scholarly journals Effects of Heat and Momentum Gain Differentiation during Gas Detonation Spraying of FeAl Powder Particles into the Water

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7443
Author(s):  
Cezary Senderowski ◽  
Andrzej J. Panas ◽  
Bartosz Fikus ◽  
Dariusz Zasada ◽  
Mateusz Kopec ◽  
...  
Keyword(s):  
Phase Transformations ◽  
Numerical Models ◽  
Substrate Material ◽  
Gaseous Detonation ◽  
Heat Diffusion ◽  
Convective Heating ◽  
Detonation Spraying ◽  
Aggregation State ◽  
Gas Detonation ◽  
Gun Barrel

In this paper, dynamic interactions between the FeAl particles and the gaseous detonation stream during supersonic D-gun spraying (DGS) conditions into the water are discussed in detail. Analytical and numerical models for the prediction of momentum and complex heat exchange, that includes radiative effects of heat transfer between the FeAl particle and the D-gun barrel wall and phase transformations due to melting and evaporation of the FeAl phase, are analyzed. Phase transformations identified during the DGS process impose the limit of FeAl grain size, which is required to maintain a solid state of aggregation during a collision with the substrate material. The identification of the characteristic time values for particle acceleration in the supersonic gas detonation flux, their convective heating and heat diffusion enable to assess the aggregation state of FeAl particles sprayed into water under certain DGS conditions.

Influence of Phase Transformations on Residual Stresses in Welded Structures

2013 ◽  
Author(s):  
R. J. Dennis ◽  
R. Kulka ◽  
O. Muransky ◽  
M. C. Smith
Keyword(s):  
Phase Transformation ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Numerical Models ◽  
Material Model ◽  
Transformation Model ◽  
Austenitic Steels ◽  
Beam Specimen ◽  
Welded Structures ◽  
The Impact

A key aspect of any numerical simulation to predict welding induced residual stresses is the development and application of an appropriate material model. Often significant effort is expended characterising the thermal, physical and hardening properties including complex phenomena such as high temperature annealing. Consideration of these aspects is sufficient to produce a realistic prediction for austenitic steels, however ferritic steels are susceptible to solid state phase transformations when heated to high temperatures. On cooling a reverse transformation occurs, with an associated volume change at the isothermal transformation temperature. Although numerical models exist (e.g. Leblond) to predict the evolution of the metallurgical phases, accounting for volumetric changes, it remains a matter of debate as to the magnitude of the impact of phase transformations on residual stresses. Often phase transformations are neglected entirely. In this work a simple phase transformation model is applied to a range of welded structures with the specific aim of assessing the impact, or otherwise, of phase transformations on the magnitude and distribution of predicted residual stresses. The welded structures considered account for a range of geometries from a simple ferritic beam specimen to a thick section multi-pass weld. The outcome of this work is an improved understanding of the role of phase transformation on residual stresses and an appreciation of the circumstances in which it should be considered.

scholarly journals Influence of gas detonation spraying parameters on the geometrical structure of Fe-Al intermetallic protective coatings

2019 ◽  
Author(s):  
Tomasz Chrostek ◽  
Mirosław Bramowicz ◽  
Kazimierz Rychlik ◽  
Wojtkowiak Adam ◽  
Cezary Senderowski
Keyword(s):  
Fractal Dimension ◽  
Geometric Structure ◽  
Geometrical Structure ◽  
Protective Coatings ◽  
Sampling Rate ◽  
Roughness Parameter ◽  
Powder Injection ◽  
Science Center ◽  
Detonation Spraying ◽  
Gas Detonation

The paper presents the results of an investigation and analysis of the geometrical structure of Fe-Al intermetallic protective coatings sprayed under specified gun detonation spraying (GDS) conditions. As GDS variable parameters there were applied two different barrel lengths and two powder injection position (PIP) at the moment of spark detonation as well as two different number of GDS shots with 6.66 Hz frequency. The measurements of the surface's profile were carried out through means of contact profilometry, in which case TOPO-01 system and Mitutoyo SJ 210 profilometer were applied. On the basis of the measurements conducted the analysis of in two-dimensional (2D) and spatial (3D) systems was made possible. The authors assumed that roughness can be considered as a non-stationary parameter of variance of surface amplitude, which is highly dependent on the sampling rate and length of an elementary segments. Therefore, the changes in the amplitude parameters and functional properties of the surface at different lengths of measuring segments (ln), respectively: 1.25, 4 and 12.5 mm, were analyzed. In the analysis of the degree of development of the geometric structure of the surface, the RMS (Root Mean Square) fractal method was used, with an assessment of the geometric structure of the surface stretched over several size levels, taking into account the correlation between the roughness parameter Rq, the measuring length (ln) and the fractal dimension (D). The application of the RMS method with the determination of the fractal dimension (D) allowed for the characterization of the geometric structure of intermetallic Fe-Al protective coatings detonation sprayed under specific conditions of the GDS process - based on the surface roughness profiles of different measured length (ln). Research undertaken within the framework of project No. 2015/19 / B / ST8 / 02000 subsidized by the National Science Center of Poland.

scholarly journals Tribological wear of Fe-Al coatings applied by gas detonation spraying

2021 ◽  
Author(s):  
Tomasz Chrostek
Keyword(s):  
Dry Friction ◽  
Shear Stresses ◽  
X Ray Diffraction ◽  
Detonation Spraying ◽  
Gas Detonation ◽  
Compressive Stresses ◽  
Spraying Parameters ◽  
Thin Oxide Films ◽  
Pin On Disc ◽  
The Coefficient Of Friction

Comparative tests of gas detonation (GDS) coatings were carried out in order to investigate the influence of spraying parameters on abrasive wear under dry friction conditions. The tests were carried out using the pin-on-disc (PoD) method at room temperature. The microstructure of the coatings was analysed by X-ray diffraction (XRD) and scanning electron microscopy (SEM / EDS) methods. The results showed that with specific GDS process parameters, the main phases in both coatings were FeAl and Fe3Al involving thin oxide films Al2O3. The tribological tests proved that the coatings sprayed with the shorter barrel of the GDS gun showed higher wear resistance. The coefficient of friction was slightly lower in the case of coatings sprayed with the longer barrel of the GDS gun. During dry friction, oxide layers form on the surface, which act as a solid lubricant. The load applied to the samples during the tests causes shear stresses, thus increasing the wear of the coatings. During friction, the surface of the coatings is subjected to alternating tensile and compressive stresses, which lead to delamination and is the main wear mechanism of the coatings.

Influence of Surface Condition on the Bonding Strength of Thermal Sprayed Coatings

1997 ◽  
Author(s):  
V.Yu. Ulianitsky ◽  
J.A. Nikolaev ◽  
T.P. Gavrilenko ◽  
M.C. Kim ◽  
J.W. Hong
Keyword(s):  
Bonding Strength ◽  
Substrate Surface ◽  
Surface Condition ◽  
Surface Preparation ◽  
Spray Coating ◽  
Thermal Spray Coating ◽  
Substrate Material ◽  
Detonation Spraying ◽  
Wide Scale ◽  
Detonation Gun

Abstract The role of surface roughness in coating adhesion mechanism is studying for detonation spraying. Roughness was produced by conventional grit blasting, D-gun blasting and was formed as a result of spraying of high-adhesive thin layer of detonation coating. Cermet and alloy powders were sprayed by detonation gun Ob. The coating bonding strength measurements show the WC+25Co adhesion to be above 200 MPa independently of a substrate surface preparation. Contrary, NiCrSiB coatings are very sensitive to surface conditions their adhesion varies from 180 MPa to zero. As-sprayed alloy particles fail in adherence because of insufficient energy to fuse substrate material at a flat surface. Only developed (wide scale) roughness may be fused partially by these particles for their bonding to the substrate. Otherwise, high heated cermet particles do not need special surface preparation (except cleaning) for fusion of substrate material to provide high bonding with it. The wide scale and ball shape roughness, which is similar to the self-reproduced coating roughness, provides the best conditions for the coating bonding and it is recommended as the purpose of surface treatment before thermal spray coating.

Transitional ballistics of electric high-velocity launchers

2019 ◽  
Author(s):  
B. Reck ◽  
S. Hundertmark ◽  
R. Hruschka ◽  
A. Zeiner ◽  
B. Sauerwein ◽  
...  
Keyword(s):  
High Velocity ◽  
Gas Flow ◽  
Mechanical Response ◽  
Numerical Models ◽  
Time Interval ◽  
Viscous Effects ◽  
Simulation Code ◽  
Package Design ◽  
Gun Barrel ◽  
Experimental Values

Abstract The high-velocity launch of a projectile is subjected to a number of disturbances which exert an influence on the flight trajectory. In the case of sub-caliber projectiles, sabot separation is one of the critical aspects. In this work, we focus on the projectiles and the launch package of an electric railgun launch, i.e. on the behavior of the launch-package, when transitioning from the gun barrel to free-flight. This work further addresses the use of a hydrocode for creating numerical models which are capable of predicting the motion and deflection of the sabot parts during their separation from the projectile after exiting the muzzle. An earlier study showed that the air flow around the projectile and the sabot can be modeled with sufficiently high accuracy by means of a simulation code that uses an Eulerian description of the gas flow. Within a time interval of several milliseconds, just the duration that a projectile needs to enter quasi-stationary flight, viscous effects of the air or gas flow have relatively little influence on the sabot discard process. If the Eulerian gas flow is coupled with the Lagrangian structural parts, the mechanical response of the latter to the gas pressure can be complex in terms of deformation and damage, and in that way, can affect the gas flow. In this study, the hydrocode model is applied to a medium caliber launch package concept for accelerating long rod projectiles. The computed results agree well with the corresponding experimental values obtained from a launch package model test in the shock tunnel at Mach 4.5. This demonstrates that the presented hydrocode model can be used for launch package design optimizations with high confidence.

EPR and Raman study of silicon layers obtained by gas detonation spraying

2017 ◽  
Vol 71 ◽  
pp. 232-239 ◽  
Author(s):  
N.I. Klyui ◽  
V.Ya. Bratus ◽  
V.P. Temchenko ◽  
V.B. Lozinskii ◽  
V.O. Yukhymchuk ◽  
...  
Keyword(s):  
Detonation Spraying ◽  
Gas Detonation ◽  
Raman Study ◽  
Gas Detonation Spraying

Influence of Particle on Gas Detonation by Shock

2019 ◽  
pp. 67-82
Author(s):  
V.P. Efremov ◽  
L.R. Obruchkova ◽  
A.D. Kiverin
Keyword(s):  
Combustible Mixture ◽  
Solid Particles ◽  
Gaseous Detonation ◽  
Temperature Pattern ◽  
Time Intervals ◽  
Gas Detonation ◽  
Micron Particle ◽  
Academy Of Sciences ◽  
Pattern Visualization ◽  
Subsonic Region

There exist evidence, that the gaseous detonation passing through a cloud of solid particles could be attenuated or even suppressed. Contrary to these known works, in the present article, we have found that just one single 160-micron particle can serve as a trigger for the detonation onset. By numerical simulation, we have obtained that there are the concentration ratio limits, in which single particle is enough to initiate gaseous detonation, although without particle the detonation is not ignited in the same conditions in a tube of restricted size. In other words, the presence of a solid particle in the combustible mixture could decrease significantly the ignition delay time. Using of temperature pattern visualization, we have demonstrated that the ignition arises in the subsonic region located between the particle and the bow shock front. The approximations of the used model are discussed. It is shown that used assumptions are valid within investigated time intervals. The work performed with use of the supercomputer resources Interdepartmental Supercomputer Center Russian Academy of Sciences (ISC RAS)

scholarly journals Numerical and Experimental Study of Phase Transformations in Welding Processes / Badania Numeryczne I Doświadczalne Przemian Fazowych W Procesach Spawania

2015 ◽  
Vol 60 (4) ◽  
pp. 2559-2568 ◽  
Author(s):  
W. Piekarska
Keyword(s):  
Solid State ◽  
Heat Source ◽  
Phase Transformations ◽  
High Speed ◽  
Numerical Models ◽  
Experimental Studies ◽  
Butt Joint ◽  
Heat Of Fusion ◽  
Large Temperature ◽  
Welding Processes

The paper concerns the mathematical and numerical modeling of phase transformations in solid state occurring during welding. The analysis of the influence of heating rate, cooling rate and maximum temperatures of thermal cycles on the kinetics of phase transformations is presented. On the basis of literature data and experimental studies the evaluation of classic mathematical and numerical models of phase transformation is presented with respect to the advanced methods of welding by using a high speed and a high power heat source. The prediction of the structure composition in laser welded butt-joint made of S460 steel is performed, where phase transformations are calculated on the basis of modified numerical models. Temperature distributions are determined as well as the shape and size of fusion zone and heat affected zone (HAZ). Temperature field is obtained by the solution of transient heat transfer equation with convective term and external volumetric heat source taken into account. Latent heat of fusion, evaporation and heats generated during phase transformations in solid state are considered in the numerical algorithm due to the large temperature range present in analyzed process. Results of the numerical prediction of structure composition in HAZ are presented in this work. Obtained results of computer simulations are compared to experimental research performered on the laser welded joint.

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