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No description available.

Pulse Pressure Metal-Organic Chemical Vapour Deposition (PP-MOCVD) is a technique for creating thin coatings. It is less dependent on the volatility of precursors than other Chemical Vapour Deposition (CVD) processes as the precursors are introduced into the reaction chamber as an aerosol; therefore sublimation of the precursor is not necessary. This allows solutions of multiple compounds to be created with a known concentration and ratio of precursors. We explored the formation of hydroxyapatite (HAp) coatings for use on bone implants, using a methanolic solution of calcium lactate and trimethyl phosphate (TMP) as a PP-MOCVD precursor solution. The thermal decomposition of the precursors and the reaction between them were investigated using Thermogravimetric Analysis (TGA). Several variables on the PP-MOCVD apparatus were varied to test their effect on the formed coating: deposition temperatures, ratio of precursors, number of pulses, precursor concentration, the use of ambient temperatures and annealing the coatings after formation. All the coatings were analysed using Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and Fourier Transform Infra-Red spectroscopy (FTIR). These coatings were not uniformly smooth in appearance at the micro level. However, using higher deposition temperatures, an excess ratio of TMP to calcium lactate and annealing the coatings for short periods of time and low temperatures improved the uniformity of the coating. When vigorous annealing was performed it resulted in surface oxidation and the production of titanium dioxide (TiO2 ). The EDS results showed that both calcium and phosphorus were present in the coatings. The use of high deposition temperatures, excess TMP or gentle annealing resulted in calcium to phosphorous ratios similar to the stoichiometry of HAp. These same conditions gave improved coating uniformity.

An anti-reflective (AR) lens is an ultrathin multilayered structure composing of AR coatings on a lens substrate. These coatings can be made by a spin-coating process with a nanocomposite of UV curable acrylic monomers and well dispersed metal oxide nanoparticles. The in-situ UV polymerization rate was reduced by oxygen inhibition and the absorption of UV energy by the metal oxide nanoparticles. There are few studies of the mechanical properties of ultrathin polymeric coatings that include the effects of substrates, the viscoelastic behaviors of polymers in submicron scales and the effects of multilayered coatings. With a coating system based on UV cured dipentaerythritol pentaacrylate on silicon wafer substrates, nanoindentation tests showed that the nominal reduced contact modulus increased with the indentation load and penetration depth due to the effect of the substrate, in quantitative agreement with an elastic contact model. Ultrathin polymeric coatings subjected to constant indentation loads exhibit shear-thinning during flow. None of the models examined completely described the elastic response of an ultrathin polymeric coating on a compliant plastic substrate. The effective modulus was a function of coating-substrate property, indenter tip size, coating thickness, adhesion and residual stress. It was logarithmic dependent on the ratio of the indentation depth to the coating thickness prior to coating fracture. An elastic model, assuming shear-lag and a plane-stress state, was used to estimate the interfacial strength between a submicron coating and a compliant substrate. The critical indentation load for the indentation-induced delamination of the coating from the substrate increased with the third power of the indentation depth and was a linear function of the reciprocal of the coating thickness. The interfacial strength was 70.4 MPa. Mechanical properties and fracture characteristics of CVD ceramic and nanocomposite coatings on polymer substrates were evaluated by nanoindentation and nanoscratching tests. The AR lenses made with polymer nanocomposite coatings have better mechanical properties due to the close match of properties between the coatings and the plastic substrate. The new approach to making AR lenses with polymer nanocomposites on plastic substrate is promising.

In the cutting tool industry, replaceable cutting edge (insert) is often used. As insert support,steel nets are used which are pre-coated before use, since the iron will affect the coatingquality of the inserts. Titanium carbide (TiC) is an ideal material for pre-coating purposes andthe deposition of TiC is performed by chemical vapor deposition (CVD) using a gaseousmixture of TiCl4, CH4 and H2. In order to optimize both the process time and to ensure goodquality, in this master thesis a series of experiments were designed to investigate the influenceof gas flow rates, the CH4/TiCl4 ratio, and the total pressure. The measured parameters werethe coating thickness and the coating quality. The experimental results showed that increasingthe TiCl4 flow rate resulted in an increased coating thickness, but generated HCl has aretarding effect by adsorption. Increasing the CH4/TiCl4 mole ratio led to higher depositionrates, but outgrowth was observed at high ratios. Increasing the total pressure resulted in anincreased deposition rate, but hazardous TiO2 white smoke was observed.The optimal receipt with higher gas flow, CH4/TiCl4 mole ratio, and depositiontemperatures gave a 3.4 μm thick TiC coating after 12.5 h. Compared with the originalprocess, the optimal process obtained in this thesis saved 47 % process time.Surface morphology and grain size were examined using an optical microscope and ascanning electron microscope, and deposited TiC had a grain size of 1-2 μm. Line profileanalysis using energy-dispersive X-ray spectroscopy showed that the coated TiC layerprevented the diffusion of iron and there was no iron on the surface of the coated steel nets.

The use of vacuum coating is mostly limited to production of high fat containing extruded aqua and pet diets. The physical characteristics of extrudates are favourable for vacuum coating due to their high porosity and durability. However, with pelleted feed for broilers, there are potentially several opportunities, but there are also challenges; these are explored here. The opportunities identified were inclusion of high level of oils, protected delivery of feed additives (e.g., enzymes, probiotics, vaccines, etc.), improved and safe use of offensive feed additives and improvement of shelf-life of feed and additives. Challenges include the relatively high density of pellets (low porosity) which limits liquid infusion, increased processing cost and decreased feed throughput. However, feed ingredients selection and alternating processing variables (temperature, moisture, die specifications etc.) were deemed to overcome the challenges of low porosity. Three experiments were conducted to evaluate the use of vacuum coating in pelleted feed. In the first experiment, the effect of particle size on post-pellet oil absorption (OA), porosity, pellet durability index (PDI) and bulk density were investigated. The three particle sizes for three grains (wheat, barley and corn) were pelleted using a 4.7 mm die to get whole grain (WP), coarse (CP), and fine (FP) grind pellets. The pellets were coated with 15% canola oil without (VC-) and with (VC+; 0.3 bar) vacuum coating. The grain type was found to have a significant effect on the particle size when ground through either fine (3.2 mm) or coarse (6.4 mm) screen. With coarse grinding, the mean particle size was 1896, 1290 and 1057 µm, respectively for barley, wheat and corn; with fine grinding, the mean particle size was 1153, 767 and 732 µm, respectively. Porosity of CP from wheat and corn was significantly (P<0.01) higher than WP and FP. For barley, there was no difference in porosity of CP and FP but both were significantly higher than WP. For wheat, OA of CP was highest (P<0.01), but no significant difference was found between FP and WP. However, for barley, higher OA was found in FP followed by CP and WP. In corn, OA of CP was higher than for FP or WP. Vacuum coating (VC+) improved (P<0.01) OA of all pellets compared to VC-. Porosity was positively correlated with OA and negatively correlated to PDI and bulk density. Overall, the first experiment suggested that alteration of particle size and grain type could be the options for improving the oil absorption by vacuum coating. A second experiment was conducted to observe the effect of enzyme addition method (EAM; E-, without enzyme; PreE+, Pre-pellet addition of enzyme; PosE+, post-pellet addition of enzyme), conditioning temperature (CT; 65 or 95°C) and coating method (CM; VC- or VC+) on broiler performance when fed wheat-rye-based diets. Enzyme addition (pre or post-pellet addition in comparison to without enzyme) significantly improved (P<0.01) the body weight at 21 and 35d. Higher CT (95°C) improved feed conversion ratio (FCR) in both starter (P<0.01) and grow/finish phase (P=0.04) and PDI of both starter and grow/finish pellets (P<0.01) when compared to low CT (65°C). Vacuum coating did not have any effect on the diet extract viscosity, animal performance or digesta viscosity in either of the phases. However, with post-pellet vacuum coating, there was high retention of xylanase activity after processing. Vacuum coating significantly (P<0.05) reduced the relative length of small intestine of broilers at 21d but not at 35d. In the third experiment, broiler grow/finish diets were stored in an incubator (37°C) to see if vacuum coating can improve the shelf-life of feed. The results showed post-pellet vacuum-coated pellets retained higher enzyme activity after 15 days of storage. Although no effect of vacuum coating on animal performance was observed, vacuum coating was able to protect the enzyme during processing and storage. Further work needs to be done to translate these benefits to improve animal performance, which might be achieved using various vacuum coating and processing conditions, and bioactives.

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