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.

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.

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 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.

scholarly journals Numerical Study of the Effects of Twin-Fluid Atomization on the Suspension Plasma Spraying Process

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 224
Author(s):  
Mehdi Jadidi ◽  
Sara Moghtadernejad ◽  
Jack Hanson
Keyword(s):  
Plasma Spraying ◽  
Fine Particles ◽  
Numerical Study ◽  
Suspension Plasma Spraying ◽  
Solid Particles ◽  
Droplet Breakup ◽  
Flight Behavior ◽  
Spray Angle ◽  
Injection System ◽  
Air Blast

Suspension plasma spraying (SPS) is an effective technique to enhance the quality of the thermal barrier, wear-resistant, corrosion-resistant, and superhydrophobic coatings. To create the suspension in the SPS technique, nano and sub-micron solid particles are added to a base liquid (typically water or ethanol). Subsequently, by using either a mechanical injection system with a plain orifice or a twin-fluid atomizer (e.g., air-blast or effervescent), the suspension is injected into the high-velocity high-temperature plasma flow. In the present work, we simulate the interactions between the air-blast suspension spray and the plasma crossflow by using a three-dimensional two-way coupled Eulerian–Lagrangian model. Here, the suspension consists of ethanol (85 wt.%) and nickel (15 wt.%). Furthermore, at the standoff distance of 40 mm, a flat substrate is placed. To model the turbulence and the droplet breakup, Reynolds Stress Model (RSM) and Kelvin-Helmholtz Rayleigh-Taylor breakup model are used, respectively. Tracking of the fine particles is continued after suspension’s fragmentation and evaporation, until their deposition on the substrate. In addition, the effects of several parameters such as suspension mass flow rate, spray angle, and injector location on the in-flight behavior of droplets/particles as well as the particle velocity and temperature upon impact are investigated. It is shown that the injector location and the spray angle have a significant influence on the droplet/particle in-flight behavior. If the injector is far from the plasma or the spray angle is too wide, the particle temperature and velocity upon impact decrease considerably.

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

2006 ◽  
pp. 2182-2187
Author(s):  
Filofteia Laura Toma ◽  
Ghislaine Bertrand ◽  
Cathy Meunier ◽  
Sylvie Begin ◽  
Didier Klein ◽  
...  
Keyword(s):  
Plasma Spraying ◽  
Suspension Plasma Spraying ◽  
Environmental Applications ◽  
Titania Coatings

Nanostructured Photocatalytic Titania Coatings Formed by Suspension Plasma Spraying

2006 ◽  
Vol 15 (4) ◽  
pp. 587-592 ◽  
Author(s):  
Filofteia-Laura Toma ◽  
Ghislaine Bertrand ◽  
Didier Klein ◽  
Christian Coddet ◽  
Cathy Meunier
Keyword(s):  
Plasma Spraying ◽  
Suspension Plasma Spraying ◽  
Titania Coatings

scholarly journals Thermal Barrier Coatings Manufactured by Suspension Plasma Spraying - A Review

2018 ◽  
Vol 18 (3) ◽  
pp. 95-117 ◽  
Author(s):  
L. Łatka
Keyword(s):  
Plasma Spraying ◽  
Thermal Barrier Coatings ◽  
Industrial Applications ◽  
Suspension Plasma Spraying ◽  
Atmospheric Plasma ◽  
Thermal Barrier ◽  
Liquid Droplets ◽  
New Materials ◽  
Barrier Coatings ◽  
Key Issues

AbstractThermal barrier coatings (TBC) is one of the most intensively studied of coatings’ applications area. From 1970’s TBC are developed in two independent ways: (i) development in new materials, with lower thermal conductivity, better erosion resistance and better thermal shock resistance or (ii) development in new deposition techniques. On this field besides conventional atmospheric plasma spraying (APS) and almost conventional (because of very common use) EB-PVD method, in the past 20 years two new techniques have been developed, namely suspension plasma spraying (SPS) and solution precursor plasma spraying (SPPS). In this paper only SPS method was described, as well as, new materials, which could be used in industrial applications of TBC. Moreover, the key issues, like suspension preparation, type of suspension injection, interaction between liquid droplets and plasma jet and deposition mechanism were described.

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