Добірка наукової літератури з теми "Solid chromium's etching"

In solid oxide fuel cells (SOFC) for operating temperatures of 800 °C or below, the use of ferritic stainless steel can lead to degradation in cell performance due to chromium migration into the cells at the cathode side [1]. Application of a coating on the ferritic stainless steel interconnect is one option to prevent Cr outward migration through the coating. MnCo1.9Fe0.1O4 (in the following designated as MCF) spinels act as a diffusion barrier and retain high conductivity during operation [2]. Knowledge about the residual stress depth distribution throughout the complete APS coating system is important and can help to optimize the coating process. This implicitly requires reliable residual stress analysis in the coating, the interface region and in the substrate.For residual stress analysis on these specific layered systems diffraction based analysis methods (XRD) using laboratory X-ray sources can only by applied at the very surface. For larger depths sublayer removal is necessary to gain reliable residual stress data. The established method for sublayer removal is electrochemical etching, which fails, since the spinel layer is inert. However, a mechanical layer removal will affect the local residual stress distribution.As an alternative, mechanical residual stress analyses techniques can be applied. Recently, we established an approach to analyse residual stress depth distributions in thick film systems by means of the incremental hole drilling method [5, 6]. In this project, we refined our approach for the application on MCF coatings with a layer thickness between 60 – 125 μm.

I founded Faraday Technology, Inc. in 1991 to conduct research and development directed towards novel electrochemical technologies for improved electrodeposition processes. The resulting innovations were patented and commercialized/transitioned to industrial/governmental partners via patent licenses or patent sales. The initial start-up funding was predominately from the U.S. Small Business Innovative Research (SBIR) or Small Business technology Transfer (STTR) programs. After initial feasibility demonstration and validation, the patented technologies were adapted to specific client needs with client funding for the option to license or acquire. In order to avoid the “feast or famine” associated Principal Investigator centric contract R&D firms, Faraday’s business model was based on a well-defined technology platform with applications in numerous markets and therefore amenable to multiple sources of funding. This business model emphasizes “strategic proposal development” based on exploring applications of the technology platform with team proposal conceptualization/writing and is used by the DOE as an instructional video for start-up companies.[1] The technology platform was pulse/pulse reverse current (P/PRC) electrolysis. Since the founding of Faraday. The pulse/pulse reverse technology platform has resulted in 129 patents and patent applications directed towards industrial markets including automotive, medical, energy, electronics and applications including electrodeposition, surface finishing and chemical conversions. The concept of P/PRC plating is not new and was first reported at least in the early part of the nineteenth century.[2] The guiding principles of P/PRC plating were presented in 1986 in a classic compendium.[3] A more recent treatise was published in 2012.[4] Many of the studies directed towards practical applications of P/PRC plating used the existing plating baths containing chemical additions optimized for DC plating. In developing practical applications of P/PRC plating, two questions were critical to Faraday’s vision: Are the plating bath additives optimized for direct current plating optimum for P/PRC plating? Assuming the answer is “no”, can P/PRC plating enable simpler plating baths with low or no chemical additives? Consequently, Faraday’s initial founding vision was to: “...change the focus of electrodeposition processes from the use of electrolytes with multicomponent chemical additions to the use of simpler electrolytes enabled by pulse current/pulse reverse current electric fields...” With the successful development of plating processes devoid of chemical additives, this vision evolved to include P/PRC anodic dissolution or surface finishing processes such as deburring, electrochemical machining, electropolishing and electrochemical through-mask etching. This broadening of the vision was based on observations and speculations that the lessons learned from cathodic P/PRC electrodeposition processes could be adapted to anodic pulse/pulse reverse surface finishing processes. Consequently, Faraday’s current vision is broadened to: “...change the focus of electrochemical manufacturing/engineering processes from the use of electrolytes with multicomponent chemical additions to the use of simpler electrolytes enabled by pulse current/pulse reverse current electric fields...” This evolving vision has led to numerous innovations in industrial surface finishing[5] and sustainable[6] industrial processes. Some of these innovations based on P/PRC have been recognized with awards including 1) the Blum Scientific Achievement Award from the National Association for Surface Finishing for “...outstanding scientific contributions which have advanced the theory and practice of electroplating, metal finishing and allied arts”, 2) a 2011 R&D 100 award for electrodeposition of cobalt manganese alloys for solid oxide fuel cell interconnects, 3) a 2013 Presidential Green Chemistry Challenge award for deposition of functional chromium from a trivalent chromium plating bath, 4) a 2016 R&D 100 finalist award for electropolishing of materials in low viscosity electrolytes devoid of hydrofluoric acid, and 5) the 2020 New Electrochemical Technology award from the IE&EE division for electropolishing of niobium superconducting devices for high energy physics applications. I will provide an overview of Faraday’s P/PRC innovations, some of which are recently summarized.[7] I will conclude with some thoughts on additional applications of P/PRC processes such as chemical conversions and high-rate electrowinning. I acknowledgeMaria Inman, Tim Hall and my many colleagues, past and present at Faraday as well as Faraday’s many collaborators and sources of funding. See https://science.osti.gov/SBIRLearning/Faraday-Technology-Inc J. Gillis, U.S. Patent No. 1,260,661 issued March 26, 1918. J.C. Puippe and F. Leaman, Eds., Theory and Practice of Pulse Plating, AESF, Orlando, FL, (1986). W. E. G. Hansel and S. Roy, Pulse Plating, Leuze Verlag KG, Germany (2012). E. J. Taylor and M. E. Inman, Electrochem. Soc. Interface Fall 23 57 (2014). T. D. Hall, M. E. Inman, and E. J. Taylor, Electrochem. Soc. Interface 29 49 (2020). 7. J. Taylor et al in Advances in Electrochemical Science & Engineering: The Path from Discovery to Product, R. C. Alkire et al., Editors, p. 193-240, Wiley-VCH, New York (2018).

ABSTRACTAdhesion layers are well-known to significantly improve the lifetime of MoS2-based solid lubricants. Typically, adhesion layers are “optimized” based on a phenomenological tests and then their deposition parameters are held fixed while the functional coating is studied. Here we examine the adhesion layer itself, while holding an MoS2 layer constant. In particular, the critical interfaces between the adhesion layer and the substrate, and between the adhesion layer and functional coating are regarded. MoS2-metal solid lubricant is chosen as the functional layer because it is a relatively brittle material whose performance is significantly affected by the quality and type of adhesion treatments. Substrate surface sputter cleaning was done by cathodic arc evaporation with different arc energies and substrate bias voltages. In addition to sputter etching of any surface oxides or other contaminants, some level of shallow implantation might be expected. The more usual surface preparation technique of argon plasma sputter etching was also used for comparison. Chromium and titanium were tested as adhesion layer materials. The adhesion layer thickness and deposition pressure were varied. Rutherford backscattering spectroscopy (RBS) and transmission electron microscopy (TEM) were used to analyze the adhesion layers and their interfaces with the substrates and with the MoS2-metal coatings. Ballon-disk tribometer sliding wear tests were made to assess changes in solid lubricant performance coming from variations in the adhesion layer. Scratch test characterizations were made to further evaluate adhesion layer performance.

Hydrodeoxygenation of oxygen-rich molecules toward hydrocarbons is attractive yet challenging in the sustainable biomass upgrading. The typical supported metal catalysts often display unstable catalytic performances owing to the migration and aggregation of metal nanoparticles (NPs) into large sizes under harsh conditions. Here, we develop a crystal growth and post-synthetic etching method to construct hollow chromium terephthalate MIL-101 (named as HoMIL-101) with one layer of sandwiched Ru NPs as robust catalysts. Impressively, HoMIL-101@Ru@MIL-101 exhibits the excellent activity and stability for hydrodeoxygenation of biomass-derived levulinic acid to gamma-valerolactone under 50°C and 1-megapascal H 2 , and its activity is about six times of solid sandwich counterparts, outperforming the state-of-the-art heterogeneous catalysts. Control experiments and theoretical simulation clearly indicate that the enrichment of levulinic acid and H 2 by nanocavity as substrate regulator enables self-regulating the backwash of both substrates toward Ru NPs sandwiched in MIL-101 shells for promoting reaction with respect to solid counterparts, thus leading to the substantially enhanced performance.

La structuration à l’échelle submicronique de la surface des aciers inoxydables permet de leur apporter de nouvelles fonctionnalités, par exemple pour des applications tribologiques et optiques. Cette thèse s’inscrit dans le cadre du projet ANR SPOT qui a pour objectif de structurer à l’échelle submicronique la surface d’aciers austénitiques et martensitiques par gravure sèche. Dans ce travail, nous avons développé un procédé plasma avec un mélange de chlore et d’argon pour la gravure des aciers inoxydables. La mise au point de ce procédé a été réalisée en se basant sur l’étude de la gravure des métaux principaux qui composent ces aciers, à savoir, le fer, le chrome et le nickel. En se basant sur des mesures de vitesses de gravure, ainsi que sur des techniques de diagnostics plasmas, nous avons montré que, dans un plasma de chlore et d’argon, le fer est l’élément qui se grave le plus, suivi du chrome puis du nickel. Les échantillons métalliques ainsi que les aciers inoxydables gravés ont été analysés par des techniques de caractérisation de surface notamment des analyses de spectrométrie photoélectronique X (XPS). Nous avons également étudié la variation des vitesses de gravures de ces métaux et de ces aciers en fonction de la température des substrats. Ces études nous ont permis d’établir les mécanismes mis en jeu en cours de la gravure des éléments métalliques. Nous avons montré que, dans un plasma de chlore et d’argon, le fer se grave principalement par un mécanisme chimique qui suit une loi d’Arrhenius. Ce mécanisme serait basé sur la formation de chlorures de fer volatiles. Dans le cas du chrome, la gravure nécessite une assistance ionique afin de désorber les chlorures de chrome non volatiles formés à la surface du matériau. Enfin, pour le nickel, nous avons observé que la vitesse de gravure diminue lorsque la température augmente. Dans ce cas, des observations au microscope électronique à balayage ont permis de mettre en évidence la formation de gonflements riches en chlore. Les analyses XPS de la surface gravée du nickel suggère que ces gonflements sont dus à la formation de chlorures de nickel non volatiles. Ces chlorures seraient à l’origine de la diminution de la vitesse de gravure du nickel dont la pulvérisation se trouverait bloquée par la présence de ces chlorures. La compréhension de ces mécanismes a permis de conclure que, dans un plasma chloré, l’élément bloquant dans la gravure des aciers inoxydables est le nickel
The structuring at sub-micronic scale of the surface of stainless steels allows to provide them with new functionalities, for example for tribological and optical applications. This thesis is part of the ANR SPOT project which aims to structure the surface of austenitic and martensitic steels on a submicronic scale by dry etching. In this work, we have developed a plasma process with a mixture of chlorine and argon for the etching of stainless steels. The development of this process was carried out based on the study of the etching of the main metals that make up these steels, namely, iron, chromium and nickel. Based on measurements of etching speeds, as well as on plasma diagnostic techniques, we have shown that, in a chlorine and argon plasma, iron is the most etched element, followed by chromium, then nickel. The metallic and the stainless steels etched samples were analyzed by surface characterization techniques, in particular X photoelectron spectrometry (XPS) analyzes. We have also studied the variation of the etching speeds of these metals and steels as a function of the temperature of the substrates. These studies have enabled us to establish the mechanisms involved in the etching of metallic elements. We have shown that in a plasma of chlorine and argon, iron is mainly etched by a chemical mechanism which follows an Arrhenius law. This mechanism would be based on the formation of volatile iron chlorides. In the case of chromium, the etching requires ionic assistance in order to desorb the non-volatile chromium chlorides formed on the surface of the material. Finally, for nickel, we observed that the etching speed decreases when the temperature increases. In this case, observations with a scanning electron microscope made it possible to highlight the formation of swellings rich in chlorine. XPS analyzes of the etched surface of nickel suggest that these swellings are due to the formation of non-volatile nickel chlorides. These chlorides would be at the origin of the decrease in the rate of etching of nickel, the sputtering of which would be blocked by the presence of these chlorides. Understanding these mechanisms led to conclude that, in a chlorinated plasma, the blocking element in the etching of stainless steels is nickel