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

Title: Comparison of Thermal Transport Property Measurements of Thermally Sprayed Coatings by the Laser and Xenon Flash Techniques

Abstract

Development of precise and reliable measurement methods is an important step in the study of the thermal transport property of inherently complex systems such as thermally sprayed coatings. In this study, the applicability and repeatability of both the laser and xenon flash techniques have been investigated through the measurements on the coatings made from ceramics, metals, alloys, and composites. For the four series of material systems, issues such as the effect of powder morphology, coating thickness, spraying technique, chemical composition, and oxidation on the thermal diffusivity as well as the corresponding measurement repeatability are assessed. This investigation provides information necessary for precise and reliable characterization of the thermal transport property of various thermally sprayed coatings.

Authors:
 [1];  [2];  [1]
  1. ORNL
  2. State University of New York, Stony Brook
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); High Temperature Materials Laboratory
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1026702
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: ITSC2007, Beijing, China, 20070514, 20070517
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALLOYS; CERAMICS; CHEMICAL COMPOSITION; COATINGS; LASERS; MORPHOLOGY; OXIDATION; SPRAYED COATINGS; THERMAL DIFFUSIVITY; THICKNESS; TRANSPORT; XENON

Citation Formats

Chi, Weiguang, Sampath, S, and Wang, Hsin. Comparison of Thermal Transport Property Measurements of Thermally Sprayed Coatings by the Laser and Xenon Flash Techniques. United States: N. p., 2007. Web.
Chi, Weiguang, Sampath, S, & Wang, Hsin. Comparison of Thermal Transport Property Measurements of Thermally Sprayed Coatings by the Laser and Xenon Flash Techniques. United States.
Chi, Weiguang, Sampath, S, and Wang, Hsin. Mon . "Comparison of Thermal Transport Property Measurements of Thermally Sprayed Coatings by the Laser and Xenon Flash Techniques". United States. doi:.
@article{osti_1026702,
title = {Comparison of Thermal Transport Property Measurements of Thermally Sprayed Coatings by the Laser and Xenon Flash Techniques},
author = {Chi, Weiguang and Sampath, S and Wang, Hsin},
abstractNote = {Development of precise and reliable measurement methods is an important step in the study of the thermal transport property of inherently complex systems such as thermally sprayed coatings. In this study, the applicability and repeatability of both the laser and xenon flash techniques have been investigated through the measurements on the coatings made from ceramics, metals, alloys, and composites. For the four series of material systems, issues such as the effect of powder morphology, coating thickness, spraying technique, chemical composition, and oxidation on the thermal diffusivity as well as the corresponding measurement repeatability are assessed. This investigation provides information necessary for precise and reliable characterization of the thermal transport property of various thermally sprayed coatings.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

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:
  • Residual stresses were calculated from the curvature of coating-substrate coupons using three different models: a simple two-beam elastic model; the Tsui-Clyne progressive deposition model; and the Tsui-Clyne progressive deposition model with substrate plasticity. The coatings studied were metallic and prepared by high-velocity oxy-fuel (HVOF) thermal spraying. The calculated stresses were compared to those measured on the same coupons using x-ray diffraction (XRD) techniques. Coating surface stresses calculated using the two-beam elastic model disagreed with those measured using XRD for coupons with significant curvature. Trends in residual stresses (with varying coating and substrate thickness, substrate material, and HVOF spray particle velocity)more » predicted by the elastic and elastic-plastic versions of the Tsui-Clyne progressive deposition model agreed with the trends measured by XRD. The magnitudes of stresses calculated using the Tsui-Clyne model agreed with the XRD measurements for coatings sprayed at low particle velocities but were significantly more compressive for coatings sprayed at higher velocities. Accounting for substrate plasticity in the Tsui-Clyne model improved the agreement with the XRD results, but only slightly.« less
  • Techniques have been developed for measuring the tensile properties of plasma-sprayed coatings which are used in thermal barrier applications. The measurements have included the average Young's modulus, bond strength and elongation at failure. The oxidation behavior of the bond coat plays an important role in the integrity and adhesion of plasma-sprayed thermal barrier coatings. This work studies the nature of the high temperature degradation on the mechanical properties of the coating. Furnace tests have been carried out on U-700 alloy with bond coats of NiCrAlY or NiCrAlZr and an overlay of ZrO2-8 percent Y2O3. Weight gain measurements on the coatingsmore » have been examined with relation to the adhesion strength and failure observations. The results from an initial study are reported in this work. 13 references.« less
  • The laser flash technique is widely used for determining the thermal diffusivity of a sample. In this work, the temperature distribution throughout the sample is investigated, identifying localized, highly-heated regions near the front surface of the sample as a function of: (1) pulse duration, (2) incident beam uniformity, and (3) sample opacity. These high-temperature regions result in an increase in the uncertainty due to temperature-dependent properties, an increase in the heat loss from the sample, and an increased risk of sample damage. The temperature within a semi-transparent media is also investigated in order to establish a regime for which themore » media can reasonably be considered as opaque. This analysis illustrates that, for same total energy deposition, treatment of the incident energy as a continuous heat source, as opposed to an infinitesimal pulse of energy, results in a factor of 2 increase in the front surface temperature during heating. Also, for the same total energy deposition and approximate beam size, use of a Gaussian intensity distribution increases the front surface temperature during heating by more than a factor of 2 as compared to the use of a uniform temperature distribution. By analyzing the front surface temperature of an absorbing and conducting semi-transparent sample subjected to a Gaussian intensity distribution, it is concluded that the media can be treated as opaque, (i.e. the energy can be applied as a boundary condition) for {var_epsilon} = kd > 50, where k is the extinction coefficient and d is the beam diameter. For materials with a sufficiently small absorption coefficient and thermal diffusivity, a closed-form solution suitable for design use is presented for the front-surface temperature at a location coincident with the beam centerline.« less
  • Surfaces of steel structures that enclose high-fluence, large-beam lasers have conventional and unconventional requirements. Aside from rust prevention, the surfaces must resist laser-induced degradation and the contamination of the optical components. The latter requires a surface that can be precision cleaned to low levels of particulate and organic residue. In addition, the surface treatment for the walls should be economical to apply because of the large surface areas involved, and accommodating with intricate joint geometries. Thermal sprayed coatings of aluminum (Al) and stainless steel are candidate surface materials. Coatings are produced and characterized for porosity, smoothness, and hardness. These propertiesmore » have a bearing on the cleanliness of the coating. The laser resistance of Al and 3 16L coatings are given. The paper summarizes the characterization of twin-wire-arc deposited Al, high-velocity-oxygen-fueled (HVOF) deposited Al, flame-sprayed 316L, and HVOF deposited316L. The most promising candidate coating is that of HVOF Al. This Al coating has the lowest porosity (8%) compared the other three coatings and relatively low hardness (100 VHN). The as-deposited roughness (Ra) is 433 pinches, but after a quick sanding by hand, the roughness decreased to 166 pinches. Other post-coat treatments are discussed. HVOF aluminum coatings are demonstrated. Al coatings are corrosion barriers for steel, and this work shows promising resistance to laser damage and low particulation rates.« less
  • Metallographic preparation of thermal spray coated samples is often difficult because hard and soft materials, which normally require different polishing techniques, are commonly present in a single spray-coated sample. In addition, the microstructures of many spray-deposited materials make them prone to pull-out damage during cutting, grinding, and polishing operations. We have compared alternative metallographic techniques to prepare three common types of thermal sprayed coatings: (1) a plasma sprayed alumina-titania wear coating, (2) a plasma sprayed zirconia thermal barrier coating, and (3) on HVOF (High Velocity Oxy-Fuel) sprayed tungsten carbide/cobalt (WC/Co) hardcoating. Each coating was deposited onto a steel substrate andmore » was prepared with metallographic protocols based on: (a) silicon carbide (SiC) papers, (b) bonded diamond platens, and (c) diamond slurries. Polishing with SiC papers generally produced edge rounding and significant pull-out that increased the apparent porosity of the coatings. Polishing with bonded diamond platens produced better results, but some pull-out was still observed. In addition, this method is typically the most expensive due to the limited lifetime and high cost of the platens. Preparation by diamond slurry lapping produced the best overall results at a reasonable cost per sample. Porosity artifacts produced by polishing with SiC papers and bonded diamonds platens also resulted in spuriously low hardness values for the WC/Co samples, but hardness results for the two ceramic coatings were not affected by the polishing method. 4 figs., 2 tabs.« less