Search

The current state of the Ukrainianeconomy causes to resolve a range of questions related to the improvement of production and increasein the ecological safety of products, including paintand-varnishes materials, in combination with ensuring high operational properties of coatings based onthem.The formation of high-quality paints and varnishes with a long service life without compromising the ecology of the environment when usingthem, is largely determined by the composition andphysical and mechanical properties of paints andvarnishes.The main disadvantage of using liquid paints andvarnishes traditional for the Ukrainian market rangeis the content of solvents in their composition up to40%, which inevitably leads to their emission during production and application, as well as environmental pollution. This problem can be solved byscaling up production using eco-friendly powdercoating.According to the research results, we have obtained eco-friendly paint-and-varnishes coatings ofhigh corrosion resistance based on powder coatingcontaining silicates as a filler in the form of metakaolin and talc.Using the mentioned range of fillers in the powder coating contributes to the decrease in the peelingwidth to 2.13 mm and metal corrosion width to 1.38mm after testing in the salt spray chamber with thecondensation of 5 % of the sodium chloride watersolution and places obtained coatings into atmospheric corrosivity categories С3 and С4 accordingto ІSO 12944-2:2017, which creates conditions forusing these compositions in the context of the excessive corrosivity. &nbsp, Сучасний стан розвитку економіки України обумовлює вирішення низки актуальних питань, пов’язаних з удосконаленням виробництва та підвищенням рівня екологічної безпеки продукції, зокрема лакофарбових матеріалів, у поєднанні із забезпеченням високихексплуатаційних властивостей покриттів на їх основі.Формування якісних лакофарбових покриттів із тривалим терміном служби без погіршення екології довкілля при їх застосуванні, значною мірою визначається складом і фізико-механічними властивостями лакофарбових матеріалів.Основним недоліком використання рідких лакофарбових матеріалів традиційного для ринку України асортименту є вміст у їхньому складі розчинників до 40 %, що неминуче призводить до їх емісії при виробництві та нанесенні,а також забрудненні навколишнього середовища. Вирішити цю проблему можна завдяки розширенню виробництва із застосуванням екологічно чистих порошкових фарб.В умовах зниження використання лакофарбових матеріалів на основі розчинників запропоновано застосування екологічних покриттів підвищеної корозійної стійкості на основі порошкових фарб, які містять в якості наповнювачасилікати у вигляді метакаоліну та тальку. Використання вказаних наповнювачів в складі порошкової фарби сприяє зменшенню ширину відшарування покриття та ширину корозії металу, а також класифікує отримані покриття до категорії атмосферної корозійної агресивності С3 та С4 згідно з ІSO 12944-2:2017, що відповідно, створює передумови для використання вказаних композицій в умовах підвищеної корозійної агресивності.

The investigations of tribo mechanical properties of coatings obtained with electrocontact welding of sintered powder materials and powder-polymer fillers of Russian manufacture are presented. It is proved that the introduction of antifriction components (powders of copper or tin) into filler material at a rate of 5-10 % increases the time to joints seizure by 1.5-2 and decreases by 1.5 the friction ratio. The application of powder-polymer and sintered fillers reinforced with metal grid produces a relief on the operating surface of the coating with the areas possessing minimum hardness. They are worn out more intensely and the forming herewith grooves help to keep lubricating oil on the friction surface. For the friction pair operating in abrasive wear conditions with adhesive wear elements, at welding it is recommended to use powder compositions (by weight): 80-90 % – PG-FBX6-2, 10-20 % of copper powder friction ratio (PMS-N); for wear conditions at adhesive wear: 90 % of iron powder (PZHR 3.200.28), 10 % of tin powder (PO-1); for abrasive wear conditions: 70-80 % – PG-FBX6-2, 30-20 % – VK8.

Fluorescent coatings have attracted attention due to their bright colors. However, they have fewer outdoor applications due to low stability, especially the poor weather resistance of the fluorescent pigments. In order to improve their weather resistance and maintain the excellent appearance, this study used polymer binders to coat a light shielding agent nano TiO2 on the surface of the fluorescent pigment to extend the durability. Three organic binders, polyester varnish, polyurethane varnish, and polyvinyl alcohol, were selected. Each binder was dissolved and mixed with pigments and nano TiO2 particles to make a polymer-TiO2 layer on the pigment surface. The effects of binder types and loadings were investigated and evaluated by accelerating weather test of corresponding fluorescent powder coatings. According to SEM and ash test, nano TiO2 was successfully coated on the surface of fluorescent pigments. The modified fluorescent pigment shows a strong ability to absorb ultraviolet rays, and the weather resistance of prepared coatings has been significantly improved compared with the original fluorescent powder coating. When using clear coat PE as a binder and setting the ratio of the binder to the nano TiO2 of 1:2, the UV exposure time of fluorescent powder coatings can be extended by over twelve times compared to the coatings with original pigment for the same color change. This study provides an effective approach to enhance the weather resistance of fluorescent coatings and thus expand their applications.

Powder coatings are gaining popularity for their economic and environmental benefits. Additives (pigments) such as zinc phosphate enhance the anti-corrosive properties of coatings, but their behavior in powder coatings has not been extensively studied. In this study, zinc phosphate was incorporated into three powder coating systems: polyester clearcoat, polyester and epoxy coatings with filler BaSO4. Neutral salt spray and electrochemical tests (OCP, LPR, and EIS) confirmed that the anti-corrosive performance improved with the addition of zinc phosphate. The optimal additive dosage was determined to be 2% for all of the coating systems studied here, based on salt spray tests. Here, the time until failure increased by 1.5 to 2 times. Using electrochemical tests, an optimal additive dosage of 8% was found for the polyester clearcoat, while the other coating systems maintained an optimal additive dosage of 2%. Performance increased by as much as one order of magnitude based on resistance/impedance measurements. This suggested a synergistic effect between the additive and the filler. The passivation layer was confirmed by both X-ray diffraction and Raman spectroscopy. Based on the results and discussion presented in this article, the discrepancy was caused by different features of the two tests, such that the electrochemical tests probe the function of intact coatings, whereas salt spray measures only the corrosion spreading from the scribe. It is proposed that the two test methods characterize different aspects of the coatings, corresponding to their service conditions. This has theoretical and practical significance in the evaluation of anti-corrosive coatings. Other properties of the coatings, including adhesion, gloss, distinctness-of-image, and pencil hardness, were measured as per applicable standards and the conformance was verified.

Powder coatings are widely applied for corrosion protection of steel, aluminum, and hot dip galvanized steel in a variety of corrosive environments. Powder coatings are subjected to a number of strict laboratory tests to determine their mechanical properties, corrosion resistance, and color stability. Among European quality certificates for powder coatings applied to galvanized steel, the most commonly recognized are GSB-ST and Qualisteelcoat certificates, which also refer to the EN 13438 standard. Certificates of quality for powder coatings are constantly updated according to the latest research results and experience of specialists operating in the field of corrosion protection. This paper presents an experimental evaluation of how the required length of selected accelerated corrosion tests can affect the final assessment of powder coatings. On the example of two powder painting systems: polyester as well as based on epoxy and polyester resins, the paper presents the influence of the time of accelerated corrosion tests: ISO 6270, ISO 9227 (Neutral Salt Spray and Acetic Acid Salt Spray), and ISO 3231 on the protective properties of the coatings. The results of damage assessment according to ISO 4628 have been correlated with the requirements of particular quality specifications. Additionally, based on FTIR (Fourier Transform Infrared Spectroscopy) and EIS (Electrochemical Impedance Spectroscopy) analyses, the influence of the applied corrosion tests on the degradation degree of the coatings studied has been presented. The paper aims to present a tests for those powder coating systems applied to facilities for which the main requirement is corrosion resistance rather than aesthetics.

Organic coatings are the most widely applied method for protection of metallic materials. Liquid coatings still dominate the coating industry, but powder coatings are capturing more of the liquid coatings market due to their economical, ecological, environmental, and energy-saving benefits. Ultrafine powder coatings have been reported to show higher surface smoothness, gloss, and represent one of the future development directions of powder coatings. However, the mechanisms behind surface improvements and the anti-corrosion abilities of ultrafine powder coatings are still uncertain. Therefore, we fabricated ultrafine powder coatings (~ 20 µm in size), compared with coarse ones (>30 µm), and found that the ultrafine powder coatings had lower surface roughness, fewer inner voids, higher barrier properties, and narrower salt spray creepage (~ 30% decrease). Zinc-rich powder coatings (ZRPCs) are important for heavy duty anti-corrosive applications, but current ZRPCs have a too low zinc content (≤70 wt.%), indicating limited anti-corrosive ability, to be used for higher anti-corrosive requirements. We fabricated ZRPCs by employing a press and the zinc dust content reached 85 wt.%. The fabricated ZRPCs with 80 wt.% zinc had a higher zinc utilization and a more uniform dispersion of zinc particles, and in turn, slightly longer cathodic protection period and narrower creepage (1.3 mm) than the extruded sample (1.5 mm) after 2500 h salt spray tests. Another challenge for ZRPCs is how to decrease zinc content while maintaining the corrosion protection. We incorporated iron phosphide to replace part of zinc in zinc-rich polyester powder coatings and found that iron phosphide, due to its conductive nature and electrochemical catalysis activities, can replace 10 wt.% zinc in 75 wt.% zinc-rich coatings with maintained cathodic protection (87 days) and significantly decreased corrosion creepage (from 1.78 to 1.42 mm) and localized corrosion. In addition, applying superhydrophobic surfaces is a recently developing approach for corrosion protection. However, there are very few reports about superhydrophobic powder coatings and their anti-corrosion abilities. We fabricated robust superhydrophobic powder coatings by incorporating polytetrafluoroethylene (PTFE) particles and achieved tunability of hydrophobicity, with the water contact angle varying from 80° to over 160°. The coatings demonstrated multifunction, multifaceted durability, and robustness against corrosion.