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1,496 results on '"Baker, Ian"'

152. Comparison of the Sliding Wear of Single-Phase F.C.C Carbon-Doped Fe40.4Ni11.3Mn34.8Al7.5Cr6and CoCrFeMnNi High-Entropy Alloys at Cryogenic Temperature

Author

Tang, Aubrey, Baker, Ian, Kennedy, Francis E., Chen, Hansheng, Ringer, Simon, Song, Min, and Alberts, Elliot

Abstract

The sliding wear behavior of pins of the face-centered cubic high-entropy alloys (HEAs), carbon-doped Fe40.4Ni11.3Mn34.8Al7.5Cr6(CHEA) and equiatomic CoCrFeMnNi (Cantor), was determined at cryogenic temperatures. Sliding wear tests were run both in dry cryogenic sliding conditions and under liquid nitrogen cryogenic conditions (wet conditions). Scanning electron microscopy, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, atom probe tomography, and scanning transmission electron microscopy were used to characterize the worn pin surfaces. It was found that at cryogenic temperatures, the CHEA generally had lower wear rates compared to the Cantor HEA pins, except for the wet high-speed sliding condition. Comparison with previous room temperature tests (Guo et al. in Mater Charact 170:110693, 2020, https://doi.org/10.1016/j.matchar.2020.110693) revealed much higher wear rates in low-speed conditions at room temperature, while cryogenic tests had higher wear rates in high-speed conditions. Oxides found on the CHEA pins were much more stable and adherent than those on the Cantor HEA pins, and they played a role in the CHEA’s overall better wear resistance. Large amounts of soft transition metal oxides seen in the Cantor HEA at dry high-speed condition allowed easy removal and therefore the highest wear rate of all conditions. Twins exclusively appeared in the CHEA samples while planar faults mainly appeared in the Cantor HEA ones. Both indicate that plastic deformation had occurred during sliding. Precipitation of secondary phases in the CHEA pins was also found and, coupled with evidence of twinning, also provided explanation for increased wear resistance of the CHEA. Wear mechanisms of cryogenic dry samples varied with sliding speed. Oxidational wear dominated at lower speeds, evidenced by composition of the surface oxide and mechanically mixed sublayer. At high sliding speeds, delamination and adhesive wear were the main mechanisms, with less useful contribution from the surface oxide layer.

Published
2024
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156. Scientific detector workshop 2022 on‐sky performance verification of near‐infrared e−APD technology for wavefront sensing and demonstration of e−APD pixel performance to improve the sensitivity of large science focal planes

Author

Finger, Gert, Eisenhauer, Frank, Genzel, Reinhard, Mandla, Christopher, Baker, Ian, Alvarez, Domingo, Amorim, Antonio, Brandner, Wolfgang, Dupuy, Christophe, Deen, Casey, Ives, Derek, Mehrgan, Leander, Meyer, Manfred, Perraut, Karin, Perrin, Guy, Stegmeier, Jörg, Straubmeier, Christian, Weller, Harald J., and Isgar, Vincent

Subjects
FOCAL planes, PIXELS, SPECTRAL sensitivity, WAVEFRONT sensors, ADAPTIVE optics, DETECTORS, GRAVITY
Abstract

Near‐infrared adaptive optics as well as fringe tracking for coherent beam combination in optical interferometry require the development of high‐speed sensors. Because of the high speed, a large analog bandwidth is required. The short exposure times result in small signal levels which require noiseless detection. Both requirements cannot be met by state‐of‐the‐art conventional CMOS technology of near‐infrared arrays as has been attempted previously. A total of five near‐infrared SAPHIRA 320 × 256 pixel HgCdTe e−APD arrays have been deployed in the wavefront sensors and in the fringe tracker of the VLTI instrument GRAVITY. The current limiting magnitude for coherent exposures with GRAVITY is mk = 19, which is made possible with ADP technology. New avalanche photo‐diode array (APD) developments since GRAVITY include the extension of the spectral sensitivity to the wavelength range from 0.8 to 2.5 μm. After GRAVITY a larger format array with 512 × 512 pixels has been developed for both AO applications at the ELT and for long integration times. Since dark currents of <10−3 e−/s have been demonstrated with 1Kx1K e−APD arrays and 2Kx2K e−APD arrays have already been developed, the possibilities and adaptations of e−APD technology to provide noiseless large‐format science‐grade arrays for long integration times are also discussed. [ABSTRACT FROM AUTHOR]

Published
2023
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159. Modeling land‐atmosphere coupling at cloud‐resolving scale within the Multiple Atmosphere Multiple Land (MAML) framework in SP‐E3SM

Author

Lin, Guangxing, primary, Leung, L. Ruby, additional, Lee, Jungmin, additional, Harrop, Bryce E., additional, Baker, Ian T., additional, Branson, Mark D., additional, Denning, A. Scott, additional, Jones, Christopher R., additional, Ovchinnikov, Mikhail, additional, Randall, David A., additional, and Yang, Zhao, additional

Published
2023
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165. Enhanced Wear Resistance, Antibacterial Performance and Biocompatibility by Nanotubes Containing Nano-Ag and Silicate/Phosphate on the Surface of βTi Alloy for Bone Application

Author

Wu, Hong, primary, Wang, Qingge, additional, Liu, Jia, additional, Liu, Jingbo, additional, Ren, Yaojia, additional, Liang, Luxin, additional, Yan, Xinxin, additional, Baker, Ian, additional, Liu, Shifeng, additional, Uglov, V.V., additional, Tang, Yujin, additional, and Wang, Liqiang, additional

Published
2023
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177. Firn

Author

Obbard, Rachel W., Baker, Ian, Lomonaco, Rachel W., Singh, Vijay P., editor, Singh, Pratap, editor, and Haritashya, Umesh K., editor

Published
2011
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188. Quantifying Northern High Latitude Gross Primary Productivity (GPP) Using Carbonyl Sulfide (OCS)

Author

Kuai, Le, primary, Parazoo, Nicholas C., additional, Shi, Mingjie, additional, Miller, Charles E., additional, Baker, Ian, additional, Bloom, Anthony A., additional, Bowman, Kevin, additional, Lee, Meemong, additional, Zeng, Zhao‐Cheng, additional, Commane, Roisin, additional, Montzka, Stephen A., additional, Berry, Joe, additional, Sweeney, Colm, additional, Miller, John B., additional, and Yung, Yuk L., additional

Published
2022
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190. Mechanisms of water supply and vegetation demand govern the seasonality and magnitude of evapotranspiration in Amazonia and Cerrado

Author

Christoffersen, Bradley O., Restrepo-Coupe, Natalia, Arain, M Altaf, Baker, Ian T., Cestaro, Bruno P., Ciais, Phillippe, Fisher, Joshua B., Galbraith, David, Guan, Xiaodan, Gulden, Lindsey, van den Hurk, Bart, Ichii, Kazuhito, Imbuzeiro, Hewlley, Jain, Atul, Levine, Naomi, Miguez-Macho, Gonzalo, Poulter, Ben, Roberti, Debora R., Sakaguchi, Koichi, Sahoo, Alok, Schaefer, Kevin, Shi, Mingjie, Verbeeck, Hans, Yang, Zong-Liang, Araújo, Alessandro C., Kruijt, Bart, Manzi, Antonio O., da Rocha, Humberto R., von Randow, Celso, Muza, Michel N., Borak, Jordan, Costa, Marcos H., Gonçalves de Gonçalves, Luis Gustavo, Zeng, Xubin, and Saleska, Scott R.

Published
2014
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197. Microstructural Evolution, Mechanical Properties and Tribological Behavior of B 4 C-Reinforced Ti In Situ Composites Produced by Laser Powder Bed Fusion.

Author

Du, Jingguang, Ren, Yaojia, Liu, Xinyan, Xu, Feng, Wang, Xiaoteng, Zhou, Runhua, Baker, Ian, and Wu, Hong

Subjects
TENSILE strength, CRYSTAL whiskers, SPECIFIC gravity, POWDERS, LASERS, FIBROUS composites
Abstract

Based on the advantage of rapid net-shape fabrication, laser powder bed fusion (LPBF) is utilized to process B4C-reinforced Ti composites. The effect of volumetric energy density (VED) on the relative density, microstructural evolution, tensile properties and wear behaviors of B4C-reinforced Ti composites were systematically investigated. The LPBF-ed samples with high relative density (>99%) can be achieved, while the pores and un-melted powders can be observed in the sample owing to the low energy input (33 J/mm3). The additive particulates B4C were transformed into needle-like TiB whiskers with nano-scale while C dissolved in the Ti matrix. Fine-scale grains (<10 μm) with random crystallographic orientation can be achieved and the residual stress shows a downtrend as the VED increases. Through the analysis of the tensile and wear tests, the sample at 61 J/mm3VED showed a good combination of strength and wear performance, with an ultimate tensile strength of 951 MPa and a wear rate of 3.91 × 10−4 mm3·N−1m−1. The microstructural evolution in VED changes and the corresponding underlying strengthening mechanisms of LPBF-ed Ti + B4C composites are conducted in detail. [ABSTRACT FROM AUTHOR]

Published
2023
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198. Overview of the Large-Scale Biosphere–Atmosphere Experiment in Amazonia Data Model Intercomparison Project (LBA-DMIP)

Author

de Gonçalves, Luis Gustavo Gonçalves, Borak, Jordan S., Costa, Marcos Heil, Saleska, Scott R., Baker, Ian, Restrepo-Coupe, Natalia, Muza, Michel Nobre, Poulter, Benjamin, Verbeeck, Hans, Fisher, Joshua B., Arain, M. Altaf, Arkin, Phillip, Cestaro, Bruno P., Christoffersen, Bradley, Galbraith, David, Guan, Xiaodan, van den Hurk, Bart J.J.M., Ichii, Kazuhito, Imbuzeiro, Hewlley M. Acioli, Jain, Atul K., Levine, Naomi, Lu, Chaoqun, Miguez-Macho, Gonzalo, Roberti, Débora R., Sahoo, Alok, Sakaguchi, Koichi, Schaefer, Kevin, Shi, Mingjie, Shuttleworth, W. James, Tian, Hanqin, Yang, Zong-Liang, and Zeng, Xubin

Published
2013
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199. Inter-annual variability of carbon and water fluxes in Amazonian forest, Cerrado and pasture sites, as simulated by terrestrial biosphere models

Author

von Randow, Celso, Zeri, Marcelo, Restrepo-Coupe, Natalia, Muza, Michel N., de Gonçalves, Luis Gustavo G., Costa, Marcos H., Araujo, Alessandro C., Manzi, Antonio O., da Rocha, Humberto R., Saleska, Scott R., Arain, M. Alaf, Baker, Ian T., Cestaro, Bruno P., Christoffersen, Bradley, Ciais, Philippe, Fisher, Joshua B., Galbraith, David, Guan, Xiaodan, van den Hurk, Bart, Ichii, Kazuhito, Imbuzeiro, Hewlley, Jain, Atul, Levine, Naomi, Miguez-Macho, Gonzalo, Poulter, Ben, Roberti, Debora R., Sahoo, Alok, Schaefer, Kevin, Shi, Mingjie, Tian, Hanqin, Verbeeck, Hans, and Yang, Zong-Liang

Published
2013
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