Search Results for aerospace industry

The internal plasma spraying for the deposition of thermal barrier coating already was introduced about 20 years ago. During the last 8 years a new generation of internal plasma torch was developed and introduced in the industry. The new generation is characterized by an improved resistance against the thermal radiation and a significantly improvement of the time life of the guns. The performances of the plasma torches regarding powder feed rate and deposition efficiency also were increased to allow the using in mass production in the automotive industry. The improvement of the time life of cathode and anode was realized by using CFD program to optimize the water cooling of the plasma torch. By the production line for cylinder bore the time life of cathode and anode was increased from 50 to more than 100 hours by the modification of the cooling geometry. Several application of internal spraying for mass production in the automotive, aerospace and the electrical industry will be discussed in details. Especially the internal spraying of the cylinder bore will be shown as typical application of high volume. The advantages of the plasma spraying in comparison with alternative technology will be demonstrated. The further development and future potential applications will be discussed at the end as outlook.

High Velocity Oxy Fuel, (HVOF), is a high energy Thermal Spraying Combustion Process, producing high density coatings with hardness values in excess of 1200 VPN. Such coatings, using metal carbide spray material, are used extensively in the aerospace industry, in areas where high wear resistance is particularly important. The Linde Detonation Gun, CD-Gun'), has until recent times been the predominant system for applying these hard faced coatings. However, the advent of a number of new HVOF systems approximately 5 years ago, allowed Gas Turbine Repair and Overhaul bases the opportunity to offer a more competitive coating service, i.e. these "1st generation" HVOF systems allowed the development of comparable, if not superior coatings to these produced by the D-Gun. Having successfully developed and approved HVOF coatings for the use on Rolls-Royce Gas Turbine components for both Repair and New Manufacture, Rolls Wood Group addressed the problem of transferring HVOF technology from aerospace components to alternative markets, i.e. refurbishment of equipment used in Oil and Gas Production.

Masking solutions for parts needing special treatments such as shot peening, grit blasting or thermal spray are now commonly used in industrial processes for the aerospace, industrial gas turbine, and medical industries. The ever-evolving special treatment methods require adapting the masking solutions so they retain their efficiency and quality level. This paper will describe the choices made in combining materials, geometry and surface finish of the masks to provide the necessary compliance with the thermal spraying processes or other special treatment requirements. We will demonstrate that successful masking designs are often the result of close collaboration between the operator’s engineering team and the masking solutions provider in order to comply with what is always a bespoke process. Innovations in materials and additive manufacturing enable the process towards tailored solutions which enable these industries to increase their productivity and level of manufacturing quality.

Niobium and its alloys have been used for several industrial applications including high strength low alloy steels (HSLA) in the automotive and aerospace industries, mainly because of being highly corrosion resistant in different media. Niobium pentoxide is an excellent option to reduce costs in repairing damages caused by corrosion, protection of industrial equipment or systems for being chemically inert to corrosive agents that cause severe corrosion and are normally present in refineries and other industrial environments. Whatever the application, mechanical properties of coatings define their effective durability and performance, mainly for tribocorrosion applications. In this work, these properties are studied and correlated for Nb 2 O 5 coatings applied by Flame Spray onto steels. Salt Spray corrosion (ASTM B117), abrasive wear resistance (ASTM G65-16) and scanning electron microscopy (SEM) microstructural analysis allowed the evaluation of the coatings.

Development of new low-cost methods for spray forming Titanium alloys is critical for many industries. Direct fabrication technologies would have an impact on many industries because of the potential for quick manufacture of parts or additive features with minimal waste. For example, in the aerospace industry the buy to fly ratios can vary from 1.5:1 for turbine blades to over 22:1 for structural members. The buy to fly ratio is the mass of material that is require to machine a part compared to the mass of material in the finished part. For compressor and ring sections, the ratio is approximately 12:1. For this family of parts, an analysis by Pratt & Whitney indicated that the buy to fly ratio could be reduced by 41% to 7:1 if cold spray could be implemented to deposit isogrids, structural ribbing, bosses, and flanges reducing the material, machining, and post processing required for the final part. This paper summarizes the results of experiments conducted in Phase I of a National Science Foundation grant to spray form Titanium alloy using the cold spray process. This paper further describes the studies performed to date in Phase II and the techniques used to decrease the porosity of the as-sprayed coating from 18% to between 2% and 5% and the post processing methods employed to further consolidate the coating and restore the as-sprayed material to near wrought properties.

Carbon fibre reinforced polymers (CFRPs) are more and more used in a wide range of industries, especially in the aerospace industry, but their low electrical conductivity has limited their application. During the past few years, metallization of CFRP has attracted increasing interest. To make the polymer composites electrically conductive, a conductive media must be either embedded into or coated onto the composites. Cold spray is one coating approach to achieve this. In this work, metallic powders were cold sprayed onto the CFRPs used in aircraft by using two different cold spray systems. The coatings as well as the coating/substrate interfaces were characterized and the deposition mechanism onto the CFRP substrate was determined.

Static mechanical properties such as Young's Modulus, Yield Stress and Ultimate Tensile Strength and especially fatigue behavior are important material properties for thermal spray coatings and their industrial application in automotive and aerospace industry. The static and dynamic mechanical properties of Al-Si, Al-Sn, Fe-Cr and Fe-Cr-B based coating materials deposited by APS, TWAS and HVOF were investigated by nanoindentation and in a three point bending test using DMA (Dynamic Mechanical Analysis). This method permits the determination of pure coating material static and dynamic mechanical properties without substrate influence over a wide temperature range. In this investigation all measurements were carried out at room temperature. The DMA method was verified by comparison of Young's modulus to those obtained by nanoindentation.

Carbon fiber (CF) composites are widely used in the aerospace industry due to their light weight and favorable mechanical properties. Nevertheless, applying protective coatings (e.g. erosion resistance) through thermal spraying presents specific challenges with defects such as distortion, oxidation, and poor coating adhesion. This study presents a new technique that combines electroless plating processes and thermal spray for depo-siting metals onto polymer-reinforced composites. Samples of low melting polyaryletherletone (LMPAEK) thermoplastic polymer reinforced with carbon fibers aligned in the normal direction (ZRT film) are plated (with copper, silver, or nickel) to provide an adhesion layer for the thermal spray processes. Subsequently, pure tin and titanium (i.e. Ti-6Al-4V) is deposited on the samples using High Velocity Air-Fuel (HVAF) and atmospheric plasma spray (APS) processes. Cross-sections of the resulting coatings are compared, and the materials are characterized for surface roughness, cracks and pores.

The aerospace industry currently applies high velocity oxy-fuel (HVOF) coatings to turbine engine, structural, and landing gear components. An increasing demand for HVOF wear resistant coatings to replace electrolytic hard chrome (EHC) on landing gear components has renewed focus on the spray limitations of HVOF WC/CoCr. One such limitation resulting from the line-of-sight HVOF process is the spray angle. In this study, HVOF WC/CoCr coatings were sprayed at several angles while maintaining consistent combustion characterisitics and standoff distance. The measured responses included tensile bond strength, microhardness, residual stress, coating surface roughness, and dry fretting wear resistance. Fatigue response was also of interest, but no results were available at the time this paper was written. The microstructure of each coating was examined, both normal to the surface and in cross section. Coatings sprayed at 90° exhibited the highest microhardness and most compressive residual stress, both considered favorable for good wear response. But these coatings also exhibited the highest as-sprayed roughness, least homogeneous microstructure normal to the surface, and lower wear resistance compared to the off-angle coatings; however, the off-angle coatings apear to cause greater wear of the contacting surface. The microstructural differences among the coatings are related to the measured responses.

The presence of defects such as voids, inter-lamellar porosities or cracks, provides a decrease of the effective thermal conductivity of plasma sprayed coatings as well as a decrease of the corresponding mechanical properties such as the Young’s modulus. In general, effective properties of thermal spray coatings are thus strongly different from that of the bulk material and have thus to be quantified to validate their in service performances. A complementary approach allowing understanding the relationships between the microstructure of a coating and its macro-properties is the use of Finite Element Modeling. The case of composite coatings is still more complicated due to the presence of different materials. In the present study, thermo-mechanical properties of a plasma sprayed composite coating were estimated by numerical modeling based on FEM. The applied method uses directly cross-sectional micrographs without simplification using a one-cell per pixel approach. Characteristics such as the thermal conductivity, the Young’s modulus, the Poisson ratio and the dilatation coefficient were considered. The selected example was an AlSi/polyester coating used as abradable seal in the aerospace industry.

High-temperature tribology plays an important role in many engineering applications such as metal forming operations and aerospace industry. Several problems in hot-metal forming of high strength steels occur such as oxidation of tool and workpiece surfaces, increased wear of tools and scaling of workpiece. Moreover, operations at elevated temperatures can significantly influence frictional behavior of tool steels. Present research attempts to analyze experimentally and understand tribological behavior of AISI H11 and AISI H13 under dry conditions at room temperatures. High velocity oxy-fuel (HVOF) thermal spray NiCrBSi coating was developed on tool steels. The room-temperature wear performance of uncoated and coated tool steels was evaluated on pin-on-disc tribometer in the laboratory. In-depth analysis of exposed as-sprayed samples was examined with X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS).

Because of their high specific strength, carbon fiber reinforced plastics (CFRPs) are widely used in the aerospace industry. Metallization of CFRP by cold spraying as a surface modification method can improve the low thermal resistance and electrical conductivity of CFRP without the need for high heat input. Herein, we cold spray a Sn coating on cured CFRP substrates and examine the Sn/epoxy interface. The results suggest that the Sn coatings are successfully obtained at a gas temperature of 473 K and indicate no severe damage to the CFRP substrates. The stress and plastic strain distributions at the cross-section of the Sn/CFRP interface when a Sn particle is impacted onto the CFRP substrate are obtained using the finite element method.

The exceptional properties of Ti-6Al-4V of high strength, lightweight, corrosion resistance and machinability make it one of the most widely used alloys in in the aerospace industry. Significant efforts are underway to establish powder bed additive manufacturing (AM) technologies for Ti-6Al-4V. There are also increasing attempts to use thermal and cold spray to build near net shape parts with buildup rates orders of magnitude higher than powder bed. Thermal spraying, such as HVOF, can oxidize and degrade the alloy due to the high processing temperature. Lowering the flame temperature through inert gas addition in full-size HVOF systems is a possible approach to retain solid state deposition of the feedstock particles, thereby limiting oxidation and detrimental α-case formation, while providing sufficient heat input for particle softening and plastic deformation at impact. Novel miniaturized HVOF systems, with spray jets of only a few millimetre in width, may further offer the possibility to improve the spatial resolution of the buildup for near net shape forming. The process parameter range for solid state deposition of Ti-6A-4V, using the liquid fuelled TAFA Model 825 JPid and the novel hydrogen fuelled Spraywerx ID-NOVA MK-6 with the addition of nitrogen will be discussed. Build-ups at over 80% deposition efficiency generally yield as-sprayed porosities below 3% and hardness above 200 HV100gf. Attainable microstructures and oxygen content as a function of spray parameters are delineated. Recrystallization and beta annealing of selected samples lowered the residual porosity and created equiaxed α and intergranular ß-phases. Ultimate tensile strengths of up to 1100 MPa were attained, however, at limited elongation.

Saving energy is a major concern in every aspect of the economy, especially in the automotive and aerospace industry. The use of lightweight materials is one way to reduce weight of moving parts and thus energy consumption. Research activities to improve the porosity on the one hand, and the coating properties like wear and corrosion resistance on the other hand, show the potential of a hybrid coating process. The creation of thermal-sprayed coatings and a laser post-treatment enable a minimization of porosity and an improvement of wear properties. Different coating materials (e.g. Al-Si alloy) have been investigated regarding microstructure, hardness, wear- and corrosion protection.

The study of corrosion protection of magnesium and aluminum becomes increasingly important as the use of these alloys increases rapidly in the automotive and aerospace industries due to their advantages of light-weight, adequate mechanical properties and moderate cost. Corrosion, however, limits the application of magnesium and aluminum alloys. Fasteners, spot welds of dissimilar materials and their galvanic corrosion is of major concern in automotive applications. The paper presents first results of Low Pressure Cold Spray (LPCS) of Al based coatings for corrosion protection. The corrosion protection provided by these coatings was evaluated by electrochemical measurements in 1M NaCl electrolyte. The microstructures and electrochemical behavior of the coated joints were investigated. The electrochemical corrosion mechanisms of the coatings and microstructure were discussed.

Thermal barrier coatings are used in the aerospace industry for thermal insulation in hot sections of gas turbines. Improved coating reliability is a common goal among jet engine designers. In-service failures, such as coating cracking and spallation, result in decreased engine performance and costly maintenance time. A research program was conducted to evaluate residual stresses, microstructure, and thermal shock life of thermal barrier coatings produced from different powder types and spray parameters. Sixteen coatings were ranked according to their performance relative to the other coatings in each evaluation category. Comparisons of residual stresses, powder morphology, and microstructure to thermal shock life indicate a strong correlation to thermal barrier coating performance. Results from these evaluations will aid in the selection of an optimum thermal barrier coating system for turbine engine applications.

The promising structural properties of fiber-reinforced polymer composites make them widely popular in the energy, automotive, defense, and aerospace industries. One of the most challenging limitations associated with the use of composites in the above applications is the maintenance and repair protocols. In this study, a novel cold spray approach is introduced as an efficient alternative for the structural repair of fiber composites. Damages in the form of circular tapered holes are created in glass fiber-reinforced polymer (GFRP) composite substrates using a conventional drilling process. The in-lab created damages are repaired by cold spray with thermoplastic (nylon 6) and thermoset (polyester epoxy resin, PER) materials. The fundamental adhesion mechanisms are investigated through microstructural observations, which point to adiabatic shear instability due to the occurrence of severe plastic deformation as a governing factor. Microstructural examinations also suggest that no significant fiber damage or surface degradation occurs after the repair by cold spray. Mechanical tests performed on neat, damaged, and repaired composites reveal the partial recovery of structural performance and load-bearing capacity after cold spray repair. Results obtained in this work highlight cold spray as a promising alternative technique for onsite structural repair of composite structures with minimal pre/post-processing requirements.

Due to excellent mechanical properties and low density compared to super alloys (e.g. Ni-based alloys) Titanium Aluminide is often used as base material in the aerospace industry. But the thermodynamic conditions within turbines limit the capabilities of the material. At the moment γ-TiAl is used for parts, which have to withstand temperatures up to 700 °C. Above this temperature oxidation kinetics cause a thick oxide layer consisting of several oxides, which tend to fast chipping. Therefore the surface of the γ-TiAl is being destroyed and the material loses its excellent mechanical properties. To enable the use of this material at higher temperatures, the development of an oxidation protection coating is necessary. Several coating techniques e.g. EB-PVD were tried in the last years, but the oxidation behaviour of the γ-TiAl could not be significantly improved. Protective thermal spray coatings so far seem to be a promising technology in order to protect γ-TiAl components against oxidation. Therefore this technique was used within this work, which aims for the development of new oxidation protection coatings. A multilayer system was developed. The multilayer consists of a ceramic ZrO 2 -7Y 2 O 3 coating with a NiCoCrAlY top coat. In this case the ceramic coating avoids the diffusion of Ti or Al of the γ-TiAl into the MCrAlY coating or the other way around. The NiCoCrAlY coating improved the oxidation behaviour of the Titanium Aluminide by building a dense oxide layer on top of the multilayer. The paper will give an overview about the results of the oxidation tests with the new developed multilayer concept for protection of the γ-TiAl against oxidation.

Pure metal coatings have successfully been cold sprayed on to carbon fiber reinforced polymers (CFRPs) in previous studies at McGill University. As a means to improve coating conductivity for lightning-strike protection (LSP) purposes, coatings with mixed metal powders were sprayed. There is also the possibility of improving the deposition efficiency (DE) since single component tin coatings previously had a maximum DE of only 20%. The studied coatings were based on a mix of tin and aluminum powders, the latter being a metal commonly used in the aerospace industry for its lightweight properties. The different coatings were characterized and compared to results on pure tin coatings and on mixed Sn-Cu and Sn-Zn coatings. The DE was measured for different conditions and compared to those of previous studies. Mixing tin and aluminum powders is discussed and various mechanisms related to cold spraying mixed powders on CFRPs are explored.

Repairing of Ni-alloy components using cold spray is being increasingly considered as an option in the aerospace industry. To further the understanding of the microstructure of Ni-alloy coatings and the bonding mechanism, gas atomised alloy 718 was sprayed onto carbon steel substrates to form 0.5mm thick coatings and single particle impacts. Spray trials were performed with different process parameters to compare the splat and coating morphology/microstructure and to optimise the parameters. The powder consumable, single particle impacts and coatings were characterised using SEM, EBSD, TEM and nanoscale XRF and XRD. Four-point bend tests were performed to test strength, ductility, cracking and de-bonding. Fine grains were observed in the substrate-particle interfaces caused by particle fragmentation, deformation and dynamic recrystallisation. Low angle grain boundaries and sub-grains form in the substrate due to strain induced by high energy impacts. The deposition efficiency, thickness, porosity, hardness and surface roughness of the coatings were measured and compared across all parameters. The porosity decreases notably (1.2% to 0.25%) and the hardness increases (410HV to 465 HV) with the increase in gas temperature and pressure. The results indicate that temperature has a larger effect on the coating properties compared to the pressure and that deformation has an important role in bonding.