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.

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.

Development of electromagnetic acceleration plasma generator for titanium nitride coatings

Vacuum ◽  
2000 ◽  
Vol 59 (1) ◽  
pp. 203-209 ◽  
Author(s):  
Tetsuji Shibata ◽  
Hirokazu Tahara ◽  
Toshiaki Yasui ◽  
Yoichi Kagaya ◽  
Takao Yoshikawa
Keyword(s):  
Titanium Nitride ◽  
Plasma Generator ◽  
Nitride Coatings

Microstructural features of wear-resistant titanium nitride coatings deposited by different methods

2000 ◽  
Vol 377-378 ◽  
pp. 512-517 ◽  
Author(s):  
Sergei V Fortuna ◽  
Yurii P Sharkeev ◽  
Anthony J Perry ◽  
Jesse N Matossian ◽  
Ivan A Shulepov
Keyword(s):  
Titanium Nitride ◽  
Wear Resistant ◽  
Nitride Coatings

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.

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