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Experimental Study of effect of Powder Coating thickness and layers on Hardness and Corrosion properties of Carbon Steel Material
Abstract
Powder coating is one of the coating techniques that are widely used today as a substitute for coating using liquid painting. In this research, we report on the effect of the various layers of powder coating on the hardness and corrosion rate of the material. Three different layers of variation were observed with 1, 2, and 4 layers to obtain the best results. The cleaning process was applied before coating the samples. The coating process was performed in a special room/box to avoid contact with air and contamination from the outside environment with a spraying distance of about 20-30 cm. The morphology is compact and bigger grains are seen to be emerging in the 1 layer deposition. Many grains are visible, and uniform grains are distributed in the 2 layers deposited. For the 4 layers, due to higher layer deposition incorporation, the grain size is seen to be enlarged due to the merging of smaller grains with each other ultimately increasing the grain size. The uncoated material has a corrosion rate of 0.505 mm/year which means fair for the relative corrosion resistance. The coated samples have a corrosion rate of 0.353, 0.252, and 0.354 mm/year for the 1 layer, 2 layers, and 4 layers, respectively. Based on the calculation, the average number of the Rockwell hardness of un-coated and coated samples for the 1 layer, 2 layers, and 4 layers, respectively were estimated at about 70, 78, 79, and 58 HRB, respectively. The highest average hardness value is in sample B with 2 layers of 79 HRB. The lowest average hardness value is in sample B with 2 layers of 58 HRB. The lowest performance of sample D with 4 layers confirms the result as shown in the corrosion rate result.
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With the environmental regulations becoming more stringent and awareness of consumers increasing to protect environment, an urgent problem is to reduce the use of volatile organic compounds (VOCs). Powder coating is a kind of solid powder coating without any solvent. Due to its excellent application performance and environment-friendly, it is widely used in the field of metal coating, especially appliances of offices and home. In recent years, the use of powder coatings has been developed very fast and the requirements of functional powder coatings are also gradually strengthened. According to resin of the film forming, powder coatings can be divided into two types: thermosetting powder coatings and thermoplastic powder coatings. Each kind of powder coatings has its own advantages and disadvantages, and they will be applied in different fields. In order to improve the properties of powder coatings, there are many reports and studies about them. The compositions of powder coatings were extruded, crushed and screened to gain powder of coating. The powder always was stored at room temperature. The powder coatings often operated by two kinds which were electrostatic spraying method and fluidized bed dipping method. After that, the powder was heated to melt and cure. Finally, a smooth bright permanent film on articles was formed to achieve the purpose of decoration and corrosion. The process flow preparation of powder coatings always separated into dry process production and wet process production. The development courses of powder coatings about resins, pigments and fillers are summarized. The future development trends of powder coatings are illustrated.
The evolution of precipitation and microstructure during a simulation of the thin slab direct rolling process, in six vanadium based, low carbon, steels with V, V-N, V-Ti-N, V-Nb, V-Nb-Ti and V-Zr additions was studied by optical microscopy, analytical transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX) and parallel electron energy loss spectroscopy (PEELS). Tensile properties and Charpy vee- notch toughness of the final strip were also determined. The effects of microalloying additions and processing conditions, including equalisation temperature (1200degreesC, 1100degreesC and 1050degreesC) and end water cool temperature, on the austenite and ferrite grain sizes, as well as the type and composition of the precipitates, were determined. The relationship between the microstructure and the properties in the steels was also ascertained.
Properties such as the specular gloss, adhesive strength, viscoelasticity, and impact resistance of thermoplastic polyester powder coating film were studied as a function of air-cooling time. Thermoplastic polyester resin is known for the fact that the heating condition has an effect on the degree of crystallinity. We focused on the relationship between the air-cooling time employed in the film preparation process and the degree of crystallinity. The test pieces were dipped into a fluidized polyester powder vessel, and then cooled in air to form the film. We refer to this cooling time in air as the “air-cooling time”. It was found that the degree of crystallinity increased as the air-cooling time increased. As the degree of crystallinity increased, the specular gloss, adhesive strength, viscosity and impact resistance decreased. We therefore found that the improvement in film performance is related to the reduction in the air-cooling time. The importance of this phenomenon is considered in relation to the widespread use of thermoplastic polyester resin. Similar behavior is expected for other polyester powder coatings.
The present study focuses on the physicochemical characterization of the interface between an epoxy/polyester-based powder coating and an epoxy/thermoplastic-based composite material. An inmold process has been used for the powder coating deposition on carbon/glass fibers reinforced composite substrates, and different methods have been performed to characterize the interface. We evidence here the strong dependence of the structural, chemical and thermal behaviors of the interface on the cure time/temperature conditions at which the powder coating was crosslinked. At a low crosslinking rate of coating (similar to 48%), experimental results reveal the development of a large heterogeneous organic/organic interphase between coating and substrate. However, thin interphases have been detected when the crosslinking rate goes beyond 69%. Besides, a phase segregation of thermoplastic additive within the composite matrix was identified in the formation of this interphase. Energy-dispersive X-ray spectroscopy (EDS) as well as FTIR/Raman experiments enabled us to put in evidence the diffusion process of the thermoplastic additive toward the coating. From thermal analysis, glass transition temperature Tg for both components was observed, which confirm the proposed mechanism. This study highlights the importance of the thermal processes on the complex competition between the interdiffusion between two epoxy matrix and the existence of thermoplastic toughening agent at the interface of powder coating and composite material.
Summaries An acrylic/polyester system has been introduced for powder coatings as an altemative system to TGIC.
In a typical polyester/blocked-isocyanate system or polyester/TGIC system, a higher terephtholic acid (TPA) content polyester
resin shows good mechanical properties, but the exterior durability is not good enough. On the other hand, a polyester based
on isophtholic acid (IPA) shows excellent exterior durability, but the high IPA content adversely affects the mechanical properties.
Both excellent exterior durability and good mechanical properties were given by this acrylic/polyester system, especially
by the combination of the acrylic resin (having glycidyl-epoxy groups and OH groups), bi-functional polyester (having OH groups
and COOH groups) and blocked isocyanate.
To Study the Various Methodologies Involved in Powder Coating Technology
- Kartikay Sankhyadhara
- Pinki Chakrabortya
Kartikay Sankhyadhara, Pinki Chakrabortya, "To Study the Various Methodologies Involved in Powder Coating
Technology." International Journal of Innovative Science and Research Technology, June 2021, vol 6, pp.247-251
Laju Korosi Baja Karbon Hasil Powder Coating Dan Pengecatan Cair
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Muhammad Arifullah, Ike Widyastuti, Mardjuki, "Laju Korosi Baja Karbon Hasil Powder Coating Dan Pengecatan Cair."
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Analisa Pelapisan Powder Coating Pada Box Panel Terhadap Kebocoran Arus Listrik
- Ristanto Febi Agusta
Febi Agusta Ristanto (2017), "Analisa Pelapisan Powder Coating Pada Box Panel Terhadap Kebocoran Arus Listrik." JTM.
2017, vol. 5, pp. 9-15.
Corrosion Engineering
- Mars Fontana
- Guy
Fontana, Mars Guy, "Corrosion Engineering." Singapore: McGraw-Hill Book Co, 1986