Painted Metal Research Articles

GVR sees world metallic pigments demand rising at 5.1% per annum

GVR sees world metallic pigments demand rising at 5.1% per annum

Nondestructive analysis of automotive paints with spectral domain optical coherence tomography.

We have demonstrated for the first time, to our knowledge, the use of optical coherence tomography (OCT) as an analytical tool for nondestructively characterizing the individual paint layer thickness of multiple layered automotive paints. A graph-based segmentation method was used for automatic analysis of the thickness distribution for the top layers of solid color paints. The thicknesses measured with OCT were in good agreement with the optical microscope and ultrasonic techniques that are the current standard in the automobile industry. Because of its high axial resolution (5.5 μm), the OCT technique was shown to be able to resolve the thickness of individual paint layers down to 11 μm. With its high lateral resolution (12.4 μm), the OCT system was also able to measure the cross-sectional area of the aluminum flakes in a metallic automotive paint. The range of values measured was 300-1850 μm2. In summary, the proposed OCT is a noncontact, high-resolution technique that has the potential for inclusion as part of the quality assurance process in automobile coating.

Microstructuring of metal effect pigments in functional coatings on textile substrate

A coating system for polyester fabrics is developed containing metal effect pigments and a polyurethane binder. The metal pigment is made of copper, is of microscaled size and anisotropic shape. It is originally used for optical modification but can also be used to introduce other functional properties. The polyurethane binder is needed to fix the pigments on the textile surface. The aim of the current investigation is to present that the binder has not only the task to fix the pigment but can be also used to structure the pigment surface. The binder application leads to formation of microstructures on top of the pigment surface, probably as a result of a dewetting process. Based on this microstructured pigment surface, in future, textile coatings for improvement of water-repellent, antimicrobial, and antistatic properties could be developed.

Feasibility study of a new approach to removal of paint coatings in remanufacturing

Environmental issues are recognised as being increasingly important, especially in the 21st century; researchers have thus proposed remanufacturing as a means of improving manufacturing sustainability. Cleaning the end-of-life products, that saves commercial values, is one of the most demanding steps and is usually one of the most polluting stages. Product surface coatings, are especially difficult to remove, in this process, because they have been designed to be robust during the service. Traditional methods, aqueous cleaning for instance, are either water consuming or use large amounts of chemical cleaning agents, which are obviously environmentally unfriendly. In this paper, a new approach to removing the paint layers on the surface of the retired product is proposed. The cleaning uses supercritical carbon dioxide (SCCO2) as the pre-treatment, and then wet shot blasting cleaning removes the residues on the treated surfaces. It is difficult to get paint layers in the same condition and the real products are too big for the experimental platform. Experiments were thus carried out using metallic paint sprayed on the steel, with uniform dimensions, mimicking the real paint coatings on the products. The mechanism of SCCO2 treatment was first analysed and specimens treated in different conditions were illustrated. Single-particle shot experiments were afterwards carried out to determine the proper cleaning parameter. The eventual cleaning results using wet shot blasting demonstrated that theoretical analysis was appropriate in this SCCO2 treatment. The resultant cleaning, by use of these two methods, showed satisfactory removal results.

A critical review of electrochemical noise measurement as a tool for evaluation of organic coatings

The simplicity of measuring equipment and versatility of data analysis makes electrochemical noise measurement an ideal technique for acquiring electrochemical information about the corrosion behavior of a painted metal relatively quickly. Hence the method has great potential for use in the laboratory as well as in field situations. However, special care must be taken in choosing data acquisition parameters, reference electrodes and symmetry of electrodes in order to achieve reproducible measurements. These areas have been discussed in this review along with methods of data analysis, alternative electrode configurations for on-site measurements and novel applications of the technique.

Spectroscopic Studies on the Characterization of a Persian Playing Card

This paper presents the results of our investigations on a playing card preserved at The Mūzih-i Āynih va Rushanāī in Yazd, Iran. Conducting micro X-ray fluorescence spectrometry (μ-XRF), micro-Raman spectroscopy (μ-Raman), infrared reflectography (IRR), ultraviolet fluorescence photography, radiography, and optical microscopy, various paints applied on the playing card were identified. According to our analytical studies, red, green, blue, black, and gold-like metallic paints were identified to be a red monoazo pigment (β-naphthol PR 53:1), chrome green, artificial ultramarine blue, carbon black, and brass powder (Dutch metal powder), respectively, dating the playing card to 1895 onward based on the manufacturing date of the red monoazo pigment. Barite was also shown to be mixed with the pigments as an extender. On the other hand, the portrait's face of the playing card was peculiarly blackened. Our analytical approach toward characterizing the blackened face showed that the black paint was achieved by carbon black and, in other words, the face was not blackened due to the darkening of Pb-bearing pigments. Moreover, it was shown that there was no underdrawing under the black face and the black paint was most probably executed in the same time with the other paints. Considering the possible use of the playing card, it was suggested not to remove the blackened face in the cleaning process since the black paint was a part of the integrity of the playing card.

Study of the oxidation process of metallic pigments in the presence of silicone resin under heating

Oxidation of particles of Stapa 4 zinc paste and its composites with Stapa 1515 n. 1 aluminum paste, Silres MSE 100 silicone resin, and microtalc under heating in air was studied by differential-thermal and X-ray phase analyses and electron microscopy. The oxidation of zinc particles starts after a temperature of 330°C is reached, whereas in the presence of Silres MSE 100 resin, the process in which zinc particles are oxidized becomes substantially slower. The oxidation of aluminum particles in the Zn–Al–resin system begins at 560°C. Additional introduction of microtalc shifts the exothermic processes to higher temperatures. A composite was developed for a zinc-aluminum paint to be used to form heat-resistant coatings on metals.

Hydrogen Permeation as a Tool for Quantitative Characterization of Oxygen Reduction Kinetics at Buried Metal-Coating Interfaces

The electrochemical stability of the buried metal-organic coating interface of painted metal is crucially governed by how effectively the oxygen reduction reaction at the interface is inhibited. As this interface is not directly accessible for study by conventional electrochemical techniques, a new non-destructive method has been developed wherein hydrogen permeation is used to quantitatively measure the oxygen reduction kinetics underneath the coatings. Presented here are results obtained with an adaptation of the Devanathan-Stachurski cell where the oxygen reduction reaction kinetics on the coated exit is probed by monitoring the dynamic electrochemical equilibrium potential established as a result of oxygen reduction and hydrogen oxidation reactions. From the hydrogen uptake on the entry side thus a full current-potential relationship curve (I (U)) can be constructed. First tested on non-coated Palladium, the results show very good concurrence of the oxygen reduction currents from the permeation experiments and that from standard cyclic-voltammetry (CV) measurements in buffered and non-buffered acidic electrolyte and under alkaline condition. Initial results obtained on coated samples are also presented.

Lead and other toxic metals in playground paints from South West England

Paints on surfaces of public playground structures in South West England have been analysed for Pb, Cr, Cd and Sb by field-portable, energy-dispersive XRF. Lead was detected (>8μgg−1) in 102 out of 242 cases, with concentrations ranging from 10 to 152,000μgg−1 (median=451μgg−1). Chromium was detected (>25μgg−1) in 48 cases, and concentrations ranged from 26 to 24,800μgg−1 (median=1040μgg−1) and exhibited a significant positive correlation with Pb concentrations. Antimony concentrations ranged from 273 to 16,000μgg−1 (median=2180μgg−1) in 56 detectable cases, and Cd was detected in eight paints and up to a concentration of 771μgg−1 (median=252μgg−1). The highest concentrations of Pb, Cr and Sb generally occurred in yellow or red paints but were encountered on a variety of structures and equipment (e.g. gates, flooring lines, railings and handles of climbing frames and seesaws, and the interior of a model train) and were observed in both flaking, extant paint and in formulations that appeared to have been recently applied. Maximum bioaccessible concentrations of Pb, Cr and Sb in a range of paints, evaluated in selected samples by ICP analysis following pepsin-dilute HCl extraction, were 2710, 205 and 23.6μgg−1, respectively, or 16.6, 0.82 and 0.56% of the respective total concentrations. Total and bioaccessible concentrations of toxic metals in playground paints that exceed various contemporary and historical standards (and in many cases for Pb, by orders of magnitude) are likely to be a more widespread and pervasive issue that needs addressing by the relevant authorities.

How to efficiently characterize special effect coatings

Coatings and plastics that contain special effect pigments show angular-dependent reflection characteristics. Interference pigments, for instance, exhibit a color impression ("appearance") that changes with the directions of illumination and observation. It is currently an open question how the appearance of such coatings can be best characterized without extensive measurements of the spectral radiance factor. In this paper, a simple and efficient approach is presented on how to characterize the appearance of surfaces composed of metallic and interference pigments. Based on the rotational symmetry of the pigment distribution around the surface normal, it is demonstrated how the appearance at any configuration of illumination and observation can be estimated from a set of in-plane measurements. For practical applications, it is shown that a rather small number of geometries (e.g., 10) are sufficient. The presented methodology is an alternative to a recent principal components analysis-based procedure and offers the advantage of being based directly on an extensible physical model while having at least the same prediction accuracy.

How color difference formulas depend on reference pairs in the underlying constant stimuli experiment.

For calculating color differences, the CIEDE2000 and CIE94 equations are widely used and recommended. These equations were derived more than a decade ago, based for a large part on the RIT-Dupont set of visual data. This data was collected from a series of psychophysical tests that use the method of constant stimuli. In this method, observers need to compare the color difference within a sample pair to that between a reference pair. In the current investigation, we show that the color difference equation significantly changes if reference pairs are chosen in the underlying visual experiments that differ from what was used when creating the RIT-Dupont dataset. The investigation is done using metallic paint samples representing two color centers, red and yellow-green. We show that the reproducibility differs for three different reference pairs, and that for modeling the visual data for the yellow-green color center, extra model terms are required as compared to the CIEDE2000 equation. Our results suggest that observers differ in their ability to mentally convert a color difference recognized in a sample pair into an equivalent color difference along the color difference direction represented by the reference pair. We also find that in these tests the tolerance to lightness differences is widened by a factor of 1.3 to 1.6, and that for the red color center the tolerance ellipsoid is rotated by 30° as compared to the CIEDE2000 equation. The latter observations are possibly due to the metallic texture in the samples used for the current experiment.

Hiding Power of Aluminum Metal Pigments Development in the Ball Mill Grinding Process

Aluminum powders are used in porous concrete constructional elements production, in coating compositions and varnish media industry, introduction of printing inks and finally but not less in chemical and pyrotechnical production. The purpose of atypical grinding processes is to obtain fine metal powders of extremely high specific surface which should be evaluated by the parameter of hiding power ability of pigment materials. This paper shows the development of this basic parameter of metal pigment products under the wet process of milling using a pilot-plant ball mill, as a function of milling time and turns of mill drum as one of the basic parameters.

Global Metallic Pigments Market to reach $1286 M by 2023

Global Metallic Pigments Market to reach $1286 M by 2023

Eckart's sales revenue from metallic pigments down again

Eckart's sales revenue from metallic pigments down again

Influence of some Oxide Coating Layers on the Mechanical Properties of Steel Plates

The paper presents a vibroacoustic method to determining the stiffness of coated steel with various materials such as metal oxides, metallic paints, polymers etc and Young's modulus for coating materials. The method consists in measuring the dynamic response of the steel in the form of a rectangular bar subjected to external impulse. One of the latest non-destructive experimental techniques in this field is based on the analysis of vibrating signal response recorded with a condenser microphone. A Fast Fourier Transform algorithm is used for processing the sampled signals. Knowing the mechanical properties of steel plates prior to coating with metal oxides, and determining the same properties after coating, can be obtained the mechanical properties of metal oxides and their influence on the properties of the ensemble.

A classe mineralógica das combinações orgânicas associadas ao hidrogênio

O hidrogênio, aparentemente, é o elemento químico mais abundante do Universo, perfazendo aproximadamente 88,6 % de todos os átomos conhecidos. Apresenta abundância geoquímica na crosta terrestre de 0,14 %, ocorrendo ainda nos gases vulcânicos, nas auroras boreais, na água, no corpo humano, nos hidrocarbonetos (petróleo, carvão mineral, turfa e folhelho pirobetuminoso), nos vegetais e animais e, também, em ampla gama de minerais. Este trabalho revisa a interessante classe mineralógica das combinações orgânicas, cujos cristais são relativamente raros. Nesta classe o hidrogênio está presente na composição de 40 das 41 substâncias conhecidas. A maioria dessas substâncias apresenta importância industrial significativa em seus correspondentes sintéticos, principalmente nas indústrias farmacêutica e química. Substâncias como os oxalatos, as amidas, os formiatos, os acetatos, o fluoreno, a níquel-porfirina, o coroneno, o citrato, a purina, o diperteno, a antraquinona, a ftalimida, o melato e o fenantreno, têm múltiplas aplicações. Entre as mesmas estão filmes eletropolimerizadores, reagentes para síntese de compostos orgânicos, plastificadores, insumos para preparação de nanomateriais, separação e concentração de ETR e elementos transurânicos, nutriente em dietas complementares, produtos para tratamento de águas, revestimento de válvulas e aditivos em cosméticos, tintas metálicas e plásticos em geral

Application of a likelihood ratio approach in solving a comparison problem of Raman spectra recorded for blue automotive paints

Evidential values of Raman spectra recorded for solid and metallic blue car paints were evaluated using visual comparison as well as a statistical approach, i.e. likelihood ratio (LR) test supported by Empirical Cross Entropy (ECE) results. Raman spectra were obtained using a Renishaw inVia spectrometer equipped with a confocal Leica microscope and a near infrared semiconductor laser (785 nm) as an excitation source.When a visual comparison was performed for solid paints, in 17.7% of comparisons (53 pairs out of 300) the samples were indistinguishable, whereas for metallic paints this value was 8.5% of such comparisons (37 pairs out of 435). Comparing the spectra using an LR approach was based on variables being the areas under the most significant Raman spectra bands of pigments present in the analysed samples. Proposed LR models delivered low false positive and false negative rates (for many models lower than 10%), and the ECE plots confirmed that their performance was much better than visual comparison. Copyright © 2015 John Wiley & Sons, Ltd.

About the Cover

About the Cover David L. Howell Click for larger view View full resolution details: The Monkey King Songokū, from the Chinese novel Journey to the West, Edo period, circa 1824–1825. Woodblock print (surimono); ink, color, and metallic pigments on paper; Shikishiban: H. 20.6 cm × W. 18.7 cm (8⅛ × 7⅜ in.). Harvard Art Museums/Arthur M. Sackler Museum, Gift of the Friends of Arthur B. Duel, 1933.4.1716. Photo: Imaging Department © President and Fellows of Harvard College. The collections of the Harvard Art Museums and the Harvard-Yenching Library include countless treasures of East and Inner Asian art. Many of these works were collected on behalf of the Harvard-Yenching Institute, which publishes the Harvard Journal of Asiatic Studies. Hereafter, we will use HJAS’s cover to showcase pieces from these remarkable collections. This issue’s cover features a print by Yashima Gakutei 八島岳亭 (ca. 1786–1868) of the Monkey King from Journey to the West 西遊記. Gakutei was a writer, surimono 摺物 (woodblock-print) artist, and kyōka 狂歌 (comic-verse) poet. In 1835, he published a partial Japanese translation of Journey to the West with his own and other prominent artists’ illustrations. The Katsushikaren 葛飾連, a kyōka circle with which Gakutei was closely affiliated, appears to have issued this print to commemorate New Year’s 1824, the year of the monkey. As was typical for surimono, it features kyōka, in this case by Ōbokuen Yoshiharu 桜木園吉治 (dates unknown) and the circle’s leader, Bunbunsha Kanikomaru 文々舎蟹子丸 (1787–1837). Both poems link the “sutra-reading monkey” (kyō yomu saru 経よむさる) to the New Year. The print reminds us that people throughout premodern East Asia knew, loved, and fully domesticated Journey to the West and other classics of Chinese literature. HJAS thanks the Harvard Art Museums for their kind permission to reproduce the image. The Journal also sincerely thanks John Carpenter, the Mary Griggs Burke Curator of Japanese Art at the Metropolitan Museum of Art, for his guidance regarding the print. [End Page vi] Copyright © 2015 Harvard-Yenching Institute

Case study of a non-destructive treatment method for the remediation of military structures containing polychlorinated biphenyl contaminated paint

Restricted by federal regulations and limited remediation options, buildings contaminated with paint laden with polychlorinated biphenyls (PCBs) have high costs associated with the disposal of hazardous materials. As opposed to current remediation methods which are often destructive and a risk to the surrounding environment, this study suggests a non-metal treatment system (NMTS) and a bimetallic treatment system (BTS) as versatile remediation options for painted industrial structures including concrete buildings, and metal machine parts. In this field study, four areas of a discontinued Department of Defense site were treated and monitored over 3 weeks. PCB levels in paint and treatment system samples were analyzed through gas chromatography/electron capture detection (GC-ECD). PCB concentrations were reduced by 95 percent on painted concrete and by 60–97 percent on painted metal with the majority of the PCB removal occurring within the first week of application. Post treatment laboratory studies including the utilization of an activated metal treatment system (AMTS) further degraded PCBs in BTS and NMTS by up to 82 percent and 99 percent, respectively, indicating that a two-step remediation option is viable. These findings demonstrate that the NMTS and BTS can be an effective, nondestructive, remediation process for large painted structures, allowing for the reuse or sale of remediated materials that otherwise may have been disposed.

Raman analysis of complex pigment mixtures in 20th century metal knight shields of the Order of the Elephant

The pigment composition of six painted metal knight shields of the Order of the Elephant dating from the second half of the 20th century belonging to the Danish royal collection were studied using Raman microscopy. By focusing a 785nm laser with a 50× objective on particles in paint cross sections, it was possible to identify the following 20 compounds: hematite, goethite, chrome red/orange, chrome yellow, zinc chrome yellow, carbon black, toluidine red PR3, chlorinated para red PR4, dinitroaniline orange PO5, phthalocyanine blue PB15, indanthrone blue PB60, ultramarine, Prussian blue, lead white, anatase, rutile, calcium carbonate, barium sulphate, gypsum and dolomite. The components were frequently present in complex pigment mixtures. Additional information was obtained by elemental analysis with scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDX) to identify cobalt blue, zinc white and cadmium red, as well as to indicate the presence of zinc white in some pigment mixtures. The study allowed a comparison between the industrially applied preparation layers and the artistic paint layers applied by the heraldic painter. Differences in the choice of paint and pigment types were observed on the earliest knight shields, demonstrating a general delay of industrial materials into artist paints.