National Science Foundation Does steam damage ceramics? Martha L. Mecartney, University of California-Irvine, DMR Ceramics are usually very stable materials but this can change when they are exposed to high temperature steam. This research measures the changes that occur when steam passes over the surface of a ceramic material with small inclusions of nickel metal particles. The results show that oxygen enters the ceramic and moves through it more quickly in humid air than in dry air. At high temperatures this causes significantly faster corrosion (oxidation) of the nickel particles embedded in the ceramic. This accelerated corrosion in the presence of water vapor can have serious economic consequences. For example, high temperature water vapor may degrade the performance of jet engines that use ceramic coatings to protect metal turbine blades. Bright Ni metal particle in dark grains of the ceramic (aluminum oxide) seen by electron microscopy at high magnification. Dry AirSteam White nickel metal particles change to grey when corroded in this scanning electron microscopy picture. The depth of corrosion (yellow line) is greater when the surface is exposed to steam. Images by Ph.D. student Jesse Angle. Used by permission.

National Science Foundation Undergraduates Taste Research Martha L. Mecartney, University of California-Irvine, DMR Undergraduate students are invited to participate in research and get hands-on experience in the lab. Spring 2013, two students were able to present their research at the undergraduate research symposium held at UC Irvine, the first step to professionalism. One of the students, Merna Salama, also plans to attend the fall MS&T 2013 conference in Montreal. Undergraduate research is a critical experience for students, whether they intend to go on for a Ph.D. or work in industry. Merna was selected for a summer 2013 internship at Boeing based on part on her research experience in the laboratory. Patrick and Merna presenting posters on research at the UCI Undergraduate Research Conference, May Preparation of samples in an inert atmosphere by undergraduate researcher Merna Salama. Pedro Cruz mixing solutions in the fume hood. Patrick Ngo consolidating powders in a cold isostatic press. Images by Ph.D. student Jesse Angle. Used by permission.

National Science Foundation Proton Assisted Diffusion in Ceramics Martha L. Mecartney, University of California-Irvine, DMR Results from this research show that oxygen enters alumina and diffuses through it more quickly when exposed to 0.2 atm P H2O than in dry air, based on observations of the depth of oxidation of embedded nickel particles that form Ni-spinel at high temperatures. The hypothesis is that since adsorbed (OH) - (an oxygen ion with an associated proton) is smaller, more polarizable, and lower valence than O 2-, it will be easier for (OH) - to diffuse along grain boundaries. Enhanced grain boundary diffusion is a plus for lowering sintering temperatures and using less energy during the firing of ceramics, but a negative consequences for undesirable creep of ceramics and corrosion of metals protected by ceramic coatings when exposed to high temperature water vapor. Bright white Ni metal particles oxidize to form gray NiAl 2 O 4 spinel in the black matrix of Al 2 O 3 grains (backscattered SEM images). J.A. Angle, P.E.D. Morgan, and M.L. Mecartney, "Water Vapor Enhanced Diffusion in Alumina,“ Rapid Communication, JACerS, accepted Oxidation depth (x) versus time indicates kinetics are 80% faster at 1300˚C when water vapor is present. Oxidation Depth ~ 29µm Oxidation Depth ~ 51µm Dry Oxidation 5 hours Humid Oxidation 5 hours