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Search Publications by: Sergey Mekhontsev (Assoc)

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Displaying 1 - 25 of 51

Design and Evaluation of Large Aperture Gallium Fixed Point Blackbody

October 12, 2021
Author(s)
V B. Khromchenko, Sergey Mekhontsev, Leonard Hanssen
To complement existing water bath blackbodies which are now serving as NIST primary standard sources in the temperature range from 15 C to 75 C, a gallium fixed point blackbody has been recently built. The main objectives of the project included creating

Measurement Uncertainty of Surface Temperature Distributions for Laser Powder Bed Fusion Processes

August 10, 2021
Author(s)
David Deisenroth, Sergey Mekhontsev, Brandon Lane, Leonard M. Hanssen, Ivan Zhirnov, Vladimir Khromchenko, Steven Grantham, Daniel Cardenas-Garcia, Alkan Donmez
This paper describes advances in measuring the characteristic spatial distribution of surface temperature and emissivity during laser-metal interaction under conditions relevant for laser powder bed fusion (LPBF) additive manufacturing processes. Detailed

Transient Laser Energy Absorption, Co-axial Melt Pool Monitoring, and Relationship to Melt Pool Morphology

August 16, 2020
Author(s)
Brandon M. Lane, Ivan Zhirnov, Sergey Mekhontsev, Steven E. Grantham, Richard E. Ricker, Santosh Rauniyar, Kevin Chou
Many recent and ongoing studies into the complex melt pool physics during laser powder bed fusion (LPBF) metal additive manufacturing (AM) process measure various aspects of energy transport surrounding the laser-induced melt pool, with focus on laser

Measurements of Melt Pool Geometry and Cooling Rates of Individual Laser Traces on IN625 Bare Plates

February 5, 2020
Author(s)
Brandon M. Lane, Jarred C. Heigel, Richard E. Ricker, Ivan Zhirnov, Vladimir Khromchenko, Jordan S. Weaver, Thien Q. Phan, Mark R. Stoudt, Sergey Mekhontsev, Lyle E. Levine
The complex physical nature of the laser powder bed fusion (LPBF) process warrants use of multiphysics computational simulations to predict or design optimal operating parameters or resultant part qualities such as microstructure or defect concentration

Influence of optical system operation on stability of single tracks in selective laser melting

August 20, 2019
Author(s)
Ivan Zhirnov, Igor Yadroitsev, Brandon Lane, Sergey Mekhontsev, Steven Grantham, Ina Yadroitsava
Additive manufacturing (AM) technologies are increasingly being studied and introduced into the modern industry, but for wide applications there exists some "lack of confidence" about the quality of the parts produced by AM. This distrust has an objective

Design, Developments, and Results from the NIST Additive Manufacturing Metrology Testbed (AMMT)

August 10, 2016
Author(s)
Brandon M. Lane, Sergey Mekhontsev, Steven E. Grantham, Mihaela Vlasea, Justin G. Whiting, Ho Yeung, Jason C. Fox, Clarence J. Zarobila, Jorge E. Neira, Michael L. McGlauflin, Leonard M. Hanssen, Shawn P. Moylan, M A. Donmez, Joseph P. Rice
NIST is developing a facility titled the Additive Manufacturing Metrology Testbed that will enable advanced research into monitoring, controls, process development, and temperature measurement for laser powder bed fusion additive manufacturing and similar

Optical design and initial Results from NIST’s AMMT/TEMPS Facility

May 9, 2016
Author(s)
Steven E. Grantham, Brandon M. Lane, Jorge E. Neira, Sergey Mekhontsev, Leonard M. Hanssen, Mihaela Vlasea
NIST’s Physical Measurement and Engineering Laboratories are jointly developing the Additive Manufacturing Measurement Testbed (AMMT)/ Temperature and Emittance of Melts, Powders and Solids (TEMPS) facilities. These facilities will be co-located on an open

New Developments in the NIST Infrared Optical Properties of Materials Program

July 1, 2014
Author(s)
Leonard M. Hanssen, Sergey Mekhontsev, Jinan Zeng, John H. Burnett
The Infrared Optical Properties of Materials program in the Sensor Science Division at the National Institute of Standards and Technology (NIST) continues to upgrade its capabilities to provide comprehensive coverage of measurable infrared optical

Measurements of Infrared Spectral Directional Emittance at NIST - A Status Update

September 12, 2012
Author(s)
Boris Wilthan, Leonard Hanssen, Sergey Mekhontsev
Over the past two decades, the Sensor Science Division at the National Institute of Standards and Technology (NIST) has developed extensive capabilities for the characterization of the infrared optical properties of materials and components. These include

A Determination Study of The Cavity Emissivity of the Eutectic Fixed Points Co-C, Pt-C and Re-C

December 5, 2011
Author(s)
Leonard M. Hanssen, Yohsiro Yamada, Pieter Bloembergen, Pablo Castro, Boris Wilthan, Sergey Mekhontsev
The eutectics Co-C, Pt-C and Re-C, with phase transition temperatures of 1597 K, 2011 K, and 2747 K, respectively, are presently investigated for their suitability to serve as reference points for dissemination of T (and T90) within the context of the

Water Heat Pipe Blackbody as a Reference Spectral Radiance Source Between 50 C and 250 C

April 17, 2006
Author(s)
Mart Noorma, Sergey Mekhontsev, V B. Khromchenko, Maritoni A. Litorja, Claus Cagran, Jinan Zeng, Leonard M. Hanssen
Realization of a radiometric temperature scale for near ambient temperatures with high accuracy is crucial for a number of demanding military and commercial applications. Reliable radiation sources with high stability and good spatial uniformity have to be

Radiation Properties of IR Calibrators With V-Grooved Surfaces

April 1, 2006
Author(s)
Leonard M. Hanssen, A Prokhorov, Sergey Mekhontsev
Use of linear or concentric grooves is a well-known approach for increasing the surface emissivity to enable the construction of compact blackbody radiators, improve absorptance of stray radiation traps, baffles and thermal radiation detectors, as well as