scholarly journals Influence of the Titania Content on the Microstructure and Properties of Plasma Sprayed Alumina-Titania Coatings

2018 ◽  
Vol 20 (3) ◽  
pp. 15-18
Author(s):  
Anna Goral ◽  
Wojciech Zorawski ◽  
Otakar Bokuvka
Keyword(s):  
Composite Coatings ◽  
Lamellar Microstructure ◽  
Tio2 Powder ◽  
Titania Content ◽  
Molten Droplets ◽  
Al2o3 Phase ◽  
Α Al2o3 ◽  
Plasma Sprayed ◽  
Titania Coatings ◽  
Steel Substrates

The composite alumina-titania coatings have been widely used in industry fields to protect metallic components from wear, corrosion and thereby prolonging their service time. This paper presents an analysis of the microstructure and mechanical properties of Al2O3-TiO2 composite coatings, plasma sprayed on steel substrates from feedstocks containing various concentrations of the TiO2 powder. The coatings revealed lamellar microstructure, formed by the rapid solidification of molten droplets of the powder on previously deposited splats. The main phase identified in the coatings was γ-Al2O3 phase, the others were TiO2 and α-Al2O3, as well as amorphous phase. The results indicated significant improvement of hardness, Young’s modulus and fracture resistance of coatings with an increase in TiO2 from 3 wt. % to 13 wt. %. The friction coefficient was found to be the same for both coatings.

Fabrication and Ablation Behavior of Plasma Sprayed ZrC-W Composite Coatings

2014 ◽  
Vol 602-603 ◽  
pp. 552-555
Author(s):  
Dan Lu ◽  
Ya Ran Niu ◽  
Xue Lian Ge ◽  
Xue Bing Zheng ◽  
Guang Chen
Keyword(s):  
Thermal Conductivity ◽  
Thermal Shock ◽  
Plasma Spray ◽  
Composite Coatings ◽  
Lamellar Microstructure ◽  
Atmospheric Plasma Spray ◽  
Atmospheric Plasma ◽  
Plasma Flame ◽  
Plasma Sprayed ◽  
Zrc Coating

In this work, atmospheric plasma spray (APS) technology was applied to fabricate ZrC-W composite coatings. The microstructure of the composite coatings was characterized. The influence of W content on the ablation-resistant and thermal shock properties of ZrC-W composite coatings was evaluated using a plasma flame. The results show that the ZrC-W composite coatings had typically lamellar microstructure, which was mainly made up of cubic ZrC, cubic W and a small amount of tetragonal ZrO2. The ZrC-W coatings had improved ablation resistant and thermal shock properties compared with those of the pure ZrC coating. It was supposed that the improved density, thermal conductivity and toughness of the composite coatings contributed to this phenomenon.

scholarly journals Fatigue behaviour of Plasma Sprayed Titania and Chromia Coatings

2021 ◽  
Vol 349 ◽  
pp. 02009
Author(s):  
Angelos Koutsomichalis ◽  
Antonios Lontos ◽  
George Loukas ◽  
Michalis Vardavoulias ◽  
Nikolaos Vaxevanidis
Keyword(s):  
Static Loading ◽  
Critical Role ◽  
Microstructural Analysis ◽  
Fatigue Behaviour ◽  
Atmospheric Plasma ◽  
Adhesion Properties ◽  
Wide Range ◽  
Plasma Sprayed ◽  
Titania Coatings ◽  
Steel Substrates

Cr2O3 and TiO2 powders were deposited by atmospheric plasma spray (APS) on steel substrates. Microstructural analysis of the coatings showed typical lamellar structure with good coating quality. Fatigue strength was studied by using cyclic testing (measuring with an inhouse-built apparatus the strength of the coated systems under a wide range of impact cycles) and static loading tests (Vickers tests standards with 600N and 1500N) measuring the adhesion properties of the coatings. In low cycles (1x103) Titania coatings exhibited better strength, while at intermediate (4.5x105) and high (1x106) number of impact cycles, both Chromia and Titania coatings exhibited quite similar strength characteristics. At low impact force the thickness of the coatings plays critical role with better performance obtained by Chromia coatings. During static loading both coatings exhibited similar characteristics at the crater diameter but with larger crater depth for Titania. Chromia coatings exhibited higher strength resistance than Titania coatings with better mechanical properties and coating structure.

scholarly journals The Effect of Heat Treatment on the Microstructure and Phase Composition of Plasma Sprayed Al2O3 and Al2O3-TiO2 Coatings for Applications in Biomass Firing Plants

Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1289
Author(s):  
Airingas Šuopys ◽  
Liutauras Marcinauskas ◽  
Viktorija Grigaitienė ◽  
Romualdas Kėželis ◽  
Mindaugas Aikas ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Phase Composition ◽  
Steel Substrate ◽  
Atmospheric Pressure Plasma ◽  
X Ray Diffraction ◽  
Before And After ◽  
Al2o3 Phase ◽  
Tio2 Coatings ◽  
Plasma Sprayed ◽  
Steel Substrates

This study presents the thermal and chemical resistance of plasma-sprayed Al2O3 and Al2O3 doped with 13 wt.% of TiO2 coatings and their suitability for the fire grate of straw pellet furnaces. Coatings were deposited on steel substrates using direct current atmospheric pressure plasma spraying. The surface structure, elemental, and phase composition of formed coatings were analyzed before and after the thermal treatment, imitating natural application conditions. For the experiment, the annealing temperature was 500 °C for twenty-five cycles (80 min each). It was found that the steel substrate oxidized after five thermal cycles, and the formation of iron oxides was observed. The elemental composition of the Al2O3 and Al2O3-13 wt.% TiO2 coatings remained unchanged even after 25 cycles of heat treatment. The X-ray diffraction (XRD) results revealed that the alpha-Al2O3 to gamma-Al2O3 phase ratio in the Al2O3-TiO2 coating was reduced by only 8.7% after 25 cycles.

scholarly journals Microstructural Charactistics of Plasma Sprayed NiCrBSi Coatings and Their Wear and Corrosion Behaviors

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 170
Author(s):  
Songqiang Huang ◽  
Jingzhong Zhou ◽  
Kuoteng Sun ◽  
Hailiang Yang ◽  
Weichen Cai ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Acid Corrosion ◽  
Composite Coatings ◽  
Atmospheric Plasma ◽  
Confocal Laser ◽  
Formation Mechanisms ◽  
Temperature Oxidation ◽  
Surface Protection ◽  
Plasma Sprayed ◽  
Nicrbsi Coatings

Nickel-based alloys are commonly used as protective coating materials for surface protection applications owing to their superior resistance to corrosion, wear and high-temperature oxidation. It is urgent to study the fundamental mechanism between the structure and corrosion properties of the Nickel-base composite coatings. This paper, therefore, focuses on clarifying the mechanisms of the microstructure influencing the acid corrosion and mechanical characteristics of the as-sprayed NiCrBSi coating and post-heat-treated coating. The formation mechanisms of the amorphous phase of flat particles during the plasma spray process were studied by using X-ray diffraction analysis, Raman spectroscopy and confocal laser scanning microscope at first. Then the evolutionary process of the corrosion structure and phase of the coating in the accelerated corrosion experiment is directly visualized by using scanning electron microscopy and energy spectrum analysis. The mechanical properties of the amorphous NiCrBSi coatings are lastly measured by microhardness and friction wear tests. The critical phenomena and results help to elucidate the relative influence of the surface features of atmospheric plasma sprayed coatings on acid corrosion responses and wear resistance, aiming at contributing to the development of a protective technique for electrical engineering.

Evaluation of Slurry Erosive Wear Performance of Plasma-Sprayed Flyash-TiO2 Composite Coatings

2021 ◽  
Vol 7 (3) ◽  
Author(s):  
R. Keshavamurthy ◽  
B. E. Naveena ◽  
C. S. Ramesh ◽  
M. R. Haseebuddin
Keyword(s):  
Composite Coatings ◽  
Erosive Wear ◽  
Wear Performance ◽  
Plasma Sprayed

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.

Laser Sintering of Nano-Al2O3 Powders on Plasma Sprayed Ceramic Based Coatings

2007 ◽  
Author(s):  
Lida Shen ◽  
Yinhui Huang ◽  
Zongjun Tian ◽  
Guoran Hua
Keyword(s):  
Wear Resistance ◽  
Corrosion Resistance ◽  
Plasma Spraying ◽  
Bond Coat ◽  
Continuous Wave ◽  
Ceramic Coatings ◽  
Laser Sintering ◽  
Al2o3 Ceramic ◽  
Plasma Sprayed ◽  
Steel Substrates

This paper describes an investigation of nano-Al2O3 powders reinforced ceramic coatings, which has included NiCrAl and Al2O3+13%wt.TiO2 coats pre-produced by atmosphere plasma spraying, implemented by laser sintering. Commercial NiCrAl powders were plasma sprayed onto 45 Steel substrates to give a bond coat with thickness of ∼100μm. The 600μm thick Al2O3+13%wt.TiO2 based coating was also plasma sprayed on top of the NiCrAl bond coat. With 2.5kw continuous wave CO2 laser, nano-Al2O3 ceramic powders were laser sintered on the based Coatings. The micro structure and chemical composition of the modified Al2O3+13%wt.TiO2 coatings were analyzed by such detection devices as scanning electronic microscope (SEM) and x-ray diffraction (XRD). Microhardness, wear resistance and corrosion resistance of the modified coatings were also tested and compared with that of the unmodified. The results show that the crystal grain size of Al2O3 had no obvious growth. In addition, due to the nanostructured Al2O3 ceramic phases, the coatings exhibited higher microhardness, better wear resistance and corrosion resistance than those unmodified counterparts. The complex process of plasma spraying with laser sintering as a potential effective way of the application of ceramic nano materials was also simply discussed and summarized in the end.

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