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1

Comparative analysis of microstructure and selected properties of WC-Co-Cr coatings sprayed by high-velocity oxy fuel on S235 and AZ31 substrates

Jonda Ewa, Myalska-Głowacka Hanna, Łatka Leszek, Szymański Krzysztof, Dziekońska Małgorzata

Materials Science Poland

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2024

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Vol. 42, No. 1

32--41

EN

The purpose of this work was to carry out comparative studies of WC-Co-Cr coatings deposited using the high velocity oxy fuel (HVOF) method onto two types of substrate material: structural steel S235 and magnesium alloy AZ31. The influence of the substrate material type on the microstructure, phase composition, crystallite size, porosity, Vickers microhardness, instrumental hardness (HIT), Young’s modulus (EIT), and fracture toughness was investigated. For both substrates, the deposited coatings deposited were characterized with fine-grained and compact microstructure. The X-ray diffraction (XRD) revealed presence of following phases: WC, W2C, Co0.9W0.1, and Co3W9C4. The WC phase was the most desirable and stable one with crystallites were below 100 nm. On the other hand, the size of the W2C crystallites was below 30 nm. The coatings obtained showed porosity values equal to 2.3 ± 0.4 vol% and 2.8 ± 0.7 vol% for AZ31 and S235, respectively. The average Vickers microhardness for both types of sample was appproximately 1200 HV0.3. The average HIT values for carbide particles and metallic matrix were around 29 GPa and 6.5 GPa, respectively. In the case of EIT, it was around 620 GPa and 190 GPa for WC and Co-Cr, respectively. The differences between coatings were negligible. The EIT value for both coatings was equal to 344 ± 11 GPa. The fracture toughness was around 4.5 MPa · m1/2 in both cases. The investigations revealed that it is possible to replace steel substrate material with a much lighter equivalent, in this case AZ31 alloy, without deterioration of the coating properties.

2

The Use of Cluster Analysis to Assess the Wear Resistance of Cermet Coatings Sprayed by High Velocity Oxy-Fuel on Magnesium Alloy Substrate

Jonda Ewa, Fydrych Dariusz, Łatka Leszek, Myalska-Głowacka Hanna

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 4

216--227

EN

Cermet coatings are one of the best surface protection of machine elements against wear. On the other hand, the most universal and economically justified method of applying such coatings is high velocity oxy-fuel (HVOF) spraying. This method makes it possible to produce coatings characterized by compact structure, low porosity and very good adhesion to the substrate. All these fundamental properties contribute to the high wear resistance of these coatings. However, carrying out full wear tests (e.g. ball-on-disc) is time-consuming, especially when it is necessary to select the proper feedstock material and carefully selected process parameters. The aim of the following researches was to statistically investigate the possibility of replacing long-term wear resistance tests with estimation of this performance on the basis of determining the fundamental mechanical properties of the coatings. Three types of coating materials were selected: WC-12Co, WC-10Co-4Cr and WC-20Cr3C2-7Ni, which were deposited on AZ31 magnesium alloy substrates from three different spray distances: 320, 360 and 400 mm. On the basis of the tests carried out and using cluster analysis techniques (the Ward and k-means methods), the relative similarity between the obtained coatings was determined. The applied methodology allowed to select from the analyzed cermet coatings such samples that were characterized by improved resistance to abrasive wear. The obtained results of the analyzes were also referred to the results of tests of resistance to abrasive wear.

3

The Effect of HVOF Spray Distance on Solid Particle Erosion Resistance of WC-based Cermets Bonded by Co, Co-Cr and Ni Deposited on Mg-alloy Substrate

Jonda Ewa, Łatka Leszek, Lont Aleksandra, Gołombek Klaudiusz, Szala Mirosław

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 2

115--128

EN

Magnesium alloys are very interesting engineering materials because of their high strength-to-density ratio. On the other hand, they are characterized by low hardness as well as low erosion resistance. Because of these reasons, their applications in the industry are very limited. The article presents the results of the high velocity oxy-fuel (HVOF) spraying of the hard cermet coatings onto AZ31 magnesium alloy substrate. Three feedstock powders were used in the process with composition (wt.%): WC-12Co, WC-10Co-4Cr and WC-20Cr3C2Ni. The spray distance (SD) was selected as a variable parameter with values equal to 320 and 400 mm. Observations carried out under a scanning electron microscope (SEM) revealed a typical HVOF-sprayed microstructure with a compact structure and low porosity (below 3 vol.%). The hardness of the manufactured coatings, ranging from 912 HV0.2 to 1328 HV0.2, what was significantly higher than the substrate. The solid particle erosion tests were carried out according to the ASTM G76-04 standard. Erosive experiments were done for 30°, 60° and 90° inclination angles of the nozzle using Al2O3 abrasive. Erosion tests confirm that cermets exhibit substantial erosion resistance better than the substrate. The highest erosion resistance was noted for WC-10Co-4Cr coatings. The erosion rate for cermet coatings was mostly below 0.9 mg/min, whereas for the AZ31 it was more than 1.5 mg/min. In the case of the average erosion value, it was between 12 and 22 times lower than for the substrate. Results analysis reveal that shorter spray distance decreases porosity, increases hardness, and finally supports erosion resistance of the cermets.

4

The influence of injection mode and spray distance on wear resistance of Al2O3+13 wt.% TiO2 coatings

Płatek Karolina, Łatka Leszek, Nowakowska Monika

Advances in Materials Science

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2024

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Vol. 24, nr 3(81)

5--17

EN

Atmospheric plasma spraying (APS) allows deposition of ceramic coatings on metallic substrate, significantly increasing the wear resistance of the component. Coating’s microstructure and consequently its properties, depend on heat treatment of the feedstock particles. This property can be controlled by process parameters, especially electric power and spray distance. On the other hand, some plasma torches allow introducing another variable, an injection mode, which could be realized in external or in internal way. In the presented research, wear resistance of Al2O3+13 wt.% TiO2 coatings deposited under various values of spray distance and different injection modes were examined using ASTM G-99 procedure. The impact of spraying parameters on the coating’s microstructure was established and connected to the functional properties of the manufactured deposits. Observed differences indicated influence of injection mode and spray distance value. Coatings deposited with internal feedstock injection exhibit lower porosity and slightly higher hardness than these made with external injection mode. In terms of wear resistance for both spray distance the wear factor was lower for internal injection system. Obtained results confirmed assumed thesis, that internal injection mode improves heat treatment and consequently ameliorate wear performance of plasma sprayed alumina-titania coatings.

5

Effect of spray distance on the microstructure and corrosion resistance of WC - based coatings sprayed by HVOF

Jonda Ewa, Łatka Leszek, Maciej Artur, Godzierz Marcin, Gołombek Klaudiusz, Radziszewski Andrzej

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 2

art. no. e144610

EN

Cermet coatings provide protection against aggressive operating environment of machine and device elements, such as corrosion, wear or high-temperature conditions. Currently WC-based cermet coatings are frequently used in the different industry branches. In this work, conventional WC-based powders (WC-Co and WC-Co-Cr) were sprayed with High Velocity Oxy Fuel (HVOF) onto AZ31 magnesium alloy with different spray distances (320 and 400 mm). The aim of the research was to investigate the effect of the spray distance on the microstructure of the coatings, phase composition and electrochemical corrosion resistance. Results revealed that higher spray distance results in greater porosity, 1.9% and 2.3% for 320 mm and 2.8% and 3.1% for 400 mm in case of WC-Co and WC-Co-Cr coatings, respectively. Also the influence has been observed for coatings microhardness, c.a. 1300 HV0.3 for shorter spray distance, whereas for longer one it was less than 1100 HV0.3. The corrosion resistance estimated in potentiodynamic polarization measurements was the best for WC-Co-Cr coating deposited from the shorter spray distance, corrosion current density was equal to 2.9 µA·cm-2 and polarization resistance was equal to 8424 Ω∙cm2.

6

Investigations on the Microstructure and Corrosion Performance of Different WC-Based Cermet Coatings Deposited by High Velocity Oxy Fuel Process onto Magnesium Alloy Substrate

Jonda Ewa, Łatka Leszek, Maciej Artur, Khozhanov Aleksandr

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 2

25--35

EN

In the field of surface engineering, thermal spraying is very wide adopted in many branches of the industry. The main reasons of such situation are its flexibility as well as cost effectiveness. Among others, High Velocity Oxy Fuel (HVOF) technique is dedicated for spraying hardmetal and cermet coatings, especially for wear- and corrosion resistance. Such type of coating could be a promising candidate as protective layer for magnesium alloys elements. These materials need a strong improvement in the corrosion protection as well as on the field of wear resistance in order to be widely used in the industry. In this work, different WC-based coatings, namely: (i) WC-Co, (ii) WC-Co-Cr and (iii) WC-Cr3C2-Ni manufactured by HVOF spraying, were investigated. The form of all feedstock materials was agglomerated and sintered powder. All coatings were sprayed with the same technological parameters, especially spray distance which was equal to 400 mm on the AZ91 magnesium alloy substrate. The main aim of the studies was to investigate the influence of the powder material on the corrosion resistance of obtained coatings. The manufactured coatings were examined in terms of its microstructure, using scanning electron microscope (SEM) and corrosion performance, which was assessed in the electrochemical corrosion investigations in 3.5% NaCl solution by Tafel method. The study showed that the corrosion resistance increasing in such order: AZ91 < WC-Cr3C2-Ni < WC-Co < WC-Co-Cr. It should be stressed that WC-Cr3C2-Ni coating exhibits very low corrosion performance, which could be effected by relatively high porosity (c.a. 3 vol.%) and because of that the more complex composition promotes creation of many corrosion cells.

7

Microplasma-sprayed multilayer coatings for electric heating elements

Kaliuzhnyi Sergii, Alontseva Dayra, Voinarovych Sergey, Kyslytsia Oleksandr, Khozhanov Aleksandr, Łatka Leszek, Faizrakhmanov Zulfat, Bektasova Gulsym

Materials Science Poland

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2022

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Vol. 40, No. 4

158--170

EN

The paper presents new results on the application of microplasma spraying (MPS) for manufacturing electric heating elements (EHEs) consisting of a St3 steel plate (the substrate) with a sprayed electrically insulating Al2O3 sublayer (400±50 μm thick) and TiO2 electric heating tracks (4 mm width; 150±50 μm thickness). Measurements of the temperature of the multilayer coating with a thermal imager enabled determination of the temperature distribution over the surface of the EHE. The electric strength and conductivity tests showed the efficiency of the sprayed EHEs up to a temperature of 200°C. The results of analysis of the causes of material losses during MPS of electric heating tracks (TiO2) are presented, and the optimal parameters for efficient MPS of coatings in the form of narrow tracks on steel substrates are determined. Using regression analyses, the equation for the influence of MPS parameters on the coating transfer efficiency (CTE) is obtained. Process parameters such as the electric current and the plasma-forming gas flow rate have been found to have the greatest influence on the CTE. In the experiment, a high efficiency of the sprayed material during MPS of electric heating tracks of TiO2 powder was established (the maximum CTE reached 89%), which indicates the prospects for using MPS technology in the production of EHEs for DC electric heating and for maintaining the temperature of product surfaces up to 200°C.

8

Microplasma spraying of hydroxyapatite coatings on additive manufacturing titanium implants with trabecular structures

Kadyroldina Albina, Alontseva Dayra, Voinarovych Sergey, Łatka Leszek, Kyslytsia Oleksandr, Azamatov Bagdat, Khozhanov Aleksandr, Prokhorenkova Nadezhda, Zhilkashinova Almira, Burburska Svitlana

Materials Science Poland

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2022

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Vol. 40, No. 4

28--42

EN

This paper presents new results of microplasma spraying (MPS) of laboratory-synthesized hydroxyapatite (HA) powder coatings onto trabecular substrates obtained by selective laser melting (SLM) of a certified titanium medical alloy powder. The aim of the study was to establish the possibility of combining the technologies of MPS and additive manufacturing (AM) for the possible production of custom-designed implants with increased surface biocompatibility, as well as to establish the MPS parameters that ensure chemical purity of the HA coating and satisfactory adhesion of the coatings to the substrate. The structural-phase compositions of the initial HA powder and the plasma-sprayed HA coating were studied by X-ray diffraction analysis and transmission electron microscopy, and the adhesion strength of the coating was tested according to the F1147 standard of the American Society for Testing and Materials (ASTM). The main results of the study are the following: the application of the MPS technology for HA coating with an average thickness of 150±50 μm on trabecular substrates obtained by the SLM method has been shown. The parameters of MPS of HA coatings onto titanium implants with a trabecular surface have been established. It is also proved that using the appropriate MPS parameters, it is possible to obtain a HA coating with a 95% level of HA phases, 93% level of crystallinity, and the adhesion strength to the trabecular substrate of 24.7±5.7 MPa, which complies with the requirements of the international medical standard (International Organization for Standardization [ISO] 13779-2:2018). These results are of significance for a wide range of researchers developing plasma spray technologies for the manufacture of biocompatible coatings.

9

The effect of cooling time t8/5 on properties of MAG-welded joints made of high-strength steels using robotic methods

Jurkowski Maciej, Łatka Leszek

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2022

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Vol. 66, No. 4

45--52

EN

The paper presents results of tests concerning butt welded joints made of structural high-strength steel S1100QL using a robotic welding station. The subject of the tests was to determine the effect of cooling time t8/5 on primary mechanical properties of joints. Time t8/5 was controlled by changing preheating temperature in relation to constant linear energy (SE specimens) and changing linear energy in relation to constant preheating temperature (ST specimens). Both of the above-named cases involved the preparation of three test plates in relation to three times, i.e. 5 seconds, 7.5 seconds and 10 seconds. The test welded joints subjected to non-destructive and destructive tests represented quality level B (in accordance with PN-EN ISO 5817). No effect of time t8/5 on mechanical properties was noticed in terms of the ST series specimens. The tensile strength identified in the tests amounted to 1020 MPa. The specimen ruptured in the weld. However, the effect of the tensile strength on hardness was noticeable, particularly in the HAZ (even above 450 HV1). The reverse tendency could be observed in relation to the SE series specimens. The value of time t8/5 was important in terms of joint strength, amounting to more than 1100 MPa in relation to the shortest time, where the specimen ruptured in the HAZ. In turn, the effect of time t8/5 was negligible as regards hardness.

PL

W artykule przedstawiono wyniki badań doczołowych złączy spawanych z wysokowytrzymałej stali konstrukcyjnej S1100QL wykonanych na stanowisku zrobotyzowanym. Przedmiotem badań było określenie wpływu czasu stygnięcia t8/5 na podstawowe własności mechaniczne uzyskanych złączy. Wartością czasu t8/5 sterowano za pomocą zmiany temperatury podgrzewania wstępnego przy stałej energii liniowej (próbki SE) oraz zmiany energii liniowej przy stałej temperaturze podgrzewania (próbki ST). W obu przypadkach zrobiono trzy płyty próbne dla czasów 5 s, 7,5 s oraz 10 s. Wykonane złącza spawane zostały poddane badaniom nieniszczącym i uzyskały poziom jakości B (wg PN-EN ISO 5817) oraz badaniom niszczącym. W przypadku próbek serii ST nie zauważono wpływu czasu t8/5 na własności mechaniczne. Wytrzymałość na rozciąganie wynosiła ok. 1020 MPa, a do zniszczenia dochodziło w spoinie. Natomiast zauważalny był jej wpływ na twardość, szczególnie w SWC (nawet powyżej 450 HV1). W przypadku próbek serii SE sytuacja była odwrotna. Wartość czasu t8/5 była istotna z punktu widzenia wytrzymałości złącza, która dla najkrótszego czasu osiągnęła ponad 1100 MPa, a do zniszczenia doszło w SWC. Natomiast w przypadku twardości wpływ czasu t8/5 był pomijalny.

10

The comparison of the effect of powder morphology on the microstructure and mechanical properties of WC-Co-Cr coatings HVOF-sprayed on substrates made of alloy AZ31

Górnik Monika, Jonda Ewa, Łatka Leszek

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2022

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Vol. 66, No. 6

7--14

EN

The paper presents results of comparative tests concerning the effect of the morphology and particle size of the WC-Co-Cr coating material on the microstructure and mechanical properties of coatings sprayed (using the high velocity oxy-fuel method (HVOF)) on substrates made of magnesium alloy AZ31. The tests involved the use of two types of commercial powders, i.e. agglomerated and sintered powder (AS) (Höganäs, Amperit 558.074) and sintered powder (S) (Höganäs, Amperit 554.071). The microstructures of the coatings were observed using digital light microscopy and scanning electron microscopy. The tests also involved the determination of porosity and roughness as well as measurements of instrumental hardness (HIT) and Young’s modulus (EIT ). The microscopic observations revealed that the coatings were characterized by the relatively compact, dense and uniform structure as well as good adhesion to the substrate. The porosity of the S-type coating was approximately 1.5 times higher than that of the AS-type coating. In addition, the S-type coating was visibly thinner (than the AS-type coating), which could be ascribed to a lower powder feed rate applied during the spraying process. The surface of the AS-type coating was characterized by lower roughness (Ra = 4.5 ± 0.1 μm) than that of the S-type coating (Ra = 5.8 ± 0.3 μm). The differences in terms of instrumental hardness (HIT) and instrumental Young’s modulus (EIT) were also small. However, it could be noticed that the more compact structure and lower porosity of the AS-type coating resulted in the obtainment of slightly higher values of both HIT and EIT.

PL

W pracy przedstawiono wyniki badań porównania wpływu morfologii oraz wielkości cząstek materiału powłokowego WC-Co-Cr na mikrostrukturę i własności mechaniczne powłok natryskiwanych płomieniowo naddźwiękowo (High Velocity Oxy-Fuel) na podłoże ze stopu magnezu AZ31. Do badań wybrano dwa rodzaje handlowego proszku: aglomerowany i spiekany (AS) – Höganäs, Amperit 558.074 oraz spiekany (S) – Höganäs, Amperit 554.071. Obserwacje mikrostruktur wytworzonych powłok wykonano przy użyciu mikroskopów: cyfrowego świetlnego oraz skaningowego elektronowego. Określono także porowatość i chropowatość oraz zmierzono twardość instrumentalną (HIT) i moduł Younga (EIT). Na podstawie wykonanych obserwacji mikroskopowych stwierdzono, że wytworzone powłoki charakteryzują się stosunkowo zwartą, gęstą oraz jednolitą strukturą i dobrze przylegają do podłoża. Porowatość powłoki S jest ok. 1,5 razy większa niż w przypadku powłoki AS. Ponadto charakteryzuje ją widocznie mniejsza grubość niż powłoki AS, co jest związane z mniejszym wydatkiem podawania proszku w trakcie procesu natryskiwania. Powierzchnia powłoki AS odznacza się mniejszą chropowatością niż powłoki S, odpowiednio: Ra = 4,5 ± 0,1 µm i Ra = 5,8 ± 0,3 µm. Różnice w wartości twardości instrumentalnej (HIT) oraz instrumentalnego modułu Younga (EIT) są również niewielkie, jednakże można zauważyć, że bardziej zwarta budowa oraz niższa porowatość powłok AS wpływają na uzyskanie nieznacznie wyższych wartości zarówno HIT, jak i EIT.

11

Fractal Dimension as Robust Estimate of Low Carbon Steels Hardness

Zając Krzysztof, Płatek Karolina, Wachel Paweł, Łatka Leszek

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 5

335--344

EN

Application of computational methods in engineering and science constantly increases, which is also visible in sector of material science, often with promising results. In following paper, authors would like to propose fractal dimension, a mathematical method of quantifying self-similarity and complexity of spatial patterns, as robust method of hardness estimation of low carbon steels. A dataset of microstructure images and corresponding Vickers hardness measurements of S235JR steel under different delivery conditions was created. Then, three different computational methods for evaluation of materials hardness based on microstructure image were tested. In this paper those methods are called: (i) Otsu-based index, (ii) fractal dimension index and (iii) vision transformer index. The results were compared with method used in literature for similar problems. Comparison showed that fractal dimension performs better than other evaluated methods, in terms of median absolute error, which value was equal to 4.12 HV1, which is significantly lower than results achieved by Otsu-based index and vision transformer index, which were 4.49 HV1 and 5.07 HV1 respectively. Those results can be attributed to the relative robustness of fractal dimension index, when compared to other methods. Robust estimation is preferable, due to the high amount of noise in the dataset, which is a consequence of the nature of used material.

12

Influence of spray distance on mechanical and tribological properties of HVOF sprayed WC-Co-Cr coatings

Górnik Monika, Jonda Ewa, Łatka Leszek, Nowakowska Monika, Godzierz Marcin

Materials Science Poland

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2021

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Vol. 39, No. 4

545--554

EN

In this work, the tungsten carbide reinforcement in cobalt matrix (WC-Co-Cr) coatings was studied. The deposition process was carried out by high-velocity oxy-fuel spraying (HVOF). The study aimed to investigate the influence of one of the key process parameters, namely spray distance, on the coatings’ microstructure and phase composition, as well as their mechanical and tribological properties. The manufactured coatings were analysed by scanning electron microscopy, X-ray diffraction (XRD), instrumented indentation test, pull-off adhesion test and ball-on-disc method. The results revealed that selection of proper spray distance caused a high index of carbide retention (ICR) amounting to 0.95, which promoted higher hardness and better wear resistance. Instrumental microhardness was in the range of 14.2–14.8 GPa, whereas the Young modulus exhibited values from 336 GPa up to 342 GPa. The bond strength of deposited coatings was in the range of 55–65 MPa. Wear factor values were in the range of 73–81 × 10−7 mm3/(N · m) and the friction coefficient was about 0.4. The dominant wear mechanism is abrasion and adhesive mode supported by the fatigue-induced material delamination.

13

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

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2021

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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.

14

Comparative Analysis of Mechanical Properties of WC-based Cermet Coatings Sprayed by HVOF onto AZ31 Magnesium Alloy Substrates

Jonda Ewa, Łatka Leszek

Advances in Science and Technology. Research Journal

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2021

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Vol. 15, no 2

57--64

EN

Magnesium alloys are very interesting engineering materials due to their very high strength to density ratio (the best among metallic alloys). However, because of low hardness as well as low resistance against erosion, abrasion and corrosion, their applications in the industry is very limited. In order to improve mechanical performances, deposition of hardening coating by thermal spraying was proposed. In this work, the WC-based coatings with different binder (Co or Ni) and co-hardening additives (Cr or Cr3C2) manufactured by high velocity oxy-fuel (HVOF) were studied. These coatings were deposited onto AZ31 magnesium alloy. The crucial problem is obtaining good-adhered coating without damage the substrate, because of relatively low temperature resistance of magnesium alloys (about 300 °C). To solve this problem, HVOF method, which is low temperature and high velocity, was proposed. Also an important role plays process parameters (e.g. spray distance, fuel medium, type of nozzle). The goal of the study was to compare three types of cermet coatings manufactured from commercially available powders (WC-Co, WC-Co-Cr and WC-Cr3C2-Ni) in terms of their microstructure features, microhardness, instrumented indentation and fracture toughness. Results revealed that selected process parameters made it possible to obtain well-adhered coating with good fulfillment of the surface unevenness of the AZ31 substrate. The most noticeable effect was influence of cobalt matrix on higher hardness (1.4 – 1.6 GPa) and Young modulus (330 – 340 GPa) of deposited coatings in compare to the nickel matrix ones (1.2 GPa and 305 GPa, respectively). The same trend was observed in case of fracture toughness, c.a. 6.5 MPa·m1/2 for Co-matrix and 4.9 MPa·m1/2 for Ni-matrix

15

The effect of spray distance on porosity, surface roughness and microhardness of WC-10Co-4Cr coatings deposited by HVOF

Górnik Monika, Jonda Ewa, Nowakowska Monika, Łatka Leszek

Advances in Materials Science

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2021

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Vol. 21, nr 4(70)

99--111

EN

The paper presents the computational studies on the microstructure of WC-Co-Cr coatings deposited by High Velocity Oxy Fuel spraying (HVOF). The study covers the porosity assessment according to ASTM E2109-01 standard, carried out in ImageJ software, in terms of volume porosity, size and shape of the pores. The evaluation was preceded by scanning electron microscope (SEM) observations at magnifications of 2000x and 5000x. Additionally, topography analysis has been performed by confocal laser scanning microscope (CLSM), and the surface roughness Ra was evaluated by the contact method with use of a stylus profilometer. Finally, the influence of porosity was observed for coatings microhardness HV0.3. According to the results, the total closed porosity was found to be in the range of 5.01 vol.% and 5.38 vol.%. The dominated pores in the coatings were of size 0.1-1.0 μm. Studies showed that HVOF process enabled deposition of dense coatings, characterized by homogenous distribution of pores and low roughness.

16

Mechanical properties investigations of the plasma sprayed coatings based on alumina powder

Spyra Joanna, Michalak Monika, Niemiec Aneta, Łatka Leszek

Welding Technology Review

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2020

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R. 92, nr 4

17--23

EN

In this paper Al2O3 + 13 wt% TiO2 ceramic coatings manufactured by Atmospheric Plasma Spraying (APS) have been investigated. The commercial feedstock materials, Metco 6221 (top coat) and Amdry 4535 (bond coat) have been deposited on stainless steel coupons. The main goal of researches was to determine the influence of critical plasma spray parameters (CPSP) on structure and properties of the coatings. In present studies, the electrical power was a variable parameter. Coatings have been characterized in the terms of microstructure, topography, bond strength adhesion, fracture toughness and wear resistance. As a result, it was observed, that coatings sprayed with higher value of the electrical power exhibit higher mechanical properties due to better cohesion as well as higher melting degree.

PL

W artykule zbadano powłoki ceramiczne Al2O3 + 13% wag. TiO2 wytwarzane przez atmosferyczne natryskiwanie plazmowe (APS). Handlowe materiały wsadowe, Meteo 6221 (warstwa wierzchnia) i Amdry 4535 (warstwa wiążąca) zostały osadzone na próbkach ze stali nierdzewnej. Głównym celem badań było określenie wpływu krytycznych parametrów natrysku plazmowego (CPSP) na strukturę i właściwości powłok. W obecnych badaniach moc elektryczna była zmiennym parametrem. Powłoki scharakteryzowano pod względem mikrostruktury, topografii, przyczepności siły wiązania, odporności na pękanie i odporności na zużycie. W rezultacie zaobserwowano, że powłoki natryskiwane wyższą wartością mocy elektrycznej wykazują wyższe właściwości mechaniczne ze względu na lepszą spójność, a także wyższy stopień topnienia.

17

Mechanical Properties and Sliding Wear Resistance of Suspension Plasma Sprayed YSZ Coatings

Łatka Leszek, Szala Mirosław, Macek Wojciech, Branco Ricardo

Advances in Science and Technology. Research Journal

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2020

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Vol. 14, no 4

307--314

EN

In this work, the yttria stabilised zirconia ZrO2 + 8 wt% Y2 O3 (YSZ) coatings were studied. The coatings were manufactured by using a relatively new method based on liquid feedstock, called suspension plasma spraying (SPS). The main aim of the study was to investigate the influence of one of the fundamental process parameters, stand-off distance, on the YSZ coating mechanical properties, namely adhesion, cohesion, hardness, and dry sliding wear resistance. Moreover, the coating surface morphology and microstructure were investigated. Despite the fact that in the SPS method, the heat flux into the substrate is much higher than in conventional atmospheric plasma spraying (APS), for the stand-off distances as short as 40 mm, the structure has not been damaged by thermal stresses. The results revealed that shorter spray distance leads to obtaining the coatings characterised by higher cohesion and adhesion to the substrate as well as higher hardness and resistance to sliding wear. The wear mechanism of both YSZ coatings relies on the adhesive mode, which is intensified by severe coating material delamination.

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The microstructure and selected mechanical properties of Al2O3 + 3 wt.% TiO2 plasma sprayed coatings

Michalak Monika, Łatka Leszek, Sokołowski Paweł

Welding Technology Review

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2019

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R. 91, nr 6

39--45

EN

The Al2O3+TiO2 coatings are of the interest of surface engineering due to their high hardness and wear resistance but also increased toughness, when compared to pure Al2O3 ones. This article describes the deposition of Al2O3+3 wt.% TiO2 coatings by Atmospheric Plasma Spraying (APS) technique. The commercial AMI 6300.1 powder (-45 + 22 μm) was used as a feedstock. The 2k+1 spraying experiment, based on two variables, namely spray distance and torch velocity, was designed. The samples were characterized in the terms of morphology, microstructure, microhardness and roughness. It was observed that the shorter spray distance resulted in lower porosity, higher microhardness and lower roughness of coatings.

PL

Powłoki Al2O3+TiO cieszą się zainteresowaniem inżynierii powierzchni ze względu na wysoką twardość i odporność na zużycie ścierne przy jednocześnie zwiększonej odporności na kruche pękanie, w porównaniu z powłokami na bazie czystego Al2O3. W artykule opisano proces natryskiwania powłok Al2O3+3% wag. TiO2 metodą proszkowego natryskiwania plazmowego (APS). Jako materiał wsadowy wykorzystano komercyjnie dostępny proszek AMI 6300.1 (-45+22 μm). Zaprojektowano plan eksperymentu 2k+1, oparty na dwóch zmiennych - odległości natryskiwania i prędkości przesuwu palnika względem podłoża. Próbki charakteryzowano pod względem morfologii, mikrostruktury, mikrotwardości oraz chropowatości. Zaobserwowano, że zmniejszenie odległości natryskiwania pozwala uzyskać powłoki o mniejszej porowatości, większej twardości i niższej chropowatości.

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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

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2019

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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.

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Tribological Properties of Al2O3 + TiO2 Coatings Manufactured by Plasma Spraying

Łatka Leszek, Niemiec Aneta, Michalak Monika, Sokołowski Paweł

Tribologia

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2019

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nr 1

19--24

EN

In the paper the results of tribological, microscopic, and mechanical research of Al2O3 + TiO2 coatings manufactured by plasma spraying are presented. The feeding material was a powder Al2O3 + 13 wt.% TiO2 (Metco 6221, OerlikonMetco) with grain size – 45 ± 15 μm. The cylinder substrates made from stainless steel (X5CrNi18-10) had a diameter equal to 25 mm and 2 mm of thickness. The variable spray parameters were plasma torch velocity in terms of substrate and spray distance. The morphology of obtained coatings was tested by scanning electron microscope (SEM), and the microstructure was investigated by light optical microscopy (LOM) and SEM. The results of mechanical properties examinations revealed the dependence of the microhardness and fracture toughness on the spray parameters. Tribological examinations were made in the ball-on-disc mode in technical dry friction conditions. Two loads were used, 5 N and 10 N. Based on the carried out tests, it could be concluded that a shorter spray distance and a reduction of the torch velocity allows one to achieve a more compact structure, which is characterized by good adhesion at the coating-substrate interface (in range from 11 to 14 MPa) and good wear resistance.

PL

W artykule przedstawiono wyniki badań tribologicznych, mikroskopowych oraz mechanicznych powłok Al2O3 + TiO2 natryskanych cieplnie metodą plazmową. Materiałem na powłoki był proszek Al2O3 + 13% wag. TiO2 (Metco 6221, OerlikonMetco) o rozkładzie wielkości cząstek -45 ±15 μm. Jako podłoże zostały użyte krążki ze stali austenitycznej X5CrNi18-10. Zmiennymi parametrami procesu była prędkość przesuwania palnika plazmowego względem podłoża oraz odległość palnika od natryskiwanej powierzchni. Morfologię otrzymanych powłok badano przy pomocy skaningowego mikroskopu elektronowego (SEM), natomiast badania mikrostruktury przeprowadzono przy użyciu mikroskopu świetlnego oraz SEM. Badania właściwości mechanicznych wykazały zależność twardości oraz odporności na kruche pękanie (KC) od zastosowanych parametrów natryskiwania. Badania tribologiczne wykonano w styku kula–tarcza w warunkach tarcia suchego (technicznie). Zastosowano obciążenie 5 N oraz 10 N. Na podstawie przeprowadzonych badań można wnioskować, że skrócenie odległości natryskiwania oraz zmniejszenie prędkości przesuwu palnika względem podłoża pozwala uzyskać zwartą strukturę, która charakteryzuje się dobrą przyczepnością na styku powłoka–podłoże (w zakresie od 11 do 14 MPa) oraz dobrą odpornością na zużycie ścierne.