Influence of KMnO4 Concentration on Infrared Emissivity of Coatings

On TC4 Alloys by Micro-Arc Oxidation (Materials EISSN 1996-1944)

Abstract:

Fig 8. Infrared emissivity curves of the MAO ceramic coatings with different KMnO4 concentrations within a waveband of 5–20 μm.[/caption]

Ceramic coatings with high emissivity were fabricated on TC4 alloys by micro-arc oxidation technique (MAO) in mixed silicate and phosphate electrolytes with varying KMnO₄ addition.

The microstructure, phase and chemical composition were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), and the infrared emissivity of the MAO coatings was measured in a waveband of 5–20 μm.

The results show that the thickness of the coatings increased with the addition of KMnO₄, but the roughness of the coatings first decreased and then increased slightly due to the inhibitory effect of KMnO₄ on Na₂SiO₃ deposition.

Ultra-thin perfect absorber employing a tunable phase change material

New device hides, on cue, from infrared cameras

November 26, 2012

Tunable material developed at Harvard boasts nearly 100% absorption on demand

Cambridge, Mass. - November 26, 2012 - Now you see it, now you don’t.

A new device invented at the Harvard School of Engineering and Applied Sciences (SEAS) can absorb 99.75% of infrared light that shines on it. When activated, it appears black to infrared cameras.

Composed of just a 180-nanometer-thick layer of vanadium dioxide (VO₂) on top of a sheet of sapphire, the device reacts to temperature changes by reflecting dramatically more or less infrared light.

Announced today in the journal Applied Physics Letters, and featured on its cover, this perfect absorber is ultrathin, tunable, and exceptionally well suited for use in a range of infrared optical devices.

Perfect absorbers have been created many times before, but not with such versatile properties. In a Fabry-Pérot cavity, for instance, two mirrors sandwich an absorbing material, and light simply reflects light back and forth until it's mostly all gone. Other devices incorporate surfaces with nanoscale metallic patterns that trap and eventually absorb the light.

Fluke Calibrator Video

Emissivity makes a temperature difference for infrared thermometers.

In the YouTube video below, Frank Liebman, an engineer with Fluke Corporation's Hart Scientific Division demonstrates the impact that surface emissivity has on temperature measurement and temperature calibration using a modified Fluke blackbody calibrator and Fluke Thermal Imager.



We were surprised to see that no one commented on this video, despite an ending that leaves one hanging, at least us, with the obvious question: How do you do a radiometric calibration of a surface of unknown emissivity using a Fluke Blackbody Calibrator?

Do you have any ideas?

What The Heck is Emissivity? (Part 2)

Fill up two soda cans with hot water and wrap one in scotch tape. Which one will cool down faster? Obvious, right?

Check it out, you might be surprised!

From the ITC Channel at YouTube.com

IR contrast of crude-oil-covered water

"Infrared contrast of crude-oil-covered water surfaces", by Wei-Chuan Shih and A. Ballard Andrews, Optics Letters, Vol. 33, Issue 24, pp. 3019-3021 (2008)

Abstract (Modified format for easier online viewing)

Emissivity of thin oil films

Unpolarized emissivity of thin oil films over anisotropic Gaussian seas in infrared window regions,"

Appl. Opt. 49, 2116-2131 (2010), by Nicolas Pinel, Christophe Bourlier, and Irina Sergievskaya is online at:
http://www.opticsinfobase.org/abstract.cfm?URI=ao-49-11-2116.

Abstract (Modified format for easier online viewing)

Thermal infrared remote sensing of crude oil slicks

In: Remote Sensing of Environment, Volume 45, Issue 2, August 1993, Pages 225-231.

by John W. Salisbury ^a, Dana M. D'Aria ^a and Floyd F. Sabins Jr.^b
aDepartment of Earth and Planetary Sciences, Johns Hopkins University, Baltimore U.S.A.
^bChevron Oil Field Research Company, La Habra, California U.S.A.

(Abstract Online)
With all the interest on the Gulf Oil spill and recent accounts of the use by British Petroleum and others of Infrared Thermal Imaging to search for surface oil slicks, it seemed very timely to be sure we had included some links and summaries of articles dealing with the thermal Infrared optical properties of crude oil on seawater.

Article Abstract

What the Heck is (Spectral) Emissivity?

Part One of Two from the mind of FLIR
It health partners pharmacies starts:

Fill two soda cans with hot water and wrap one with scotch tape. Which one will radiate more heat?

You might be surprised at the answer

(It has all to do with Spectral Emissivity, although this video continues the illusion that it's really simple "Emissivity" at work! The concept of Emissivity is simple and easy to grasp as the video shows. The understanding is a bit more difficult and begins when one realizes that it is really Spectral Emissivity.)

But looking beyond that technical fine point, the video illustrates two other things:

Electro Optical Industries BB Emissivity Coatings

Electro Optical Industries (EOI) uses one of two high emissivity coatings on the surface of its blackbodies.

The EOI mid-temperature coating is used on both cavity and flat plate blackbodies that have a maximum operating temperatures of up to 210 °C.



Read the rest by visiting their webpage at: www.electro-optical.com/eoi_page.asp?h=What%20Is%20Emissivity?

Exact spectral emissivity measurements for radiation thermometry (IR thermometry)

Modern emissivity measuring facility for industry-orientated calibrations developed at PTB

This news release is available in German.
CAPTION: Local variation of the directed spectral emissivity of a car paint sample at a wavelength of 4 µm, measured using a thermography camera. (IMAGE COURTESY PTB)
Industry and research are increasingly relying on non-contact temperature measurements with the aid of heat radiation, for example, for the reliable and reproducible drying of car paint.

In order to attain exact and reliable results, the emissivity of the measured surface has to be known. It can only be determined precisely in complex measuring facilities.

The Physikalisch-Technische Bundesanstalt (PTB) has developed a modern emissivity measuring facility for industry-oriented calibrations.

ET10 Reflectometer Measures Emissivity

San Diego CA, USA --Surface Optics' ET10 measures emissivity values in two most commonly used spectral regions, 3 to 5 and 8 to 12 microns.

Its main application is to produce emissivity values for the infrared cameras.

Advanced IR cameras require the input of an emissivity value for accurate temperature calculations. The emissivity values obtained from tables can be far from real leading to large temperature uncertainties.

The ET10 can be used in the lab or in the field and on small or large objects. With the ET10 one can measure emissivity of any surface in just a few seconds.

Spectral emittance - spectrally selective solar absorbing layers

Infrared spectral emittance profiles of spectrally selective solar absorbing layers at elevated temperatures

D. E. Soule and D. W. Smith

Applied Optics, Vol. 16, Issue 11, pp. 2818- (1977)

Infrared Emission Spectroscopy of Polymer Reactions

Noninvasive Polymer Reaction Monitoring by Infrared Emission Spectroscopy with Multivariate Statistical Modeling
Randy J. Pell, James B. Callis, and Bruce R. Kowalski
Applied Spectroscopy, Vol. 45, Issue 5, pp. 808-818 (1991)

Abstract

"Infrared absorption and emission spectroscopy have been used to monitor the curing of a commercial paint product. Principal component analysis of the absorption data indicates that three factors are needed to explain the observed spectral/temporal variance. The interpretation of this finding in terms of changes in the physical state of the reaction mixture is discussed. A similar analysis of the emission data proved more difficult due to a nonlinear concentration/response relationship. A linearization step based on an approximate theoretical model is suggested. The absorption, linearized emittance, and raw emittance data are fit to a two-step sequential rate model using multivariate nonlinear optimization and error estimates derived by Monte Carlo calculations. Better agreement of the model parameters between the absorbance and emittance data is found after linearization, but it is found that linearization introduces large errors in the nonlinear parameter estimates. Comparisons of model parameters for the raw emittance data at different temperatures are made."

Citation
R. J. Pell, J. B. Callis, and B. R. Kowalski, "Noninvasive Polymer Reaction Monitoring by Infrared Emission Spectroscopy with Multivariate Statistical Modeling," Appl. Spectrosc. 45, 808-818 (1991)

Spectral Reflectivity of Epner Laser Gold

[caption id="attachment_372" align="alignleft" width="150" caption="Courtesy of Epner Technology, Inc."][/caption]

(CLICK ON GRAPH TO ENLARGE)
Almost everyone who attends the SPIE DSS Exposition and many other optical and optical engineering Conferences & Expos has received a gold-plated paper clip from Mr. David Epner, personally.

Well, the gold costing that Epner supplies to the optics industry has some interesting infrared reflectance (and emittance) properties.

Those properties, specifically the hemispherical spectral reflectance in the near, mid and far infrared is now available for all to view first hand on the Epner website.

A copy of the curve and the data related to it can be downloaded from the site, too.

Shown here, of course, is the Spectral Reflectance of "Laser Gold", which as most know is the complement of Spectral Emittance at each and every wavelength from the formula: e(lambda) = 1 - r(lambda) - t(lambda),

where, respectively:

e is the emittance,
r is the reflectance,
t is the transmittance and
lambda is the wavelength (on this graph shown in units of micrometers). (Note: the usual expressions for these terms are in the Greek letters, epsilon, rho, tau and lambda and have been modified for use on this webpage)

The assumption most often made is that the transmittance of solid gold is zero, or so nearly so that it can be neglected.

That can be an false assumption in some cases according to the degree of precision required in a specific measurement situation. For instance, a very thin film of gold may be partially transparent especially in the long wavelength regions of the infrared and the optical properties on the material under the gold layer may come into play.