Papers by Keyword: Deposition

Abstract: Pulverized coal ash can be used as an additive to reduce corrosion on heating surface of biomass boiler. Biomass ash and pulverized coal ash were mixed and coated on the metal surface for experiment; the results showed that the corrosion rate of the metal decreases by adding pulverized coal ash. With the increase of additive content, the corrosion gradually reduces. The effect of different pulverized coal ash on corrosion is different, but as the proportion of pulverized coal ash increases, the effect tends to be close. When the molar content of (Si+Al)/(Na+K) is about 2 and the ratio of Si/Al is about 1, the pulverized coal ash additive works best.

Abstract: In this work Zinc oxide thin films prepared by spray pyrolysis technique. A set of ZnO thin films were deposited with various deposition times, on glass substrate at 350 °C. The precursor solution is formed with zinc acetate in distilled methanol with 0.1 molarity. The deposition time was ranged from 2 to 8 min. The structural and optical properties of those films were examined by X-ray diffraction (XRD) and ultraviolet-visible spectrometer (UV). X-ray diffraction patterns of the ZnO thin films showed polycrystalline hexagonal wurtzite structure and the preferred orientation was along (002) plane when the grain size varied between 9.66 and 16.67nm. ZnO thin films were highly transparent in the visible with the maximum transmittance of 85% and the optical band gap was found between 3.25 and 3.28 eV.

Abstract: Cold spray (CS) is a deposition technique to form a coating from the particles with temperature lower than their melting point. In this technique, particles are accelerated by a supersonic flow of a carrier gas such as air or nitrogen. Upon impact, particles undergo significant plastic deformation that bonds them to the substrate. Since the particles are not molten, this deposition method does not apply a lot of heat to the substrate and this makes CS the best candidate for temperature sensitive and oxygen sensitive materials. CS can be adapted to form 3D objects following layer-by-layer approach. This is called cold gas dynamic manufacturing (CGDM) or cold spray as additive manufacturing. Developing complex shapes by CGDM may result in formation of inclined surfaces, corners and sharp edges. Deposition in those regions is often accompanied with challenges that affect the accuracy and efficiency of the manufacturing. In this study, CGDM for two typical shapes such as cylinder and frustum on a flat substrate has been simulated to represent the additively manufactured parts. Particle trajectories and impact conditions i.e. velocity and size distributions have been compared. The results of numerical modelling provided useful information for understanding the limitations and challenges associated with CGDM that can help us to improve the quality and precision of particle deposition.

Abstract: Impurities and resulting inclusions are an issue when processing higher amounts of scrap during steel making. To increase the recycling rate, the removal of impurities from the scrap in form of inclusions is of great interest. In previous studies was found that inclusions attach primarily on carbon containing refractories, especially if on their surface an interfacial layer (1–3 µm thickness) was formed in-situ. This study investigates the formation mechanism of this in-situ layer in detail by application of computer tomography (CT) measurements on two scales. The large scale CT scans visualized the general appearance whereas the small scale measurement regarded the in-situ formed layer and the attached inclusions in detail. Based on these measurements, previous results and a literature review it was concluded that the layer formed mainly due to carbothermally reduced impurities which moved to the decarburized surface of the refractory in gaseous form and enhanced sintering of the surface region to develop the layer.

Abstract: Technological features of obtaining of tin films in a vacuum by liquid-phase target magnetron sputtering were reviewed. With high deposition rate the white color tin coating with amorphous structure is formed on the substrate. X-ray microanalysis of the obtained tin films showed the presence of micro-and nanoparticles of an impurity of the crucible material in the structure of the films. The use of the tantalum crucible with liquid-phase target magnetron sputtering with deposition rate of 3.2 μm / min allows obtaining ultra-pure, continuous, homogeneous tin film on a stationary substrate without impurity material of the crucible.

Abstract: The hybrid plasma reactor is based on the combined magnetron or arc discharge and radio-frequency inductive discharge located in the external magnetic field. Magnetron or arc discharge provides the generation of atoms and ions of the target materials while the flow of accelerated ions used for the ion assistance is provided by the RF inductive discharge. An external magnetic field is used to optimize the power input to the discharge, to increase the ion current density in the realm of substrate and to enhance the area of uniform plasma. The high value of the ion flow bombarding the substrate gives the possibility to organize the effective ion assistance to the films growth in case of high rate deposition by the arc sources.The deposition of Ti, Al, Si and permalloy films showed that the presence of ion assistance leads to the substantial change of the films structure and properties.

Abstract: Porosity plays an important role on a particle deposition process which determines the strength of material. The structure of a material from deposition process can be viewed as a random close packed. References show that random close packing structure of uniform-sized particles gives a porosity of around 36%. In this work we simulate the deposition process using a particle method to study the effect of particle size ratio into a porosity of a material with the ratio of particles’ radius is ranged from 1:1 to 1:5. From the simulation we get an interesting result that shows the porosity is decreased when the size ratio is increased in range from 1:1 to 1:1.5 with its minimum porosity is 31.92% at ratio 1:1.5. Then as the ratio increases from 1:1.5 to 1:5, the porosity is also increasing.

Abstract: The synthesized and characterization on the growth of copper oxide thin films on fluorine-doped tin oxide (FTO) coated glass with annealing and without annealing process has been studied by immersion techniques. Furthermore, ZnO layer has been used in order to improved the absorption spectrum of CuO films. The copper oxide films were analyzed on the morphological, structural, optical and electrical by field emission scanning electron microscopy (FESEM), X-ray diffractometer (XRD), UV-Vis spectroscopy (absorbance) and I-V characteristics instruments. The atomic force microscope (AFM) was used in order to characterize the surface imaging of copper oxide films and the thicknesses were measured using a surface profiler. The AFM studies revealed that the roughness of the CuO films increased after annealing was applied this is due to the formation of large clusters of grains from the merging of small clusters grains. The CuO films thicknesses also becomes two times higher than the CuO films without annealing process.

Abstract: Ceramic oxide thin films are an important material, with applications in many areas of science and technology. Titanium oxide (TiO₂) is also a well-known and important material for applications such as gas sensors [1], photocatalysis materials [3], and electrochemicals [1], due to its self-cleaning [2], good corrosion resistance and biocompatibility. Atomic Layer Deposition (ALD) is a nanotechnology tool that is used for the deposition of nanostructured thin films. The unique advantage of ALD is the self-limiting film growth mechanism, which offers attractive properties, simple and accurate film thickness control, sharp interfaces, uniformity over large areas, excellent conformality, good reproducibility, a multilayer processing capability, and high quality films at low temperatures [3, 4]. TiO₂ thin films were grown using TTIP (Titanium isopropoxide) ALD on silicon wafers, glass slides, and stainless steel plates in order to study the effect of substrates on the growth of TiO₂. In order to achieve the desired advantages of using TTIP, a series of experiments were performed to study the growth mechanism of TiO₂ thin films using TTIP and H₂O by ALD.

Abstract: Recently, the display industry is focusing on making bendable or flexible displays with higher quality and larger area. Ultimately, there is a very high possibility that future displays will be rollable. The biggest problem with rollable displays is the fabrication of a polarizer film to prevent reflection of the OLED. To develop a rollable display, the display should be made of material with a very thin thickness, like that of paper. However, the thickness of the polarizer film used for displays is only approximately 180 μm. This means that the film is too thick to be applied to rollable displays. If a polarizer of wire grid type, which we investigate in this study, is used, it can reduce the thickness of this film to a value under approximately 1 μm. One research result has been to discover that Fe₃O₄ is a very slightly absorptive material. Especially, most research into Fe₃O₄ thin films has concentrated on its characteristics in nanotubes. So, our purpose in this research is to investigate the deposition process of Fe₃O₄ thin-film under various conditions using an E-beam evaporator; we intend to compare these various processes with each other after measuring the refractive index.