Powder Paint Research Articles

The development of environmentally friendly Pr/W Co-doped Bi2MoO6 green pigment with high near-infrared reflectivity

In this article, a green pigment Bi1.95-xPrxW0.05MoO6+δ (x = 0.1–0.5) co-doped with Pr and W was developed using high temperature solid-phase synthesis method. The microstructure, color performance, and optical characteristics of the novel pigment was analyzed using x-ray diffraction instrument (XRD), field-emission scanning electron microscopy (FESEM), L∗ a∗ b∗ color date, and ultraviolet–visible–near infrared light spectrophotometer. The results indicate that all the samples possess a monoclinic structure, characterized by the space group P21/c(14). Compared to Bi2-xPrxMoO6+δ doped solely with Pr6O11, the Pr/W co-doped Bi2MoO6 pigment demonstrates superior green coloration. The solar reflectance in the near-infrared region of all pigment samples exceeds 80 %, highest value reaches 92.82 %. In thermal insulation tests, the temperature difference between the Bi1.95-xPrxW0.05MoO6+δ pigment coating and a blank galvanized sheet reaches up to 10.3 °C after 60 min under infrared lamp irradiation. The color difference ΔE∗ of the pigment powder after immersion in acid and alkali solution and high-temperature calcination are less than 5, indicating good chemical stabilities in acidic, alkaline and high-temperature environments. To our knowledge, Bi1.95-xPrxW0.05MoO6+δ has the highest reflectivity among green pigments without toxic metals.

Integrating multimodal Raman and photoluminescence microscopy with enhanced insights through multivariate analysis

This paper introduces a novel multimodal optical microscope, integrating Raman and laser-induced photoluminescence (PL) spectroscopy for the analysis of micro-samples relevant in Heritage Science. Micro-samples extracted from artworks, such as paintings, exhibit intricate material compositions characterized by high complexity and spatial heterogeneity, featuring multiple layers of paint that may be also affected by degradation phenomena. Employing a multimodal strategy becomes imperative for a comprehensive understanding of their material composition and condition. The effectiveness of the proposed setup derives from synergistically harnessing the distinct strengths of Raman and laser-induced PL spectroscopy. The capacity to identify various chemical species through the latter technique is enhanced by using multiple excitation wavelengths and two distinct excitation fluence regimes. The combination of the two complementary techniques allows the setup to effectively achieve comprehensive chemical mapping of sample through a raster scanning approach. To attain a competitive overall measurement time, we employ a short integration time for each measurement point. We further propose an analysis protocol rooted in a multivariate approach. Specifically, we employ non-negative matrix factorization as the spectral decomposition method. This enables the identification of spectral endmembers, effectively correlated with specific chemical compounds present in samples. To demonstrate its efficacy in Heritage Science, we present examples involving pigment powder dispersions and stratigraphic micro-samples from paintings. Through these examples, we show how the multimodal approach reinforces material identification and, more importantly, facilitates the extraction of complementary information. This is pivotal as the two optical techniques exhibit sensitivity to different materials. Looking ahead, our method holds potential applications in diverse research fields, including material science and biology.

Production of iron triad-based colored spinels by the self-propagating high-temperature synthesis

Blue, green, and khaki spinels were produced by self-propagating high-temperature synthesis (SHS) using Co3O4–ZnO–Mg(NO3)2·6H2O–Al(OH)3–Al, Ni2O3–ZnO–Cr2O3–Al(OH)3–Al, and Co2O3–Fe2O3–Al(OH)3–Al mixtures. The composition of the synthesis products was characterized by X-ray diffraction and IR spectroscopy. The oxides Co3O4, Co2O3, ZnO, Ni2O3, Cr2O3, Fe2O3, and aluminum hydroxide Al(OH)3 were used for the synthesis. Fuel was provided by aluminum powder (ASD-4). The spinel-type ceramic pigments were synthesized using layer-by-layer combustion, which involves two parallel exothermic reactions: aluminum oxidation and aluminothermic reactions. The fast self-propagating reactions and high synthesis temperatures rapidly destroy the structure of Al(OH)3 hydroxide in the starting mixture, producing gaseous reaction products that prevent the sintering of the spinels. The surface morphology of pigment powders and their composition was studied using a Quanta 3D 200i, FEI Co. scanning electron microscope and a Philips SEM 515 scanning electron microscope equipped with a local energy dispersive X-ray analysis (EDAX). The particle size of the synthesized spinels was approximately 1–5 μm. Colored spinels powders obtained by the SHS process can be used as ceramic pigments.

Yellow rare earth sulfide powders with near‐infrared reflectance and spectral modulation for energy‐saving applications

AbstractRadiative cooling pigments offer new opportunities for sustainable carbon neutrality as zero‐energy and zero‐pollution functional materials. However, it is a challenge to prepare inorganic yellow pigments simultaneously with environmentally friendly, high color value, and weather resistance. In this study, a series of alkali metal‐doped γ‐Sm2S3 yellow pigments with near‐infrared reflectance were synthesized. The doping of alkali metal ions reduced synthesis temperature of Sm2S3 from 1300°C to 1000°C. The change in energy band structure induced by alkali metal doping allows the products to exhibit modifiable colors. Typical γ‐[Na]‐Sm2S3 pigment powders have a high near‐infrared reflectance and impressive colors (b* = 78.6, C* = 77.6). Furthermore, colored films made by prepared yellow powders with polyvinylidene fluoride in certain ratios had high near‐infrared reflectance and excellent environmental weathering, resulting in an effective cooling of 4–8°C in outdoor experiments. This work expands the range of options for energy‐efficient building and yellow colorant.

Determination of operational properties of paint coating materials

Problem. Varnishes are used in all branches of industry and economy. With their help, you can protect metals from the effects of aggressive environment, prevent from the negative effects of corrosion, preserve consumer properties, and give the treated surface an aesthetic look. One of the methods of protecting metal from corrosion is the application of coatings, including paints and varnishes, which form a protective film on the surface of the metal and prevent corrosion processes on the surface. Methodology. The research was conducted on the operational characteristics of enamel-type paint coatings: paint powder UD-1028-07040-T and soil FL-03K. Determination of moisture absorption of the free coating film was carried out using the desiccator method. In order to determine the penetration time of aggressive solutions through the paint coating film, an electrochemical method was used, whose purpose is to determine the change in the electrochemical potential of the object under study during the penetration of aggressive solutions through the paint coating film to the metal. The study of the hardness of paint coatings was carried out by the method of static indentation, respectively, using a microhardness meter. Originality. The research results showed the advantage of the UD-1028-07040-T powder paint coating over the FL-03K soil, which can be explained by such factors as the structure of the paint coating, the porosity of the surface, and the phenomenon of adhesion between the paint and the surface on which it is applied. Practical value. Powder paint UD-1028-07040-T absorbs water much less (up to 2.12%) compared to FL-03K soil (up to 5.14%), this indicates a relatively higher porosity of FL-03K soil; it is confirmed by the results of porosity determination, which was 1 point. When determining the penetration time of aggressive solutions through the paint film, it was found that FL-03K soil quickly passes aggressive solutions through its surface (in 144 hours) compared to powder paint (192 hours). This indicates that the use of powder paint in conditions involving contact with aggressive substances will be more appropriate.

Anti-corrosion resistance of coatings based on powder epoxy paints containing modifiers

The corrosion resistance of coatings (thickness 70 µm) based on epoxy powder paints modified with aliphatic amine or a mixture of anticorrosive pigments to the action of sodium chloride solution and salt spray has been studied. It is showed that with the increase of molecuar weight of initial epoxy oligomer and also at the incorporation of chemisorbing alifatic amine, containing polar groups, to the decrease in the permeability of the sodium chloride solution into the coating material is observed. It has been established that the observed changes in the properties of the coatings are due to the formation of a spatial structure of the polymer with different cross-link frequencies. It is shown that the introduction of a mixture of anti-corrosion pigments into the composition of paints provides a significant increase in the protective properties of coatings and a high preservation of the physical and mechanical properties of coatings in comparison with the base compositions. For 9000 hours of testing in a sodium chloride solution, the strength characteristics of the coatings decrease by about 10–12 % from the original ones. Based on the results of tests of coatings to the action of salt spray, the possibility of using the developed epoxy powder paints for operation in environments of a high atmospheric-corrosive category – C 5–1, including the application of coatings directly on a metal surface (Direct to metal) without multi-stage preparation of the metal surface for painting, is shown.

Low-temperature powder paint modified with graphene oxide

Low-temperature powder paint modified with graphene oxide

An analytical survey of zinc white historical and modern artists’ materials

This study is the first systematic survey of a large corpus of zinc white (ZnO) artists’ materials. Zinc white is a white pigment developed within the wave of 19th-century technological developments in the paint industry. The composition, particle morphology and size, and luminescence of 49 zinc white samples from artists’ materials were characterized, including three references of known synthesis methods (indirect and direct) and synthesized by the authors (ZnO nanosmoke). The corpus included historical and modern zinc white pigment powders and paint materials from the leading European and American color manufacturers. The study aims to characterize and evaluate the variability of the properties of zinc white and its paint formulations. The reference materials presented properties in agreement with the literature: indirect ZnO exhibited submicron prismoidal blue-luminescent particles of higher purity than direct ZnO, which had larger acicular green-luminescent particles. ZnO nanosmoke presented acicular (tetrapod-like) blue/green-luminescent nanoparticles. Composition, particle morphology, size, and documentary sources suggested a production via the indirect method for the analyzed corpus. However, the luminescence behavior was more complex to interpret. The fundamental emission of ZnO was not always detected, even in pure ZnO powders. Three trends were identified: smaller ZnO particles for the most recent samples; green luminescence connected to larger particle size; fewer trace elements, and of the same type (i.e., lead, sulfur) for historical materials. Another interesting finding was the detection of hydrozincite in some powders, likely a degradation product of ZnO. In terms of methodology, cathodoluminescence proved a valuable tool for pigment identification. The study provides a database of zinc white references for pigment and artwork analysis.

Enhancing the color of inorganic yellow pigments using yellow fluorescent materials: The case of BiVO4, PbCrO4/(Y,Gd)AG:Ce3+, Sr2SiO4:Eu2+

This paper presents a novel approach to enhancing the color of inorganic yellow pigments using yellow fluorescent materials. The results demonstrate that the inclusion of phosphor leads to a significant improvement in various color attributes. Specifically, the addition of 15 %–20 % phosphor of YAG:Ce3+, (Sr,Ba)2SiO4:Eu2+ or YAG:Ce3+,Gd3+ in BiVO4 or PbCrO4 increases the brightness value (L*) by 5.0 %–8.7 %, the yellowness value (b*) by 4.2 %–9.2 %, and the color saturation value (C*) by 4.1 %–8.7 %. Furthermore, the reflections in the yellow region show a notable increase of 13.7 %–22.1 %, while remaining relatively low in the blue region (the complementary color of yellow), at approximately 10 %. This phenomenon can be attributed to the strong yellow emission performance of phosphor and the interesting synergistic effect between phosphor and pigment. The strong blue absorption of conventional pigment powder compensates for the inherent lack of blue absorption in phosphor alone, thereby maintaining a low reflectivity for the complementary color (blue) of yellow. Moreover, the fluorescence lifetime of yellow substantially increases with the addition of phosphor in the mixed material. This observation aligns with the quantitative relationship between reabsorption and fluorescence lifetime, suggesting widespread reabsorption of yellow emission. This finding supports our hypothesis that positive synergies occur within the mixed layer. In summary, incorporating a small amount of phosphor into conventional pigments effectively enhances the coloring effect of the pigments.

Non-resonant inelastic X-ray scattering for discrimination of pigments.

Inelastic X-ray scattering (IXS) spectroscopy has been used in many fields of solid-state physics and theoretical chemistry as an accurate and quantitative probe of elementary excitations. We show that non-resonant IXS spectra in the energy loss range below 100 eV exhibit a strong contrast across a wide range of commercially available pigments, opening new routes for their discrimination. These signatures combine plasmonic transitions, collective excitations and low energy absorption edges. We have performed IXS to discriminate different artists' pigments within complex mixtures and to quantitatively determine rutile and anatase polymorphs of TiO2. The integration of experimental data on pigment powders with suitable ab initio simulations shows a precise fit of the spectroscopic data both in the position of the resonances and in their relative intensity.

ВЛИЯНИЕ ПАРАМЕТРОВ ТЕРМИЧЕСКОЙ ОБРАБОТКИ НА КАЧЕСТВО ПОЛИМЕРНО-ПОРОШКОВОГО ПОКРЫТИЯ ДРЕВЕСНЫХ МАТЕРИАЛОВ

This paper presents the results of a study of the qualitative parameters of the coating of the polymer-powder composition of coniferous wood, depending on the modes of heat treatment during its production. The quality of the polymer coating was assessed by abrasion, lattice incision and pencil hardness methods. To obtain coatings, an epoxy-polyester composition applied to wood by spraying followed by curing during heat treatment was used. The temperature of the heat treatment varied in the range of 80-120 ° C with an exposure time of 5-20 minutes. The intervals of thermal effects were chosen based on the analysis of domestic and international research experience in this area. The influence of the curing time and temperature of the polymer-powder coating on the following parameters of the material surface is shown: wear resistance, water absorption, adhesion, hardness. It was found that the wood coating based on an epoxy-polyester powder composition, treated at a temperature of 90 ° C for 15 minutes, has the highest quality technological and operational parameters. An increase in temperature and processing time has a negative effect on the quality of the coating due to the release of resins from the wood. This is especially noticeable at a curing temperature of 120 °C, when the process of resin extraction from coniferous wood increases. The results obtained make it possible to optimize the process of processing wood using polymer-powder coatings to achieve maximum protection and decorative characteristics with simultaneous drying or thermal exposure. Based on a comparative analysis with the literature data, it is shown that the technological modes of processing polymer powder paint significantly depend on the type of wood.

Exploitation of IR statistical results as a guidance for the multi-technique study of synthetic and natural iron-based pigments

Ochres are natural deposits particularly enriched in iron oxides and hydroxides giving them their typical colours spanning from bright red to yellow or brown. For this reason, they have been widely exploited over millennia for artistic purposes, becoming among the most known pigments.A series of 16 iron-based powder pigments including both commercial and natural ochres was investigated. Specifically, natural materials came from the Røros (Norway) district, where they were historically extensively used for painting the wooden houses’ facades.The set of samples was studied by applying a multi-analytical approach involving colorimetry, X-ray fluorescence, infrared spectroscopy in multiple spectral ranges and configurations, Raman spectroscopy, and X-ray diffraction. The potentiality of coupling infrared spectroscopy with Principal Component Analysis (PCA) in characterising and discriminating iron-based pigments represents an innovative approach to guide the interpretation of results obtained by applying a variety of analytical techniques, thanks to the identified clusters. This allowed, in turn, for depicting an extremely consistent description of the samples and specifically of those used in the conservation intervention of the UNESCO World Heritage site of Røros (Norway) and whose composition has never been studied before.

US: Pan Technology – colour pigment powders & dispersions

US: Pan Technology – colour pigment powders & dispersions

Effects of Coloration of Spinel CoAl2O4 Cobalt Blue Pigments: Composition, Structure, and Cation Distribution

Cobalt blue ceramic pigments mainly consisting of CoAl2O4 are subject to the difficulty of color control. Here, a perspective is reported regarding research on the reasons for color change based on the control of the heat treatment and ratio of components. Macroscopically, the composition of pigment powders determines the color. Microscopically, the crystallite characters including size, cation distribution, and structure have an important effect on the color. The ingredient, structural, and color properties of the pigment powders are analyzed using thermo gravimetry–differential scanning calorimetry (TG–DSC), X-ray diffraction (XRD) measurement, Rietveld refinement, energy dispersive spectrometer (EDS), and colorimetry analysis. The color is proven to be associated with cation distribution, such as that of Co2+ and Co3+. It is indicated that high heating temperature, long heating time, and a large proportion of Al3+ can, respectively, induce the Co2+ and Al3+ in tetrahedral and octahedral sites.

3Y-TZP electrostatic painting to increase bond strength to dentin and dental prostheses

Although the clinical method used to improve the adhesion of zirconia prostheses to other materials is sandblasting or acid etching surface, the failure rate of the bond is high. The present work aims to propose an innovative method of zirconia surface painting with an electrostatic technique using epoxy powder paint with antibacterial and antifungal properties to improve the adhesion to dentin. The zirconia samples were divided into 4 groups: without surface painting (GC), painted without surface treatment (G1), hydrofluoric acid etching before painting (G2), and blasted with alumina before painting (G3). The samples were characterized by X-ray diffraction, scanning electron microscopy, Vickers hardness, 3D roughness, and cytotoxicity. Shear bond strength (SBS) tests were used to measure the zirconia bonding to synthetic dentin (NG-10 polymer). The opacity of painted zirconia was evaluated using a spectrophotometer with contrast ratio as a translucency parameter. The results showed the sintered zirconia had high densification, and submicrometric tetragonal (t-ZrO2) and cubic (c-ZrO2) grains. The bonding shear strength of zirconia without surface painting and surface treatment (3.51 MPa) was the lowest. The highest bonding strength was painted zirconia without surface treatment (15.51 MPa). The zirconia etched with HF had a lower shear strength (5.75 MPa) than the zirconia blasted with alumina (7.76 MPa). As the painting coating thickness increased, the opacity increased. The cytotoxicity tests showed that the coated zirconia is biocompatible. The zirconia painting with epoxy powder paint methodology facilitates the manufacture of dental prostheses and increases the shear bonding strength to dentin.

Ce doped LaAlO3 pigments with high NIR reflectance and modification of thermal aging properties of polyvinyl chloride

Based on the modified weather resistance of PVC plastics, a series of La1-xCexAlO3 inorganic pigments were synthesized in this study. A single La1-xCexAlO3 (x varies from 0.00 to 0.20) phase replacement solid solution of rhombohedral crystal structure with the addition of more Ce3+ doping. The sample pigments demonstrated a curved rod to spherical particle morphology change as Ce doping amount increased. The analysis by X-ray photoelectron spectroscopy (XPS) demonstrated that the cerium ion chemical valence states in the synthesized samples were + 3 and + 4. The carrier concentration and electron trap theory can be used to understand the variation in near-infrared reflectance of La1-xCexAlO3 pigment powder from 72.55% to 83.35%. Electric charge transfer (La 3d ↔ Ce 3d) can be used to describe how the La1-xCexAlO3 pigment shifts from white to orange to yellow. When PVC plastic is modified with pigment, the near-infrared reflectance varies from 52.87% to 61.63%. Inner surface temperature of La1-xCexAlO3/PVC composite plastics can be lowered by 8.5–13.7 °C, and the weather resistance of the modified PVC plastic is greatly increased. In conclusion, the modification of PVC plastics with La1-xCexAlO3 inorganic pigments can significantly reduce the surface temperature of plastics and prolong their service life.

Study of Titanium Dioxide (TiO2) Extraction Process from Ilmenite Banten

Ilmenite is found in the form of iron sand with reserves of 927,315,827 tons spread across several regions in Indonesia, including Banten which has seven million tons of iron sand. This mineral can be used as a raw material for making TiO2 pigments. The problem faced in the use of Ilmenite is its complex mineral structure which causes difficulties at the processing stage. The synthesis of TiO2 from ilmenite ore commonly used the sulfate process and the chloride process. The sulfate process is less environmentally friendly, has excessive costs, and produces a lot of liquid waste. While the chloride process requires high-grade raw materials and requires chlorine gas. Therefore, in this study, the synthesis of TiO2 from ilmenite Banten using caustic fusion, acid leaching using hydrochloric acid, and the use of citric acid were conducted. Caustic fusion is conducted with ratio between ilmenite and NaOH is 1:2, with a fusion temperature of 850 °C and a fusion time of 60 minutes. Then next process is water leaching and acid leaching. The result of this study is that the TiO2 obtained from each acid leaching is hydrochloric acid leaching producing powder pigment with 94.189% TiO2, acetic acid leaching producing 37.099% TiO2, citric acid leaching producing 41.480% and hydrochloric acid leaching without fusion process producing 43.991% TiO2.

Study on the Influence of Electron Beam Radiation Sterilization Method on Chinese Mural Pigment

Murals are one of the important cultural heritages of mankind. The microbial control of murals is an important subject in mural painting conservation. In recent years, electron beam radiation sterilization has attracted more and more attention in the field of cultural relic protection. Murals are immovable cultural relics, so conventional electron beam irradiation equipment can not be used. However, the development of small mobile electron beam irradiation equipment shows the potential of radiation’s application in the sterilization protection of immovable cultural relics such as murals. A feasibility study of radiation sterilization in mural paintings is needed to investigate the effect of sterilization and the influence of sterilization dose on the stability of mural painting pigments and bonding materials. In this paper, the radiation effects of typical bacteria in tomb murals and mineral pigment powder in ancient Chinese paintings were studied in a laboratory. Firstly, aeromonas hydrophila (Aer.h) and penicillium flavigenum (PNC) were selected as representative strains to determine the appropriate sterilization dose for murals. Then, the effects of radiation on seven kinds of ancient Chinese mineral pigments and white calcium carbonate in the ground layer were verified. The results are as follows: the radiation dose of 10 kGy can effectively remove the two typical strains. This sterilization dose will cause a color difference in calcium carbonate and lead white, while other color pigments are essentially stable. Based on the color difference and UV-vis intensities of the four white carbonate samples, the color change in two of them increased with increasing the dose up to 30 kGy, after which signs of saturation began to appear. X-ray diffraction (XRD), Raman spectra, X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES) spectra showed that the chemical structure of the samples did not change after irradiation. The formation of free radicals in treated samples was confirmed using an electron paramagnetic resonance (EPR) spectrum test. According to all characterization results, the color difference between the four white carbonate samples may be due to the combination of unpaired electrons and defects in the process of electron beam irradiation to form color centers. After forming the color center, the light absorption of the four samples changed. This is a reversible change, but the samples will take a long time to return to their original state. This study focuses on the influence of electron beam radiation on pigment composition, which is a preliminary exploration of whether radiation sterilization can be applied to the protection of ancient Chinese mural paintings, and the experimental results can provide basic data for later application.

Development of Oil Purification Process in Metal Sheet Products

Today, the use of metal sheet is quite high in order to provide the required strength and endurance values in the automotive industry. Metal sheets take form by going through different operations. Special oils are used in order to create the geometric forms they have easily and to prevent the sheet metal from being damaged. These used oils come into contact with metals during the geometric forming and machining processes and most of them remain on the metals. These oils cause difficulties in operations such as welding, coating and painting after the forming process. For this reason, a clean surface is considered as the most important step in the preliminary preparation of the next processes. There is an increase in the stickiness of the oil on the metal, which reaches a certain temperature by applying the welding process. This situation causes problems such as non-adhesion to the surface and peeling of the coating in the powder paint and zinc coating applied to increase the corrosion resistance of metals and the life of the product. In addition, when the oil residues on the metal are not cleaned, undesirable boiling occurs in the coating pool and causes an ash problem. 
 In this study, it is aimed to develop a metal-specific degreasing process to clean the oils of different viscosities used in different processes while forming the geometric form of the metal. Thus, the surface quality will increase and it will be ensured that the errors that occur in the next operations that require surface cleaning will be prevented.

Solution combustion synthesis of FeCr2O4:Zn,Al pigment powders

AbstractFeCr2O4:Zn,Al pigment powders were prepared via a solution combustion synthesis method. Effects of Zn and Al dopants and less/extra Fe content on the structure, molecular bonds, and optical properties of powders were studied. Results showed that addition of dopants as well as extra/less content of Fe led to weaker combustion and consequently lower X‐ray diffraction peak intensities, lattice parameters, and differential thermal analysis peak intensities. Moreover, Fourier transform infrared analysis illustrated that the band position of Cr–O and Fe–O bonds were shifted to higher frequencies with moving away from stoichiometry. In addition, scanning electron micrographs showed that in all samples, porous spongy microstructures were formed with highly flake‐like agglomerated particles. Furthermore, there was a significant difference between the powder samples and the tiles colored with in glaze powders due to the partial dissolution of pigments in contact with the molten glaze of tiles. In comparison to the tile colored with the stoichiometric FeCr2O4 pigments without dopants, the color difference (ΔE) in the tiles colored by the iron chromite pigments doped with Zn and Al dopants and less/extra Fe content reached the high values as large as ΔE = 36.19. The solar reflectance values (Rs) in near‐infrared region were above 50% in all samples. Near 80% Rs in the tile colored by the iron chromite pigment doped with 3 mol% Zn and the yellowish brown appearance (L* = 43.44, a* = 6.77, b* = 18.38, c* = 19.59, h = 69.79) showed that the sample was a good candidate for cool building materials such as roof tiles.