Painted Aluminum Research Articles

Development of a Reliable Accelerated Corrosion Test for Painted Aluminum Alloys Used in the Aerospace Industry

New environmental regulations have led to major changes in aluminum corrosion protection by prohibiting, for example, Cr(VI). Thus, the assessment of the corrosion behavior of Cr-free systems under atmospheric conditions is a major topic of interest for the aerospace industry. One major difficulty in this task is the lack of robust and reliable accelerated corrosion test(s) in this field. The aim of the present study is to compare the results of various accelerated corrosion standards (ASTM B117, ISO 4623-2, VCS 1027,149) to results obtained after 5 years of exposure at a marine atmospheric site in Brest, France. Additional accelerated corrosion tests were designed by varying several parameters in the VCS 1027, 149, such as the salt concentration, the time of wetness, and the relative humidity. The different modes of failure obtained in accelerated corrosion tests on the painted samples were then compared to field exposures in a marine atmospheric site. The first results obtained showed that the developed tests are more representative of service conditions than standard tests.

Desorption Electrospray Ionization Mass Spectrometry Imaging of Powder-Treated Fingermarks on Forensic Gelatin Lifters and its Application for Separating Overlapping Fingermarks.

Fingermarks are frequently collected at crime scenes by using gelatin lifters for preservation and transport of the marks to a forensic laboratory for inspection. The gelatin lifters preserve both the imprint of the fingermark pattern necessary for identification purposes and the chemical residue of the mark potentially useful for profiling the person who left the fingermark. The fingermark patterns are traditionally recorded using photography/optical imaging, but methods for chemical analysis of fingermark residues on gelatin lifters are scarce. Here we report the first method for the chemical analysis of fingermarks on gelatin lifters using desorption electrospray ionization mass spectrometry (DESI-MS) imaging. The imaging can be done directly on the gelatin support without any sample preparation, supporting immediate operational use of the method for fingermarks collected at crime scenes. Operational use of the method is further supported by successful chemical imaging of fingermarks enhanced by traditional dusting with forensic powders and lifted off different surfaces (glass, stainless steel, painted aluminum, polystyrene, cardboard, and plastic) as well as fingermarks lifted multiple times. We also demonstrate that the present method can be used to visually separate natural overlapping powder-treated fingermarks, and the chemical composition of the fingermarks can be analyzed on the gelatin support by DESI-MS/MS. The presented method has potential for integration into the traditional workflow for fingermark analysis, and will allow more fingermarks collected at crime scenes to be evaluated both visually and chemically.

A double-layer scheme for extrapolating terahertz complex refractivity from reflectance of aerocraft materials

The complex refractive indexes of aero craft materials are seldom investigated. In this paper, we fabricate two aero craft materials: a white painted aluminum plate and a coated window glass, and measure the reflectance spectra in the region of 3–50 THz. Different from the acquainted metal materials, the reflectance spectra of the two materials have apparent peaks and valleys, which is known as the spectral fingerprint. With the preliminary analysis by using Lorentz-Drude/Lorentz dispersion oscillator models and Kramers-Kronig (KK) algorithm, we find that the errors of the extracted complex refractivity from the dispersion oscillator models are apparent at the abrupt regions, and the accuracy of the real refractive index n and extinction coefficient κ from KK algorithm differs dramatically. To reduce the inevitable errors, we design a double-layer extraction scheme to reestablish the oscillator models based on the KK relation. Compared with the inversed data from KK relation and dispersion oscillator models, the procedure assures the accuracy of the real refractive index and extinction coefficient concurrently, the error of n/κ values at the abrupt region is also improved significantly. The method is reliable and convenient to obtain the precise broadband refractive index from spectra with apparent spectral fingerprints. And the obtained complex refractivity can support the further THz scattering analysis for aero craft targets.

Long‐term atmospheric corrosion of Cr‐free painted aluminum alloys during outdoor worldwide exposures

AbstractCr‐free paints applied on different aluminum alloys were exposed for 5 years at different atmospheric weathering sites worldwide. By image analysis, the extent, and the type of corrosion (filiform or blistering) were determined after 1, 2, and 5 years. In that way, it was possible to rank the different systems as a function of their resistance to corrosion. The kinetics of degradation of each system at all sites was also determined. From the results, it is shown that the kinetics of degradation is system dependent. It is also shown that it is the combination of several climatic parameters which contributes to the corrosivity of the site and not only one single parameter such as chloride deposition, relative humidity, and so on.

The Use of Hydrogels in the Treatment of Metal Cultural Heritage Objects.

Currently gels are widely used in the restoration of paintings, graphic arts, stuccowork and stonework, but their use in metal restoration is less widespread. In this study, several polysaccharide-based hydrogels (agar, gellan and xanthan gum) were selected for use in metal treatments. The use of hydrogels allows to localize a chemical or electrochemical treatment. This paper presents several examples of treatment of metal objects of cultural heritage, i.e., historical or archaeological objects. The advantages, disadvantages and limits of hydrogel treatments are discussed. The best results are obtained for the cleaning of copper alloys via associating an agar gel with a chelating agent (EDTA (ethylenediaminetetraacetic acid) or TAC (tri-ammonium citrate)). The hot application allows to obtain a peelable gel, particularly adapted for historical objects. Electrochemical treatments using hydrogels have been successful for the cleaning of silver and for the dechlorination of ferrous or copper alloys. The use of hydrogels for the cleaning of painted aluminum alloys is possible but it has to be coupled with mechanical cleaning. However, for the cleaning of archaeological lead, the cleaning using hydrogels was not very effective. This paper shows the new possibilities of using hydrogels for the treatment of metal cultural heritage objects: agar is the most promising hydrogel.

Adhesion of lunar simulant dust to materials under simulated lunar environment conditions

A test stand was designed to semi quantitively measure the adhesion of JSC-1/1A lunar simulant dust to materials proposed for use in the lunar surface environment. Sieved simulant <45 μm in diameter was uniformly deposited on sample surfaces. Dust adhesion was indicated as the centrifugal force created from rotation of the test stand to shed dust under high vacuum and UV exposure conditions The device generated a maximum centripetal force greater than 400 g's. Dust adhesion on aluminum, anodized aluminum, Ortho fabric and Z93P painted aluminum was observed and analyzed over a 12 step, increasing acceleration profile. At each rotation cycle, dust coverage was recorded using a camera and changes in the coverage were analyzed in post-processing to provide an indication of the adhesive force dust particles would have to overcome to be removed from the surface. Results showed that all material coverage amounts exhibited a similar shedding profile with individual plateaus occurring below 30 μm depending on material. Bare and anodized aluminum had higher adhesion values in vacuum than did the samples exposed to UV at high centripetal acceleration levels. The Z93P painted aluminum and Ortho fabric indicated the opposite, whereby UV exposed samples retained more dust at higher acceleration levels and thereby larger dust particles likely adhered to the surfaces. Ultimately, this testing indicates that the apparatus provides acceptable control and conditions to assess dust adhesion of lunar simulants. Increased precision can be attained by changes in lighting, camera orientation and clarity, and sample dust application.

Review: Neoclásicos: Edgar Negret y Eduardo Ramírez Villamizar entre París, Nueva York y Bogotá, 1944–1964, by Ana M. Franco

Review: <i>Neoclásicos: Edgar Negret y Eduardo Ramírez Villamizar entre París, Nueva York y Bogotá, 1944–1964</i>, by Ana M. Franco

Utilization and efficient computation of polarization factor Q for fast, accurate BRDF modeling.

The Bidirectional Reflectance Distribution Function (BRDF) is of substantial use in remote sensing, scene generation, and computer graphics, to describe optical scatter off realistic surfaces. This paper begins by summarizing our prior work in relating wave optics and geometric optics models, culminating with the Modified Cook-Torrance (MCT) model. The MCT model is evaluated here against aluminum, Infragold, and silver paint at various wavelengths in the IR. In each case, the MCT model is shown to outperform a standard microfacet model. Then, this paper shows a non-trivial method of computing the primary new term, the polarization factor Q. This optimization requires manipulation of the polarization factor in the complex plane, and results in code that runs nearly 2 times faster when compared to the more straightforward implementation of Q. The code presented here is easily adapted to languages other than Matlab, as the code does not use complex variables and uses only cosines of relevant angles (which can trivially be computed by the dot product of unit vectors in scene rendering). It is anticipated that these results will lead to more widespread use of the polarization factor in scene rendering, to produce more accurate optical scatter results.

Detection of corrosion under insulation on aerospace structures via pulsed eddy current thermography

Corrosion degradation mechanics play a significant role in the safe operability and availability of aircraft components. To defend against corrosion, coating systems and insulation are used on aircraft structures to protect them from corrosion promoters. Due to this layer of protection, corrosion under insulation (CUI) and early onset corrosion remain difficult to characterize on exterior aircraft structures in a timely manner. Pulsed eddy current thermography (PECT) shows promise in enabling the detection of corrosion on aircraft while rapidly scanning large areas. However, the limitations of this technique and appropriate measurement parameters have yet to be explored on painted aluminum aircraft structures. In this work, pulsed phase thermography using electromagnetic coil excitation was performed on painted corroded aluminum samples to capture thermal transient localized responses for defect characterization. Defects ranging from 0.4 mm to 5 mm in a painted corroded aluminum sample were identified using PECT through the capture and analysis of changes in phase and amplitude. The results show that saturation of thermal response from larger defects overshadows smaller outlying defects, suggesting the need for an alternative approach to characterizing defects smaller than 1 mm in diameter. Despite inherently longer measurement times, phase measurements during the cooling period result in higher sensitivity thus enabling detection of smaller defects. This study helps to define a range of operation and measurement parameters for PECT to be effective as a means for corrosion detection on aluminum painted panels. The outcomes pave the way to further extend PECT as a non-destructive, non-contact method for detection of CUI.

Role of aluminium paint on the management of peristomal skin excoriation . A case.control study.

Peristomal skin excoriation is the most common complication of any stoma, especially of ileostomy and entero-cutaneous fistula. Effluent is erosive to skin and at times leads to excoriation of skin and pain or discomfort to the patient. Many strategies or local medications are being used to treat excoriated skin and give comfort to the patient. Aluminium paint is a cheap and effective means of managing skin excoriation. This case-control study was conducted in NEIGRIHMS from January 2015 to October 2020 on the role of aluminium paint for the management of skin excoriations due to stoma and fistula. A total of 19 patients were managed with aluminium paint and compared with the data of 19 other patients who were managed by conventional dressings as controls. Aluminium paint helped in the earlier healing of skin excoriations and give comfort to the patients as compared to normal dressings. Aluminium paint is safe and cost-effective skin barrier to prevent and to manage skin excoriations.

Role of aluminium paint on the management of peristomal skin excoriation . A case.control study

Role of aluminium paint on the management of peristomal skin excoriation . A case.control study

An Infrared DoLP Model Considering the Radiation Coupling Effect

The polarization degree of objects in the marine background are affected by infrared radiation from sea surface. Taking into account the radiation coupling effect (RCE), a degree of linear polarization (DoLP) model is deduced. The DoLP of painted aluminum plates at different observation angles are simulated. The simulation results show the trend of the DoLP of the object decreases first and then increases as the observation angle θO, with the minimum value at θO=53∘. Nevertheless, we get a monotonically increasing trend and the minimum value is at θO=0∘ without considering RCE. The experimental results accord closely with those of the simulation with RCE. This conclusion is useful for the polarization detection and identification of infrared objects in the marine background.

A comparative study for selecting more efficient black selective coating in solar water heating system

Solar thermal collector represents a common system for efficient solar energy conversion. In the field of solar panels, there are numerous types of coatings, their absorptivity is almost more than 90%. The challenge now is to lower the heat loss through emissivity as it predicts the ultimate efficiency (i.e. performance). The solar selective coating is showing higher solar absorption efficiency compared to the commercial black paint, that are applied in most usual solar water heating systems. The present research is devoted to test two types of coatings: second anodized aluminum and traditional matte black paint. Two prototypes of solar water heating system were designed, one having aluminum solar panel coated by matte black paint and the other including solar panel of anodized aluminum electrolytically colored by tin metal ions after two steps of anodization. The second anodized was found to be superior. The calculated performance or efficiency was about 62%. The efficiency of matte black paint was less than the second anodized type. Moreover, the performance without collector glass cover is lowered drastically

Effect of Different Absorbing Materials on The Performance of Basin Solar Still Under Libyan Climate Conditions

This experimental study deals with a single-basin solar still using various absorbing materials with and without black painting. Different types of absorbing materials with and without black painting were used to enhance the solar still productivity through improvement in absorptivity. These materials are steel and aluminum with and without black painting and rubber. Two identical solar stills were manufactured using locally available materials. All the results were compared together to reach the best absorbing materials with and without painting that can be used for solar still. It was found that the rubber absorber has the highest water collection during daytime, followed by the black painted steel absorber, then by black painted aluminum absorber and steel without painting absorber. The average enhancement in the daily productivity was about 50% for the rubber absorber compared with the black painted aluminum absorber and about 43% for the rubber absorber compared with the black painted steel absorber.

Acquisition and Analysis of Hyperspectral Thermal Images for Sample Segregation.

This study presents the first results of a new type of hyperspectral imager in the long-wave thermal radiation range from 8.0 to 14.0 µm which is simpler than readily available Fourier transform infrared spectroscopy-based imagers. Conventional thermography images the thermal radiation from hot objects, but an accurate determination of temperature is hampered by the often unknown emissivities of different materials present in the same image. This paper describes the setup and development of a hyperspectral thermal camera based on a low-order scanning Fabry-Pérot interferometer acting as a bandpass filter. A three-dimensional hyperspectral data cube (two spatial and one spectral dimension) was measured by imaging a high-emissivity carbon nanotube-coated surface (Vantablack), black painted aluminum, borosilicate glass, Kapton tape, and bare aluminum. A principal component analysis (PCA) of the hyperspectral thermal image clearly segregates the individual samples. The most distinguishable sample from the PCA is the borosilicate Petri dish of which the Si-O-Si bond in borosilicate glass was the most noticeable. Additionally, it was found that the relatively large 1024 × 768 × 70 data cube can be reduced to a much smaller cube of size 1024 × 768 × 5 containing 92% of the variance in the original dataset. The possibility of discriminating between the samples by their spectroscopic signature was tested using a logistic regression classifier. The model was fitted to a chosen set of principal components obtained from a PCA of the original hyperspectral data cube. The model was used to predict all pixels in the original data cube resulting in estimates with very high true positive rate (TPR). The highest TPR was obtained for borosilicate glass with a value of 99% correctly predicted pixels. The remaining TPRs were 94% for black painted aluminum, 81% for bare aluminum, 79% for Kapton tape, and 70% for Vantablack. A standard thermographic image was acquired of the same objects where it was found that the samples were mutually indistinguishable in this image. This shows that the hyperspectral thermal image contains sample characteristics which are material related and therefore outperforms standard thermography in the amount of information contained in an image.

Enhancing tubular solar still productivity using composite aluminum/copper/sand sensible energy storage tubes

Water scarcity is a big challenge especially for developing countries and desert areas like Saudi Arabia. Using solar energy for freshwater production is the way forward for future development of the water industry. The present study developed a new composite sensible heat storage tubes (CSHSTs) to improve the freshwater productivity of a tubular solar still activated by a parabolic concentrator solar tracking system. 12-CSHSTs were inserted inside the trough of the tubular solar still forming heterogeneous cavities for the saline water. Each CSHST consists of three main solid components (black painted aluminum tube, copper wire and silica sand). The experimental work was conducted under the climatic conditions of Ha'il city in Saudi Arabia. Results showed enhancements by 24.05% and 20.06% in the freshwater yield and thermal daily efficiency, respectively. The developed device produced 4.9 L/m2day with 13% lower freshwater production cost of $0.0087 per liter. Inserting the 12-CSHSTs inside the trough with the heterogeneous cavities increased the contact area with the saline water. This novel configuration enhanced significantly the heat transfer mechanism. The developed device showed higher performance compared to the previous studies in the literature.

EXPERIMENTAL STUDY ON ASCORBIC ACID ADDITIVE AS GREEN INHIBITOR AGAINST CORROSION OF MILD STEEL

Purpose of study: The corrosion behavior of mild steel and the inhibition effect of ascorbic acid (an anti-oxidant additive) on aluminum coatings on the mild steel have been studied by weight loss technique under different corrosive medium. Methodology: Tap water, 3% Na2CO3 solution, seawater and open-air were chosen as different corrosive medium at ambient temperature range of 35- 400C. Corrosion was recorded using the weight-loss method and the rate was calculated. Later similar mid steel samples were coated with Sodium Bicarbonate paste, aluminum paint with ascorbic acid additive, and aluminum paint without ascorbic acid additive, in similar corroding medium, and the corrosion rate was calculated using the weight-loss method. Main Findings: Results show that the percentage of mild steel corrosion was found to be highest in the seawater and lowest in 3% Na2CO3 solution. Sodium Bicarbonate paste reduces the corrosion rate more studies on the corrosion protection was performed by coating the mild steel surface with aluminum paint along with ascorbic acid inhibitor i.e., a green corrosion inhibitor and it was found that the weight loss data is: 85.03 g from 85.05 g, 82.39 g from 82.43 g, no weight loss and 85.73 g from 85.74 g in tap water, seawater, 3% Na2CO3 solution and air medium respectively. Thus, the addition of ascorbic acid inhibitor gave the highest inhibition efficiency for aluminum paint.

Comparative study of antireflection coating materials for solar thermal collectors

Locally available absorber and antireflection coating materials for solar thermal collectors have been assessed and tested for performance compared to ordinary commercial black paint used in solar water heaters and solar cookers. Absorber plates made of aluminum and iron sheet metals coated with blackboard paint, commercial black paint, and black ABRO spray were prepared. These materials were tested for thermal performance on a natural circulation flat plate solar water heater and plastic bottles. Comparison has been made separately for both absorber material and coating materials which showed that the iron sheet and black ABRO spray to have the highest absorptance. On a clear sky radiation of 973.5W/m 2 , a maximum stagnation temperature of 99.2°C and 107.5°C is achieved on the black ABRO spray painted aluminum sheet metal and iron sheet metal respectively. This is because ABRO black paint has the highest absorptance for wavelengths of below 2.5μm and low thermal emittance for wavelengths above 2.5μm. During the testing of solar water heaters, an increase in temperature of 14.9°C at the outlet from absorber plate and 7.5°C at the surface of storage tanker has been achieved when using ABRO black spray. This is attributed to the highest absorptance for wave lengths of below 2.5μm and low thermal emittance for wave lengths above 2.5μm of ABRO black paint. As can be concluded, iron sheet metal which is cheap and easily available is best for solar thermal applications and provides significant benefit in cost reduction. Furthermore, the cost for ABRO black paint is similar to other coating materials and it can easily be applied on the surface of absorber materials. Keywords : Thermal collectors, Antireflection, Absorptance, Ethiopia.

Acrylic white paint of industrial sector for cool roofing application: Experimental investigation of summer behavior and aging problem under Mediterranean climate

The paper proposes a complete experimental characterization of an acrylic white paint, widespread in the field of household appliances or automotive sector. This paints has been already studied by means of in-lab tests; results have suggested that it is suitable for cool roof application.In this study, the results of a measurement campaign are discussed; it has been carried out by means of test-room of the University of Sannio, in Benevento city, under Mediterranean climatic conditions starting from the summer 2016 until the summer 2017. In detail, the in-field monitoring concerns: all data for describing indoor and outdoor climatic conditions; the measure of solar reflectance at start and after one year from paint’s application; the indoor and outdoor surface temperatures, the heat flux; optical investigations in visual and infrared field. The proposed paint has been compared with a commercial cool roof product and with a polished aluminum varnish in term of improvement respect to traditional dark bituminous membrane. Also the in-field aging effect is studied to compare degradation of proposed paint and commercial cool paint.Data elaborations bring to interesting conclusions; first of all, the in-field performance of acrylic paint is comparable to cool product and it is better than aluminum paint. Proposed product shows very fast drying, good gloss and appearance, lower application time and positive economic analysis. However, the aging is faster with in-field reduction of solar reflectance of around 20–25%. It could be due to application technique and to adopted product to favor the adhesion. This makes suitable other researches also for evaluate the application of a protective gloss that could assure greater durability than traditional product.

Thermal modelling of insulator for energy saving in existing residential building

The present work aims to check the energy consumption of typical household buildings located in hot and humid environment using passive energy conservation techniques. The primary tenet of sustainable development is energy conservation. The recent advance in construction technology gives seminal importance to minimisation of energy demand. However, the already built environment, consumes sustained amount of energy hampering sustainability. In this research, thermal simulation is carried out for observing reduction in energy consumption of three residential buildings in the Bhopal city of India. Ambient temperature, surface temperature and Heat transfer has been analyzed after using modern insulating techniques, namely ceramic tiles, high reflective coating, aluminum paint on roof, along with rock wool spread on opaque components of the building. The results of the investigation suggest that the use of reflective solar coating in roof and walls of buildings reduces heat gain by as much as 25%. Simulations are carried out using Computational Fluid Dynamics (CFD) tools with fluent software.