Influence of Particle Velocity on Adhesion of Cold-Sprayed Splats

Guetta, Dafne; Berger, Marie‐Hélène; Borit, François; Guipont, Vincent; Jeandin, Michel; Boustie, M.; Ichikawa, Yuji; Sakaguchi, Kei; Ogawa, Kōichi

doi:10.1007/s11666-009-9327-0

Cited by 141 publications

(76 citation statements)

References 13 publications

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“…as observed in a cold-sprayed Al-Mg alloy [110]. There have also been reports of dynamic amorphization in Al-Al, Ni-Al [124], Al-Cu [125], Cu-Ni [126], Al-Mg [127] and Fe-Al [128,129] systems, over a layer of up to tens of nanometres thickness. For the case of metallic glasses, on the other hand, CS may result in nanocrystallisation of the initially amorphous phase [89].…”

Section: Microstructurementioning

confidence: 70%

Cold spraying – A materials perspective

et al. 2016

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Cold spraying is a solid-state powder deposition process with several unique characteristics, allowing production of coatings or bulk components from a wide range of materials. The process has attracted much attention from academia and industry over the past two decades.The technical interest in cold spraying is twofold: first as a coating process for applications in surface technology, and second as a solid-state additive manufacturing process, offering an alternative to selective laser melting or electron beam melting methods. Moreover, cold spraying can be used to study materials behaviour under extremely high strain rates, high pressures and high cooling rates. The cold spraying process is thus considered to be relevant for various industrial applications, as well as for fundamental studies in materials science.This article aims to provide an overview of the cold spray process, the current understanding of the deposition mechanisms, and the related models and experiments, from a materials science perspective. IntroductionCold spraying (CS) is a solid-state material deposition technique, where micron-sized particles of a powder bond to a substrate as a result of high-velocity impact and the associated severe plastic deformation. Acceleration of particles to high velocities is obtained via expansion of a pressurised and (ironically) 'hot' gas through a diverging-converging nozzle.Despite heating the process gas -which is to provide higher acceleration of the gas and also to facilitate particle deformation through thermal softening -the feedstock remains in the solid state throughout the entire process; hence the name 'cold' spraying. This is to underline the contrast to conventional thermal spraying where particles are completely or partially molten upon impact onto the substrate. Alternative terminology includes cold gas spray, micro cold spray, cold gas dynamic spray, kinetic spray, supersonic particle deposition and metal powder application (MPA), all of which refer to the same principle of solid-state powder deposition as described above. CS is used for coating and repair. It is also used for additive manufacturing (AM) at relatively high deposition rates as compared to the methods based on selective laser or electron beam melting. The main advantage of CS is that it alleviates the problems associated with high temperature processing of materials, such as oxidation and unfavourable structural changes. It is possibly the only continuous method to produce bulk components of metastable materials that are available only in the powder form, e.g. as obtained from mechanical attrition or gas atomisation. The aim of the present paper is to provide an overview of CS from a materials perspective, particularly for a broader audience in materials research, e.g. with interest in dynamic phenomena, plasticity and phase transformations. In terms of application and properties, CS is perhaps best to be compared to thermal spraying processes, as in [24,25]. In view of relevant physical phenomena, however, CS is mos...

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Section: Microstructurementioning

confidence: 70%

Cold spraying – A materials perspective

et al. 2016

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“…The intimate contact between the splat and the substrate contributes to a more continuous, void or oxide free, bond between two interfaces and even stronger splat adhesion as can be seen in Fig. 1(c) (Ref 9,13). Figure 1 illustrates three commonly known deposition mechanisms in cold spray splats.…”

Section: Introductionmentioning

confidence: 93%

The Effect of Deposition Conditions on Adhesion Strength of Ti and Ti6Al4V Cold Spray Splats

et al. 2011

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Cold spray is a complex process where many parameters have to be considered in order to achieve optimized material deposition and properties. In the cold spray process, deposition velocity influences the degree of material deformation and material adhesion. While most materials can be easily deposited at relatively low deposition velocity (<700 m/s), this is not the case for high yield strength materials like Ti and its alloys. In the present study, we evaluate the effects of deposition velocity, powder size, particle position in the gas jet, gas temperature, and substrate temperature on the adhesion strength of cold spayed Ti and Ti6Al4V splats. A micromechanical test technique was used to shear individual splats of Ti or Ti6Al4V and measure their adhesion strength. The splats were deposited onto Ti or Ti6Al4V substrates over a range of deposition conditions with either nitrogen or helium as the propelling gas. The splat adhesion testing coupled with microstructural characterization was used to define the strength, the type and the continuity of the bonded interface between splat and substrate material. The results demonstrated that optimization of spray conditions makes it possible to obtain splats with continuous bonding along the splat/substrate interface and measured adhesion strengths approaching the shear strength of bulk material. The parameters shown to improve the splat adhesion included the increase of the splat deposition velocity well above the critical deposition velocity of the tested material, increase in the temperature of both powder and the substrate material, decrease in the powder size, and optimization of the flow dynamics for the cold spray gun nozzle. Through comparisons to the literature, the adhesion strength of Ti splats measured with the splat adhesion technique correlated well with the cohesion strength of Ti coatings deposited under similar conditions and measured with tubular coating tensile (TCT) test.

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“…A variety of proposals including adiabatic shear instability [16], oxide layer breakup [18], diffusion [19] and localized melting [20] have been put forth to explain the underlying mechanism(s) of impact-induced adhesion, each of which enjoys partial support from observational data. For instance, sharp jumps observed in the temperature and strain in Lagrangian impact simulations have been used to support an argument for adiabatic shear localization [16,21].…”

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confidence: 99%

Melting Can Hinder Impact-Induced Adhesion

et al. 2017

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Melting has long been used to join metallic materials, from welding to selective laser melting in additive manufacturing. In the same school of thought, localized melting has been generally perceived as an advantage, if not the main mechanism, for the adhesion of metallic microparticles to substrates during a supersonic impact. Here, we conduct the first in situ supersonic impact observations of individual metallic microparticles aimed at the explicit study of melting effects. Counterintuitively, we find that under at least some conditions melting is disadvantageous and hinders impact-induced adhesion. In the parameter space explored, i.e., ∼10 μm particle size and ∼1 km=s particle velocity, we argue that the solidification time is much longer than the residence time of the particle on the substrate, so that resolidification cannot be a significant factor in adhesion. DOI: 10.1103/PhysRevLett.119.175701 Understanding materials physics under impact has motivated extensive research in areas ranging from asteroid strikes [1] and ballistic deposition [2] to mechanochemical synthesis [3], materials failures [4,5], structural modification [6], and phase transformation [7]. Less conventionally, three decades ago, metallic powder particles were first observed to bond to metallic substrates under supersonicimpact conditions at low temperatures [8]. The notion of impact-induced adhesion, thereafter, has been implemented in powder processing through kinetic deposition or cold spray [9,10]. Kinetic deposition has proven successful in making coatings [11][12][13], in reclaiming damaged metallic surfaces [14], and in additively manufacturing bulk metallic materials [15].In this area of impact science, researchers have repeatedly observed a material-dependent critical velocity [16,17] [20] have been put forth to explain the underlying mechanism(s) of impact-induced adhesion, each of which enjoys partial support from observational data. For instance, sharp jumps observed in the temperature and strain in Lagrangian impact simulations have been used to support an argument for adiabatic shear localization [16,21]. Experimental measurements of reduced oxide content in cold spray coatings as compared to initial powder feedstock underpins an argument for oxide layer breakup [22]. Small spherical ejecta found in the coating [20] or intermetallic detected at the interface [23] suggest localized melting or interdiffusion.More consensus, however, has been attained around postmortem observations of material jets around the periphery of adhered particles [16,24,25]. We have recently, for the first time, conducted in situ observations of the impact behavior of individual supersonic metallic microparticles below and above the critical velocity and found that material ejection and jetting are crucial for adhesion [26,27]. We argued that neither shear localization nor melting are needed to account for material ejection. Rather, it can arise from the interaction of the impactinduced pressure wave with the contact periphery of the particle. A...

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Influence of Particle Velocity on Adhesion of Cold-Sprayed Splats

Cited by 141 publications

References 13 publications

Cold spraying – A materials perspective

Cold spraying – A materials perspective

The Effect of Deposition Conditions on Adhesion Strength of Ti and Ti6Al4V Cold Spray Splats

Melting Can Hinder Impact-Induced Adhesion

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