Publications
Showing 72 results for Author: Govindarajan Muralidharan
Dec, 2023
Journal
On the Quantitative Characterization of Weld Microstructures
A new technique to quantify grain shape and grain boundary curvature in the fusion zone (FZ) and the heat-effected zone (HAZ) of refractory metals and alloys has been developed. The application of this technique to quantify the effect of welding speed on these microstructural characteristics in simulated molybdenum welds is highlighted in this study. A 50% increase in weld…
Nov, 2023
Journal
High temperature materials for heavy duty diesel engines: Historical and future trends
Heavy duty (HD) vehicles are projected to be the largest fuel-use subsector in transportation, with current demand for diesel fuel projected to grow 30% by 2040. Historically, a primary strategy for increasing diesel engine efficiency has been to increase peak cylinder pressure (PCP). However, increasing PCP imparts greater mechanical and thermal loads on engine components…
Nov, 2023
Journal
Microstructural Analysis and Transport Properties of Thermally Sprayed Multiple-Layer Ceramic Coatings
Multilayer, graded ceramic/metal coatings were prepared by an air plasma spray method on Ti-6Al-4V, 4140 steel and graphite substrates. The coatings were designed to provide thermal barriers for diesel engine pistons to operate at higher temperatures with improved thermal efficiency and cleaner emissions. A systematic, progressive variation in the mixture of yttria-stabili…
Nov, 2023
Conference Paper
Development of Creep-Resistant, Alumina-Forming Ferrous Alloys for High-Temperature Structural Use
This paper overviews recent advances in developing novel alloy design concepts of creep-resistant, alumina-forming Fe-base alloys, including both ferritic and austenitic steels, for high-temperature structural applications in fossil-fired power generation systems. Protective, external alumina-scales offer improved oxidation resistance compared to chromia-scales in steam-co…
Nov, 2023
Journal
Distinct Recrystallization Pathways in a Cold-Rolled Al-2%Mg Alloy Evidenced by In-Situ Neutron Diffraction
The time-of-flight neutron diffraction data collected in-situ on Oak Ridge National Laboratory’s (ORNL, Oak Ridge, TN, USA) VULCAN and Los Alamos National Laboratory’s (LANL, Los Alamos, NM, USA) High-Pressure-Preferred-Orientation (HIPPO) diffractometers have been analyzed complementarily to show the texture evolution during annealing of a cold-rolled Al-2%Mg alloy. The t…
Nov, 2023
Conference Paper
AN ADVANCED ULTRASONIC WAVEGUIDE CONCEPT FOR SPATIALLY DISTRIBUTED MONITORING OF IN-CORE TEMPERATURES
Critical process temperatures in a reactor core are conventionally measured using either resistance temperature detectors or thermocouples, both of which exhibit performance degradation at the temperature ranges of advanced reactors. Ultrasonic thermometry (UT) has long been offered as an alternative, potentially robust measurement option. With emerging interest in advance…
Nov, 2023
Journal
Evaluating the efficacy of aluminide coatings to improve oxidation resistance of high performance engine valve alloys
Increasing peak cylinder pressures and operating temperatures of turbo-charged internal combustion engines (ICEs) engines present new challenges for existing materials employed in engine exhaust valves. Oxidation induced degradation of current Ni based alloys for these components will be a life-limiting mechanism while strict cost margins in the automotive transportation i…