Nov_Dec_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | N O V E M B E R / D E C E M B E R 2 0 1 7 1 1 trillionth of a meter occurring over a time scale as short as 10 billionths of a second. The researchers exercised the in- strument’s new capabilities in an ex- periment using photothermal indu- ced resonance (PTIR), which combines AFM and infrared light to determine material composition. The AMF-PTIR system allows researchers to record how long it takes for microcrystals in a metal-organic framework (MOF) to cool and resume their original size after thermal expansion, and with this data, the thermoconductivity of individual MOF microcrystals was determined for the first time. The system could allow the study of other phenomena—such as protein folding or heat diffusion—that cannot be measured by existing AFMs. nist.gov. TRACKING CORROSION IN TINY SPACES Scientists at the University of Cali- fornia, Santa Barbara (UCSB) snagged a difference between the film and the opposing surface reaches a certain crit- ical value. In this case, the nickel film corrodes while the more chemically inert mica remains whole. The work could lead to predictive models for material failure in confined spaces and be used to control corrosion rates in dif- ferent applications. ucsb.edu . UCSB researchers are now able to capture a nanoscale glimpse of crevice and pitting corrosion as it happens. real-time glimpse into how crevice and pitting corrosion progresses in confined spaces—like gaps between machine parts or seams where two surfaces meet. The researchers studied the ini- tiation and progression of the process where a nickel film contacted a mica plane. Using a surface forces appara- tus, the team determined the thick- ness of the metal film and observed electrochemical dissolution over time, discovering that the process was not homogeneous. Instead, areas with mi- croscale surface defects experienced intense local corrosion and sudden pitting. Once a protective surface layer was breached, corrosion spread from the pits—often rapidly. “Because you’ve got diffusion occurring, it affects the rate at which the metal dissolves both in and out of the crevice,” says Professor Jacob Israelachvili. “It’s very anisotropic.” The researchers also found that corrosion is more likely to begin, and to spread quickly, when the electric potential