Investigation of Surface Interactions between Volatile Chromium Species & Ceramics, by Greg Tatar
- Monday, November 13, 2017 from 2:10pm to 3:00pm
- Jake Jabs Hall, Room 415 - view map
Volatile chromium species are formed when chromium containing materials are exposed to high temperature (>500°C) oxidizing environments. The most prevalent chromium containing material exposed to high temperature environments is stainless steel. Chromium in stainless steel generally forms a protective surface oxide layer (e.g., Cr2O3), which provides a barrier to corrosive species and slows the rate of corrosion. However, under certain conditions the chromium in this protective layer may volatilize to form CrO3 or CrO2(OH)2. The generation of these volatile species are accompanied by several detrimental effects. In solid oxide fuel cells (SOFCs) these species are generated from stainless steel interconnects and subsequently poison the nearby cathode, severely diminishing performance of the SOFC. Generation of volatile chromium species from stainless steel in heat exchangers, boilers, and piping in industry may lead to hexavalent chromium formation in waste water. Hexavalent chromium is toxic and a known carcinogen, so its presence in waste water is an environmental and health concern. Additionally, volatile chromium species may accelerate corrosion of the source material, in this case stainless steel.
The generation of these species and their potential detrimental effects are well established facts, but less is known about how these species interact with materials. Understanding how volatile chromium interacts with materials may allow for mitigation of detrimental effects such as SOFC poisoning or hexavalent chromium formation. To that aim, this research will focus on how volatile chromium species interact with ceramics over a range of temperatures and exposure times. Post exposure characterization will be performed to obtain information about chromium speciation in the form of oxidation states and phase formation.