Effects of metal atomization, arc and pressure fluctuations on the final particle size distribution in the wire arc spraying process

This study aims to model grinding of a Polish ferronickel slag and evaluate the particle size distributions (PSDs) of the products obtained after different grinding times. Then, selected products were alkali activated in order to investigate the effect of particle size on the compressive strength of the produced alkali activated materials (AAMs). Other parameters affecting alkali activation, i.e., temperature, curing, and ageing time were also examined. Among the different mathematical models used to simulate the particle size distribution, Rosin–Rammler (RR) was found to be the most suitable. When piecewise regression analysis was applied to experimental data it was found that the particle size distribution of the slag products exhibits multifractal character. In addition, grinding of slag exhibits non-first-order behavior and the reduction rate of each size is time dependent. The grinding rate and consequently the grinding efficiency increases when the particle size increases, but drops sharply near zero after prolonged grinding periods. Regarding alkali activation, it is deduced that among the parameters studied, particle size (and the respective specific surface area) of the raw slag product and curing temperature have the most noticeable impact on the compressive strength of the produced AAMs.

Download Full-text

Atomization and Particle-Jet Interactions in the Wire-Arc Spraying Process

CrossRef Listing of Deleted DOIs ◽

10.1361/105996301770349123 ◽

2001 ◽

Vol 10 (4) ◽

pp. 604-610 ◽

Cited By ~ 30

Author(s):

N.A. Hussary ◽

J.V.R. Heberlein

Keyword(s):

Arc Spraying ◽

Wire Arc Spraying ◽

The Wire ◽

Jet Interactions ◽

Spraying Process

Download Full-text

Monitoring Fluidization Dynamics for Detection of Changes in Fluidized Bed Composition and Operating Conditions

Journal of Fluids Engineering ◽

10.1115/1.2823551 ◽

1999 ◽

Vol 121 (4) ◽

pp. 887-894 ◽

Cited By ~ 6

Author(s):

J. Ruud van Ommen ◽

Jaap C. Schouten ◽

Cor M. van den Bleek

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Fluidized Bed ◽

Pressure Fluctuations ◽

Industrial Applications ◽

Operating Conditions ◽

Gradual Change ◽

Monitoring Method ◽

Superficial Gas Velocity

In many industrial applications of gas-solids fluidized beds, it is worthwhile to have an on-line monitoring method for detecting changes in the hydrodynamics of the bed (due for example to agglomeration) quickly. In this paper, such a method, based on the short-term predictability of fluidized bed pressure fluctuations, is examined. Its sensitivity is shown by experiments with small step changes in the superficial gas velocity and by experiments with a gradual change in the particle size distribution of the solids in the bed. Furthermore, it is demonstrated that the method is well able to indicate if a stationary hydrodynamic state has been reached after a change in the particle size distribution (a ‘grade change’).

Download Full-text

Supervision and Measuring of Particle Parameters During the Wire-Arc Spraying Process with the Diagnostic Systems Accuraspray-g3 and LDA (Laser-Doppler-Anemometry)

Journal of Thermal Spray Technology ◽

10.1007/s11666-009-9466-3 ◽

2010 ◽

Vol 19 (4) ◽

pp. 745-755 ◽

Cited By ~ 12

Author(s):

S. Zimmermann ◽

E. Vogli ◽

M. Kauffeldt ◽

M. Abdulgader ◽

B. Krebs ◽

...

Keyword(s):

Laser Doppler Anemometry ◽

Laser Doppler ◽

Arc Spraying ◽

Diagnostic Systems ◽

Wire Arc Spraying ◽

Particle Parameters ◽

The Wire ◽

Spraying Process

Download Full-text

Tailoring hydroxyapatite microspheres by spray-drying for powder bed fusion feedstock

10.31224/osf.io/jctr2 ◽

2021 ◽

Author(s):

Pedro Navarrete-Segado ◽

Christine Frances ◽

David Grossin ◽

Mallorie Tourbin

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Spray Drying ◽

Laser Processing ◽

Operating Conditions ◽

Air Pressure ◽

Final Particle ◽

Powder Bed ◽

Powder Feedstock

The present work deals with a study on the physical characteristics of hydroxyapatite microspheres produced by spray-drying process through different operating conditions. Obtained hydroxyapatite microspheres will be used as powder feedstock in powder bed selective laser processing additive manufacturing technologies where the flowability and the particle size distribution of the powder feedstock is of special importance. Spray air pressure and solid content of the slurries were the most influent parameters to control the final particle size distribution, while higher air pressure and temperatures gave the higher process recovery rate. The use of polyvinyl alcohol as organic binder increased the granules strength. The produced hydroxyapatite microspheres were found to fulfil the powder bed selective laser processing feedstock requirements, keeping the physico-chemical properties of the material. These promising results confirm the use of a spray dryer as an efficient method for the production of hydroxyapatite microspheres for powder bed selective laser processing.

Download Full-text

A numerical study of the particle size distribution of an aerosol undergoing turbulent coagulation

Journal of Fluid Mechanics ◽

10.1017/s0022112000008521 ◽

2000 ◽

Vol 415 ◽

pp. 45-64 ◽

Cited By ~ 56

Author(s):

WALTER C. READE ◽

LANCE R. COLLINS

Keyword(s):

Particle Size ◽

Standard Deviation ◽

Particle Size Distribution ◽

Size Distribution ◽

Radial Distribution ◽

Isotropic Turbulence ◽

Numerical Study ◽

Functional Dependence ◽

Stokes Number ◽

Final Particle

Coagulation and growth of aerosol particles subject to isotropic turbulence has been explored using direct numerical simulations. The computations follow the trajectories of 262 144 initial particles as they are convected by the turbulent flow field. Collision between two parent particles leads to the formation of a new daughter particle with the mass and momentum (but not necessarily the energy) of the parent particles. The initially monodisperse population of particles will develop a size distribution over time that is controlled by the collision dynamics. In an earlier study, Sundaram & Collins (1997) showed that collision rates in isotropic turbulence are controlled by two statistics: (i) the radial distribution of the particles and (ii) the relative velocity probability density function. Their study considered particles that rebound elastically; however, we find that the formula that they derived is equally valid in a coagulating system. However, coagulation alters the numerical values of these statistics from the values they attain for the elastic rebound case. This difference is substantial and must be taken into consideration to properly predict the evolution of the size distribution of a population of particles. The DNS results also show surprising trends in the relative breadth of the particle size distribution. First, in all cases, the standard deviation of the particle size distribution of particles with finite Stokes numbers is much larger than the standard deviation for either the zero-Stokes-number or infinite-Stokes-number limits. Secondly, for particles with small initial Stokes numbers, the standard deviation of the final particle size distribution decreases with increasing initial particle size; however, the opposite trend is observed for particles with slightly larger initial Stokes numbers. An explanation for these phenomena can be found by carefully examining the functional dependence of the radial distribution function on the particle size and Stokes number.

Download Full-text

Grinding Kinetics of Slag and Effect of Final Particle Size on the Compressive Strength of Alkali Activated Materials

10.20944/preprints201910.0261.v1 ◽

2019 ◽

Author(s):

Evangelos Petrakis ◽

Vasiliki Karmali ◽

Georgios Bartzas ◽

Konstantinos Komnitsas

Keyword(s):

Particle Size ◽

Compressive Strength ◽

Particle Size Distribution ◽

Size Distribution ◽

Ageing Time ◽

Reduction Rate ◽

Curing Temperature ◽

Alkali Activation ◽

Final Particle ◽

Alkali Activated

This study aims to model grinding of a Polish slag and evaluate the particle size distributions of the products obtained after different grinding times. Then, selected products were alkali activated in order to investigate the effect of particle size on the compressive strength of the produced alkali activated materials (AAMs). Other parameters affecting alkali activation, i.e. temperature, curing and ageing time were also examined. Among the different mathematical models used to simulate the particle size distribution, Rosin-Rammler (RR) was found to be the most suitable. When piecewise regression analysis was applied to experimental data it was found that the particle size distribution of the slag products exhibits multi fractal character. In addition, grinding of slag exhibits non-first-order behavior and the reduction rate of each size is time dependent. The grinding rate and consequently the grinding efficiency increases when the particle size increases, but drops sharply near zero after prolonged grinding periods. Regarding alkali activation, it is deduced that among the parameters studied, particle size (and the respective specific surface area) of the raw slag product and curing temperature have the most noticeable impact on the compressive strength of the produced AAMs.

Download Full-text