Forming near net shape free-standing components by plasma spraying

2002 ◽  
Vol 57 (4) ◽  
pp. 882-886 ◽  
Author(s):  
A Devasenapathi ◽  
H.W Ng ◽  
S.C.M Yu ◽  
A.B Indra
Keyword(s):  
Plasma Spraying ◽  
Free Standing ◽  
Near Net Shape

Plasma Spraying of Solid Oxide Fuel Cell Components

1997 ◽  
Author(s):  
G. Schiller ◽  
M. Müller ◽  
R. Ruckdäschel ◽  
R. Henne ◽  
M. Lang
Keyword(s):  
Plasma Spraying ◽  
Plasma Spray ◽  
Solid Oxide ◽  
Rf Plasma ◽  
Spray Parameters ◽  
Oxide Fuel ◽  
Bipolar Plates ◽  
Metallic Bipolar Plates ◽  
Protective Layers ◽  
Near Net Shape

Abstract The central components for solid oxide fuel cells (SOFC) are the electrodes-electrolyte multilayer arrangement (PEN) and the separating bipolar plates. The PEN (Positive electrode- Electrolyte-Negative electrode) assembly consists of a dense gastight yttria-stabilized zirconia (YSZ) electrolyte and porous electrodes for which usually Ni-YSZ cermet anode and Sr-doped LaMnO3 cathode layers are used. The various PEN units are connected in a cell stack by bipolar plates which are either metallic or ceramic ones. Furthermore, a protective layer on the metallic bipolar plates consisting of a chromium alloy is required to prevent chromium evaporation leading to a rapid and strong degradation of the SOFC performance. At the DLR Stuttgart both the DC and the RF vacuum plasma spraying technique have been further developed and adapted to meet the requirements for the manufacture of the different SOFC components. The DCVPS process using specially developed Laval-like nozzles is especially appropriate to the production of thin and dense coatings as required for the electrolyte and the protective layers. However, applying special spray parameters and nozzles it is also possible to deposit porous electrode layers. The production of the entire PEN arrangement in one consecutive DC-VPS process is the objective of the actual development. On the other hand, the RF plasma spray technique is suitable for the near net-shape production of bulk components such as the metallic bipolar plate. The development of the deposition processes for the production of SOFC components using DC and RF plasma spray methods and the results obtained concerning PEN fabrication, deposition of protective layers and the near net-shape production of metallic bipolar plates are presented in the paper.

Electrical Property Characterization of Plasma Sprayed Polycrystalline Silicon

2009 ◽  
Vol 620-622 ◽  
pp. 303-306 ◽  
Author(s):  
Ya Ran Niu ◽  
Xuan Yong Liu ◽  
Yi Zeng ◽  
Xue Bin Zheng ◽  
Heng Ji ◽  
...  
Keyword(s):  
Electrical Property ◽  
Plasma Spraying ◽  
Air Plasma ◽  
Free Standing ◽  
Vacuum Plasma Spraying ◽  
Significant Difference ◽  
Plasma Sprayed ◽  
Silicon Based ◽  
Property Characterization

Silicon-based materials have been widely applied in industrial fields, such as microelectronic and solar power, for the specific electronic properties. In the present work, free-standing thick silicon coatings were fabricated by air plasma spraying (APS) and vacuum plasma spraying (VPS) technologies. The microstructure and electrical property of the coatings were characterized. It was found that the electrical resistance of APS-Si coating was higher than that of VPS-Si coating. The impedance spectroscopy results showed there was significant difference in impedance curves of APS-Si and VPS-Si coatings. The grain boundary semicircle appeared in the plot of VPS-Si coating, while did not appeared in that of APS-Si coating. It was thought that the electrical property difference of the two kind coatings was related with the oxidation and microstructure difference of the coatings.

RF-Plasma Technology for Near Net-Shape Deposition

1996 ◽  
Author(s):  
E. Fendler ◽  
M. Müller ◽  
R. Henne ◽  
F. Gitzhofer ◽  
M.L. Boulas
Keyword(s):  
Bipolar Plate ◽  
Rf Plasma ◽  
Spray Parameters ◽  
Chromium Alloy ◽  
Free Standing ◽  
Inclined Surfaces ◽  
Different Types ◽  
Metallic Bipolar Plate ◽  
Near Net Shape ◽  
Rf Plasma Spraying

Abstract A chromium alloy as used for the metallic bipolar plate of a solid oxide fuel cell was processed by RF-plasma spraying to dense free-standing parts. The plasma spray parameters were successfully adapted for two different types of powder. The layer properties, particularly the porosity and the splat shape were investigated in dependence on the spray angles. All the coatings produced with off-normal spray angles show higher porosity increasing from spray angles of 60° to 30°. The splat orientation changes from parallel to the inclined surfaces to almost perpendicular to the plasma jet axis with shallower angles.

Relation Between Thermal Expansion Coefficient and Porosity in Thick Zircon and Alumina Coatings

2000 ◽  
Author(s):  
P. Rohan ◽  
P. Chraska ◽  
P. Ctibor ◽  
K. Neufuss
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Plasma Spraying ◽  
Expansion Coefficient ◽  
Linear Thermal Expansion ◽  
Measuring System ◽  
Plasma Stream ◽  
Free Standing ◽  
General Applicability ◽  
Plasma Gun

Abstract For utilization of free-standing ceramic parts produced by plasma spraying it is very important to know the temperature dependence of the linear thermal expansion coefficient and its relation to the porosity of the structure. Zircon ZrSiO4 and gray alumina (96 wt % AI2O3) were plasma sprayed by the water stabilized plasma gun WSP PAL 160. Samples of both materials were cut from thick coatings with respect to their orientation to the gun axis during the gun's horizontal spraying cycling with a constant speed. Thermal expansion coefficients and the differential thermal analysis were performed using SETARAM complex measuring system (up to 1750 °C), the density/porosity was measured by several techniques, such as Archimedean weighing, helium pycnometry, etc. It was found that both, the porosity and the thermal expansion coefficient, change for different locations in the thick deposit due to the varying trajectories of individual particles/droplets in the plasma stream. Measured data for deposits are then compared with data for bulk ceramics. The dependence of the thermal expansion coefficient on porosity in a given location was determined and its general applicability for free-standing plasma spraying is then discussed in the paper.

Suspension Plasma Spraying of Triboactive Coatings for High Temperature Applications

2010 ◽  
Vol 438 ◽  
pp. 139-146
Author(s):  
Martin Erne ◽  
Daniel Kolar ◽  
Kai Möhwald ◽  
Friedrich Wilhelm Bach
Keyword(s):  
High Temperature ◽  
Plasma Spraying ◽  
Ceramic Coatings ◽  
Suspension Plasma Spraying ◽  
Dry Sliding ◽  
Oxide Ceramic ◽  
Functional Coatings ◽  
Oxide Ceramic Coatings ◽  
Near Net Shape ◽  
Sprayed Coatings

In recent years, suspension plasma spraying (SPS) was investigated regarding the spraying of functional coatings with deterministic abilities. In this contribution the possibilities are discussed to achieve oxide ceramic coatings based on titania by SPS, which show a reduction of their coefficient of friction under dry sliding conditions. Besides the possibility to mix different feedstock suspensions in the process, the achievable low thickness and homogenous microstructure of suspension-sprayed coatings shall allow an operation in fields, where high demands towards the adhesion, cohesion and near net shape are made.

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