Coatings and Surface Engineering for Environmental Protection II: Corrosion Control Session I
Sponsored by: TMS Structural Materials Division, TMS: Corrosion and Environmental Effects Committee
Program Organizers: Arif Mubarok, PPG; Raul Rebak, GE Global Research; Rajeev Gupta, North Carolina State University; Tushar Borkar, Cleveland State University; Brian Okerberg, PPG Industries; Michael Mayo, PPG Industries
Wednesday 8:30 AM
February 26, 2020
Room: 19
Location: San Diego Convention Ctr
Session Chair: Rajeev Gupta, North Carolina State University; Tushar Borkar, Cleveland State University
8:30 AM Invited
Chloride Susceptibility Index (CSI) : An Ab initio Based Corrosion Resistance Indicator: Huibin Ke1; Pin Lu2; Christopher Taylor1; 1The Ohio State University; 2QuesTek
Many properties have been used to indicate the corrosion resistance of metallic materials. However, there is still no single property that can be used to compare across different alloy system and predict the corrosion resistance of metallic materials. Here, a universal scientifically based quantitative indicator called chloride susceptibility index (CSI) is introduced based on a multi-scale modeling framework. This framework can be applied to study the effect of different factors on corrosion resistance of alloys, including alloy composition, solution pH, Cl- concentration and temperature. Firstly, ab initio modeling is used to study the adsorption energy of O and Cl to alloy surfaces with different solutes. Then, a Langmuir model is used to study the competitive adsorption of Cl vs. O under different conditions, from which CSI will be calculated. Finally, experimental measured repassivation potential is compared with CSI and a strong linear relationship is found between these two.
8:50 AM
A Study of the Effects of Laser Shock Peening (LSP) on the Susceptibility of Sensitized 304L Stainless Steel to Intergranular Corrosion: Richard Chiang1; Harsha Naralasetty1; Seetha Mannava1; Matthew Steiner1; Vijay Vasudevan1; 1University of Cincinnati
Austenitic 304L stainless steel is the main material used for spent nuclear fuel storage canisters and is susceptible to pitting and stress corrosion cracking under certain conditions of humidity, temperature and salt chemistry. In this investigation, the effects of laser shock peening (LSP) with and without an ablative coating on the corrosion resistance of sensitized 304L stainless steel (SS) was studied using DLEPR to evaluate the degree of sensitization (DOS) and susceptibility to intergranular attack (IGA). Characterization of the microstructure was conducted using SEM, TEM, EBSD and XRD. The results indicate a notable impact of the LSP process on the susceptibility of 304L SS under corrosive conditions. The specific complexities as effected by the varying LSP treatments (residual stress, deformation-induced martensite, etc.) and their aforementioned effects will be presented and discussed.
9:10 AM
Contact Resistance and Corrosion Response of Non-chromate Passivations on ZnNi Coatings: Kevin Foster1; William Fahrenholtz1; Matthew O'Keefe2; James Claypool1; 1Missouri University of Science and Technology; 2The University of Mississippi
Two electrically conductive <100 nm thick non-chromate passivations on ZnNi coatings were studied, a trivalent chromium based passivation (TCP), and a cobalt-free TCP. Contact resistance measurements were taken according to MIL-STD-81706B and showed that unpolished panels had lower resistances than polished panels for both passivations. In addition, Co-Free TCP passivations tended to have lower resistance after salt spray exposure than TCP. Optical microscopy showed less corrosion after 1000 hours salt spray on Co-Free TCP, but open circuit potentials, chronopotentiodynamic scans, and electrochemical impedance spectra for both passivations suggested little change in chemical behavior at sample surface. Both passivations offer increased corrosion resistance compared with unpassivated samples and the removal of cobalt may increase the corrosion resistance of trivalent chromium based passivations.
9:30 AM
Corrosion Phenomena in Powder-processed Icosahedral-phase-strengthened Aluminum Alloys: Sarshad Rommel1; Hannah Leonard1; Mingxuan Li1; Thomas Watson2; Tod Policandriotes3; Mark Aindow1; 1University of Connecticut; 2Pratt & Whitney; 3Collins Aerospace
Recently, we have developed an Al-Cr-Mn-Co-Zr alloy that exhibits a nano-composite FCC Al matrix plus I-phase dispersoid microstructure in gas-atomized powder. This alloy shows a variation in both the morphology/distribution of the I-phase, and the composition of the matrix, depending on the size range of the gas atomized powder particles. These microstructures are retained during consolidation of the powder to form bulk materials, but are altered significantly during upset forging of this consolidated bulk alloy. The corrosion resistance and near-surface I-phase stability of both the as-consolidated and the upset forged alloys upon exposure to chloride-rich aqueous media are investigated through a combination of electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy techniques. These results are discussed as a function of the local variation in the I-phase microstructure and the Al matrix composition.
9:50 AM
Effect of Surface Coating on Corrosion Product Deposition Behavior in PWR Fuel Cladding: Junhyuk Ham1; Yunju Lee1; Seung Chang Yoo1; Ji Hyun Kim1; 1UNIST
CRUD resistant coating effect on fuel cladding in primary water condition of pressurized water reactor was investigated. Two different materials which can reduce Van der Waals force between surface and CRUD particle were coated; TiN and ZrN. Each substance was coated under physical vapor deposition method. Test conditions were set by thermohydraulics calculations to generate sub-cooled boiling on the upper side of cladding surface. CRUD distribution and cross-sectional morphology analyses were conducted by scanning electron microscope and focused ion beam. Chemical composition of CRUD was measured by energy dispersive X-ray spectroscopy.The experiments with zirconium cladding and CRUD resistant coated claddings were conducted during 7 and 14 days respectively. The thickness of CRUD on zirconium cladding was the thickest compared to that of TiN and ZrN coated cladding. The chemical composition of CRUD deposited right above the heated zirconium cladding surface was different to that of other cases.
10:10 AM Break
10:25 AM
Electrochemical Impedance Spectroscopic Study of Oxide Scales on Pure Iron in Liquid Lead-bismuth Eutectic: Jie Qiu1; Peter Hosemann1; Digby Macdonald1; John Scully1; 1University of California at Berkeley
The impedance behavior of pre-oxidized pure iron in liquid lead-bismuth eutectic (LBE) was studied using electrochemical impedance spectroscopy. The resistance of the oxide scale on the iron oxidized in air at different temperatures and for different durations are studied. Results show that the impedance of the oxide film increases with increasing the oxidation temperature. The impedance of the samples oxide at 200 oC and 400 oC were negligible, indicating the oxide film formed at low temperature was too thin to prevent LBE penetrate into the oxide scale. At temperatures above 600 oC, a compact “p-type” Wüstite oxide scale is formed on iron while the resistance of the oxide film increases with increasing temperature, due to the formation of a thicker scale. At the same temperature, prolonging the oxidation time in air can reduce the defect concentration in the oxide film and improve the oxide scale corrosion resistance in LBE.
10:45 AM
Estimating the Effect that Interactions between Chemical Reactions and Environmental Influences Have on the Corrosivity of the Electrolyte: Steven Policastro1; Rachel Anderson1; Carlos Hangarter1; 1Naval Research Laboratory
Bulk electrolytes generally maintain consistent chemical properties even as the environment changes or as chemical reactions occur. However, because of the discrete nature of the electrolytes formed from atmospheric processes, changes in temperature and relative humidity as well as chemical reactions between oxidized metal atoms and electrolyte components can impact the nature of the electrolyte, and thereby its corrosivity, over relatively short time scales. In this work, we develop a continuum model of the atmospheric processes that affect water film formation and loss that includes effects on solution resistivity, dissolved gas concentrations, and chemical reactions, in order to simulate the effect these changes have on the corrosion of a galvanic couple between a stainless steel and an aluminum alloy and compare the results of the calculated corrosion current under a variety of conditions to experimental measurements made on a galvanic couple set-up in a controlled atmosphere chamber.
11:05 AM
Evaluation of Surface Characteristics of Cr-coated Zr-4 Accident Tolerant Fuel Cladding Material after Critical Heat Flux Testing under Atmospheric Pressure: Rajnikant Umretiya1; Jessika Rojas1; Mark Anderson2; Barret Elward2; Raul Rebak3; Sama Bilbao y Leon1; 1Virginia Commonwealth University; 2University of Wisconsin-Madison; 3GE Global Research
Fuels with enhanced accident tolerance are those that, in comparison with the current UO2 – zirconium alloy fuel system, can tolerate a loss of active cooling in the reactor core for a considerably longer amount of time, while maintaining, or improving the fuel performance during normal operations and operational transients. Preliminary studies for the proposed ATF concepts indicate their cladding surface characteristics may result in substantial impacts in their Critical Heat Flux (CHF) behavior. In this work, the surface characteristics of ATF cladding tubes of Cr-coated Zircaloy-4 before and after CHF testing were investigated. Before CHF test, surface of Cr-coated sample gives a rougher appearance with 10% of increase in average surface roughness (Ra) measured by contact profilometry and qualitatively confirmed using AFM and SEM. Static and dynamic contact angle were assessed using goniometer. Additionally, the surface chemistry was investigated before and after flow boiling test using X-Ray Photoelectron Spectroscopy.
11:25 AM
Elucidating the Degradation Mechanisms of Ti-6Al-4V Dental Implants: Xin Chen1; Kumar Shah1; Shiqi Dong1; Lars Peterson1; Erika La Plante1; Gaurav Sant1; 1University of California, Los Angeles
Titanium alloys (e.g., Ti-6Al-4V alloy) are often used as dental implants due to their suitable durability in oral environments. This study elaborates upon degradation processes undergone by a failed commercial implant, revealing crevice corrosion of the Ti-6Al-4V abutment as the potential cause for bone loss. Because fluorides, which are common additives in dental products, can induce the buildup of aggressive F- ions in crevice environments, the failure mechanism is further rationalized by evaluating the alloy’s electrochemical behavior in fluoride-containing solutions. The electrochemical responses were embodied by topographical evolution revealed using vertical scanning interferometry. Interestingly, a reversal in preferential corrosion of the α-phase to the β-phase, under conditions of applied potentials was observed. These findings elucidate the degradation mechanisms of the Ti-6Al-4V alloy in simulated biological fluids, reveal the releasing behavior of corrosion by-products, so that provide insights to means improving the longevity of commercial Ti-6Al-4V implants.