Sensor Technology for Non Destructive Assessment of Corrosion in Structural Steels J. Ernesto Indacochea & Ming L. Wang, Civil & Materials Engineering National Science Foundation Problem Statement and Motivation Technical Approach Key Achievements and Future Goals Corrosion of materials is one of the most important challenges facing engineers in the selection of structural materials for operation in corrosive environment. Corrosion is estimated to cause loses of about 500 billion dollars per year only in the USA. About 90% of corrosion is associated with iron based materials. Early detection and close monitoring of corrosion by non- destructive examination (NDE) is most effective to extend the life of structures. The material is a key part of the sensor. A magnetic field is applied to the component being assessed and its magnetic response is monitored. The hysteresis loop is affected by steel chemistry, microstructure, surface condition and geometry. Corrosion is a surface phenomenon, it gradually reduces the cross section of the steel and induces the formation of diverse iron oxides on the surface. Iron oxide formation and surface morphology changes affect the magnetic properties of the steel. The sensor is able to detect such subtle changes in magnetic properties and thus estimates the level of corrosion. The sensor is very sensitive to the metallurgical characteristics of the steel. Corrosion damage with 0.5% mass loss of structural steels can be detected with a 95% confidence limit. This sensor is capable of the detecting early corrosion in steels. Future Goals Characterize precisely the diverse iron oxides formed during corrosion and evaluate its individual contribution on the magnetic response obtained by the sensor. Explore different configurations of the sensor for its application in the field.

Nanostructured Sensors for Detecting Low Levels of Hydrogen at Low Temperatures Investigators: J. Ernesto Indacochea & Ming L. Wang, Materials Engineering Department Prime Grant Support: National Science Foundation Problem Statement and Motivation Technical Approach Key Achievements and Future Goals Recent research thrusts for alternate methods of power generation has turn to production and storage of H 2 as alternative fuel, as it is the most environmental friendly fuel. It is foreseen that H 2 will become a basic energy infrastructure to power future generations; however it is also recognized that if it is not handled properly (e.g. transportation, storage), it is as dangerous as any other fuel available. Ultra sensitive hydrogen sensors are urgently needed for fast detection of hydrogen leakage at any level, such as the H 2 leaks in solid oxide fuel cells (SOFC). This investigation is being performed in collaboration with the Materials Science Division of Argonne National Laboratory. Nanotubes have been selected because their high surface-to- volume ratio will lower requirements for critical volumes of H 2 to be detected without compromising the sensitivity of the sensor. Pd-nanotube assemblies will be processed by ANL and initial hydrogen sensing tests will be conducted at their facilities. The nanostructured MOS sensor will be assembled at UIC- Microfabrication Laboratory; this will be tested first in H 2 atmospheres, where the H 2 levels and temperature will be adjusted. The final stage of the study will involve field testing in SOFC’s and detect hydrogen evolution in acidic corrosion of metals. Pd nanotube assemblies have been fabricated successfully at the Argonne National Laboratory. Pd nanotubes excel in high sensitivity, low detection limit, and fast response times in hydrogen sensing. These nanotubes show an expanded surface area and granular nature, in addition to the high capability for dissociation of molecular hydrogen. Electrochemical techniques will be used to monitor H 2 evolution with time. These nanotubes will be incorporated into the design and fabrication of a nanostructured MOS sensor which will be evaluated for H 2 detection. Self-sustained membrane oxide material p - Semiconductor Pd imbedded nanotubes p - Semiconductor

Nanocrystalline Carbide Derived Carbon for Tribological Applications Investigators: Michael McNallan, Civil and Materials Engineering, UIC; Ali Erdemir, Argonne National Laboratory Prime Grant Support: U.S. Department of Energy Problem Statement and Motivation Technical Approach Key Achievements and Future Goals Mechanical Seals and bearings fail due to frictional heating and wear Materials used are hard ceramics, such as SiC or WC Friction can be reduced by coating with carbon as graphite or diamond Graphitic coatings are not wear resistant Diamond coatings are wear resistant, but fail by spallation or delamination from the underlying ceramic Produce a low friction carbon layer by chemical conversion of the surface of the carbide SiC(s) + 2C l2 (g)  SiCl 4 (g) + C(s) At temperatures < 1000 o C, carbon cannot relax into equilibrium graphitic state and remains as Carbide Derived Carbon (CDC) CDC coating contains nano-porous amorphous C, fullerenes, and nanocrystalline diamond CDC is low friction, wear resistant, and resistant to spallation and delamination CDC has been produced in the laboratory It’s structure and conversion kinetics have been characterized Tribological performance was verified in laboratory and industrial scale pump tests with water CDC was patented and selected for an R&D 100 Award in 2003 CDC was Licensed to Carbide Derivative Technologies, Inc.in 2006 Scale up to industrial production rates, characterization of process reliability and testing in specific industrial environments is the next goal. max. safe temperature SiC-CDC SiC-SiC Pump seal face temperature during dry running at 4000 rpm With and without CDC coating