skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Direct Absorptivity Measurements of Metallic Powders Under 1-Micron Wavelength Laser Light

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1150049
Report Number(s):
LLNL-CONF-658053
DOE Contract Number:
DE-AC52-07NA27344
Resource Type:
Conference
Resource Relation:
Conference: Presented at: 25th Annual International Solid Freeform Fabrication Symposium, Austin, TX, United States, Aug 04 - Aug 06, 2014
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUMM MECHANICS, GENERAL PHYSICS

Citation Formats

Wu, S, Golosker, I, LeBlanc, M, Mitchell, S, Rubenchik, A, Stanley, J, and Gallegos, G. Direct Absorptivity Measurements of Metallic Powders Under 1-Micron Wavelength Laser Light. United States: N. p., 2014. Web.
Wu, S, Golosker, I, LeBlanc, M, Mitchell, S, Rubenchik, A, Stanley, J, & Gallegos, G. Direct Absorptivity Measurements of Metallic Powders Under 1-Micron Wavelength Laser Light. United States.
Wu, S, Golosker, I, LeBlanc, M, Mitchell, S, Rubenchik, A, Stanley, J, and Gallegos, G. Wed . "Direct Absorptivity Measurements of Metallic Powders Under 1-Micron Wavelength Laser Light". United States. doi:. https://www.osti.gov/servlets/purl/1150049.
@article{osti_1150049,
title = {Direct Absorptivity Measurements of Metallic Powders Under 1-Micron Wavelength Laser Light},
author = {Wu, S and Golosker, I and LeBlanc, M and Mitchell, S and Rubenchik, A and Stanley, J and Gallegos, G},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jul 30 00:00:00 EDT 2014},
month = {Wed Jul 30 00:00:00 EDT 2014}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:
  • Here, the effective absorptivity of continuous wave 1070 nm laser light has been studied for bare and metal powder-coated discs of 316L stainless steel as well as for aluminum alloy 1100 and tungsten by use of direct calorimetric measurements. After carefully validating the applicability of the method, the effective absorptivity is plotted as a function of incident laser power from 30 up to ≈540 W for scanning speeds of 100, 500 and 1500 mm s –1. The effective absorptivity versus power curves of the bulk materials typically show a slight change in effective absorptivity from 30 W until the onsetmore » of the formation of a recoil pressure-induced surface depression. As observed using high-speed video, this change in surface morphology leads to an increase in absorption of the laser light. At the higher powers beyond the keyhole transition, a saturation value is reached for both bare discs and powder-coated disks. For ≈100 μm thick powder layers, the measured absorptivity was found to be two times that of the bare polished discs for low-laser power. There is a sharp decrease when full melting of the powder tracks is achieved, followed by a keyhole-driven increase at higher powers, similar to the bare disc case. It is shown that, under conditions associated with laser powder-bed fusion additive manufacturing, absorptivity values can vary greatly, and differ from both powder-layer measurements and liquid metal estimates from the literature.« less
  • Here, the effective absorptivity of continuous wave 1070 nm laser light has been studied for bare and metal powder-coated discs of 316L stainless steel as well as for aluminum alloy 1100 and tungsten by use of direct calorimetric measurements. After carefully validating the applicability of the method, the effective absorptivity is plotted as a function of incident laser power from 30 up to ≈540 W for scanning speeds of 100, 500 and 1500 mm s –1. The effective absorptivity versus power curves of the bulk materials typically show a slight change in effective absorptivity from 30 W until the onsetmore » of the formation of a recoil pressure-induced surface depression. As observed using high-speed video, this change in surface morphology leads to an increase in absorption of the laser light. At the higher powers beyond the keyhole transition, a saturation value is reached for both bare discs and powder-coated disks. For ≈100 μm thick powder layers, the measured absorptivity was found to be two times that of the bare polished discs for low-laser power. There is a sharp decrease when full melting of the powder tracks is achieved, followed by a keyhole-driven increase at higher powers, similar to the bare disc case. It is shown that, under conditions associated with laser powder-bed fusion additive manufacturing, absorptivity values can vary greatly, and differ from both powder-layer measurements and liquid metal estimates from the literature.« less
  • Cited by 7
  • Here, a compact system is developed to measure laser absorptivity for a variety of powder materials (metals, ceramics, etc.) with different powder size distributions and thicknesses. The measured results for several metal powders are presented. The results are consistent with those from ray tracing calculations.
  • We have used a bolometric technique to obtain accurate low temperature loss data for epitaxial thin films of Ba[sub 0.6]K[sub 0.4]BiO[sub 3] from 30 to 700 cm[sup [minus]1]. These films were grown on MgO and SrTiO[sub 3] substrates by MBE, off-axis sputtering and laser deposition techniques. All films show a strong absorption onset near the BCS tunneling gap of 3.5k[sub B]T[sub c]. We have analyzed these data using a Kramers-Kronig transformation and have corrected for finite film thickness effects. Results indicate that the absorption onset is consistent with a superconducting energy gap. Comparison is made with predictions based on strongmore » coupling Eliashberg theory using [alpha][sup 2]F([omega]) spectra obtained from the literature. While we are able to fit the overall measured absorptivity, we are unable to fit the structure observed in our data.« less