On the Formation of a Diffusion Bond from Cold-Spray Coatings

This paper provides a review of recent developments in the field of Mg corrosion and puts those into context. This includes considerations of corrosion manifestations, material influences, surface treatment, anodization, coatings, inhibition, biodegradable medical applications, stress corrosion cracking, flammability, corrosion mechanisms for HP Mg, critical evaluation of corrosion mechanisms, and concluding remarks. There has been much research recently, and much research continues in this area. This is expected to produce significantly better, more-corrosion-resistant Mg alloys.

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“…Recently, cold‐pray has also become an option for Mg alloys . As the cold‐spray coating is porous, it must be sufficiently thick …”

Section: Surface Treatment Anodization and Coatingsmentioning

confidence: 99%

Review of Recent Developments in the Field of Magnesium Corrosion

et al. 2015

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“…On the contrary, a disbond in the crack region significantly reduces the stress transfer between the sheet and the coating leading to a pronounced drop in the repairing efficiency. In this case also, the residual stresses at the interfaces start to strongly affect the crack behavior (Ref [29][30][31][32][33]. Figure 14 shows the crack growth rate versus the applied DK for all the produced sheets.…”

Section: Resultsmentioning

confidence: 97%

Crack Initiation and Growth Behavior of Cold-Sprayed Ni Particles on IN718 Alloy

Cavaliere

Silvello

2017

J. of Materi Eng and Perform

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Cold spray processing parameters, governing particle velocity and impact energy, are analyzed in the present paper for pure Ni sprayed on IN718 substrates. Finite element modeling (FEM) was used to calculate the particle impact velocity and temperature as a function of gas temperature and pressure and particle density and dimensions. Experimental evidence underlines the possibility of performing repairing through cold spray thanks to the good level of adhesion achievable by employing optimal combinations of materials and spray processing parameters. In the present paper, the potential repairing of cracked superalloys sheets, by employing cold spray technology, is presented. 30°surface V-notched IN718 panels have been repaired by using pure Ni cold-sprayed powders. The bending behavior of the repaired sheets was analyzed by FEM and mechanical testing in order to compare the properties with those belonging to the unrepaired panels. Simulations and mechanical results showed a reduction in the stress intensity factor, a modification of the crack initiation site and a crack retardation in the repaired structures if compared with the unrepaired ones. The K factor was quantified; the resistance of repaired panels was increased of more than eight times in the case of repairing with Ni cold spray particles. Geometrical and mechanical properties of the coating-substrate interfaces, such as adhesion strength and residual stresses influencing the coatings behavior, were largely analyzed.

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“…Various studies have been carried out to further modify the bonding property of cold-sprayed coatings. Among them, post-spray annealing provided an alternative route by promoting diffusion bond with the accelerated atomic diffusion at higher temperatures [8,13]. However, the temperature and duration of diffusion annealing should be selected so that defects such as brittle IMCs and Kirkendall pores will not extensively form at coating/substrate interfaces.…”

Section: Effect Of Diffusion Annealing On Bonding Propertymentioning

confidence: 99%

“…Usually, the coating/substrate interface is the most vulnerable part in the coated components processed by cold spray. And a large number of works have been carried out to improve the bonding property [8,[12][13][14][15][16]. Several works indicated that to improve metallurgical bonding might be a possible way by enhancing atomic diffusion kinetics at high temperature.…”

Section: Introductionmentioning

confidence: 99%

“…For example, the bonding strength between cold-sprayed Ni coating and Cu substrate increased significantly after annealing at 450 • C for 5 h [13], and the stripping resistance of cold-sprayed Zn-Al coating from IF steel increased slightly after annealing at 400 • C for 1 h [8]. However, the results also showed that such defects as brittle intermetallic compounds (IMCs) and Kirkendall pores are prone to rapidly form at coating/substrate interfaces at high temperatures, and lead into fast deterioration in bonding property [8,13]. In addition, high temperatures applied during annealing may cause some other problems in the coating and substrate, such as oxidation, phase transformation, and thermal stress.…”

Section: Introductionmentioning

confidence: 99%

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