Wyniki wyszukiwania - BazTech

1

Evaluation of the Possibility of Applying Thermal Barrier Coatings to AlSi7Mg Alloy Castings

Mróz Marek, Rąb Patryk

Archives of Foundry Engineering

|

2023

|

Vol. 23, iss. 3

104--109

EN

This paper analyses the possibility of applying thermal barrier coatings (TBCs) onto a substrate made of the AlSi7Mg alloy, intended for, among other things, internal combustion engine components. Engine components made of aluminum-silicon alloys, especially pistons and valve heads, are exposed to high temperature, pressure and thermal shock resulting from the combustion of the fuel-air mixture. These factors cause degradation of these components and can lead to damage. To minimize the risk of damage to engine components caused by heat stress, one way is to apply TBCs. Applying TBCs coatings to engine components improves their durability, increases power output and reduces fuel consumption. The research scope includes the application of an Al2O3-TiO3 coating via the APS (Air Plasma Spraying or Atmospheric Plasma Spraying) method onto a substrate of the AlSi7Mg alloy, analysis of the microstructure and chemical composition of the substrate and coating material, and assessment of the quality of the coating's bond with the AlSi7Mg alloy substrate using the scratch test method.

2

Microstructure, mechanical and thermal properties of YSZ thermal barrier coatings deposited by axial suspension plasma spraying

Poliarus Olena, Morgiel Jerzy, Żórawski Wojciech, Góral Anna, Pomorska Małgorzata, Wojciechowski Krzysztof T., Cherniushok Oleksandr

Archives of Civil and Mechanical Engineering

|

2023

|

Vol. 23, no. 2

art. no., e89, 2023

EN

Yttrium-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) are indispensable elements of present-day turbine propulsion systems. The ones deposited with atmospheric plasma spraying (APS) are characterized by required low thermal conductivity, but they are unable to survive frequent thermomechanical loading and therefore their application is limited to parts remaining stationary. Expanding capability of TBCs is sought in various areas, but the one realized through modification of most proliferated apparatus used for plasma spraying (PS) (from radial to axial injection) and substituting micrometric powders with the nano-structured suspension needs least changes in the industry established procedures and offers the highest property improvement. The present experiment covered the deposition of ZrO2-8Y2O3 YSZ TBC using both atmospheric and suspension PS processes. They were performed with commercial micrometric and nano-structured YSZ (8% Y2O3) powders. The coatings morphology and microstructure were characterized with 3D profilometry, scanning and transmission electron microscopy (SEM/TEM) methods. Finally, the coating’s hardness and heat conductivity were measured. This complex approach allowed to state that PS of micrometric t’-ZrO2 powder having an admixture of m-ZrO2 phase is capable of only partial improvement in its homogenization. However, the suspension PS process of nano-structured powder eliminated any traces of the monoclinic phase from the coating. The TEM microstructure observations indicated that the suspension PS coating is built by in-flight solidified droplets as well as by the melted ones flattened on arrival. A surface layer of liquefied material on solid droplets increases their adhesion to surface asperities promoting pseudo-columnar growth of the coating. The preservation of monotonic slow increase of thermal conductivity during heating of the suspension PS coating means, that its pseudo-columnar microstructure is better suited to withstand high strains during such treatment.

3

Obtaining and Analyzing the Al2O3-ZrO2 Ceramic Layers on Metallic Substrate

Lutcanu Marian, Coteață Margareta, Bernevig Mihai Adrian, Nechifor Cristina-Delia, Cazacu Marius Mihai, Paraschiv Petronela, Istrate Bogdan, Bădărău Gheorghe, Sandu Ioan Gabriel, Cimpoeșu Nicanor

Archives of Metallurgy and Materials

|

2022

|

Vol. 67, iss. 2

479--485

EN

In this case ceramic layers from Metco ZrO2 and Al2O3 powders mixture (25/75; 50/50 and 75/25) were obtained through atmospheric plasma spraying (APS) after five passes on low carbon steel substrate. The sample surfaces mechanically grinded (160-2400) before and after ceramic layer deposition. Powder’s mixtures and the surface of ceramic thin layers were analyzed through: scanning electron microscopy (SEM). In order to understand the effect of surface wettability of the ceramic layers, before and after grinding the surface, three different liquids were used. Experimental results confirm the modification of the steel substrate surface characteristic from hydrophilic to hydrophobic when the ceramic layer was deposited. Surface free energy of hydration increases for all the samples with zirconia percentage addition before polishing process.

4

Effect of TiO₂ on the microstructure and phase composition of Al₂O₃ and Al₂O₃–TiO₂ APS sprayed coatings

Michalak Monika, Łatka Leszek, Sokołowski Paweł, Candidato Rolando T., Ambroziak Andrzej

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2021

|

Vol. 69, nr 2

art. no. e136735

EN

Plasma sprayed ceramic coatings serve as protective layers and are frequently exposed to aggressive wear, corrosion, or high-temperature environment. Currently, alumina and alumina-titania are some of the most popular protective ceramic composite coatings used in the industry. The present work deals with the investigation of the influence of TiO₂ content in the feedstock powder on the resulting microstructure and properties of Al₂O₃, Al₂O₃ + 3 wt% TiO₂, Al₂O₃ + 13 wt% TiO₂ and Al₂O₃ + 40 wt% TiO₂ coatings developed via atmospheric plasma spraying (APS). Specifically, the phase composition, morphology, and microstructure, as well as the mechanical and tribological performance of the coatings were examined. Results revealed that higher content of TiO₂ induced the transformation of phases, leading to the formation of intermediary Al₂TiO₅ and Al₂- xTi₁- xO₅ phases. Also, the dominant α–Al₂O₃ to γ–Al₂O₃ transformation confirmed the formulation of well-melted lamellas within the coating structure. It was also shown that the increase in TiO₂ content decreased the micro-hardness of the coatings due to the formation of the intermediary phases as mentioned above and thus, affected their tribological performance. The lowest volumetric wear, equal to 7.2×10⁻⁵ mm³/(N ∙ m), was reported for Al₂O₃ + 13 wt% TiO₂ coating.

5

Investigations of microstructure and selected mechanical properties of Al2O3 + 40 wt.% TiO2 coatings deposited by Atmospheric Plasma Spraying (APS)

Michalak Monika, Łatka Leszek, Sokołowski Paweł, Ambroziak Andrzej

Welding Technology Review

|

2019

|

R. 91, nr 8

7--11

EN

Atmospheric Plasma Spraying (APS) enables deposition of coatings from different materials, including those based on Al2O3 and TiO2. In this work, Al2O3 + 40 wt.% TiO2 coatings were tested. The relationships between mechanical properties, microstructure and spraying parameters (namely: spraying distance and torch scan velocity) were investigated. Commercial -45 + 5 μm powders in agglomerated as-produced state were sprayed onto the stainless steel 1.4301 substrates. The aim of the study was to determine the adhesion, microhardness and roughness of coatings but also to characterize their microstructure. It was observed that coatings sprayed from shorter distance were well melted and revealed good adhesion, but at the same time they were more porous and of lower microhardness than those deposited from the longer spraying distance.

PL

Metoda natryskiwania plazmowego, APS (ang. Atmospheric Plasma Spraying) umożliwia nanoszenie powłok z różnych materiałów, w tym na bazie Al2O3 oraz TiO2. W pracy zbadano powłoki Al2O3 + 40% wag. TiO2. Przedmiotem badań były właściwości mechaniczne oraz mikrostruktura uzyskanych powłok, w zależności od odległości natryskiwania i prędkości przesuwu palnika względem podłoża. Wykorzystano komercyjne proszki w stanie aglomerowanym o granulacji -45 + 5 μm, którymi pokryto podłoża ze stali nierdzewnej 1.4301. Przeprowadzone badania miały na celu określenie przyczepności powłok, ich mikrotwardości, chropowatości oraz charakteryzację mikrostruktury. Zaobserwowano, że krótsza odległość natryskiwania skutkuje wyższym stopniem przetopienia cząsteczek proszku w powłoce oraz wyższą przyczepnością powłok, ale jednocześnie powoduje wyższą porowatość i niższą mikrotwardość powłok.

6

Atmospheric plasma spraying of Al2O3 + 13% TiO2 coatings using external and internal injection system

Łatka L., Michalak M., Jonda E.

Advances in Materials Science

|

2019

|

Vol. 19, nr 4(62)

5--17

EN

The ceramic coatings based on mixture of Al2O3 and TiO2 have better properties in comparison to the pure alumina ones. Among many techniques, plasma spraying is very useful method of ceramic coatings manufacturing. In this paper, the results of microscopic, mechanical and tribological properties investigations of Al2O3 + 13 wt% TiO2 coatings manufactured by atmospheric plasma spraying are presented. The cylinder substrates made from stainless steel (X5CrNi18-10) had a diameter equal to 25 mm and thickness equal to 2 mm. The plasma spray experimental parameters included three variables: (i) type of injection system (external or internal), (ii) size of corundum particles for sandblasting and (iii) torch linear speed. The results confirm, that type of injection system is a dominant parameter. Internal injection results in better degree of particles melting, what influences on wear resistance performance, as well as higher values of bond strength.