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Critical ionization velocity

About: Critical ionization velocity is a research topic. Over the lifetime, 2170 publications have been published within this topic receiving 43381 citations.


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Journal ArticleDOI
TL;DR: In this paper, a hypothesis for the bonding of particles in cold gas spraying, by making use of numerical modelling of the deformation during particle impact, is presented, with the results of modelling assessed with respect to the experimentally evaluated critical velocities, impact morphologies and strengths of coatings.

1,366 citations

Journal ArticleDOI
TL;DR: In this article, the influence of impact conditions and related phenomena on the coating quality was investigated through spray experiments, which were complemented by ballistic impact tests and explosive powder compaction.

923 citations

Journal ArticleDOI
TL;DR: In this paper, the interaction between particles and an advancing solid-liquid interface has been investigated both experimentally and theoretically, and a theory has been developed, based on the assumption that a very short-range repulsion exists between the particle and the solid.
Abstract: The interaction between particles and an advancing solid‐liquid interface has been investigated both experimentally and theoretically. For each particular type of particle, a ``critical velocity'' was observed, below which the particles are rejected by the interface, and above which they are trapped in the solid. The dependence of the critical velocity on various properties of matrix and particle was investigated. A theory has been developed, based on the assumption that a very short‐range repulsion exists between the particle and the solid. This repulsion occurs when the particle‐solid interfacial free energy is greater than the sum of the particle‐liquid and liquid‐solid interfacial free energies. The particle is pushed along ahead of the advancing interface and becomes incorporated into the solid if liquid cannot diffuse sufficiently rapidly to the growing solid behind the particle. Reasonable agreement was obtained between the calculated and experimentally observed critical velocities.

609 citations

Journal ArticleDOI
TL;DR: In this paper, computational fluid dynamics (CFD) and extensive spray tests were performed for detailed analyses of the cold spray process, and the modeling of the gas and particle flow field for different nozzle geometries and process parameters in correlation with the results of the experiments reveal that adhesion only occurs when the powder particles exceed a critical impact velocity that is specific to the spray material.
Abstract: In this study, computational fluid dynamics (CFD) and extensive spray tests were performed for detailed analyses of the cold spray process. The modeling of the gas and particle flow field for different nozzle geometries and process parameters in correlation with the results of the experiments reveal that adhesion only occurs when the powder particles exceed a critical impact velocity that is specific to the spray material. For spherical copper powder with low oxygen content, the critical velocity was determined to be about 570 m/s. With nitrogen as the process gas and particle grain sizes from 5–25 µm, deposition efficiencies of more than 70% were achieved. The cold sprayed coatings show negligible porosity and oxygen contents comparable to the initial powder feedstock. Therefore, properties such as the electrical conductivity at room temperature correspond to those of the bulk material. The methods presented here can also be applied to develop strategies for cold spraying of other materials such as zinc, stainless steel, or nickel-based super-alloys.

540 citations

Journal ArticleDOI
TL;DR: In this article, a series of experimental tests in five model tunnels having the same height but different cross-sectional geometry were carried out and the experimental results showed that the critical velocity did vary with the tunnel crosssectional geometry and that there are two regimes of variation of critical velocity against fire heat release rate.

510 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202314
202255
202171
202097
201975
201878