Engineering topics

Tripathy, Prabhat K.

Publications and source records attributed to Tripathy, Prabhat K..

10 records

DOE OSTI2024

Metal coated articles comprising a refractory metal region and a platinum-group metal region, and related methods

A metal coated article includes a platinum-group metal region adjacent a refractory metal region, which is adjacent a substrate comprising an inorganic material. A refractory metal carbide layer is adjacent the substrate and the refractory metal layer is adjacent the refractory metal carbide layer. The platinum-group metal region comprises a refractory metal/platinum-group metal layer and a platinum-group metal layer. Related methods are also disclosed.

Tripathy, Prabhat K.↗

DOE OSTI2024

Methods of forming near-net shape structures from non-stoichiometric oxides

A method of forming a near-net shape structure comprises forming a structure comprising non-stoichiometric metal oxide comprising at least one metal and less than a stoichiometric amount of oxygen, and electrochemically reducing the non-stoichiometric metal oxide in an electrochemical cell to form a structure having a near-net shape and comprising the at least one metal having less than about 1,500 ppm oxygen. Related methods of forming a non-stoichiometric metal oxide by sintering, annealing, or additive manufacturing, and forming a near-net shape structure from the non-stoichiometric metal oxide, as well as related electrochemical cells are also disclosed.

Tripathy, Prabhat K.↗

DOE OSTI2023

Methods of forming a metal coated article

A method of forming a metal coated article, comprises forming a metal halide in a molten salt plating bath at a first temperature, wherein forming the metal halide in the molten salt further comprises forming at least one functional metal halide electrolyte; and forming at least two auxiliary metal halide electrolytes at eutectic conditions; increasing the first temperature to a second temperature; forming a plated metal coating from the at least one functional metal halide electrolyte onto a thermally conductive substrate; and introducing at least one of deuterium and tritium into the plated metal coating.

Tripathy, Prabhat K.↗

DOE OSTI2023

Methods for manufacturing electrochemical sensors, and related electrochemical sensors

Methods for manufacturing an electrochemical sensor include forming at least one electrode by printing at least one conductive ink on a surface of at least one substrate. The conductive ink may comprise, e.g., a platinum-group metal, another transition-group metal with a high-temperature melting point, a conductive ceramic material, glass-like carbon, or a combination thereof. The electrochemical sensor may be free of another material over the at least one electrode. An electrochemical sensor, formed according to such methods, may be configured for use in harsh environments (e.g., a molten salt environment). Electrodes of the electrochemical sensor comprise conductive material formed from a printed, conductive ink. In some embodiments, at least a portion of the electrochemical sensor is free of silver, gold, copper, silicon, and polymer materials, such portion being that which is to be exposed to the harsh environment during use of the electrochemical sensor.

Shaltry, Michael R.↗

DOE OSTI2023

Solution Processed Schottky Diodes Enabled by Silicon Carbide Nanowires for Harsh Environment Applications

Silicon carbide nanowires (SiC NWs) exhibit promising features to allow solution-processable electronics to be deployed in harsh environments. By utilizing a nanoscale form of SiC, we were able to disperse the material into liquid solvents, while maintaining the resilience of bulk SiC. Here, this letter reports the fabrication of SiC NW Schottky diodes. Each diode consisted of just one nanowire with an approximate diameter of 160 nm. In addition to analyzing the diode performance, the effects of elevated temperatures and proton irradiation on the current–voltage characteristics of SiC NW Schottky diodes were also examined. The device could maintain similar values for ideality factor, barrier height, and effective Richardson constant upon proton irradiation with a fluence of 10 16 ion/cm 2 at 873 K. As a result, these metrics have clearly demonstrated the high-temperature tolerance and irradiation resistance of SiC NWs, ultimately indicating that they may provide utility in allowing solution-processable electronics in harsh environments.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2022

On the Sintering Behavior of Nb2O5 and Ta2O5 Mixed Oxide Powders

A mixed oxide system consisting of Nb2O5 and Ta2O5, was subjected to annealing in air/hydrogen up to 950 °C for 1–4 h to study its sintering behavior. The thermogravimetric–differential scanning calorimetry (TGA–DSC) thermograms indicated the formation of multiple endothermic peaks at temperatures higher than 925 °C. Subsequently, a 30% Ta2O5 and 70% Nb2O5 (mol%) pellet resulted in good sintering behavior at both 900 and 950 °C. The scanning electron microscope (SEM) images corroborated these observations with necking and particle coarsening. The sintered pellets contained a 20.4 and 20.8% mixed oxide (Nb4Ta2O15) phase, along with Ta2O5 and Nb2O5, at both 900 and 950 °C, indicating the possibility of the formation of a solid solution phase. In situ high-temperature X-ray diffraction (XRD) scans also confirmed the formation of the ternary oxide phase at 6 and 19.8% at 890 and 950 °C, respectively. The Hume–Rothery rules could explain the good sintering behavior of the Ta2O5 and Nb2O5 mixed oxides. An oxide composition of 30% Ta2O5 and 70% Nb2O5 (mol%) and a sintering temperature of 950 °C appeared adequate for fabricating well-sintered oxide precursors for subsequent electrochemical polarization studies in fused salts.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Transition metal-based materials for use in high temperature and corrosive environments

A material (e.g., an alloy) comprises molybdenum, rhenium, and at least one element selected from the group consisting of tellurium, iodine, selenium, chromium, nickel, copper, titanium, zirconium, tungsten, vanadium, and niobium. Methods of forming the material (e.g., the alloy) comprise mixing molybdenum powder, rhenium powder, and a powder comprising at least one element selected from the group consisting of tellurium, iodine, selenium, chromium, nickel, copper, titanium, zirconium, tungsten, vanadium, and niobium. The mixed powders may be coalesced to form the material (e.g., the alloy).

Tripathy, Prabhat K.↗

DOE OSTI2021

Methods and systems for aluminum electroplating

Systems and methods for coating a metallic component are provided. In one embodiment, a metallic coating may be disposed in a plating bath comprising AlBr3. The metallic coating may be coupled with, or configured as, a working electrode. A counter electrode formed of aluminum may be disposed within the plating bath. An electric current may be applied between the two electrodes resulting in the electrodeposition of aluminum on the metallic component. In one particular embodiment, the plating bath may include LiBr, KBr and CsBr, with AlBr3 being present in an amount of approximately 80 percent or greater by weight. Various types of metals may be coated with aluminum using embodiments of the present disclosure. Additionally, the methods and systems described herein are amenable to coating of complex geometries.

Tripathy, Prabhat K.↗

DOE OSTI2021

Electrochemical measurement and analysis of YCl 3 , ScCl 3 , GdCl 3 and MgCl 2 in molten eutectic LiCl-KCl

For this work, electrochemical measurements of YCl 3 , ScCl 3 , GdCl 3 and MgCl 2 were obtained in molten LiCl-KCl eutectic at 773 K using a three-electrode configuration. Tungsten rods were used as the working and counter electrodes. Two quasi- and one reference electrode(s) (glassy carbon, nickel wire, and Ni/NiO) were used to collect electrochemical measurements of the analyte salts. Cyclic voltammetry data were analyzed to calculate values of diffusion coefficient, exchange current density, and charge transfer resistance and were determined to be on the order of 10 –5 cm 2 s –1 , 10 –2 A cm –2 , and 10 0 Ω; respectively. In general, the values of diffusion coefficients were found to be consistent with those reported of high-temperature molten salts. Relatively large values of exchange current density corresponded with smaller values of charge transfer resistance. These values were found to be reasonable in comparison to results available in the literature. The measured cyclic voltammograms were normalized with respect to both lithium reduction and chloride ion oxidation potentials. Such a normalization technique is effective for comparing experimentally obtained cyclic voltammetry data to those that have been published. An analysis of experimentally obtained results indicates the relation of electrode reactions (e.g., differences of reduction potentials) are independent of the choice of reference electrode. Additionally, the choice of reference electrode did not affect the electrochemical window, exchange current density, or diffusion coefficient values.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2020

Electrochemical cells for direct oxide reduction, and related methods

A method of direct oxide reduction includes forming a molten salt electrolyte in an electrochemical cell, disposing at least one metal oxide in the electrochemical cell, disposing a counter electrode comprising a material selected from the group consisting of osmium, ruthenium, rhodium, iridium, palladium, platinum, silver, gold, lithium iridate, lithium ruthenate, a lithium rhodate, a lithium tin oxygen compound, a lithium manganese compound, strontium ruthenium ternary compounds, calcium iridate, strontium iridate, calcium platinate, strontium platinate, magnesium ruthenate, magnesium iridate, sodium ruthenate, sodium iridate, potassium iridate, and potassium ruthenate in the electrochemical cell, and applying a current between the counter electrode and the at least one metal oxide to reduce the at least one metal oxide. Related methods of direct oxide reduction and related electrochemical cells are also disclosed.

Tripathy, Prabhat K.↗