surface energy; roughness; contact angle; drop shape analysis; profilometer; atomic force microscope; language barrier; foreign language
Research is a vital aspect in science and engineering. Not only does it further ideas and technology around the world, it brings people around the world together through collaborations. More often than not, the common language spoken among collaborators is English. This makes it easy for native English speakers. It becomes very difficult, however, when the common language spoken among collaborators is not one’s native tongue. New vocabulary, oftentimes very complex and technical, must be learned. It becomes even more of a challenge to present results and findings in a manner that is clear and concise. A collaboration between the University of Rhode Island and the Technische Universität Braunschweig (TU Braunschweig) was set up to look at surface roughness effects on surface energy. In many processes in the chemical, petrochemical, food and pharmaceutical industry wetting of solid surfaces plays a prominent role. The desired characteristic wetting behavior ranges from an almost complete wetting of the surface by the liquid to complete repulsion between surface and liquid. Therefore corresponding contact angles varied from 0° to 180°. At the Institute for Chemical and Thermal Process Engineering at TU Braunschweig fouling of heat transfer surfaces resulting from the crystallization of salts was investigated. Surface energy determined from contact angle measurements was used as a primary parameter to characterize deposition tendency of crystals. Surface roughness exerts a major influence on the interaction between substrate and liquid. Different interaction conditions occur for wetting and de-wetting as the liquid has wetted the flanks of the surface roughness after a first full contact. This results in a hysteresis effect depending on the direction of the process. For two different substrates, stainless steel and copper, surface roughness was changed through mechanical treatment. The influence of surface roughness on surface energy was then determined. Also two different types of coatings on stainless steel, Sol Gel and DLC (Diamond like Carbon), were characterized with respect to surface energy and roughness. A Profilometer and an Atomic Force Microscope (AFM) were available to determine surface roughness. As these techniques cover different surface areas, some cm2 with the Profilometer vs. 100 µm x 100 µm for the AFM, results are identical. A Drop Shape Analyzer (DSA) was used to measure the contact angle and from this calculate surface energy. The entire project was conducted in the German language, culminating in a presentation of results to a panel of faculty and graduate students. The language barrier added to the challenge of conducting the research in a meaningful way and gave a new perspective on international collaborations.