Influence of Substrate Characteristics on Single Ti Splat Bonding to Ceramic Substrates by Cold Spray
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Influence of Substrate Characteristics on Single Ti Splat Bonding to Ceramic Substrates by Cold Spray Sara I. Imbriglio1 • Nicolas Brodusch1 • Maniya Aghasibeig2 • Raynald Gauvin1 Richard R. Chromik1
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Submitted: 4 May 2018 / in revised form: 9 July 2018 Ó ASM International 2018
Abstract The cold spray technique may be used to fabricate metal matrix composites and to metallize ceramics. Both applications involve the creation of metal/ceramic interfaces, which are well researched for other processes but not nearly as much for cold spray. Here, the effect of ceramic substrate composition and surface roughness on adhesion strength of metallic splats is investigated. Splat adhesion testing was performed on Ti splats deposited on Al2O3 substrates with varying average reduced peak height roughness (Rpk) values. Ti splats sprayed onto Al2O3 with the lowest surface roughness had a higher bond strength (305 ± 87 MPa) than splats deposited on the higher surface roughness Al2O3 (237 ± 47 MPa). Failed interfaces revealed that the bonding mechanism for substrates with higher surface roughness is predominantly mechanical interlocking. Adhesion to the Al2O3 substrate with low surface roughness is predominantly along the periphery of the particle where jetting occurs. Splat adhesion testing was also performed on Ti splats deposited on SiC. Ti splats had a significantly higher bond strength to all Al2O3 substrates than to SiC. Posttest observations of SiC substrates showed little evidence of bonding. Several rebounded or detached splats left traces of Ti along the periphery of the impacted particle.
& Richard R. Chromik [email protected] 1
Department of Mining and Materials Engineering, McGill University, 3610 University Street, Montreal, QC H3A 0C5, Canada
2
National Research Council Canada, Boucherville, QC J4B 6Y4, Canada
Keywords adhesion alumina cold spray interface silicon carbide titanium
Introduction High-pressure cold spray is a coating deposition technique by which powder is fed into a heated high-pressure gas flow and accelerated to supersonic velocities by a de Laval nozzle. The powders, accelerated to high velocity, impact on a substrate and if bonded create a ‘splat.’ The gas temperature is maintained below the melting temperature of the powder (Ref 1, 2). Thus, for metal/metal interfaces, solid-state bonding between the powder and substrate occurs by extreme plastic deformation and the formation of adiabatic shear instabilities (ASI). Mechanical clamping and metallurgical bonding are reported for these interfaces (Ref 3-5). While a significant amount of work has been done to understand adhesion in metal/metal interfaces by cold spray, metal/ceramic interfaces are not well understood given the low deformability of the ceramic (Ref 6-8). Two types of metal/ceramic interfaces created by cold spray are addressed in the literature. Metal matrix composites (MMCs) with ceramic reinforcements have been deposited to improve adhesion, increase hardness, reduce porosity and improve trib
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