Thermal spray coating was studied as one of the techniques used for coating graphite reinforced polymer composites, which are extensively used in the aviation industry. These coatings were studied for improvement of surface properties such as erosion resistance, UV protection, hardness and electro magnetic shielding. NiAl (65%Ni,35%Al) intermetallic, NiAl (95%Ni,5%Al), Aluminum and Zinc coating were thermal-spray deposited using different procedures (plasma, flame, electric wire arc) onto polymer composite substrate. Two categories of coating were evaluated: Coatings with bond coat and coatings without bond coat. Different levels of pre-surface preparation for thermal spray coatings were also studied. The microstructures, micro-hardness and electrical conductivity of these coatings were determined. Effect of different parameters on coating properties like micro-hardness and electrical conductivity were studied. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering / "December 2006."

Obtaining geometrical and physical information of industrially manufactured products or manually created artifacts has increased dramatically in the past few years. These data are usually generated by means of specific devices which are called 3D scanners. 3D scanners generate virtual 3D models of objects which in different fields can be used for various applications such as reverse engineering and quality control in manufacturing industry or data archiving of valuable unique objects of cultural heritage. There are basically two types of 3D scanning depending on whether contact or non-contact techniques are used. Non-contact scanners have been developed to overcome the problems of contacts. Optical methods are the most developed and major category of non-contact scanning techniques. Remarkable progress in computer science has been the key element of optical 3D scanning development. Apart from this improvement, optical scanners are affected by surface characteristics of the target object, such as transparency and reflectivity, since optical scanners work based on reflected light from the object surface. For solving this problem, in most cases the object is sprayed with an aerosol spray to change its characteristics temporarily, e.g. from shiny to dull or transparent to opaque. It is important to apply coating of minimum possible thickness to keep the object geometry unchanged. To study this issue, an atomization-based spray coating system was developed in this thesis research and used in sets of experiments to evaluate the effects of thin layer coating on 3D scanning results. In this thesis, firstly the spray coating system structure and coating specifications will be offered. Then, for appraising the efficiency of atomization-based spray coating in 3D scanning process, some examples are presented. These examples are based on some actual parts from different industries which were used as target objects to be coated and scanned. / Graduate / 0548 / behzadv@uvic.ca

Obtaining geometrical and physical information of industrially manufactured products or manually created artifacts has increased dramatically in the past few years. These data are usually generated by means of specific devices which are called 3D scanners. 3D scanners generate virtual 3D models of objects which in different fields can be used for various applications such as reverse engineering and quality control in manufacturing industry or data archiving of valuable unique objects of cultural heritage. There are basically two types of 3D scanning depending on whether contact or non-contact techniques are used. Non-contact scanners have been developed to overcome the problems of contacts. Optical methods are the most developed and major category of non-contact scanning techniques. Remarkable progress in computer science has been the key element of optical 3D scanning development. Apart from this improvement, optical scanners are affected by surface characteristics of the target object, such as transparency and reflectivity, since optical scanners work based on reflected light from the object surface. For solving this problem, in most cases the object is sprayed with an aerosol spray to change its characteristics temporarily, e.g. from shiny to dull or transparent to opaque. It is important to apply coating of minimum possible thickness to keep the object geometry unchanged. To study this issue, an atomization-based spray coating system was developed in this thesis research and used in sets of experiments to evaluate the effects of thin layer coating on 3D scanning results. In this thesis, firstly the spray coating system structure and coating specifications will be offered. Then, for appraising the efficiency of atomization-based spray coating in 3D scanning process, some examples are presented. These examples are based on some actual parts from different industries which were used as target objects to be coated and scanned. / Graduate / 0548 / behzadv@uvic.ca

Wrought magnesium alloys are considered attractive candidates for structural members in automotive and aerospace industries due to their high specific strength. Although new processes have helped to produce high purity magnesium alloys with higher resistance to corrosion, these alloys still need protection against corrosion when they are used in aggressive environments. Cold spray coating is one of the protective methods that are employed for this purpose. The similarity between cold spray coating and shot peening process poses the question whether cold spray coating can improve the fatigue strength in addition to providing corrosion protection. The objective of this research is to answer this question for the specific case of the coating of wrought magnesium alloy AZ31B with aluminum powder. This study comprises two parts. The first part characterises the residual stress induced by cold spray coating. This investigation employs both numerical and experimental methods. For the numerical study, the cold spray coating process has been simulated via ANSYS software classic package. The numerical results have been compared to experimental results from X-Ray Diffraction (XRD) stress measurement of a coated sample. For the second part of this research, the fatigue strength of as received, stress relieved, and stress relieved/coated specimens have been compared. Three groups of AZ31B specimens have been prepared and tested by rotating bending machine and their S-N curves have been prepared. Comparison of the results reveals that there is a considerable loss in fatigue strength of as received specimens after stress relief. This is due to the removal of compressive residual stress in the raw material induced by the extrusion process. Also, comparison of S-N curves of stress relieved and stress relieved/coated specimens shows fatigue life improvement after cold spray coating. The maximum improvement is 49 percent in the load of 120 MPa and the endurance limit has improved 9 percent.

Wrought magnesium alloys are considered attractive candidates for structural members in automotive and aerospace industries due to their high specific strength. Although new processes have helped to produce high purity magnesium alloys with higher resistance to corrosion, these alloys still need protection against corrosion when they are used in aggressive environments. Cold spray coating is one of the protective methods that are employed for this purpose. The similarity between cold spray coating and shot peening process poses the question whether cold spray coating can improve the fatigue strength in addition to providing corrosion protection. The objective of this research is to answer this question for the specific case of the coating of wrought magnesium alloy AZ31B with aluminum powder. This study comprises two parts. The first part characterises the residual stress induced by cold spray coating. This investigation employs both numerical and experimental methods. For the numerical study, the cold spray coating process has been simulated via ANSYS software classic package. The numerical results have been compared to experimental results from X-Ray Diffraction (XRD) stress measurement of a coated sample. For the second part of this research, the fatigue strength of as received, stress relieved, and stress relieved/coated specimens have been compared. Three groups of AZ31B specimens have been prepared and tested by rotating bending machine and their S-N curves have been prepared. Comparison of the results reveals that there is a considerable loss in fatigue strength of as received specimens after stress relief. This is due to the removal of compressive residual stress in the raw material induced by the extrusion process. Also, comparison of S-N curves of stress relieved and stress relieved/coated specimens shows fatigue life improvement after cold spray coating. The maximum improvement is 49 percent in the load of 120 MPa and the endurance limit has improved 9 percent.

Made available in DSpace on 2014-10-09T12:35:20Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:11Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:35:20Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:11Z (GMT). No. of bitstreams: 0 / O processo de conformação por spray é interessante devido à capacidade de conjugar, em apenas uma etapa do processo, a vantagem da técnica de solidificação rápida combinada com alta produtividade dos processos de fundição convencional. Este processo permite a obtenção de materiais livre de macrossegregações, livre de porosidades e com microestrutura refinada. A evolução recente das pesquisas está levando ao desenvolvimento de novas ligas e os resultados têm sido interessantes. O processo de solidificação rápida inerente da conformação por spray permite a produção de ligas com composições diferentes das obtidas pela fundição convencional. O objetivo deste trabalho foi o de caracterizar mecanicamente uma liga de alumínio AA-6082 conformada por spray. Os resultados de testes de dureza Vickers são apresentados para seções de um preformado em relação a sua altura (em um arranjo tridimensional). O material foi avaliado na condição como conformado por spray e após tratamento térmico de solubilização a 525 ºC por 1 h, seguido por envelhecimento a 125 ºC por períodos distintos de 1 h, 10 h, 100 h e 500 h. É mostrado que o a liga AA 6082 conformada por spray mostra uma boa estabilidade térmica em relação a variação da dureza durante o envelhecimento. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Yes / The fluidized bed coating system is a conventional process of particles coating in various industries. In this work, an experimental investigation was conducted using Response Surface Methodology (RSM) to optimize the coating mass of particles in a top-spray fluidized bed coating. The design of experiments (DOEs) is a useful tool for controlling and optimization of products in industry. Thus, DOE was conducted using MINITAB software, version 16. This process used a sodium silicate solution for coating the sodium percarbonate particles. The effect of the fluidization air flow rate, atomization air flow rate and liquid flow rate on the coating mass in the top-spray fluidized bed coating was investigated. The experimental results indicated that the coating mass of particles is directly proportional to the liquid flow rate of the coating solution and inversely proportional to the air flow rate. It was demonstrated that the flow rate of the coating solution had the greatest influence on the coating efficiency. / Metallic Material Processing Research Group, ACECR, Branch of Tehran University, Tehran, Iran.

Neste trabalho, filmes planos de polipropileno (CPP) cobertos com nanopartículas de dióxido de titânio (TiO2) foram feitos a partir da metodologia spray coating, facilmente reproduzida para a imobilização das nanopartículas de titânia nos suportes de polipropileno (PP). O tratamento superficial dos filmes CPP com plasma de nitrogênio (N2) e oxigênio (O2) foi utilizado com sucesso para a produção de polipropileno revestido com TiO2 com excelente estabilidade mecânica do revestimento, assim como atividade fotocatalítica / de autolimpeza como evidenciado pelos testes com corante cristal violeta (CV). Microscopia eletrônica de varredura (MEV) e microscopia confocal à laser de varredura (MCLV) foi utilizada para observar a morfologia de superfície / das fibras e topografia. A presença do revestimento de titânia foi confirmada por espectroscopia de emissão de raios-x com detecção dispersiva de energia (EDX). Tanto o tratamento com plasma como o carregamento significativo de revestimento de titânia resultam em maior hidrofilicidade, como observado pelas medidas de ângulo de contato estático em água. Os filmes CPP revestidos foram testados quanto à sua atividade fotocatalítica contra o corante CV. Os espectros eletrônicos no UV-vis mostraram que a eficiência da atividade fotocatalítica das amostras foi afetada pela quantidade de titânia. A fotoestabilidade do PP revestido com titânia foi medida por ressonância paramagnética eletrônica (RPE), uma vez que esta técnica é capaz de detectar pequena quantidade de radicais livres formados durante a precoce etapa de oxidação do polipropileno. Observa-se a partir das medições de RPE que o polipropileno tratado com plasma gerou as mesmas espécies de radicais livres que foram produzidas durante a radiação UV do polipropileno revestido e não-revestido. Entretanto, aumentando o número de ciclos de deposição da titânia a quantidade relativa de radicais livres diminui, sem perda de atividade fotocatalítica. Portanto, a metodologia empregada se mostrou eficiente para produzir uma superfície fotoativa/autolimpante no polipropileno revestido com dióxido de titânio, levando à diferentes aplicações neste campo, como por exemplo sistemas de filtragem de ar/água, remoção de poluentes orgânicos, produtos termoplásticos com características antibacterianas para uso doméstico e hospitalar, dispositivos de autolimpeza, entre outros. / Cast polypropylene (CPP) films were coated with titanium dioxide (TiO2) nanoparticles by na easily scaled-up spray coating methodology. The O2 and N2 plasma surface treatment of polypropylene was successfully used to produce TiO2-coated polypropylene with outstanding mechanical stability of the coating, as well as photocatalytic/self-cleaning activity toward crystal violet dye. Scanning Electron Microscopy and Confocal Scanning Laser Microscopy were used to observe surface / fibers morphology and topography. The presence of titânia coating was confirmed by X-ray Emission Spectroscopy with Energy Dispersive Detection (EDX). Titania coating results on higher hydrophilicity, as observed by measurements of static water contact angle. The CPP films were tested for their photocatalytic activity against Crystal Violet dye (CV). The UV/Vis electronic spectra showed that the photocatalytic activity efficiency of TiO2-coated CPP film was affected by both the plasma treatment and the titânia amount. The photostability of the titania coated polypropylene was measured by Electron Paramagnetic Resonance (EPR) since this technique is capable to detect tiny amount of free radicals formed during the early oxidation step of the polypropylene. It was observed from EPR measurements that the plasma treated polypropylene generated the same free radicals species that were produced during UV irradiation of the uncoated and TiO2-coated polypropylene. However, by increasing the number of deposition cycles of the titania the relative amount of free radicals decreases without loss of the photocatalytic activity. Therefore, the essayed methodology has been proved efficient to produce photoactive/selfcleaning surface of titania coated polypropylene, leading to different applications in this field, as water/air filtration systems, organic pollutant removal, hospital and domestic thermoplastic goods with antibacterial features, self-cleaning devices and others.

Two new mechanisms of droplet splashing and breakup during impact have been identified and analyzed. One is the internal rupture of spreading droplet film through formation of holes, and the other is the splashing of droplet due to its freezing during spreading. The mechanism of film rupture was investigated by two different methods. In the first method, circular water films were produced by directing a 1 mm diameter water jet onto a flat, horizontal plate for 10 ms. In the second method, films were produced by making 0.6 mm water droplets impact a solid surface mounted on the rim of a rotating flywheel. Substrate wettability was varied over a wide range, including superhydrophobic. In both cases, the tendency to film rupture first increased and then decreased with contact angle. A thermodynamic stability analysis predicted this behavior by showing that films would be stable at very small or very large contact angle, but unstable in between. Film rupture was also found to be promoted by increasing surface roughness or decreasing film thickness. To study the effect of solidification, the impact of molten tin droplets (0.6 mm diameter) on solid surfaces was observed for a range of impact velocities (10 to 30 m/s), substrate temperatures (25 to 200°C) and substrate materials (stainless steel, aluminum and glass) using the rotating flywheel apparatus. Droplets splashed extensively on a cold surface but on a hot surface there was no splashing. Splashing could be completely suppressed by either increasing the substrate temperature or reducing its thermal diffusivity. An analytical model was developed to predict this splashing behavior. The above two theories of freezing-induced splashing and film rupture were combined to predict the morphology of splats typically observed in a thermal spray process. A dimensionless solidification parameter, which takes into account factors such as the droplet diameter and velocity, substrate temperature, splat and substrate thermophysical properties, and thermal contact resistance between the two, was developed. Predictions from the model were compared with a wide range of experimental data and found to agree well.