scholarly journals Development of Photocatalytic Active TiO2Surfaces by Thermal Spraying of Nanopowders

2008 ◽  
Vol 2008 ◽  
pp. 1-8 ◽  
Author(s):  
Filofteia-Laura Toma ◽  
Ghislaine Bertrand ◽  
Didier Klein ◽  
Cathy Meunier ◽  
Sylvie Begin
Keyword(s):  
Plasma Spraying ◽  
High Performance ◽  
Photocatalytic Performance ◽  
Thermal Spraying ◽  
Environmental Water ◽  
Suspension Plasma Spraying ◽  
Atmospheric Plasma ◽  
Spray Process ◽  
Coating Characteristics ◽  
Titania Coatings

Titanium dioxide is a very useful photocatalyst for the decomposition and diminution of environmental water and air pollutants. In such applications, it can be used as slurry or as immobilized coating obtained by different deposition methods. The studies performed in the last years showed that thermal spraying could be employed to elaborate TiO2coatings with high performance for the decomposition of organic compounds. This manuscript presents a comparative study on the microstructure and photocatalytic performance of titania coatings obtained by different thermal spray techniques: atmospheric plasma spraying (APS), suspension plasma spraying (SPS) and high-velocity oxygen fuel spray process (HVOF). Different titania powders and suspensions were used to study the influence of the feedstock materials on the coating characteristics. The deposits were mainly characterised by SEM and X-ray diffraction. The photocatalytic performance was evaluated from the removal of nitrogen oxides. The experimental results showed that a drastic reduction of the pollutant concentration was obtained in presence of coatings elaborated by suspension plasma spraying. TiO2coatings resulting from the spraying of agglomerated powder presentd less efficiency. That was mainly explained by the significant phase transformation from anatase to rutile that occurred in the enthalpic source during the spray processes.

Environmental Applications of the Reactive Titania Coatings Elaborated by Suspension Plasma Spraying

2006 ◽  
Vol 45 ◽  
pp. 2182-2187
Author(s):  
Filofteia Laura Toma ◽  
Ghislaine Bertrand ◽  
Cathy Meunier ◽  
Sylvie Begin ◽  
Didier Klein ◽  
...  
Keyword(s):  
Plasma Spraying ◽  
Air Pollutants ◽  
Fine Particles ◽  
Suspension Plasma Spraying ◽  
Atmospheric Plasma ◽  
Atmospheric Conditions ◽  
Titania Coatings ◽  
Reactive Surfaces ◽  
Feedstock Material ◽  
Photocatalytic Applications

This paper deals with the elaboration of titanium dioxide coatings, designed for photocatalytic applications, obtained by a non-conventional method of deposition: suspension plasma spraying (SPS). SPS is an alternative of the atmospheric plasma spraying (APS) in which the feedstock material is a suspension of the powder to be sprayed. The method consists in injection and atomization of a slurry (suspension of fine particles in a solvent) in an enthalpic source (plasma). TiO2 P25 powder (Degussa AG) was mechanically dispersed in distilled water and ethanol and injected in Ar-H2 or Ar-H2-He plasma under atmospheric conditions. SEM and XRD were performed to study the microstructure and the crystalline phases of the titania coatings. Photocatalytic efficiency of the elaborated samples was evaluated from the conversion rate of nitrogen oxides. The present results showed that the suspension plasma spraying allows to produce reactive surfaces for the removal of air pollutants, that in the same working conditions, present a higher photocatalytic activity compared to that of the initial raw powders.

Modelling Sequential Impact of Molten Droplets on a Solid Surface in Plasma Spray Process

2011 ◽  
Vol 227 ◽  
pp. 111-115
Author(s):  
Ilhem R. Kriba ◽  
A. Djebaili
Keyword(s):  
Plasma Spray ◽  
High Performance ◽  
Spray Deposition ◽  
Thermal Spraying ◽  
Spray Coating ◽  
Atmospheric Plasma ◽  
Formation Mechanisms ◽  
Temperature Plasma ◽  
Spray Process ◽  
Spraying Process

Plasma spray deposition is one of the most important technologies available for producing the high-performance surfaces required by modern industry. In this process, powder of the coating material is fed into high-temperature plasma, which melts and accelerates the powder; the molten particles subsequently hit and solidify on the surface to be coated. To obtain good quality coating, the powder particle must be at least partially molten and hit the substrate with a high velocity. The flattening characteristics of the droplets impinging on a substrate are important determinants in governing the eventual quality of the plasma spray coating. Different codes have been developed in recent years to simulate the overall thermal spraying process, as well as the growth of the 3D coatings, in which entrained particles are modeled by stochastic particle models, fully coupled to the plasma flow. The present investigation was carried out to have an approach to systematize the atmospheric plasma spraying process in order to create a basis for numerically modeling the plasma dynamics, the coating formation mechanisms and to predict the particle thermo- kinetic state at impact.

scholarly journals Exploiting Suspension Plasma Spraying to Deposit Wear-Resistant Carbide Coatings

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2344 ◽  
Author(s):  
Satyapal Mahade ◽  
Karthik Narayan ◽  
Sivakumar Govindarajan ◽  
Stefan Björklund ◽  
Nicholas Curry ◽  
...  
Keyword(s):  
Plasma Spraying ◽  
High Performance ◽  
Suspension Plasma Spraying ◽  
Coating Materials ◽  
Wear Resistant ◽  
Thermal Spray Process ◽  
Wear Resistant Coatings ◽  
Spray Process ◽  
Carbide Coatings

Titanium- and chromium-based carbides are attractive coating materials to impart wear resistance. Suspension plasma spraying (SPS) is a relatively new thermal spray process which has shown a facile ability to use sub-micron and nano-sized feedstock to deposit high-performance coatings. The specific novelty of this work lies in the processing of fine-sized titanium and chromium carbides (TiC and Cr3C2) in the form of aqueous suspensions to fabricate wear-resistant coatings by SPS. The resulting coatings were characterized by surface morphology, microstructure, phase constitution, and micro-hardness. The abrasive, erosive, and sliding wear performance of the SPS-processed TiC and Cr3C2 coatings was also evaluated. The results amply demonstrate that SPS is a promising route to manufacture superior wear-resistant carbide-based coatings with minimal in situ oxidation during their processing.

scholarly journals Wear Behavior Analysis of Al2O3 Coatings Manufactured by APS and HVOF Spraying Processes Using Powder and Suspension Feedstocks

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 879
Author(s):  
Monika Michalak ◽  
Paweł Sokołowski ◽  
Mirosław Szala ◽  
Mariusz Walczak ◽  
Leszek Łatka ◽  
...  
Keyword(s):  
Plasma Spraying ◽  
Wear Behavior ◽  
Ceramic Coatings ◽  
Suspension Plasma Spraying ◽  
Atmospheric Plasma ◽  
Hvof Spraying ◽  
The Coefficient Of Friction ◽  
Wear Mode ◽  
Α Al2o3 ◽  
Plasma Sprayed

Thermally sprayed ceramic coatings are applied for the protection of surfaces that are exposed mainly to wear, high temperatures, and corrosion. In recent years, great interest has been garnered by spray processes with submicrometric and nanometric feedstock materials, due to the refinement of the structure and improved coating properties. This paper compares the microstructure and tribological properties of alumina coatings sprayed using conventional atmospheric plasma spraying (APS), and various methods that use finely grained suspension feedstocks, namely, suspension plasma spraying (SPS) and suspension high-velocity oxy-fuel spraying (S-HVOF). Furthermore, the suspension plasma-sprayed Al2O3 coatings have been deposited with radial (SPS) and axial (A-SPS) feedstock injection. The results showed that all suspension-based coatings demonstrated much better wear resistance than the powder-sprayed ones. S-HVOF and axial suspension plasma spraying (A-SPS) allowed for the deposition of the most dense and homogeneous coatings. Dense-structured coatings with low porosity (4 vol.%) and good cohesion to the metallic substrate, containing a high content of α–Al2O3 phase (56 vol.%) and a very low wear rate (0.2 ± 0.04 mm3 × 10−6/(N∙m)), were produced with the S-HVOF method. The wear mechanism of ceramic coatings included the adhesive wear mode supported by the fatigue-induced material delamination. Moreover, the presence of wear debris and tribofilm was confirmed. Finally, the coefficient of friction for the coatings was in the range between 0.44 and 0.68, with the highest values being recorded for APS sprayed coatings.

scholarly journals Coatings of Carbide-Metal Systems (Cr3C2-NiCr and WC-Co-Cr) Deposited by High-Velocity Atmospheric Plasma Spraying from Specially Modified Fine-Grained Powders

2018 ◽  
Vol 1 (1) ◽  
pp. 18-23
Author(s):  
Vadim Verlotski ◽  
Keyword(s):  
Plasma Spraying ◽  
High Speed ◽  
Plasma Deposition ◽  
Thermal Spraying ◽  
Atmospheric Plasma ◽  
Metal Particles ◽  
Fine Grained ◽  
Plasma Torches ◽  
Carbide Coatings ◽  
Gas Tight

In this article, the author poses and responds to a provocative question that has practically ceased to be asked in the field of thermal spraying of carbide coatings: Is the current worldwide trend of using only unmelted metal particles to form coatings (HVOF, HVAF and cold spray methods) correct, and is the deposition of completely melted powders (plasma spraying methods) really outdated? The results of high-speed plasma deposition of new carbide powders allowed the author to prove that only coatings from molten particles can solve the main problem of such coatings, namely the problem of permeability along the grain boundaries. Through the use of modern Axial III plasma torches combined with optimized fine-grained powders, it has been possible to create Cr3C2-NiCr as well as WC-Co-Cr gas-tight layers.

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

scholarly journals A Study on the Microstructural Characterization and Phase Compositions of Thermally Sprayed Al2O3-TiO2 Coatings Obtained from Powders and Water-Based Suspensions

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2638 ◽  
Author(s):  
Monika Michalak ◽  
Filofteia-Laura Toma ◽  
Leszek Latka ◽  
Pawel Sokolowski ◽  
Maria Barbosa ◽  
...  
Keyword(s):  
Phase Composition ◽  
Plasma Spraying ◽  
Microstructural Characterization ◽  
Atmospheric Plasma ◽  
Coating Morphology ◽  
Liquid Feedstock ◽  
Α Al2o3 ◽  
Titania Coatings ◽  
Thermal Spray Processes ◽  
Oxygen Fuel

In this work, the alumina (Al2O3) and alumina-titania coatings with different contents of TiO2, i.e., Al2O3 + 13 wt.% TiO2 and Al2O3 + 40 wt.% TiO2, were studied. The coatings were produced by means of powder and liquid feedstock thermal spray processes, namely atmospheric plasma spraying (APS), suspension plasma spraying (SPS) and suspension high-velocity oxygen fuel spraying (S-HVOF). The aim of the study was to investigate the influence of spray feedstocks characteristics and spray processes on the coating morphology, microstructure and phase composition. The results revealed that the microstructural features were clearly related both to the spray processes and chemical composition of feedstocks. In terms of phase composition, in Al2O3 (AT0) and Al2O3 + 13 wt.% TiO2 (AT13) coatings, the decrease in α-Al2O3, which partially transformed into γ-Al2O3, was the dominant change. The increased content of TiO2 to 40 wt.% (AT40) involved also an increase in phases related to the binary system Al2O3-TiO2 (Al2TiO5 and Al2−xTi1+xO5). The obtained results confirmed that desired α-Al2O3 or α-Al2O3, together with rutile-TiO2 phases, may be preserved more easily in alumina-titania coatings sprayed by liquid feedstocks.

Novel Approaches to Prepare the High Performance Dense Electolyte and Interconnect Applicable to SOFC by Atmospheric Plasma Spraying

2017 ◽  
Vol 78 (1) ◽  
pp. 1831-1838
Author(s):  
Chang-Jiu Li ◽  
Xu Chen ◽  
Shan-Lin Zhang ◽  
Cheng-Xin Li ◽  
Guan-Jun Yang
Keyword(s):  
Plasma Spraying ◽  
High Performance ◽  
Atmospheric Plasma Spraying ◽  
Atmospheric Plasma ◽  
Novel Approaches

The Interaction between Particles and a Plasma Beam in the Thermal Projection Process

2009 ◽  
Vol 83-86 ◽  
pp. 801-809
Author(s):  
Ilhem Kriba ◽  
A. Djebaili
Keyword(s):  
Process Parameters ◽  
High Performance ◽  
Particle Interaction ◽  
Extreme Temperature ◽  
Thermal Spraying ◽  
Spray Parameters ◽  
Spray Process ◽  
Wide Range ◽  
Coating Formation ◽  
Jet Characteristics

Plasma spray processes have been widely used to produce high performance coatings of a wide range of Materials (metallic, non-metallic, ceramics), offering protection from, eg. wear, extreme temperature, chemical attack and environmental corrosion. To obtain good quality coatings, spray parameters must be carefully selected. Due to the large variety in process parameters, it is difficult to optimize the process for each specific coating and substrate combinations. Furthermore modelling the spray process allows a better understanding of the process sequences during thermal spraying. Good agreement of the virtual spraying process with the real coating formation is achieved by modelling the particular process steps. The simulation of coating formation to estimate the process parameters is an important tool to develop new coating structures with defined properties. In this work, the process of plasma sprayed coating has been analyzed by numerical simulation. Commercial code is used to predict the plasma jet characteristics, plasma –particle interaction, and coating formation. Using this model we can obtain coating microstructure and characteristics which form a foundation for further improvement of an advanced ceramic coating build up model.

Sign in / Sign up

Export Citation Format

Share Document