Successful deposition of thick copper coatings on low carbon steel is a challenge for the Cold Gas Dynamic Spray (CGDS) process if one is to avoid the use of helium as the process gas for the initial pre-coat layer. The issue stems from the presence of accumulated residual stresses, which causes delamination of the weakly bonded coating. Even after exploring different deposition parameters, several copper powders and various steel substrate preparations, copper coating delamination still occurs. The purpose of the current study is to produce copper coatings using only nitrogen as the process gas, while avoiding delamination of the deposited material. To this end, the current work focuses on the study of the effect of steel substrate temperature on particle deposition and adhesion processes. Steel substrates were heated to temperatures between 25°C and 600°C using induction heating and laser. Once the substrate reached the desired temperature, three different copper particle sizes were deposited using the CGDS process. Individual particle impact tests (wipe-tests) were performed to characterize bonded particles and craters from rebounded particles. Further analysis was performed by extracting particles from the surface to understand the effect of substrate temperature and particle size on the particle/substrate deformation and bonding processes. Mechanical adhesion prediction modeling at substrate preheated was also performed to obtain a greater understanding of the bonding mechanism. This prediction is in order to compare with the coating developed with a bond layer coating with helium as process gas and then build the rest of the coating with nitrogen. The experimental results show a significant trend as the substrate temperature increases, indicating proper conditions for enhanced adhesion.

The majority of the structural weight of many common commercial aircrafts is composed of high strength aluminum alloys. The properties of high performance aluminum alloys such as a high strength to weight ratio (specific strength), ease of recycling, crash energy absorption capacity, and corrosion resistance make them ideal for use in the aerospace field. As a result of the high performance nature of the parts and specific properties of the materials, manufacturing requires intricate casting, precision machining, and specific heat treatments – which results in expensive components. As a result of its excellent corrosion resistance properties, pure aluminum coatings are commonly used in the aerospace field for corrosion protection of steel, aluminum alloy components, and titanium alloy components. The common method to deposit these coatings is called ion vapour deposition (IVD). These IVD aluminum coatings provide the coating adhesion, coverage, thickness, and corrosion resistance required to protect the part. The present study was motivated by the potential use of the cold gas dynamic spray (CGDS) process to repair a) damaged aluminum alloy aerospace parts and b) damaged pure aluminum IVD coatings. The primary research objective was to successfully produce these repairs using commercially available aluminum alloy feedstock powders deposited with commercially available CGDS equipment. This work was treated as prequalification work for The Boeing Company to commercialize this process and therefore the repairs aim to meet the same standards (military and industrial) required of the original aluminum alloy parts and IVD aluminum coatings. The use of CGDS was shown in this research to be a very promising as a process for the restoration of aluminum alloy aerospace components. The adhesion strength of the repaired aluminum components was found to be well above the accepted range for thermally sprayed repairs according to industrial standards. The repairs were subjected to a highly corrosive environment and showed only minor pitting. These sites could be reduced in the future with improved machining techniques and attention to surface detail prior to exposure to the salt fog. The only requirement that the repaired components did not meet was for the wear properties of the anodized layer, measured thought Taber abrasion testing. The results of this test, at times, approached the desired values, and it is believed that, in the future, the quality and consistency of the coatings could be improved and the test would meet industrial standards. The results of this research show that the use of CGDS as a process for the restoration of damaged aluminum IVD coatings is possible and is a promising alternative to conventional methods. The CGDS coatings were scrutinized to the same level as required of IVD coatings when they replaced toxic cadmium coatings in the late 1980s. The coating adhesion, demonstrated through glass bead abrasion and strip rupture testing, was shown to meet the current industrial standards. The corrosion testing of the repairs resulted in no visible red rust of the steel components, even when the steel was exposed.

Significant efforts have been made in the last decades to decrease the world’s dependency to fossil fuels. One of the fronts which has shown major improvement is gas turbine efficiency. To this end, components such as recuperators have been developed to recover heat that is usually trapped and wasted in the exhaust gases of combustion processes. Brayton Energy Canada has recently developed a promising compact heat exchanger that could be used as a recuperator in gas turbines. Nevertheless, this novel type of wire mesh heat exchanger still has room for improvement, especially regarding the way that its fin arrays are manufactured due to the fact that the technique presently used is time consuming and consequently costly. The present research aims to manufacture near-net shaped pin fin arrays using cold gas dynamic spray as an additive manufacturing technique by selectively covering the substrate by the means of a mask. Moreover, this research work studies the feasibility of using CGDS as an additive manufacturing technique to produce pin fin arrays, the thermal and hydrodynamic performances of this new type of pin fin created, the effect of geometric parameters such as fin density and height on the performances, the viability of the sprayed pin fins in a real environment by means of finding mechanical properties such as adhesion strength, the possibility of producing a streamwise material anisotropic fin arrays, and finally the different adhesion mechanisms by means of numerical modeling of the relevant impact physics.

The objective of this study is to successfully deposit Titanium Ti-6Al-4V layers onto Ti-6Al-4V substrate using two new commercially available Cold Spray processes such as Low Pressure Cold Spray (LPCS) and Pulsed Gas Dynamic Spray (PGDS). The second objective of this work is to develop a technique to repair Titanium parts since there is currently no repair technique commercially available. It is envisioned that commercial cold spray systems could be used to repair gashes on Titanium components. The examination of both feedstock powders and coatings were performed by different techniques such as optical microscopy and Scanning Electron Microscopy (SEM). Porosity, hardness, adhesion strength, flattening ratio, wipe test, fracture surface, wear test, XRD and chemical composition of the coatings using EDS have been evaluated. Cold spray has shown to be a promising technique for the deposition of heat sensitive particles such as titanium. LPCS and PGDS both produced high quality coatings. Low porosity, high hardness, adhesion strength over 40 MPa, metallurgical bonding, similar to bulk material wear rate, no oxide and nitride phases inside coating were measured.

Aluminum alloys have been used for decades in aircraft as they offer a wide range of properties explicitly developed to provide a set of characteristics adapted to structural and non-structural components. However, aircraft components inevitably undergo degradation during service due to their extensive use and exposure to harsh environments. Typical repair methods are either not efficient for large scale repairs due to their low material growth rate, not suitable for field repair or involve the use of high process temperatures. The present research aims at evaluating the cold gas dynamic spray (CGDS) as a potential repair technology to restore Al7075-T6 nose landing gear steering actuator threads found on the Boeing 757 aircraft. Moreover, it studies the suitability of using cold spray to deposit Al2024 material. The influence of process parameters and substrate surface preparation on the material deposition efficiency and resulting microstructural and mechanical repair properties is also evaluated.

Carbon fibre reinforced composites are known for their high specific strength-to-weight ratio and are of great interest to the aerospace industry. Incorporating these materials into the fuselage, like in Boeing's 787 "Dreamliner", offers considerable weight reduction which increases flying efficiency, and reduces the cost of flying. In flight, aircraft are often subject to lightning strikes which, in the case of composites, can result in localized melting given the high resistive nature of the material. Aerospace carbon fibre composites often incorporate a metallic mesh or foil within the composite layers to dissipate the electrical charge through the large aircraft. The damage to the aircraft is minimized but not always eliminated. This research aims to elaborate a practical technique to deposit thin layers of conductive material on the surface of aerospace grade composites. Using Cold Gas Dynamic Spray (CGDS), such coatings could be used to repair damaged components. An experimental research approach was used to develop metallic coated composites. Using the CGDS equipment of Centerline (SST-P), specific parameters (such as gas temperature and stagnation pressure) were determined for each type of metallic coating (tin-based & copper-based). The use of bond coats was explored in order to attain the desired coatings. Once optimized, these coatings were evaluated with respect to their corrosive, adhesive, and electrical properties following industry standards.

The purpose of this research work was to develop a nozzle capable of depositing dense CoNiCrAlY coatings via cold gas dynamic spray (CGDS) as well as compare the oxidation performance of bond coats manufactured by CGDS, high-velocity oxy-fuel (HVOF) and air plasma spray (APS) at temperatures of 1000°C and 1100°C. The work was divided in two sections, the design and manufacturing of a CGDS nozzle with an optimal profile for the deposition of CoNiCrAlY powders and the comparison of the oxidation performance of CoNiCrAlY bond coats. Throughout this work, it was shown that the quality of coatings deposited via CGDS can be increased by the use of a nozzle of optimal profile and that early formation of protective α-Al2O3 due to an oxidation temperature of 1100°C as opposed to 1000°C is beneficial to the overall oxidation performance of CoNiCrAlY coatings.

The purpose of this research work was to develop a nozzle capable of depositing dense CoNiCrAlY coatings via cold gas dynamic spray (CGDS) as well as compare the oxidation performance of bond coats manufactured by CGDS, high-velocity oxy-fuel (HVOF) and air plasma spray (APS) at temperatures of 1000°C and 1100°C. The work was divided in two sections, the design and manufacturing of a CGDS nozzle with an optimal profile for the deposition of CoNiCrAlY powders and the comparison of the oxidation performance of CoNiCrAlY bond coats. Throughout this work, it was shown that the quality of coatings deposited via CGDS can be increased by the use of a nozzle of optimal profile and that early formation of protective α-Al2O3 due to an oxidation temperature of 1100°C as opposed to 1000°C is beneficial to the overall oxidation performance of CoNiCrAlY coatings.

The purpose of this research work was to develop a nozzle capable of depositing dense CoNiCrAlY coatings via cold gas dynamic spray (CGDS) as well as compare the oxidation performance of bond coats manufactured by CGDS, high-velocity oxy-fuel (HVOF) and air plasma spray (APS) at temperatures of 1000°C and 1100°C. The work was divided in two sections, the design and manufacturing of a CGDS nozzle with an optimal profile for the deposition of CoNiCrAlY powders and the comparison of the oxidation performance of CoNiCrAlY bond coats. Throughout this work, it was shown that the quality of coatings deposited via CGDS can be increased by the use of a nozzle of optimal profile and that early formation of protective α-Al2O3 due to an oxidation temperature of 1100°C as opposed to 1000°C is beneficial to the overall oxidation performance of CoNiCrAlY coatings.

The purpose of this research work was to develop a nozzle capable of depositing dense CoNiCrAlY coatings via cold gas dynamic spray (CGDS) as well as compare the oxidation performance of bond coats manufactured by CGDS, high-velocity oxy-fuel (HVOF) and air plasma spray (APS) at temperatures of 1000°C and 1100°C. The work was divided in two sections, the design and manufacturing of a CGDS nozzle with an optimal profile for the deposition of CoNiCrAlY powders and the comparison of the oxidation performance of CoNiCrAlY bond coats. Throughout this work, it was shown that the quality of coatings deposited via CGDS can be increased by the use of a nozzle of optimal profile and that early formation of protective α-Al2O3 due to an oxidation temperature of 1100°C as opposed to 1000°C is beneficial to the overall oxidation performance of CoNiCrAlY coatings.