Papers by Keyword: Spray Coating

Abstract: One of the major toxicants for living things is copper which consists of ions form in most of the manufacturing wastewater treatment. The drain water before releasing it into the water source is desired to eliminate copper ions (Cu²⁺) by using adsorption. The bio-wastes as adsorbents applied in this work, such as a dried pineapple pulp (DPP), chitosan flake (CTS), and chitosan spray coating on dried pineapple pulp (CPP) have a surface area of about 45.34, 60.02, and 70.01 m²/g, respectively. The effective Cu²⁺ eliminated efficiency and adsorption capacity from the copper (II) sulfate in aqueous solution was high with the high surface area. At optimum operating conditions, i.e., initial feed concentration 250 mg/L, pH 6.0, temperature 30 °C, and adsorption time 1 h, the Cu²⁺ eliminated efficiency in the percentage of DPP, CTS, and, CCP was 63.89, 80.83 and 86.92%, respectively, and adsorption capacity was 31.95, 40.22 and 43.46 mg/g, respectively.

Abstract: Automotive air conditioning (AAC) is essential, particularly in tropical countries like the Philippines, where temperatures can go beyond 40 °C during the summer. AAC system is installed for the comfort and safety of passengers. However, AAC may consume up to 30% of the fuel and increase fuel consumption by up to 20%. Consequently, increasing fuel consumption can lead to high costs and greenhouse emissions worldwide. Commercially available car tints can block harmful ultraviolet (UV) rays but selectively block IR rays which primarily cause heating. Therefore, sustainable cooling solutions must be developed. This study developed a silver nanowire (AgNW)-PVB (polyvinyl butyral) composite spray coating. The coating decreased the transmittance by at least 30% in the UV region and at least 25% in the near-infrared (NIR). Average transmittance in the visible region (Vis) is as much as 63.50% which highly depends on the concentration of PVB and AgNWs. More AgNWs decrease the transmittance at UV, Vis, and NIR regions.

Abstract: Titanium dioxide (TiO₂) has been exploited extensively as it shows remarkable performance in photocatalytic applications. TiO₂ thin films can be deposited onto window glass which is workable for self-cleaning applications. In this article, we have studied the role of substrate temperature for spray pyrolysis (SP) of TiO₂ thin films for studying self-cleaning applications. For thin film deposition, TiO₂ sol is prepared by the sol-gel synthesis technique. The samples are deposited at room temperature and 250 °C, respectively. The samples are characterized via Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and UV-Vis spectroscopy to determine the morphology, surface roughness, and optical properties of the thin films. SEM and AFM results show that samples deposited at 250 °C (pre-heated samples) have uniform size distribution, and defined grain boundaries, respectively. The results also show that the pre-heated sample is highly transparent in the visible region of the solar spectrum when analyzed by the steady-state UV-Vis spectrophotometer. The wettability of the prepared thin films is measured, and the results show that the pre-heated sample shows a hydrophilic character. The self-cleaning property of prepared thin films is evaluated by the photodegradation of Rhodamine B dye. It is observed that the pre-heated substrates show better photoactivity in presence of UV light irradiation. Hence, due to their hydrophilic nature and better photoactivity, these pre-heated thin films deposited by spray pyrolysis can be employed as efficient coatings for self-cleaning glass applications.

Abstract: N-ZnO thin layer is widely used in application of wastewater photo catalyst. N-ZnO thin films have been successfully deposited on glass substrate using spray coating technique at 450 °C with varying concentrations of N from Urea source. XRD test results showed that the N-ZnO has a polycrystalline structure with diffraction field (100), (002), (101) and (110). The presence of nitrogen atoms in the lattice of ZnO causes a shift in diffraction angle between 0.08^o - 0.18^o. N-ZnO thin layer showed the occurrence of tensile strain. Surface morphology of N-ZnO is shaped like mine (like root). All samples have band gap energies lower than that of ZnO and the smallest is sample N6 with Eg = 3.249 eV. The presence of nitrogen atom increases surface roughness and decreases band gap energy.

Abstract: ZnO doped with 2~6 mol% Silver (Ag) photocatalyst thin films has been deposited on glass substrate by thermal spray coating with temperature deposition of 250°C. A gel of ZnO:Ag precursor has been synthesized by sol-gel route from aqueous/alcoholic solution of zinc acetate dehydrate and silver nitrate mixture at room temperature. The morphology of ZnO:Ag films were investigated scanning electron microscopy (SEM). 3D SEM images of ZnO:Ag thin films show the rough morphology with roughness mean square (rms) of 150 to 195 nm. The grain size of ZnO:Ag films were found in the range 76,5 to 304,8 nm. The photoactivity examination of ZnO:Ag photocatalyst films show the E. Coli bacteria degraded up to 99.99% under sunlight irradiation for 4 hours.

Abstract: We report on the preparation of thin conducting films from the poly (N-vinylpyrrolidone) stabilized polyaniline dispersions for the ammonia gas sensor applications. The dispersion is water-based and prepared by means of relatively simple chemical oxidation polymerization of aniline. Two processes were used for the ink deposition, the ink-jet printing and the spray-coating technique. With the former one, the ink was at first tested on the poly (ethylene terephthalate) foil to find a suitable combination of ink formulation and print parameters. After that, the final ammonia gas sensors were fabricated by both deposition techniques and compared. The aspects of the ink preparation and alteration, as well as the active layer properties, are analyzed by means of UV-vis spectroscopy, optical microscopy, atomic force microscopy, profilometry and electrical measurements. The results obtained from each deposition technique are discussed. In both cases, the sensitivity to the ammonia gas has been demonstrated, making the proposed ink in combination with the two named deposition processes feasible for the potential large-area sensor production.

Abstract: This study presents a simple and low-cost spray coating process for producing high performance CO (carbon monoxide) sensors utilizing toluene-based gold nanoparticles (Au-NPs). Thanks to the success synthesis of Au-NPs in toluene, this low surface tension organic solvent prevents Au-NPs from colligation. And therefore Au-NPs can be well dispersed on the surface of the electrodes as the sensing layer during spraying. To compare with the typical metal oxide based CO sensors that have to work at a higher working temperature of about 150~350°C, the produced sensor can work at room temperature and have a better detection limit for CO gas (5 ppm). Experimental results indicate good linear sensitivity under repeated measurements for concentration range from 5 250 ppm (R²=0.996). The repeatability is also confirmed by measuring 100 ppm CO gas, the calculated variation is less than 2.8% for six repeating measurements. The process developed in this study can be used to produce not only high performance CO gas sensors but other related gas sensors.

Abstract: A homogeneous photoresist for IC or read-write data storage head fabrication requires a certain flowing of the resist film on the topography surface for at least few micrometers, thus defining certain minimal resist viscosity for the remaining solvent concentration for spraying technique. The high photoresist solvent evaporates during flight (between spray nozzle and substrate) prevents the droplets from sticking to the substrate and causes a rough surface. The limitation of very low photoresist viscosity for micro droplets spraying is a drawback of the technique. Because of very low viscosity of spray coating resist, nitrogen in spray coating system will act as 2 functions. First is for spread photoresist to be micro droplets. In the same time nitrogen can dry the small droplet before locating to substrate and perform obstacle for UV exposure. The unsatisfied resist was protected UV light during exposure cause pattern deformation. The study was investigated the particles which always found on finished photoresist surface spraying, and aimed to find the solution to decrease or eliminate dry droplet. EDX identified element of the obstacle particles is photoresist. They are dry resist ball about 1 – 6 um size. The selected chemicals for the investigation to dilute or dissolve the resist ball, IPA, acetone and mixing solution between 70% IPA and 30% acetone. Acetone is most effective. The proper time for dissolve dry resist ball with slight photoresist degradation is 40 s, very short because of high vapor pressure of acetone at room temperature. There is a trade-off between resist surface smoothness and reflow characteristics. Final resist thickness with the acetone vaporization condition will be achieved 7.5 um as expectation with less corner coverage problem. SEM and AFM images were confirmed that morphology after acetone vapor exposure was improved. Surface roughness was reduced for 3 times to 8 nm with acetone vaporization environment. The end of this study was include on corrosion characterization for magnetic CoFe alloys underlying photoresist to explore the method to determine photoresist type in future manufacturing which necessary to run the process with sensitive material. With AZ4999 spray photoresist protection indicated corrosion rate of CoFe films was reduced for 100 times compare to bare films.

Abstract: Coating systems consist of acrylic polyol resin and silicone intermediate resins were tested for their corrosion resistance properties. The corrosion protection property of the coating was evaluated by using Electrochemical Impedance Spectroscopy (EIS) which showed that system with 70 % of acrylic has the highest corrosion resistance. The maximum value of corrosion resistance obtained was found to be 1.40 x 10⁹ Ω on the 30^th day for the 70 % of acrylic sample. The glass transition temperature (T_g) obtained using the Differential Scanning Calorimetry (DSC) were in the range of 23 °C to 65 °C. It showed that all samples are suitable for decorative paints, general industrial coatings and floor care coatings. The functional groups and also the cross-linking between the organic resins were analyzed using Fourier Transform Infra-Red Spectroscopy.

Abstract: This study aims at the array ultrasonic nozzle sprayed atomization flow field on flat plate, and uses different design and operating parameter combinations to analyze the distribution of spray flow field, the analytic results can be used to improve the flat plate coating performance of the array ultrasonic nozzle spraying equipment. The simulation analysis results will be compared and validated by practical spray coating experiment, so as to determine the reliability of simulation to implement the spray flow field simulation technique for large area uniform spray coating. The mean error value is less than 24%, proving that the simulation results have certain feasibility and accuracy.