics and quantum computing components.

The researchers' finding could see diamond coatings being applied not only to industrial pipes in the future, but it could also find use in water desalination, oil and gas production, and power generation equipment.

Source: Rice University