Material Spraying Using Electromagnetically Accelerated Plasma Jet

2004 ◽  
Vol 449-452 ◽  
pp. 389-392 ◽  
Author(s):  
Hirokazu Tahara
Keyword(s):  
Titanium Nitride ◽  
Ceramic Coatings ◽  
Plasma Diagnostic ◽  
Plasma Dynamic ◽  
Spray Coatings ◽  
Spray Process ◽  
Plasma Torches ◽  
Coating Characteristics ◽  
Higher Temperature ◽  
Chemically Active Plasma

In magneto-plasma-dynamic (MPD) arcjet generators, plasma is accelerated by electromagnetic body forces. The MPD arcjet generator can produce higher-velocity, higher-temperature, higher-density and larger-area plasmas than those of conventional thermal plasma torches. Two types of MPD arcjet generator were developed for applications to mullite, zirconia and titanium-nitride spraycoatings. The MPD spray process could successfully form dense, uniform and hard ceramic coatings. In titanium nitride reactive spraying, plasma diagnostic measurement and flowfield analysis were also carried out. A large amount of N and N+ was expected to be exhausted with a high velocity from the MPD generator. Both the electron temperature and the electron number density were kept high at a substrate position compared with those for conventional low-pressure thermal sprayings. A chemically active plasma with excited particles of N+, Ti, Ti+ and Ti2+ was considered to contribute to better titanium nitride coatings. All coating characteristics showed that the MPD arcjet generators had high potentials for ceramic spray coatings.

An Electromagnetic Acceleration Plasma Generator for Titanium Nitride Reactive Spray Coatings

2000 ◽  
Author(s):  
T. Shibata ◽  
H. Tahara ◽  
T. Yasui ◽  
Y. Kagaya ◽  
T. Yoshikawa
Keyword(s):  
Titanium Nitride ◽  
Steel Substrate ◽  
Plasma Generator ◽  
Input Power ◽  
Plasma Dynamic ◽  
Spray Coatings ◽  
Spray Process ◽  
Plasma Torches ◽  
Nitride Coatings ◽  
Substrate Surfaces

Abstract Electromagnetic acceleration plasma generators, which are called Magneto-Plasma-Dynamic (MPD) arcjet generators, can produce higher-velocity, higher-temperature and higher-density plasmas than those of conventional thermal plasma torches, because MPD arcjet plasma is efficiently accelerated by electromagnetic body forces in MW-class input power operation. These properties are effective for deposition of rigid coatings adhering strongly to substrate surfaces. In the present study, we newly developed an ablation type MPD arcjet generator for titanium nitride (TiN) reactive spray coatings. The coatings were deposited onto steel substrate. The phase structure and the composition of the coatings were analyzed by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD), and their Vickers hardness were measured. These analyses showed that the MPD spray process could successfully form dense and uniform titanium nitride coatings. The properties of the titanium nitride coatings were highly sensitive to the titanium cathode diameter and discharge current.

Spraying Using Electromagnetically Accelerated Plasma

2007 ◽  
Vol 127 ◽  
pp. 319-324 ◽  
Author(s):  
Hirokazu Tahara ◽  
Naozumi Yoshimura ◽  
Yoji Koshiro
Keyword(s):  
Silicon Carbide ◽  
Silicon Nitride ◽  
Substrate Temperature ◽  
Nitrogen Gas ◽  
Crystal Silicon ◽  
Plasma Dynamic ◽  
Plasma Torches ◽  
High Potentials ◽  
Higher Temperature ◽  
Silicon Rods

In magneto-plasma-dynamic (MPD) arcjet generators, plasma is accelerated by electromagnetic body forces. Silicon nitride reactive spraying was carried out using an MPD arcjet generator with crystal silicon rods and nitrogen gas. Because higher-velocity, higher-temperature and higher-density and larger-area plasmas are produced with the MPD arcjet generator than those with conventional thermal plasma torches, nitriding of silicon can be enhanced. A dense and uniform β-Si3N4 coating with 30 μm in thickness was formed after 200 shots at a repetitive frequency of 0.03 Hz with a discharge current of 9 kA and a substrate temperature of 700 °C. The Vickers hardness reached about 1300. Furthermore, silicon carbide and aluminum nitride sprayings were conducted with some spraying systems. All results showed that the MPD arcjet generator had high potentials for spraying.

High Velocity Oxy-Fuel Flame Spraying-Process and Coating Characteristics

1996 ◽  
Author(s):  
H. Kreye ◽  
R. Schwetzke ◽  
S. Zimmermann
Keyword(s):  
Thermal Energy ◽  
High Velocity ◽  
Flame Spraying ◽  
Internal Stresses ◽  
Spray Coatings ◽  
Spray Process ◽  
Carbide Coatings ◽  
Coating Characteristics ◽  
Particle Velocities ◽  
First And Second Generation

Abstract High velocity oxy-fuel (HVOF) spray experiments were carried out using various spray systems. A comparison is made of the systems introduced as a first and second generation (Jet Kote, Diamond Jet, Top Gun, CDS) with the more recently introduced systems of the third generation (JP 5000, DJ 2600, DJ 2700). The comparison is based on particle velocities and experiments to evaluate the heat transfer to the particles. The results show that the systems of the new generation with a converging-diverging nozzle section can produce up to 50% higher particle velocities. The higher kinetic energy allows to reduce the thermal energy and to reduce thermally activated phase transformations of the coating material during the spray process. Carbide coatings produced with one of the new HVOF systems exhibit a higher density, higher bond strength and higher hardness as compared to coatings produced with one of the systems of the first and second HVOF generation. Furthermore, the reduced thermal energy yields less oxidative loss of carbon and opens the possibility to spray coatings with neutral or compressive internal stresses, a prerequisite to produce carbide coatings up to a thickness of several millimeters.

Lead-Free Piezoelectric Ceramic Coatings Fabricated by Thermal Spray Process

2017 ◽  
Vol 64 (11) ◽  
pp. 1758-1765 ◽  
Author(s):  
Kui Yao ◽  
Shuting Chen ◽  
Kun Guo ◽  
Chee Kiang Ivan Tan ◽  
Meysam Sharifzadeh Mirshekarloo ◽  
...  
Keyword(s):  
Thermal Spray ◽  
Piezoelectric Ceramic ◽  
Ceramic Coatings ◽  
Lead Free ◽  
Thermal Spray Process ◽  
Spray Process

Granule spray process for fabrication of adherent, low thermal conductivity ceramic coatings

2021 ◽  
Author(s):  
Sae-Jung Yun ◽  
Jung Hwan Kim ◽  
Jongmoon Jang ◽  
Cheol-Woo Ahn ◽  
Woon-Ha Yoon ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Ceramic Coatings ◽  
Low Thermal Conductivity ◽  
Spray Process

Plasma Technology TRIPLEX for the Deposition of Ceramic Coatings in the Industry

2000 ◽  
Author(s):  
G. Barbezat ◽  
K. Landes
Keyword(s):  
Plasma Jet ◽  
Life Time ◽  
Deposition Efficiency ◽  
Ceramic Coatings ◽  
Injection System ◽  
Oxide Ceramic ◽  
Long Distance ◽  
Plasma Gun ◽  
Plasma Torches ◽  
Improved Stability

Abstract As a new plasma gun technology the TRIPLEX system has been introduced in the industrial field two years ago. The core of the TRIPLEX technology is a plasma gun with three cathodes and a long cascaded nozzle consisting of several insulated rings. Only the last ring with a relatively long distance to the cathode is operated as anode. Because of the equal and constant lengths of the three independent arcs, stretching from the three cathodes to the common anode, a stationary plasma jet is generated. Compared to conventional torches, the improved stability of the plasma jet allows a more uniform powder treatment and a higher deposition efficiency as well as the powder feed rate can be increased using a triple injection system. A significantly longer life time of the electrodes reduces the cost for quality control in the coating process. The characteristic properties of oxide ceramic coatings are improved in comparison with the coatings produced by conventional plasma torches. The results of two years industrial application of the innovative torch system TRIPLEX are presented in the paper.

Micro-Porous Coatings and Enhanced CHF for Downward Facing Boiling During Passive Emergency Reactor Cooling

2016 ◽  
Author(s):  
Albert E. Segall ◽  
Faruk A. Sohag ◽  
Faith R. Beck ◽  
Lokanath Mohanta ◽  
Fan-Bill Cheung ◽  
...  
Keyword(s):  
Cold Spray ◽  
Heat Removal ◽  
Porous Coating ◽  
Porous Coatings ◽  
Spray Coatings ◽  
Spray Process ◽  
External Cooling ◽  
Loss Of Coolant Accident ◽  
Lower Head ◽  
Viable Approach

During a Reaction Initiated Accident (RIA) or Loss of Coolant Accident (LOCA), passive external-cooling of the reactor lower head is a viable approach for the in-vessel retention of Corium; while this concept can certainly be applied to new constructions, it may also be viable for operational systems with existing cavities below the reactor. However, a boiling crisis will inevitably develop on the reactor lower head owing to the occurrence of Critical Heat Flux or CHF that could reduce the decay heat removal capability as the vapor phase impedes continuous boiling. Fortunately, this effect can be minimized for both new and existing reactors through the use of a Cold-Spray delivered, micro-porous coating that facilitates the formation of vapor micro-jets from the reactor surface. The micro-porous coatings were created by first spraying a binary mixture with the sacrificial material then removed via etching. Subsequent quenching experiments on uncoated and coated hemispherical surfaces showed that local CHF values for the coated vessel were consistently higher relative to the bare surface. Moreover, it was observed for both coated and uncoated surfaces that the local rate of boiling and local CHF limit varied appreciably along the outer surface. Nevertheless, the results of this intriguing study clearly show that the use of Cold Spray coatings could enhance the local CHF limit for downward facing boiling by more than 88%. Moreover, the Cold-Spray process is amenable to coating the lower heads of operating reactors.

Development & Characterization of Alumina Coating by Atmospheric Plasma Spraying

2018 ◽  
Vol 877 ◽  
pp. 104-109 ◽  
Author(s):  
Jobin Sebastian ◽  
Abyson Scaria ◽  
Don George Kurian
Keyword(s):  
Plasma Spraying ◽  
Elevated Temperatures ◽  
Steel Substrate ◽  
Oxide Coating ◽  
Ceramic Coatings ◽  
Substrate Material ◽  
Atmospheric Plasma ◽  
Flame Spraying ◽  
Alumina Coating ◽  
Spray Process

Ceramic coatings are applied on metals to prevent them from oxidation and corrosion at room as well as elevated temperatures. The service environment, mechanisms of protection, chemical and mechanical compatibility, application method, control of coating quality and ability of the coating to be repaired are the factors that need to be considered while selecting the required coating. The coatings based on oxide materials provides high degree of thermal insulation and protection against oxidation at high temperatures for the underlying substrate materials. These coatings are usually applied by the flame or plasma spraying methods. The surface cleanliness needs to be ensured before spraying. Abrasive blasting can be used to provide the required surface roughness for good adhesion between the substrate and the coating. A pre bond coat like Nickel Chromium can be applied on to the substrate material before spraying the oxide coating to avoid chances of poor adhesion between the oxide coating and the metallic substrate. Plasma spraying produces oxide coatings of greater density, higher hardness, and smooth surface finish than that of the flame spraying process Inert gas is often used for generation of plasma gas so as to avoid the oxidation of the substrate material. The work focuses to develop, characterize and optimize the parameters used in Al2O3 coating on transition stainless steel substrate material for minimizing the wear rate and maximizing the leak tightness using plasma spray process. The experiment is designed using Taguchi’s L9 orthogonal array. The parameters that are to be optimized are plasma voltage, spraying distance and the cooling jet pressure. The characterization techniques includes micro-hardness and porosity tests followed by Grey relational analysis of the results

Characterization of Cr2O3-TiO2-CaF2 Coatings Using Plasma Spray Process

1997 ◽  
Author(s):  
A.Ph. Ilyuschenko ◽  
N.I. Shipica ◽  
P.A. Vityaz ◽  
A.A. Yerstak ◽  
A.Y. Beliaev
Keyword(s):  
Wear Resistance ◽  
Plasma Spray ◽  
Composite Coatings ◽  
Wear Testing ◽  
Material System ◽  
Composite Powders ◽  
Spray Coatings ◽  
Spray Process ◽  
Plasma Spray Coatings ◽  
High Temperature Synthesis

Abstract This paper presents the results of a study on the wear resistance of plasma spray coatings made from Cr2O3-TiO2-CaF2 powders. The composite powders used were produced by self-propagating high temperature synthesis. They were then applied under various conditions in order to optimize the material system, spray process, and application procedures. Based on the results of microstructural examination and wear testing, the thermally sprayed composite coatings have excellent wear resistance, good adhesion, and are self-lubricating at high temperatures.

The Tribology of Amorphous Surfaces Formed by Wear of Thermal Spray Coatings

1998 ◽  
Author(s):  
D.M. Scruggs
Keyword(s):  
High Energy ◽  
X Ray Diffraction ◽  
Coating Structure ◽  
Flow Process ◽  
Wear Process ◽  
Spray Coatings ◽  
Fundamental Properties ◽  
Coating Characteristics ◽  
Equipment Wear ◽  
Temperature Crystallization

Abstract This paper describes the wear induced transformation of crystaline metal surfaces into amorphous and/or microcrystalline surfaces that exhibit gross changes in the fundamental properties of friction, wear, hardness and toughness. The coatings are applied using wire and powder feed to TWAS and HVOF equipment. Wear processes investigated include adhesive wear, low stress abrasion, grinding wear and galling. The effects of chemical makeup of the surfaces and the alloy structure are examined using microscopy and x-ray diffraction. The surface & underlying coating characteristics including roughness, microstructure, hardness and friction coefficient are determined. Results show that the surface structure is dependent on the wear vector. The structural transformation is a function of the chemical makeup and intrinsic wear resistance of the crystalline alloy coupled with the energy input of the wear process. High energy wear such as grinding wear can overcome the transformation. The results also suggest that the micro-welding that occurs between asperities in crystalline alloys is replaced by a flow process on the transformed surface. Coating structure, glass transition temperature, crystallization temperature and critical cooling rate of the transformed surface are much more significant than the chemistry of the alloy once the transformation takes place.

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