共查询到20条相似文献,搜索用时 46 毫秒
1.
Yanguang Shan Thomas W. Coyle Javad Mostaghimi 《Journal of Thermal Spray Technology》2007,16(5-6):736-743
Solution precursor plasma spraying has been used to produce finely structured ceramic coatings with nano- and sub-micrometric
features. This process involves the injection of a solution spray of ceramic salts into a DC plasma jet under atmospheric
condition. During the process, the solvent vaporizes as the droplet travel downstream. Solid particles are finally formed
due to the precipitation of the solute, and the particle are heated up and accelerated to the substrate to generate the coating.
This article describes a 3D model to simulate the transport phenomena and the trajectory and heating of the solution spray
in the process. The jet-spray two-way interactions are considered. A simplified model is employed to simulate the evolution
process and the formation of the solid particle from the solution droplet in the plasma jet. The temperature and velocity
fields of the jet are obtained and validated. The particle size, velocity, temperature, and position distribution on the substrate
are predicted.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
2.
Numerical Study of Combination Parameters for Particle Impact Velocity and Temperature in Cold Spray
Numerical simulations of gas/particle flows of cold spray are performed for N2 and He, respectively, to investigate the usefulness of the two material-independent combination parameters derived from the
equations of particle motion and temperature. The first combination parameter is the particle-diameter multiplied by the material
density, which governs the particle velocity. The second one is the squared particle-diameter multiplied by the material density
and specific heat, which affects the particle temperature. In the numerical simulation, the materials of the spray particle
selected are WC-12Co, Cu and Ti. The numerical results show that the maximum impact velocity of particle is obtained, when
the first combination parameter takes specific value regardless of the material type. Furthermore, it is shown that the particle
diameter and its temperature corresponding to the maximum impact velocity can be graphically estimated by using the two combination
parameters for any powder-materials normally used for the thermal spray.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
3.
Carl Christoph Stahr Sabine Saaro Lutz-Michael Berger Jiri Dubský Karel Neufuss Mathias Herrmann 《Journal of Thermal Spray Technology》2007,16(5-6):822-830
A phase change from α-alumina (corundum) in the feedstock powder to predominantly other alumina phases, such as γ-alumina
in the coating normally takes place, as a result of the spray process. It is expected that the prevention of this phase transformation
will significantly improve the mechanical, electrical, and other properties of thermally sprayed alumina coatings. The results
regarding the possibility of stabilization of α-alumina through addition of chromia published in the literature are ambiguous.
In this work, stabilization using different spray processes (water-stabilized plasma (WSP), gas-stabilized plasma (APS), and
high-velocity oxy-fuel spray (HVOF)) was studied. Mechanical mixtures of alumina and chromia were used, as were prealloyed
powders consisting of solid solutions. The investigations focused on mechanical mixtures with both APS and WSP and on prealloyed
powders with WSP. The coatings were studied by x-ray diffraction, including Rietveld analysis, and analysis of the lattice
parameters. Microstructures were investigated by optical microscopy using metallographic cross-sections. It was shown that
in the case of the mechanically mixed powders, the stabilization predominantly depends on the applied spray process. The stabilization
of the α phase by use of the WSP process starting from mechanical mixtures was confirmed. It appears that stabilization exhibits
a complex dependence on the spray process, the process parameters (in particular the thermal history), the nature of the powder
(mechanically mixed or prealloyed), and the chromia content.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
4.
Abdoul-Fatah Kanta Ghislain Montavon Marie-Pierre Planche Christian Coddet 《Journal of Thermal Spray Technology》2007,16(5-6):913-918
The behavior modeling of Atmospheric Plasma Spray (APS) process requires a global approach which considers interrelated non-linear
relationships between coating characteristics/properties in-service and process parameters (power, feedstock injection, kinematics,
etc.). Such an approach would permit to reduce the development costs. To reach this objective, the knowledge of the interactions
between process parameters plays a relevant role in the optimization. This work intends to develop a behavior model based
on fuzzy logic concepts. Here, the model considers the deposition yield as the result of the process and it establishes relationships
with power process parameter (arc current intensity, plasma gas total flow rate, hydrogen content) on the basis of fuzzy rules.
The model hence permits to discriminate the role and the effects of each power process parameters. The modeling results are
compared to experimental data. The specific case of the deposition of alumina-titania (Al2O3-TiO2, 13% by weight) by Atmospheric Plasma Spraying (APS) is considered.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
5.
Finely structured ceramic coatings can be obtained by solution precursor plasma spraying. The final structure of the coating
highly depends on the droplet size and velocity distribution at the injection, the evolution of the spray in the jet, and
droplet breakup and collision within the spray. This article describes a 3D model to simulate the transport phenomena and
the trajectory and heating of the solution spray in the process. O’Rourke’s droplet collision model is used to take into account
the influence of droplet collision. The influence of droplet breakup is also considered by implementing TAB droplet breakup
models into the plasma jet model. The effects of droplet collisions and breakup on the droplet size, velocity, and temperature
distribution of the solution spray are investigated. The results indicate that droplet breakup and collision play an important
role in determining the final particle size and velocity distributions on the substrate.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
6.
A three-dimensional model of a Cold Gas Dynamic Spray system with a peripheral nonaxisymmetric powder feeder is studied in
this work. It is found that the stagnation pressure alternates for different substrate standoff distances due to the nature
of the supersonic flow interaction with the substrate. One can find the optimum substrate location for any given operating
condition, which results in minimum pressure buildup on the substrate. The three-dimensional analysis sheds more light on
the complex gas and particle flow fields generated due to the three-dimensional particle injection process. In addition, the
three-dimensional model allows us to further investigate the effect of practical substrate shapes (such as convex and concave)
on the flow field and consequently to determine the optimum conditions to deposit coating particles.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
7.
Effect of Substrate Temperature on Deposition Behavior of Copper Particles on Substrate Surfaces in the Cold Spray Process 总被引:2,自引:0,他引:2
M. Fukumoto H. Wada K. Tanabe M. Yamada E. Yamaguchi A. Niwa M. Sugimoto M. Izawa 《Journal of Thermal Spray Technology》2007,16(5-6):643-650
The deposition behavior of sprayed individual metallic particles on the substrate surface in the cold spray process was fundamentally
investigated. As a preliminary experiment, pure copper (Cu) particles were sprayed on mirror-polished stainless steel and
aluminum (Al) alloy substrate surfaces. Process parameters that changed systematically were particle diameter, working gas,
gas pressure, gas temperature, and substrate temperature, and the effect of these parameters on the flattening or adhesive
behavior of an individual particle was precisely investigated. Deposition ratio on the substrate surface was also evaluated
using these parameters. From the results obtained, it was quite noticeable that the higher substrate temperature brought about
a higher deposition rate of Cu particles, even under the condition where particles were kept at room temperature. This tendency
was promoted more effectively using helium instead of air or nitrogen as a working gas. Both higher velocity and temperature
of the particles sprayed are the necessary conditions for the higher deposition ratio in the cold spraying. However, instead
of particle heating, substrate heating may bring about the equivalent effect for particle deposition.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
8.
Eric Irissou Jean-Gabriel Legoux Bernard Arsenault Christian Moreau 《Journal of Thermal Spray Technology》2007,16(5-6):661-668
Coating build-up mechanisms and properties of cold-sprayed aluminum-alumina cermets were investigated using two spherical
aluminum powders having average diameters of 36 and 81 μm. Those powders were blended with alumina at several concentrations.
Coatings were produced using a commercial low-pressure cold spray system. Powders and coatings were characterized by electronic
microscopy and microhardness measurements. In-flight particle velocities were monitored for all powders. The deposition efficiency
was measured for all experimental conditions. Coating performance and properties were investigated by performing bond strength
test, abrasion test, and corrosion tests, namely, salt spray and alternated immersion in saltwater tests. These coating properties
were correlated to the alumina fraction either in the starting powder or in the coating.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
9.
E. Noguès P. Fauchais M. Vardelle P. Granger 《Journal of Thermal Spray Technology》2007,16(5-6):919-926
In plasma spraying, the arc-root fluctuations, modifying the length and characteristics of the plasma jet, have an important
influence on particle thermal treatment. These voltage fluctuations are strongly linked to the thickness of the cold boundary
layer (CBL), surrounding the arc column. This thickness depends on the plasma spray parameters (composition and plasma forming
gas mass flow rate, arc current, etc.) and the plasma torch design (anode-nozzle internal diameter and shape, etc.). In order
to determine the influence of these different spray parameters on the CBL properties and voltage fluctuations, experiments
were performed with two different plasma torches from Sulzer Metco. The first one is a PTF4 torch with a cylindrical anode-nozzle,
working with Ar-H2 plasma gas mixtures and the second one is a 3MB torch with either a conical or a cylindrical anode-nozzle, working with N2-H2 plasma gas mixtures. Moreover, arc voltage fluctuations influence on particle thermal treatment was studied through the measurements
of transient temperature and velocity of particles, issued from an yttria partially stabilized zirconia powder with a size
distribution between 5 and 25 μm.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
10.
The hybrid spray process that combines arc spray with a high-velocity oxyfuel (HVOF)/plasma jet has recently demonstrated
its effectiveness in deposition of functionally gradient coatings. This approach aims at exploiting the combined attributes
of the arc-spray technique and the HVOF/air plasma spraying (APS) technique. This paper presents high-speed visualization
and plume characterization of an arc/HVOF hybrid spray gun as well as a twin-wire arc-spray gun. The physics of atomization
in the hybrid spray process is examined using a high-speed camera. A DPV/CPS-2000 (Tecnar, St-Bruno, QC, Canada) particle
diagnostics sensor is used to measure particle velocity, temperature, size, and distribution. The influence of feed material,
arc parameters, and HVOF parameters on the particle characteristics is presented. Differences in the in-flight characteristics
between the hybrid and the twin-wire arc process are discussed aided by the observed atomization phenomena with the high-speed
camera.
This article was originally published inBuilding on 100 Years of Success, Proceedings of the 2006 International Thermal Spray Conference (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials
Park, OH, 2006. 相似文献
11.
Vasyl Pokhmurskii Hrygorij Nykyforchyn Mykhajlo Student Mykhajlo Klapkiv Hanna Pokhmurska Bernhard Wielage Thomas Grund Andreas Wank 《Journal of Thermal Spray Technology》2007,16(5-6):998-1004
Different posttreatment methods, such as heat treatment, mechanical processing, sealing, etc., are known to be capable to
improve microstructure and exploitation properties of thermal spray coatings. In this work, a plasma electrolytic oxidation
of aluminum coatings obtained by arc spraying on aluminum and carbon steel substrates is carried out. Microstructure and properties
of oxidized layers formed on sprayed coating as well as on bulk material are investigated. Oxidation is performed in electrolyte
containing KOH and liquid glass under different process parameters. It is shown that thick uniform oxidized layers can be
formed on arc-sprayed aluminum coatings as well as on solid material. Distribution of alloying elements and phase composition
of obtained layers are investigated. A significant improvement of wear resistance of treated layers in two types of abrasive
wear conditions is observed.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
12.
This article reports on a series of experiments with various high-velocity oxygen fuel spray systems (Jet Kote, Top Gun, Diamond
Jet (DJ) Standard, DJ 2600 and 2700, JP-5000, Top Gun-K) using different WC-Co and WC-Co-Cr powders. The microstructure and
phase composition of powders and coatings were analyzed by optical and scanning electron microscopy and x-ray diffraction.
Carbon and oxygen content of the coatings were determined to study the decarburization and oxidation of the material during
the spray process. Coatings were also characterized by their hardness, bond strength, abrasive wear, and corrosion resistance.
The results demonstrate that the powders exhibit various degrees of phase transformation during the spray process depending
on type of powder, spray system, and spray parameters. Within a relatively wide range, the extent of phase transformation
has only little effect on coating properties. Therefore, coatings of high hardness and wear resistance can be produced with
all HVOF spray systems when the proper spray powder and process parameters are chosen.
This paper originally appeared in Thermal Spray: Meeting the Challenges of the 21st Century; Proceedings of the 15th International Thermal Spray Conference, C. Coddet, Ed., ASM International, Materials Park, OH, 1998. This proceedings paper has been extensively reviewed according
to the editorial policy of the Journal of Thermal Spray Technology. 相似文献
13.
Use of a comprehensive validated computer model of a thermal spray process enables an ability to improve, optimize, and fine-tune
the performance of that thermal spray process. A validated model of the Sulzer Metco TriplexPro™ 200 plasma gun has been used to improve the performance of the actual gun in terms of enhancing gas flow dynamics, thermal
management, and overall performance in terms of a robust design. Internal changes to the gun geometry using the model have
extended the life of the hardware. In addition the model has permitted the investigation of the fundamental operation of the
gun, specific to the behavior and path of the arcs, as well as the ability to operate the plasma gun, under simulation, in
operating regimes that currently cannot be supported by the physical hardware. The model has been run at gas pressures above
1.4 Mpa and/or voltages above 300 V that currently cannot be obtained with the physical hardware due to equipment limitations
to evaluate the potential to extend the operating window of the Sulzer Metco TriplexPro™ 200 gun beyond current levels in terms of particle velocity and temperature. The end result is an improved process tool
for applying thermal spray coatings ranging from ceramics applied at high particle temperature and low particle velocities
to carbides and alloys applied at lower temperatures and higher velocities.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
14.
Georg Mauer José-Luis Marqués-López Robert Vaßen Detlev Stöver 《Journal of Thermal Spray Technology》2007,16(5-6):933-939
Wear at the electrode surfaces of a one-cathode plasma torch changes the characteristic fluctuation pattern of the plasma
jet. This affects the trajectory of the particles injected into the plasma jet in a non-controllable way, which degrades the
reproducibility of the process. Time-based voltage measurements and Fourier analysis were carried out on a one-cathode F4
torch at different wear conditions to determine the evolution of wear dependant characteristics. A significant correlation
is observed between increasing torch wear and decreasing voltage roughness and high frequency noise. Furthermore, by means
of particle diagnostic systems, the change in the particle velocity and temperature has been measured. The variations of the
particle characteristics are significant and thus an influence on the sprayed coating microstructure is to be expected.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
15.
Dowon Seo Kazuhiro Ogawa Tetsuo Shoji Shozo Murata 《Journal of Thermal Spray Technology》2007,16(5-6):954-966
The effect of particle size distribution on the degradation behavior of plasma sprayed CoNi- and CoCrAlY coatings during isothermal
oxidation was investigated, in terms of the oxygen content, porosity, surface roughness, and oxide scale formation. The results
show that the degradation of both coatings was considerably influenced by the starting particle size distribution. It also
shows that in the as-sprayed vacuum plasma spray (VPS) coatings the oxygen content on the coating surface increased significantly
with decreased average particle size. But after thermal exposure, the difference of the oxygen contents between the coatings
with different particle size was decreased. The powder with various particle size resulted in low porosity inside the coatings
during the deposition process. The surface roughness of the coatings increased with increased particle size. The small particles
produced a relatively smooth surface, and the oxide growth in the coating deposited by small particle was slower than that
in the large particle coating.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
16.
R. Nickel K. Bobzin E. Lugscheider D. Parkot W. Varava H. Olivier X. Luo 《Journal of Thermal Spray Technology》2007,16(5-6):729-735
A new method for a combustion-free spraying is studied fundamentally by modeling and simulation in comparison with first experiments.
The article focuses on the numerical simulation of the gas-particle nozzle flow, which is generated by the shock reflection
at the end wall section of a shock tube. To study the physical fundamentals of this process, at present only a single shot
operation is considered. The particles are injected downstream of the nozzle throat into a supersonic nozzle flow. The measurements
of the particle velocity made by a laser Doppler anemometry (LDA) set up show that the maximum velocity amounts to 1220 m/s
for stainless steel particles of 15 μm diameter. The CFD-Code (Fluent) is first verified by a comparison with available numerical
and experimental data for gas and gas-particle flow fields in a long Laval-nozzle. The good agreement implied the great potential
of the new dynamic process concept for cold-gas coating applications. Then the flow fields in the short Laval nozzle designed
and realized by the Shock Wave Laboratory (SWL) are investigated. The gas flow for experimentally obtained stagnation conditions
is simulated. The gas-particle flow without and with the influence of the particles on the gas flow is calculated by the Surface
Engineering Institute (IOT) and compared with experiments. The influence of the injection parameters on the particle velocities
is investigated, as well.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
17.
Solution Precursor Plasma Spray of Nickel-Yittia Stabilized Zirconia Anodes for Solid Oxide Fuel Cell Application 总被引:1,自引:0,他引:1
In conventional plasma spray of SOFC components, the large NiO and YSZ particles used, about 50-150 microns for high porosity
coating, reduce the density of three-phase sites for electrode reaction. In this article, the SPPS process was used to synthesize
and deposit Ni-YSZ anodes. The results show that several process parameters have significant effects on the microstructure
and phase composition of the deposited material. The deposits were composed of tower-like, irregularly shaped agglomerates
and smooth surface deposits. The sizes of the agglomerates increase with the decrease of the plasma-torch power and most are
not completely molten during the impact. After heat treatment to reduce the NiO present in the as deposited coatings, the
coatings were found to contain spherical YSZ particles about 0.5 μm in diameter distributed in a continuous Ni matrix, which
is verified by both SEM observation and electrical resistance measurement. The coatings have 30-50% porosity.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
18.
Production of titanium deposits by cold-gas dynamic spray: Numerical modeling and experimental characterization 总被引:2,自引:1,他引:2
T. Marrocco D. G. McCartney P. H. Shipway A. J. Sturgeon 《Journal of Thermal Spray Technology》2006,15(2):263-272
Over the past five years, interest in cold-gas dynamics spraying (CGDS) has increased substantially. Considerable effort has
been devoted to process development and optimization for such metals as copper and aluminium. This paper describes work undertaken
to expand the understanding of the deposition of titanium by cold-spray methods. CGDS deposits have been produced from commercially
pure titanium using room-temperature helium gas. The effect of different powder paticle size ranges, types of substrate, substrate
preparation methods, and spray parameter conditions on powder deposition have been investigated. Microhardness testing of
deposits was conducted, and their microstructures have been examined by scanning electron microscopy. Samples for pull-off
bond-strength tests have been prepared from a number of the more promising sets of spray parameters and adhesive strengths
determined. A one-dimensional numerical model of particle acceleration, employing isentropic gas flow behavior in the nozzle,
has also been used to estimate particle exit velocities. This model explicitly addresses the dependence of the drag coefficient
on gas compressibility and demonstrates its significance in terms of predicted particel velocities. By linking this model
with the measured particle size distributions, estimates of particle velocity distributions at the nozzle exit plane have
been computed. These allow an approximate value of the critical velocity for deposition of titanium to be made. Experimental
observations on the microstructure and properties of the deposits are discussed in light of powder particle size and velocity
distributions and the underlying physical and mechanical properties of the powders and substrates.
The original version of this paper was published in the CD ROM Thermal Spray Commects: Explore Its Surfacing Potential, International Thermal Spray Conference, sponsored by DVS, ASM International, and HW International Institute of Welding,
Basel, Switzerland, May 2–4, 2005, DVS-Verlag GmbH, Düsseldorf, Germany. 相似文献
19.
This article represents an effort to systematize an understanding of the cold-spray process and the suitability of materials
for such a process. The evaluation is based on a brief analysis of the powder particle impact and literature research concerning
shock-compression phenomena in matter and related physical effects, such as impact heating and dynamic yielding. The finite-element
modeling (FEM) allows the estimation of the maximum impact pressures, the deformation rates, and the deformation kinetics
during impact. The calculations can be verified experimentally and are supported by the published data. From a brief analysis
of the equations of state applied to shock compression, key material parameters are derived and investigated. A parameterization
of physical properties and correlation with the crystal types endeavors to provide a qualitative ranking of material suitability.
The original version of this article was published as part of the ASM Proceedings, Thermal Spray 2003: Advancing the Science and Applying the Technology, International Thermal Spray Conference (Orlando, FL), May 5–8, 2003, Basil R. Marple and Christian Moreau, Eds., ASM International,
2003. 相似文献
20.
M. Fukumoto T. Yamaguchi M. Yamada T. Yasui 《Journal of Thermal Spray Technology》2007,16(5-6):905-912
A variety of metallic powder particles were thermally sprayed onto the mirror polished metallic substrate surface and the
effect of both substrate temperature and ambient pressure on the flattening behavior of the particle was systematically investigated.
In the flattening behavior of the sprayed particle onto the substrate surface, critical conditions were recognized both in
the substrate temperature and ambient pressure. That is, the flattening behavior changed transitionally on that critical temperature
and pressure range, respectively. A transition temperature, T
t, and transition pressure, P
t, were defined and introduced, respectively for those critical conditions. The fact that the dependence of both transition
temperature and transition pressure on the sprayed particle material had similar tendency indicated that the wetting of the
substrate by the molten particles seemed to be a domination in the flattening. Three-dimensional transition curvature by combining
both transition temperature and transition pressure dependence was proposed as a practical and effective controlling principle
of the thermal spray process.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献