This page contains a Flash digital edition of a book.
DESIGN IDEAS


GRAPHENE CRACKS THE GLASS CORROSION PROBLEM


Researchers at the Center for Multidimensional CarbonMaterials (CMCM), within the Institute for Basic Science (IBS) have demonstrated howgraphene coating protects glass fromcorrosion. Their research can contribute to solving problems related to glass corrosion in several industries. Glass has a high degree of both corrosion


and chemical resistance. For this reason it is a primary packagingmaterial to preserve medicines and chemicals. However, over time at high humidity and pH, some glass types corrode. Corroded glass loses its transparency and its strength is reduced. As a result, the corrosion bywater of silicate glass, themost common and oldest formof glass, is a serious problem, especially for the pharmaceutical, environmental and optical industries, and in particular in hot and humid climates. Although there are different types of glass, ordinary glazing and containers are


made of silicon dioxide (Si02), sodiumoxide (Na20) alongwithminor additives. Glass corrosion beginswith the adsorption of


water on the glass surface. Hydrogen ions fromwater then diffuse into the glass and exchangewith the sodiumions present on the glass surface. The pH of thewater near the glass surface increases, allowing the silicate structure to dissolve. Scientists have been looking at howto


coat glass to protect it fromdamage. An ideal protective coating should be thin, transparent, and provide a good diffusion barrier to chemical attack. Graphenewith its chemical inertness, thinness, and high transparencymakes it very promising as a coatingmaterial.Moreover, owing to its excellent chemical barrier properties, it blocks heliumatoms frompenetrating


 An example of a glass showing cracking and opacity due to corrosion


through it. The use of graphene coating is being explored as a protective layer for othermaterials requiring resistance to corrosion, oxidation, friction, bacterial infection, electromagnetic radiation, etc.


IBS scientists grewgraphene on copper  Corrosion mechanism on the glass surface


using a technique previously invented by Prof Rodney S Ruoff, director of the CMCM and Professor at the Ulsan National Institute of Science and Technology (UNIST), and transferred either one or two atom-thick layers of graphene onto both sides of rectangular pieces of glass. The effectiveness of the graphene coatingwas evaluated bywater immersion testing and observing the differences between uncoated and coated glass. After 120 days of immersion inwater at 60°C, uncoated glass samples had significantly increased in surface roughness and defects, and reduced in fracture strength. In contrast, both the single and double layer graphene-coated glasses had essentially no change in both fracture strength and surface roughness. “The purpose of the studywas to


 Graphene coatings protect glass from corrosion as shown in the atomic force microscopy images on the right. On uncoated glass (top right), the surface roughness increases after immersion in water for 120 days. In contrast, glass plates coated with graphene films were much more stable and the increase in roughness was negligible after immersion in water for 120 days


8 /// Environmental Engineering /// December 2016


determinewhether graphene grown by chemical vapour deposition on copper foils, a nowestablishedmethod, could be transferred onto glass, and protect the glass fromcorrosion. Our study shows that even one atom-thick layer of graphene does the trick,” explains Ruoff. “In the future,when it is possible to produce larger and yet higher- quality graphene sheets and to optimise the transfer on glass, it seems reasonably likely that graphene coating on glasswill be used on an industrial scale.”


DIAGRAMS: BIN WANG ET AL, ACS NANO 2016. 2016 AMERICAN CHEMICAL SOCIETY


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60