Last week I had a pleasure to attend Fysikermøtet 2019 – a meeting of Norwegian physicists in academia, industry, and schools. The plenary talks, starting from the story about lasers given by the 2012 Nobel laureate Serge Haroche and ending with not-so-impossible-anymore visions of smart farming and transport by Bjørn Tore Orvik, were a proper boost of inspiration. So hearing about all this state-of-the-art progress in fusion, superconductors, imaging of atoms, or solar energy, I should ask myself why studying mineral materials? Is there still any progress to be made? Can the same material that is used to produce blackboard chalk be also used to manufacture extremely durable ceramics?
My take on this is rather optimistic as advanced materials based on abundant minerals already exist and are produced on a global scale. Unfortunately, this rarely happens in industrial processes, but it is mastered by organisms when they produce functional biominerals. Marine organisms produce their skeletons and functional devices from what they can find locally and in abundance. These might be not the best existent materials for a given specific function, but they are possible to get with little effort; an example for us to follow.
Although the way to go might seem still long, we learn more and more about reactive mineral particles, which comprise the smallest building blocks of mineral-based materials. Some very recent findings show that the interactions between these particles can be affected by the amount and type of even the most common ionic species dissolved in waters, not to mention the more complex interactions with organics. Experiments like that, are necessary to develop a meticulous recipe of how to control interactions between mineral particles; having it, will bring us closer to engineer the materials we need.
But what is the whole project all about? Titled ‘‘Solid-solid interfaces as critical regions in rocks and materials: probing forces, electrochemical reactions, friction, and reactivity”, the project aims to investigate key interfacial processes that contribute to the mechanical strength of granular solids. Often, the overall strength of such solids is associated with what happens in tiny spaces between contacting individual grains. These are frequently the most reactive regions, in which minerals can grow or dissolve in the presence of water or more concentrated salt solutions. The growth and dissolution frequently determine if contact will be strong or weak, as they may cement solid grains together or push the grains away from each other. Thus, the overarching goal I set for this project is to recognize which of these processes make the solid-solid interfaces weak, and how to convert the weak interfaces into the strong ones.
Although we see the destructive effects of weak interfaces at a macroscopic scale (earthquakes, rock compaction and subsidence, general material failure), the very mechanisms governing the interfacial strength are frequently operating at much smaller scales (10-9m). To learn about these mechanisms, and to be able to modify them, we need new analytical methods that enable us to investigate the relevant nano and micro-scale processes. In my experimental project, I’ve chosen to work with the Surface Forces Apparatus (SFA). SFA allows studying of a multitude of interfacial processes, and all in one go: surface forces (adhesion and repulsion), friction between surfaces that move laterally, surface reactivity or even electrochemical surface corrosion! If you are looking forward to reading more, stay tuned, and follow the project’s progress!