Thermal Spray Processing of Ceramic Oxide Coatings: An Integrated Approach

Abstract of Dissertation: Thermal Spray Processing of Ceramic Oxide Coatings: An Integrated Approachby Jose Rafael Colmenares AnguloDoctor of Philosophy in Materials Science and EngineeringStony Brook University 2010Thermal spray represents a complex processing technology given the stochastic nature of rapid splat melting, impact and solidification. The present work represents a series of studies with the aim of improving the understanding of process-property relationships on ceramic oxides integrating recent work from the Center of Thermal Spray Research regarding particle and non-particle state issues intrinsic to thermal spray processing with material specific applicationsIssues regarding reliability of two-wavelength pyrometry and time-of-flight methods for thermal spray sensing are analyzed using a simultaneous comparative approach for HVOF and APS techniques with 5 different commercial sensors. Injection visualization techniques are included to analyze particle-plume interactions and the limitations of commercial ensemble measurements for first order process maps and repeatability measurements are discussed.Titanium dioxide coating formation mechanisms are examined with a wide range of process techniques and conditions applying an extended process map approach. Routes for coating formation from a microstructural, crystalline and stoichiometric perspective are correlated to issues of photocatalytical, electrical and thermal transport. The role of deposition rate as a key parameter in defining coating stress state is discussed, while particle state variations are found to be more significant in controlling phase content and transport properties. A key finding of this work is that the stochiometric distortions on TiO2 induced by thermal spray processing have a higher effect on coating photocatalytical activity than the fraction of metastable anatase phase.Novel techniques and applications are analyzed from a process oriented perspective including characterization of individual splats and ensemble coating properties. Precursor/Solution thermal spray coating and splat morphological characteristics are attributed mainly to atomization issues. 1st and 2nd order process maps of alumina-chromia coatings for fluorescent mapping of accelerated proton beams where constructed with the aim of increasing the fraction of the stable alpha phase and optimizing coating luminescence for the intended applicatio

Thermal Spray Processing of Ceramic Oxide Coatings: An Integrated Approach

Abstract of Dissertation: Thermal Spray Processing of Ceramic Oxide Coatings: An Integrated Approachby Jose Rafael Colmenares AnguloDoctor of Philosophy in Materials Science and EngineeringStony Brook University 2010Thermal spray represents a complex processing technology given the stochastic nature of rapid splat melting, impact and solidification. The present work represents a series of studies with the aim of improving the understanding of process-property relationships on ceramic oxides integrating recent work from the Center of Thermal Spray Research regarding particle and non-particle state issues intrinsic to thermal spray processing with material specific applicationsIssues regarding reliability of two-wavelength pyrometry and time-of-flight methods for thermal spray sensing are analyzed using a simultaneous comparative approach for HVOF and APS techniques with 5 different commercial sensors. Injection visualization techniques are included to analyze particle-plume interactions and the limitations of commercial ensemble measurements for first order process maps and repeatability measurements are discussed.Titanium dioxide coating formation mechanisms are examined with a wide range of process techniques and conditions applying an extended process map approach. Routes for coating formation from a microstructural, crystalline and stoichiometric perspective are correlated to issues of photocatalytical, electrical and thermal transport. The role of deposition rate as a key parameter in defining coating stress state is discussed, while particle state variations are found to be more significant in controlling phase content and transport properties. A key finding of this work is that the stochiometric distortions on TiO2 induced by thermal spray processing have a higher effect on coating photocatalytical activity than the fraction of metastable anatase phase.Novel techniques and applications are analyzed from a process oriented perspective including characterization of individual splats and ensemble coating properties. Precursor/Solution thermal spray coating and splat morphological characteristics are attributed mainly to atomization issues. 1st and 2nd order process maps of alumina-chromia coatings for fluorescent mapping of accelerated proton beams where constructed with the aim of increasing the fraction of the stable alpha phase and optimizing coating luminescence for the intended applicationAdvisor(s): Sanjay Sampath. Committee Member(s): Herbert Herman; David Welch; Seiji Kuroda.Stony Brook University Libraries. SBU Graduate School in Department of Materials Science and Engineering. Lawrence Martin (Dean of Graduate School)

Between algorithm and model: different Molecular Surface definitions for the Poisson-Boltzmann based electrostatic characterization of biomolecules in solution.

The definition of a molecular surface which is physically sound and computationally efficient is a very interesting and long standing problem in the implicit solvent continuum modeling of biomolecular systems as well as in the molecular graphics field. In this work, two molecular surfaces are evaluated with respect to their suitability for electrostatic computation as alternatives to the widely used Connolly-Richards surface: the blobby surface, an implicit Gaussian atom centered surface, and the skin surface. As figures of merit, we considered surface differentiability and surface area continuity with respect to atom positions, and the agreement with explicit solvent simulations. Geometric analysis seems to privilege the skin to the blobby surface, and points to an unexpected relationship between the non connectedness of the surface, caused by interstices in the solute volume, and the surface area dependence on atomic centers. In order to assess the ability to reproduce explicit solvent results, specific software tools have been developed to enable the use of the skin surface in Poisson-Boltzmann calculations with the DelPhi solver. Results indicate that the skin and Connolly surfaces have a comparable performance from this last point of view

Machine learning risk prediction of mortality for patients undergoing surgery with perioperative SARS-CoV-2: the COVIDSurg mortality score

To support the global restart of elective surgery, data from an international prospective cohort study of 8492 patients (69 countries) was analysed using artificial intelligence (machine learning techniques) to develop a predictive score for mortality in surgical patients with SARS-CoV-2. We found that patient rather than operation factors were the best predictors and used these to create the COVIDsurg Mortality Score (https://covidsurgrisk.app). Our data demonstrates that it is safe to restart a wide range of surgical services for selected patients.</jats:p