@article{fusco_oldham_parsons_2019, title={Investigation of the Corrosion Behavior of Atomic Layer Deposited Al2O3/TiO2 Nanolaminate Thin Films on Copper in 0.1 M NaCl}, volume={12}, ISSN={["1996-1944"]}, url={https://www.mdpi.com/1996-1944/12/4/672}, DOI={10.3390/ma12040672}, abstractNote={Fifty nanometers of Al2O3 and TiO2 nanolaminate thin films deposited by atomic layer deposition (ALD) were investigated for protection of copper in 0.1 M NaCl using electrochemical techniques. Coated samples showed increases in polarization resistance over uncoated copper, up to 12 MΩ-cm2, as measured by impedance spectroscopy. Over a 72-h immersion period, impedance of the titania-heavy films was found to be the most stable, as the alumina films experienced degradation after less than 24 h, regardless of the presence of dissolved oxygen. A film comprised of alternating Al2O3 and TiO2 layers of 5 nm each (referenced as ATx5), was determined to be the best corrosion barrier of the films tested based on impedance spectroscopy measurements over 72 h and equivalent circuit modeling. Dissolved oxygen had a minimal effect on ALD film stability, and increasing the deposition temperature from 150 °C to 250 °C, although useful for increasing film quality, was found to be counterproductive for long-term corrosion protection. Implications of ALD film aging and copper-based surface film formation during immersion and testing are also discussed briefly. The results presented here demonstrate the potential for ultra-thin corrosion barrier coatings, especially for high aspect ratios and component interiors, for which ALD is uniquely suited.}, number={4}, journal={MATERIALS}, author={Fusco, Michael A. and Oldham, Christopher J. and Parsons, Gregory N.}, year={2019}, month={Feb} } @article{kumar_fusco_komarasamy_mishra_bourham_murty_2017, title={Understanding effect of 3.5 wt.% NaCl on the corrosion of Al0.1CoCrFeNi high-entropy alloy}, volume={495}, ISSN={0022-3115}, url={http://dx.doi.org/10.1016/j.jnucmat.2017.08.015}, DOI={10.1016/j.jnucmat.2017.08.015}, abstractNote={High entropy alloys are a new class of metallic materials with potential for use in a wide variety of applications including their use in corrosive environment. The present study focused on the corrosion behavior of a single-phase, face-centered cubic high entropy alloy (HEA) Al0.1CoCrFeNi in as-cast condition, and the results are compared with the corrosion behavior of the SS304. The microstructural characterization of the alloys in as-received condition was carried out using optical microscopy, electron backscattered diffraction, energy dispersive spectroscopy, and X-ray diffraction. Corrosion behavior was studied using potentiodynamic polarization test in a 3.5 wt% NaCl solution and electrochemical impedance spectroscopy at room temperature. It was observed that the general corrosion resistance of the HEA was better than that of SS304. Pitting potential of the HEA was found to be superior to that of the SS304. Corrosion pits size was slightly smaller in SS304 than that in the HEA. 3D imaging determined that the pit depths were of the same order in both cases. Overall, the HEA Al0.1CoCrFeNi demonstrated a better resistance to general and pitting corrosion.}, journal={Journal of Nuclear Materials}, publisher={Elsevier BV}, author={Kumar, N. and Fusco, M. and Komarasamy, M. and Mishra, R.S. and Bourham, M. and Murty, K.L.}, year={2017}, month={Nov}, pages={154–163} } @article{fusco_ay_casey_bourham_winfrey_2016, title={Corrosion of single layer thin film protective coatings on steel substrates for high level waste containers}, volume={89}, ISSN={["0149-1970"]}, DOI={10.1016/j.pnucene.2016.02.016}, abstractNote={Single-layer thin film coatings have been deposited on steel substrates and tested for their corrosion resistance. These coatings include TiN, ZrO2, TiO2, Al2O3, and MoS2, and it is proposed that they will act as barriers to provide protection to the steel canisters that are part of the dry cask storage system for high level nuclear waste. Corrosion testing was completed using electrochemical potentiodynamic polarization techniques in aerated 1 M NaCl solution. Results show an exponential increase in corrosion rate with increasing temperature and an exponential decrease in the passive breakdown overpotential, which is directly related to the ability of a material to form and sustain a corrosion-inhibiting passive film in a given environment. Additionally, kinetic activation parameters have been experimentally determined for each material, leading to predictive equations for corrosion rates. The bare and coated samples corrode analogously, indicative of pores allowing the coating and substrate to corrode simultaneously. The samples were also placed in circulating salt brines of varying pH as a supplementary corrosion testing mechanism to explore their corrosivity over extended time. Negligible weight change was experienced by the bare and coated steel samples over a period of 5 months. Increasing the coating thickness and the number of layers may provide higher resistance to uniform and localized corrosion.}, journal={PROGRESS IN NUCLEAR ENERGY}, author={Fusco, Michael A. and Ay, Yasar and Casey, Abigail H. M. and Bourham, Mohamed A. and Winfrey, A. Leigh}, year={2016}, month={May}, pages={159–169} } @article{waly_fusco_bourham_2016, title={Gamma-ray mass attenuation coefficient and half value layer factor of some oxide glass shielding materials}, volume={96}, ISSN={["0306-4549"]}, DOI={10.1016/j.anucene.2016.05.028}, abstractNote={The variation in dosimetric parameters such as mass attenuation coefficient, half value layer factor, exposure buildup factor, and the photon mean free path for different oxide glasses for the incident gamma energy range 0.015–15 MeV has been studied using MicroShield code. It has been inferred that the addition of PbO and Bi2O3 improves the gamma ray shielding properties. Thus, the effect of chemical composition on these parameters is investigated in the form of six different glass compositions, which are compared with specialty concrete for nuclear radiation shielding. The composition termed 'Glass 6' in this paper has the highest mass attenuation and the smallest half value layer and may have potential applications in radiation shielding. An example dry storage cask utilizing an additional layer of Glass 6 as an intermediate shielding layer, simulated in MicroShield, is capable of reducing the exposure rate at the cask surface by over 20 orders of magnitude compared to the case without a glass layer. Based on this study, Glass 6 shows promise as a gamma-ray shielding material, particularly for dry cask storage.}, journal={ANNALS OF NUCLEAR ENERGY}, author={Waly, El-Sayed A. and Fusco, Michael A. and Bourham, Mohamed A.}, year={2016}, month={Oct}, pages={26–30} } @article{waly_fusco_bourham_2017, title={Impact of specialty glass and concrete on gamma shielding in multi-layered PWR dry casks}, volume={94}, ISSN={0149-1970}, url={http://dx.doi.org/10.1016/j.pnucene.2016.09.017}, DOI={10.1016/j.pnucene.2016.09.017}, abstractNote={There is a strong likelihood that dry casks will be relied upon for many decades to come as the storage system for nuclear spent-fuel high-level waste (HLW), which places importance on robust shielding materials for cask construction. A dry cask with multi-layered shielding has been simulated in MicroShield v9.05 to determine exposure rates due to gamma-rays at the outer cask surface. The cask consists of a 0.27 ft thick stainless steel type 303Cu waste basket, a 0.2 ft thick lead oxide glass shielding layer (named as Glass 6), and a 1.8 ft thick overpack made of a specialty high density concrete (named as Concrete 6). Three spent fuel configurations have been used as photon sources, which include one high burnup (72 GWd/MTU) and two medium burnup (38.6 GWd/MTU) fuels. The cumulative exposure rate over all photon energies from 15 keV to 2 MeV is 6.81E-6 mR/h at the outer cask surface for the high burnup spent fuel. This is roughly one order of magnitude smaller than if the glass layer were replaced with an equivalent thickness of Concrete 6 and is 3–4 orders of magnitude smaller than replacing the specialty concrete with ordinary, standard density concrete. Varying the ratio of the glass thickness to the concrete thickness significantly impacts the shielding effectiveness, which should be considered along with structural and thermal stability for dry cask designs.}, journal={Progress in Nuclear Energy}, publisher={Elsevier BV}, author={Waly, El-Sayed A. and Fusco, Michael A. and Bourham, Mohamed A.}, year={2017}, month={Jan}, pages={64–70} } @article{gallala_hayouni_gaied_fusco_alsaied_bailey_bourham_2017, title={Mechanical and radiation shielding properties of mortars with additive fine aggregate mine waste}, volume={101}, ISSN={0306-4549}, url={http://dx.doi.org/10.1016/j.anucene.2016.11.022}, DOI={10.1016/j.anucene.2016.11.022}, abstractNote={Incorporation of barite-fluorspar mine waste (BFMW) as a fine aggregate additive has been investigated for its effect on the mechanical and shielding properties of cement mortar. Several mortar mixtures were prepared with different proportions of BFMW ranging from 0% to 30% as fine aggregate replacement. Cement mortar mixtures were evaluated for density, compressive and tensile strengths, and gamma ray radiation shielding. The results revealed that the mortar mixes containing 25% BFMW reaches the highest compressive strength values, which exceeded 50 MPa. Evaluation of gamma-ray attenuation was both measured by experimental tests and computationally calculated using MicroShield software package, and results have shown that using BFMW aggregates increases attenuation coefficient by about 20%. These findings have demonstrated that the mine waste can be suitably used as partial replacement aggregate to improve radiation shielding as well as to reduce the mortar and concrete costs.}, journal={Annals of Nuclear Energy}, publisher={Elsevier BV}, author={Gallala, Wissem and Hayouni, Yousra and Gaied, Mohamed Essghaier and Fusco, Michael and Alsaied, Jasmin and Bailey, Kathryn and Bourham, Mohamed}, year={2017}, month={Mar}, pages={600–606} } @article{fusco_winfrey_bourham_2016, title={Shielding properties of protective thin film coatings and blended concrete compositions for high level waste storage packages}, volume={89}, ISSN={["0306-4549"]}, DOI={10.1016/j.anucene.2015.11.026}, abstractNote={Various thin film coatings have been proposed to protect stainless steel high level waste (HLW) containers from premature failure due to localized corrosion, hydrogen embrittlement, and mechanical wear. These coatings include TiN, ZrO2, MoS2, TiO2, and Al2O3, to be deposited either in multiple layers or as a thicker, single-layer composite. Linear attenuation coefficients of these materials have been simulated using MicroShield and measured experimentally for various photon energies. Additionally, spent fuel casks with overpacks made of two different types of concrete were simulated to compare exposure rate at the cask surface. In the energy range that is significant for high level waste storage all coating materials possess very similar attenuation behavior. A specialty concrete, containing magnetite (Fe3O4) and lead oxide (PbO), reduces the exposure rate at the outer surface of the overpack by several orders of magnitude. The higher-Z elements not present in ordinary concrete greatly increase attenuation of intermediate-energy gammas (0.4–1.0 MeV). The thin film coatings do not affect the shielding capabilities of the HLW packaging, as their total proposed thickness is nearly three orders of magnitude less than the mean free path (MFP) of the primary photons of interest.}, journal={ANNALS OF NUCLEAR ENERGY}, author={Fusco, Michael A. and Winfrey, Leigh and Bourham, Mohamed A.}, year={2016}, month={Mar}, pages={63–69} }