The surface of the nanodiamond material (left) was measured in atomic scale with a transmission electron microscope. The local slope…
The surface of the nanodiamond material (left) was measured in atomic scale with a transmission electron microscope. The local slope proved to be brighter than that of the Austrian Alps (right), measured on a human scale. Credit: Tevis Jacobs
People can usually tell if something is rough or smooth by running their fingers along the surface. But how are things that are too small or too big to drive a finger over? Earth looks giant out of space, but someone standing at the foot of Himalayas would be disagreeable. Researchers measure surfaces in different scales to take into account different sizes, but these waves are not always consistent.
New research from the University of Pittsburgh’s Swanson School of Engineering saturated an ultrananocrystalline diamond coating, praised for its tough but smooth properties, and proved to be much harder than previously thought. Their results can help researchers better predict how yttopography affects surface properties of materials used in different environments from microsurgery and satellites or spacecraft engines.
An important measure of “roughness” on a surface is its average slope is how steep it is, “says Tevis Jacobs, Assistant Professor of Mechanical Engineering and Materials Science at Pitt.” We found that the surface of this nanodimellem film looks very different depending on the scale you use. “
Dr. Jacobs and his team’s research appeared in the American Chemical Society (ACS) Journal ACS Applied Materials and Interfaces . They took more than 1
00 measurements of the diamond film that combine Conventional Techniques With A New Approach Based On Transmission Electron Microscopy. The results spaned magnitudes from one centimeter down to the atomic scale.
Dr. Jacobs explains, “The nanodiamond surface is even so you can see your reflection in it. But by combining all of our measurements, including down to the smallest waves, we showed that this “smooth” material has an average gradient of 50 degrees. is brighter than the Austrian Alps when measured on a human footstep scale (39 degrees). “
” By using electron microscopy we could get the smallest end of the measuring range, we can not even define topography under the atomic scale, “says Dr. Jacobs. “Then, by combining all the scales together, we could solve the problem of having roughness deviates between scales. We can calculate” true “scale-invariant roughness parameters.”
“We have known for a hundred years that exceed the crude control of surface properties. The missing link is that we have not been able to quantify its effect. For example, in various biomedical applications, various studies have come to the contrary conclusions as to whether raw material promotes or degrades cell adhesion . New understanding of roughness over scales opens the door to finally solve this old-fashioned puzzle in surface analysis. “
The ultimate goal is to have predictive models of how roughness determines surface attributes such as adhesion, friction or heat conduction or electricity. Dr Jacobs breakthrough is the first step in an upward and very steep battle to create and validate these models.
“We currently do properties of this nanodiamond material and many other surfaces to apply mechanical models to link topography and properties,” he says. “By finding scales or the combination of scales that are most important for a given application, we can determine which surface treatment techniques will achieve best results, reducing the need for an expensive and time-consuming test and error approach.”
Researchers grow rough with nanomaterials to eliminate problematic tackiness caused by smooth surfaces
Abhijeet Gujrati et al. Combine TEM, AFM, and Profilometry for Quantitative Topographical Characterization across all scales, ACS Applied Materials & Interfaces (2018). DOI: 10,1021 / acsami.8b09899