Dennis Michael Gray

Corrosion Potential Behavior in High-Temperature Water of Noble Metal-Doped Alloy Coatings Deposited by Underwater Thermal Spraying

Abstract The electrochemical corrosion potential (ECP) of type 304 (UNS S30400) stainless steel (SS) coated under water by hyper-velocity oxy-fuel (HVOF) and plasma-spray (PS) techniques using noble metal-doped powders was measured to evaluate the catalytic behavior in high-temperature water under various water chemistry conditions. Thermal-spray coatings of noble metal-doped powders exhibited catalytic behavior for the recombination of oxygen and hydrogen in high-temperature water, which caused ECP to decrease well below a critical value of −230 mVSHE for intergranular stress corrosion cracking (IGSCC) protection in water. This was observed in water containing various amounts of oxygen and hydrogen peroxide (H2O2) when stoichiometric excess hydrogen was present.

Modification of Surface Property for Controlling the Type 304 Stainless Steel Electrochemical Corrosion Potential in 288°C Water

Abstract The thermal spray coating technique was used to produce insulated protective coatings (IPC) on Type 304 (UNS S30400) stainless steel (SS) surfaces. The electrochemical corrosion potential ...

Surface Temperature Measurement of Thermal Barrier Coatings Using Infrared Pyrometry

A method for measuring surface temperature of semitransparent materials was developed and used to measure temperature gradients through a yttria-stabilized zirconia thermal barrier coating (TBC) heated on the front surface with a natural gas flame. A Pt stripe was deposited on the TBC surface, and its temperature was measured using infrared pyrometry at 10.6 μm. A model was developed to determine the radiant intensity emitted from a TBC on a metal substrate with a thermal gradient. The radiant intensity from TBCs was measured as a function of thermal gradient and compared with results of the model.Copyright

Development of Nanostructured and Nanoparticle Dispersion-Reinforced Metallic Systems - Progress and Challenges

Investigations on nanostructured metallic systems have shown that exceptional property enhancements are potentially achievable through structural refinement to the nano-scale. While dramatic property improvements have been reported on these materials in the past, significant technical challenges exist in processing, as well as in retention of microstructural stability and useful properties at elevated temperatures. This presentation will summarize the key challenges in developing nanostructured metallic systems, and highlight our progress and selected successes in the understanding of structure-property relationships in bulk nanostructures as well as nanostructured multilayered systems. Work in nanoparticle dispersion-strengthened metallic systems will also be highlighted in this presentation.