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Article

The Study of Tribological Characteristics of YSZ/NiCrAlY Coatings and Their Resistance to CMAS at High Temperatures

by
Dastan Buitkenov
1,
Zhuldyz Sagdoldina
1,
Aiym Nabioldina
1,* and
Cezary Drenda
2
1
Research Center “Surface Engineering and Tribology”, Sarsen Amanzholov East Kazakhstan University, Ust-Kamenogorsk 070000, Kazakhstan
2
Department of Machine Design and Maintenance, Faculty of Mechanical Engineering and Robotics, AGH University of Krakow, 30-059 Krakow, Poland
*
Author to whom correspondence should be addressed.
Appl. Sci. 2025, 15(14), 8109; https://doi.org/10.3390/app15148109
Submission received: 29 May 2025 / Revised: 17 July 2025 / Accepted: 18 July 2025 / Published: 21 July 2025
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Abstract

This paper presents the results of a comprehensive study of the structure, phase composition, thermal corrosion, and tribological properties of multilayer gradient coatings based on YSZ/NiCrAlY obtained using detonation spraying. X-ray phase analysis showed that the coatings consist entirely of metastable tetragonal zirconium dioxide (t’-ZrO2) phase stabilized by high temperature and rapid cooling during spraying. SEM analysis confirmed the multilayer gradient phase distribution and high density of the structure. Wear resistance, optical profilometry, wear quantification, and coefficient of friction measurements were used to evaluate the operational stability. The results confirm that the structural parameters of the coating, such as porosity and phase gradient, play a key role in improving its resistance to thermal corrosion and CMAS melt, which makes such coatings promising for use in high-temperature applications. It is shown that a dense and thick coating effectively prevents the penetration of aggressive media, providing a high barrier effect and minimal structural damage. Tribological tests in the temperature range from 21 °C to 650 °C revealed that the best characteristics are observed at 550 °C: minimum coefficient of friction (0.63) and high stability in the stage of stable wear. At room temperature and at 650 °C, there is an increase in wear due to the absence or destabilization of the protective layer.

1. Introduction

Yttria-stabilized zirconium dioxide (YSZ) coatings have attracted considerable attention due to a combination of unique physicochemical properties, including a high melting point (2700 °C), low thermal conductivity (1.1 W/mK at 1200 °C), high coefficient of thermal expansion (11 × 10−6–13 × 10−6 °C), as well as high hardness and strength [1,2,3,4,5,6]. These characteristics make YSZ particularly effective under high-temperature and aggressive environments. Due to these properties, YSZ-based coatings are widely used as thermal barrier coatings for aircraft and gas turbine engine turbine blades, solid oxide fuel cell components, oxygen sensors, catalyst carriers, and other functional elements [7,8,9,10,11,12]. In recent years, YSZ has also been considered as a promising wear-resistant material for operation under intense friction, which is especially important for the aviation, space, power, and mechanical engineering industries [13,14,15,16,17].
The most efficient operation of such coatings is demonstrated by a multilayer structure including a metal sublayer, usually based on the NiCrAlY alloy [18,19,20]. This intermediate layer provides chemical and thermal stability, improves adhesion between the substrate and ceramics, and protects the base from oxidation under thermal cycling loads. Currently, the main methods for producing a YSZ/NiCrAlY system coating are atmospheric plasma spraying (APS) [21,22,23,24], electron-beam physical vapor deposition (EB-PVD) [5,25,26,27], and high-velocity air fuel spraying (HVAF) [28,29,30]. Each of these technologies forms coatings with different microstructures and performance characteristics. Thus, APS forms a relatively porous, lamellar structure with microcracks. This allows the coating to better withstand temperature changes without destruction. Coatings obtained using the EB-PVD method have a directional columnar structure with low porosity, which ensures high thermal stability. In recent years, the detonation spraying (DS) method has also been used to produce coatings that feature high density, good adhesion, and increased wear resistance due to the high kinetic energy of the sprayed particles [23,31]. The technology is based on the cyclic explosions of a combustible mixture in a detonation chamber, where a shock wave and a high-speed flow of combustion products are formed. A powder material is introduced into this flow, the particles of which are accelerated to supersonic speeds, partially heated, and then deposited on the substrate, forming a dense and strongly bonded coating [32,33,34,35]. Studies show that coatings obtained using detonation spraying (DS) are characterized by improved mechanical properties, high hardness and density, low porosity, and excellent adhesion to the substrate [36,37].
However, despite the known advantages of YSZ/NiCrAlY coatings, their durability depends to a large extent on tribological properties at elevated temperatures. Under thermal operation conditions, the coatings are subject to abrasive and oxidative wear, which can lead to the destruction of the structure and a decrease in protective properties. The tribological properties of YSZ/NiCrAlY coatings obtained using APS, EB-PVD, and other traditional technologies are actively studied. For example, in [7], APS coatings are studied, where the friction coefficient decreased from 0.68 to 0.39 due to the formation of a thin protective film on the wear surface. However, the tribological properties of YSZ/NiCrAlY coatings obtained by detonation spraying, especially under high-temperature friction conditions, remain virtually unstudied. Meanwhile, the wear resistance of such coatings plays a decisive role in their application, especially under friction, abrasive action, and thermal cycling loads. The aim of this work is a comprehensive study of the tribological characteristics of YSZ/NiCrAlY coatings obtained by detonation spraying, with an emphasis on the effect of temperature on wear, friction coefficient, and surface morphology after testing. The results obtained will allow us to determine the optimal operating temperature conditions and deepen our understanding of wear mechanisms during high-temperature tribotesting.

2. Materials and Methods

In this work, multilayer gradient coatings consisting of YSZ/NiCrAlY layers and 12Kh18N10T stainless steel substrate with chemical composition: Fe—base, Ni—10%, C—0.12%, Ti—0.5%, Cr—18%, Mn—<2% were used as samples. Metco 233B (YSZ) and PNH20K20Yu13 (NiCrAlY) were used as starting powders.
Figure 1 shows the SEM images, X-ray diffraction patterns, and particle size distribution of YSZ and NiCrAlY powders. According to the results of SEM image analysis, YSZ powder is characterized by spherical morphology with an average particle size of 30 ± 5 μm, whereas NiCrAlY powder has a spherical particle shape with an average particle size of 16 ± 6 μm. X-ray phase analysis showed that YSZ powder consists of monoclinic (m-ZrO2) and tetragonal (t-ZrO2) zirconium dioxide phases, whereas, in NiCrAlY powder, β-NiAl, γ-Ni3Al, and NiCoCr phases were identified.
The multilayer gradient coatings of YSZ/NiCrAlY were obtained by detonation spraying (CCDS2000, LIH SB RAS, Novosibirsk, Russia) [38]. Figure 2 shows the external appearance of the CCDS2000 installation and a diagram of the principle of the operation of detonation spraying. Before coating application, the surface of the 12Kh18N10T stainless steel substrate was sandblasted to form the required roughness. Corundum with a particle size of 60–80 μm was used as an abrasive material at an air pressure of 0.6 MPa. After preparing the substrate, a NiCrAlY binder layer was applied first, then a gradient transition was formed by gradually changing the ratio of the supplied materials, ending with the top YSZ layer. To regulate the layer composition, two independent dispensers were used, providing a sequential change in the ratio of the supplied powders. The detonation spraying regimes of NiCrAlY and YSZ coatings are given in Table 1.
Two different regimes of the deposition of multilayer gradient coatings were used in the experiment, in which the key adjustable parameter was the number of shots during the detonation spraying process. By changing the number of shots, it was possible to control the ratio of metal and ceramic phases in the coating, forming the required gradient in thickness.
In the first regime (sample No. 1), the number of shots for the NiCrAlY metal layer was gradually decreased from 5 to 1, while the number of shots for the YSZ ceramic material was consistently increased from 1 to 20. In the second regime (sample No. 2), similarly, the number of shots for NiCrAlY varied from 10 to 2, while the number of shots for YSZ varied from 2 to 40. This method of spraying provided the formation of a more pronounced gradient structure with increased ceramic content in the upper part of the coating. Table 2 shows the sequential layer application patterns and the corresponding number of shots for regime 1 (sample No. 1) and regime 2 (sample No. 2).
The crystallographic structure of the initial powder and the obtained coatings was investigated by X-ray diffraction on an X’Pert Pro diffractometer (Philips Corporation, Amsterdam, The Netherlands) using a copper anode (Cu-Kα radiation, λ = 1.54 Å). Imaging was performed in the 2θ range from 20° to 90°, with phase identification based on the JCPDS database (01-081-1545). The diffractograms were processed, and the phase composition was determined in the HighScore Plus (version 3.0e) software environment.
Microstructural analysis of initial powders and cross-sections of the obtained coatings was carried out using scanning electron microscopy (SEM) on a TESCAN MIRA3 LMH device (TESCAN, Brno, Czech Republic) [39]. For a quantitative assessment of porosity, cross-sectional images obtained in the SEM mode were used, followed by processing according to the method described in the ASTM E2109 standard [40]. Calculations were carried out using ImageJ software (version 1.54g).
To simulate the corrosive effect of silicate melts, a model CMAS mixture with a molar composition of 33CaO-9MgO-13Al2O3-45SiO2 was used, recommended in a number of previous studies [41,42]. The starting reagents (CaO, MgO, Al2O3, SiO2) with a chemical purity of 99.9% were precisely measured in the specified molar ratios and dispersed in anhydrous ethanol. The mixture was processed in a planetary ball mill (Emax, Retsch GmbH., Haan, North Rhine–Westphalia, Germany) at 1000 rpm for 1 h. The resulting suspension was dried at 120 °C for 5 h, after which the dried powder was melted at 1550 °C for 1 h to obtain a homogeneous melt. Rapid cooling of the melt in deionized water ensured the formation of an amorphous glassy phase of CMAS. The resulting glass was additionally crushed and sieved through a sieve with a mesh size of 200 μm. To simulate the effect on the coating, CMAS powder was applied to the surface of the samples, followed by heat treatment at 1200 °C for 1 h, followed by slow cooling to room temperature in an SNOL7.2/1100 muffle furnace (SNOL (Umega Group AB), Utena, Lithuania).
Tribological tests of the coatings at room and elevated temperatures were carried out on a T-21 tribotester located at the Department of Machine Design and Tribotechnology of the AGH University (Kraków, Poland) in accordance with the international standard ISO 20808:2016 [43]. The configuration of the ball-on-disk contact pair was used. The test parameters included a normal force of 10 N, 2000 cycles, a wear scar radius of 3.5 mm, a linear velocity of 0.1 m/s, temperatures of 21 °C, 450 °C, 550 °C, and 650 °C, and the use of aluminum oxide (Al2O3). This range was chosen to evaluate the tribological behavior of coatings under conditions covering both room temperature and temperature regimes close to the actual operating conditions of thermal protection systems. Elevated temperatures allow tracking changes in the wear mechanism, as well as the effect of thermal exposure on the structure and stability of the coating. After the completion of the tests, the samples were cooled to ambient temperature and cleaned of possible contamination. A non-contact interferometric profilometer, ProFilm 3D (Filmetrics, San Diego, CA, USA), was used to assess the surface condition after high-temperature exposure. The volumetric wear of the samples was determined by Formula (1) as follows:
W v = V F n ⋅ s m m 3 N ⋅ m
where:
  • V—volume of wear material [mm3],
  • Fn—normal force applied to the sample [N],
  • s—friction path [m].

3. Results and Discussion

Figure 3 shows the X-ray diffraction pattern of the multilayer gradient coatings, demonstrating that their crystal structure consists entirely of non-transformable (metastable) tetragonal phase of zirconia (JCPDS: # 01-081-1545). According to the X-ray diffraction pattern of YSZ powder (Figure 1), the original material contained both monoclinic and tetragonal phases of zirconia. However, during the detonation spraying process, a phase transition from the monoclinic phase to the tetragonal phase occurs (Figure 3), which is confirmed using X-ray phase analysis. This transition is caused by the high heating temperature of the particles during the spraying process and their subsequent rapid cooling during deposition on the substrate, which leads to the stabilization of the tetragonal phase in the coating structure.
The phase behavior of the material is determined by extreme temperatures exceeding 2000 °C, which is significantly higher than the stability limit of the monoclinic phase. The monoclinic phase of ZrO2, which is stable at room temperature, loses its stability when high temperatures are reached. Under detonation spraying conditions, where the particle temperature can instantly increase to more than 2000–3000 °C, the atoms in the crystal lattice begin to exhibit greater mobility, which contributes to the destruction of the energy barriers holding the monoclinic phase. As a result, Zr and O atoms begin to redistribute into a more symmetrical and stable tetragonal structure, which is more stable at high temperatures. Another key factor ensuring the stabilization of the tetragonal phase is the rapid cooling of ZrO2 particles that occurs after their impact on the substrate. This cooling occurs several times faster than under conventional heat treatment conditions, which prevents the material from returning to the monoclinic state. As a result, the tetragonal phase is “frozen”, which, despite its thermodynamic instability at low temperatures, remains stable at room temperature. The tetragonal phase of ZrO2 is characterized by high symmetry and a less distorted crystal lattice compared to the monoclinic phase. These features give the material increased crack resistance and durability, especially in conditions of heat-protective coatings, where the material experiences both high temperatures and mechanical loads.
X-ray diffraction patterns of the coatings reveal differences in the intensity of phase reflections corresponding to the tetragonal phase of ZrO2. In sample No. 1, the peaks of the tetragonal phase have a higher intensity, which may indicate its higher concentration in the crystal structure. In sample No. 2, on the contrary, a decrease in the intensity of these peaks is observed, especially in the intervals 2θ ≈ 33–35°, 49–52°, and around 60°. This weakening may be associated with the increased porosity of sample No. 2, which affects the number and structure of defects in the material, as well as its diffraction characteristics.
The analysis of the ratio of the crystal lattice parameters (c/a√2) allows us to distinguish between the t-ZrO2 and t’-ZrO2 phases, since the degree of tetragonality directly reflects their structural features. As shown in a number of studies [44], the non-transformable t’-ZrO2 phase is characterized by a reduced tetragonality value (about 1.010 and below), whereas for the transformable t-ZrO2 phase, this parameter is higher. Table 3 presents the tetragonality values obtained for the studied multilayer gradient coatings, which indicate the predominant content of the t’-ZrO2 phase (the values are 1.008–1.009).
Figure 4 shows the cross-sectional microstructure of multilayer gradient coatings obtained using SEM. These coatings were formed by successively depositing layers with varying ratios of ceramic (YSZ) and metallic (NiCrAlY) phases. This approach allows obtaining a gradient structure in which the concentration of components smoothly changes from the substrate to the outer surface. The results of the microstructural analysis showed that the proportion of the ceramic component (YSZ) increases towards the coating surface, while the content of the metallic phase (NiCrAlY) consistently decreases. This confirms that the gradient transition between the layers was successfully implemented. Energy-dispersive X-ray analysis (EDS) confirmed the phase distribution: the light areas in the image correspond to yttrium oxide-stabilized zirconium dioxide (YSZ), and the dark areas to the NiCrAlY metallic alloy. The resulting coatings are characterized by a dense structure without visible defects, inclusions, or cracks, which indicates the high quality of layer formation and the efficiency of the selected technological parameters.
Figure 5 shows enlarged SEM micrographs of the cross-sections of the ceramic coatings, on the basis of which the porosity was quantitatively assessed. The upper row of images shows the original structure of coatings in high resolution (5 μm scale), and the lower row shows the processed images with pore extraction for porosity quantification. Both coatings demonstrate a uniform distribution of pores, with no signs of large cavities or structural defects. However, the coating of sample No. 1 is characterized by a more homogeneous structure with a smaller number and size of pores. Quantitative evaluation showed porosity at 3.21%, indicating a dense and well-compacted structure. In contrast, sample No. 2 shows a more developed porous network with a porosity of 4.47%, and the pores tend to aggregate, which may indicate instability of the spraying process at the selected regime. The increase in porosity may be due to a decrease in the kinetic energy of the particles, their insufficient heating, or a decrease in the frequency of detonation pulses, which leads to a decrease in the degree of compaction of the particles during their deposition on the substrate. Differences in porosity directly affect the resistance of coatings to CMAS and high-temperature corrosion. Lower porosity helps to limit the penetration of aggressive components such as CMAS, melting deep into the material, reducing the risk of chemical reactions and cracking.
Additionally, the differences in coating thicknesses, also noted in the analysis, may be due to the same technological reasons. In particular, sample No. 1 has a coating thickness of 963.67 ± 13.59 μm, while sample No. 2 has only 273.72 ± 1.26 μm. This may indicate a more intense deposition of the material in the first case, possibly due to a greater number of detonation pulses or higher temperature and particle velocity. A detailed analysis of the effect of detonation spraying regimes on the physical and mechanical properties of multilayer gradient coatings based on YSZ/NiCrAlY is presented in our previous studies [37,38].
In thermal corrosion experiments of multilayer gradient coatings conducted at 1150 °C with exposure to CMAS melt, changes in the surface morphology of the coatings were studied using scanning electron microscopy in the backscattered electron (BSE) mode (Figure 6). Both coatings underwent thermal corrosion; however, the degree of degradation varies markedly depending on the morphology and thickness of the coating formed under different spraying regimes. The CMAS melt, which is a eutectic mixture of calcium, magnesium, aluminum, and silicon (CaO-MgO-Al2O3-SiO2), is able to penetrate into the surface layers of the coatings and interact with zirconium dioxide, which is the base of the thermal protection layer. As a result of this interaction, glassy phases and secondary reaction products such as monoclinic ZrO2, spinel structures, and silicates are formed, which leads to the destruction of the protective layer and a reduction in its wear resistance.
The image on the left (sample No. 1) shows some areas of CMAS penetration, but corrosion spreading is limited, indicating an effective barrier effect of the coating. This is confirmed by the low porosity and large layer thickness, which prevents deep penetration of the aggressive phase and slows down the degradation of the material. There is an even structure without pronounced cracking. In the image on the right (sample No. 2), the situation is different: higher porosity and lower coating thickness promote rapid penetration of CMAS melt, which causes intensive cracking (indicated by red lines). These cracks are a direct consequence of the internal stresses generated by the interaction of CMAS with the coating, especially under conditions of thermal expansion and the glass transition of the surface layer. Such degradation significantly reduces the performance of the coating and leads to the loss of its protective properties.
Thus, the resistance of coatings to CMAS is determined not only by chemical composition, but also by morphological parameters—primarily thickness and porosity. A denser and thicker structure ensures slower melt penetration, limiting the volume of the reaction-capable zone and thus increasing corrosion resistance.
During the present work, as well as on the basis of the results of previous studies [36,37], it was established that sample No. 1 demonstrates more stable and preferable characteristics in comparison with sample No. 2. In this regard, in this work, the main attention is paid to the study of the tribological properties of this sample at various temperatures—from room temperature to 650 °C.
Figure 7 shows the dependence of the coefficient of friction (CoF) on the number of sliding cycles for sample No. 1, tested at temperatures of 21 °C (room temperature), 450 °C, 550 °C, and 650 °C. As can be seen from the graph, at the initial stage of testing at all temperatures, a short-term increase in the CoF value is observed, associated with the running-in of the contacting surfaces. At a temperature of 21 °C, significant instability of the friction coefficient is observed with pronounced fluctuations throughout the test, despite reaching an average level of ~0.65–0.7. At 450 °C, the friction coefficient reaches a stable state faster and demonstrates a smoother curve without sharp fluctuations, which may be associated with improved running-in due to thermal softening of the surface layers. At 550 °C, the lowest average CoF value is observed among all temperature conditions, which indicates a decrease in friction resistance due to thermally activated deformation mechanisms and, possibly, the formation of a protective oxide film. With an increase in temperature to 650 °C, the friction coefficient increases again and reaches maximum average values. This may be associated with increased oxidation processes on the coating surface, a change in the nature of contact interaction, and an increase in the brittleness of materials at high temperatures.
To assess the nature of coating wear and to establish the relationship between the temperature regime and the degree of surface damage, three-dimensional topographic images and cross-sectional profiles of wear tracks were obtained after tribological tests at temperatures of 21 °C, 450 °C, 550 °C, and 650 °C (Figure 8). At room temperature (21 °C), the widest and deepest wear track with a maximum depth of up to ~80 μm is observed (Figure 8a,e). Wear is characterized by significant plastic deformation and the absence of signs of self-organization or the formation of protective layers. Irregularities and pronounced defects along the profile edges indicate an unstable friction regime and intense abrasive action. At 450 °C, a distinct concave wear track with pronounced irregularities along the edges and noticeable asymmetry in width can be observed on the wear surface topography (Figure 8b,f). The wear depth reaches approximately 60 μm, and the track width is significantly narrower compared to wear at room temperature. On the side sections, areas with increased roughness are visualized, which may indicate partial microchipping [45]. The central part of the profile demonstrates a deepening characteristic of plastic deformation under conditions of initial softening of the coating. The most favorable nature of wear is observed at a temperature of 550 °C (Figure 8c,g). Three-dimensional surface topography shows a uniformly formed wear track with a small depth of no more than ~20 μm. The transverse profile has a smoothed shape with minimal height fluctuations, which indicates a stable friction process. Moderate thermal exposure probably activates the mechanisms of plastic deformation of the upper layers of the coating and promotes the formation of a thin oxide film, which plays the role of a lubricating layer. Such a film reduces contact friction between the surfaces and simultaneously limits the wear intensity. The absence of sharp depressions and deformations in the profile confirms that the destruction of the coating at this temperature occurs mainly by the mechanism of soft oxidative wear, without significant brittle destruction. This also correlates with the minimum value of the friction coefficient recorded at this temperature. At a temperature of 650 °C, the opposite trend is observed (Figure 8d,h). The wear track becomes deeper, reaching ~65–70 μm, and wider compared to 550 °C. The surface topography shows a symmetrical concave track shape with clearly defined edge zones, indicating increased brittle destruction of the coating material. The transverse profile demonstrates a significant deepening with sharp height differences, which may be associated with the degradation of the previously formed oxide film and the activation of intense oxidation processes. At high temperatures, a loose and non-adhesive oxide phase can form, which does not provide protection against friction, but on the contrary, contributes to its growth.
Figure 9 shows the analysis results of the wear of sample No. 1 obtained during tribological tests in the temperature range from 21 °C to 650 °C. The diagram reflects changes in the volumetric wear of the sample, volumetric wear of the ball, and mass wear of the sample depending on the test temperature. The highest wear value is observed at room temperature: the volumetric wear of the coating reaches 599.9 × 10−6 mm3/N × m, the volumetric wear of the ball is 101 × 10−6 mm3/N × m, and the mass wear of the coating is 6.371 × 10−6 g/N × m. The probable cause of the increased wear is the high surface roughness, as well as the absence of oxide phases capable of protecting the material from intense abrasive interaction. At a temperature of 450 °C, wear is significantly reduced. The volumetric wear of the coating decreases almost eight times compared to room temperature. These observations indicate a positive effect of thermal heating, under which partial running-in and compaction of the contacting surfaces occur. In addition, it is possible to form an initial thin oxide layer, which helps to reduce the friction coefficient and wear intensity due to improved lubricating properties and stabilization of the contact zone. The maximum wear reduction is observed at a temperature of 550 °C, where the volumetric wear of the sample is 41.2 × 10−6 mm3/N × m, the volumetric wear of the ball is 11.8 × 10−6 mm3/N × m, and the mass wear is 0.839 × 10−6 g/N × m. This behavior can be explained by the stable formation of a protective oxide film with high thermal and mechanical stability. In addition, under these conditions, optimal running-in and hardening of the surface layer occur, helping to minimize material losses. However, with a further increase in temperature to 650 °C, the wear increases again. Increased wear at this stage may be associated with the thermal destabilization of the previously formed oxide film, its cracking or peeling as a result of thermomechanical stresses. In addition, at such a temperature, an increase in the brittleness of the surface layer of the coating is possible, contributing to the intensification of the processes of microcrack formation and destruction.

4. Conclusions

The results of the study confirmed the high thermal and tribological stability of multilayer gradient coatings with optimized morphology. It was found that the dense and thick coating structure effectively prevents the penetration of CMAS melt, limits the reaction interaction zone, and significantly slows down material degradation. The coating demonstrates a pronounced barrier effect, uniform microstructure, and absence of critical damage even when exposed to a temperature of 1150 °C, which confirms its high thermal stability.
Tribological tests have shown that sample No. 1 maintains a low coefficient of friction and minimal wear over a wide temperature range. The optimum characteristics were recorded at 550 °C, where the formation of a stable oxide film with lubricating properties and contributing to the stabilization of contact interaction is ensured. At this temperature, the minimum values of friction coefficient and volumetric wear of both coating and counterbody are achieved. It is confirmed that wear resistance and resistance to high-temperature corrosion depend not only on the chemical composition, but also on the morphological parameters of the coating. A denser and thicker structure provides complex protection against thermomechanical fracture, reduces the intensity of cracking, and increases the service life of the material in aggressive operating environments.

Author Contributions

D.B. and Z.S. designed the experiments; A.N. and C.D. performed the experiments; D.B. and A.N. analyzed the data; D.B., Z.S. and A.N. wrote, reviewed, and edited the paper. All authors have read and agreed to the published version of the manuscript.

Funding

This research is funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. BR24992876).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The original contributions presented in the study are included in this article; further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare no conflicts of interest.

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Applsci 15 08109 g001
Figure 1. SEM images (a,b,d,e), XRD patterns (g,h), and particle size distribution (c,f) of YSZ and NiCrAlY powders.
Figure 1. SEM images (a,b,d,e), XRD patterns (g,h), and particle size distribution (c,f) of YSZ and NiCrAlY powders.
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Figure 2. CCDS2000 equipment (a) and the operating principle (b) of detonation spraying of coatings.
Figure 2. CCDS2000 equipment (a) and the operating principle (b) of detonation spraying of coatings.
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Figure 3. X-ray diffraction patterns of multilayer gradient coatings.
Figure 3. X-ray diffraction patterns of multilayer gradient coatings.
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Figure 4. Microstructure of the cross-section of multilayer gradient coatings: (a,e) linear scanning, (b,f) BSE image, and (c,d,g,h) elemental mapping.
Figure 4. Microstructure of the cross-section of multilayer gradient coatings: (a,e) linear scanning, (b,f) BSE image, and (c,d,g,h) elemental mapping.
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Figure 5. Porosity of coatings according to the results of microstructure analysis.
Figure 5. Porosity of coatings according to the results of microstructure analysis.
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Figure 6. Surface morphology of coatings after exposure to CMAS.
Figure 6. Surface morphology of coatings after exposure to CMAS.
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Figure 7. Dependences of the friction coefficient on time (number of cycles) at different temperatures: (a) 21 °C; (b) 450 °C; (c) 550 °C; (d) 650 °C.
Figure 7. Dependences of the friction coefficient on time (number of cycles) at different temperatures: (a) 21 °C; (b) 450 °C; (c) 550 °C; (d) 650 °C.
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Figure 8. Comparative analysis of the coatings surface topography (a–d) and corresponding wear tracks (b–h) at various testing temperatures: (a,e) at 21 °C; (b,f) at 450 °C; (c–g) at 550 °C; (d,h) at 650 °C.
Figure 8. Comparative analysis of the coatings surface topography (a–d) and corresponding wear tracks (b–h) at various testing temperatures: (a,e) at 21 °C; (b,f) at 450 °C; (c–g) at 550 °C; (d,h) at 650 °C.
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Figure 9. (a) Average volumetric and mass wear of the sample and the counter body (ball) at various temperatures; (b) microstructure of the wear track after tribological testing.
Figure 9. (a) Average volumetric and mass wear of the sample and the counter body (ball) at various temperatures; (b) microstructure of the wear track after tribological testing.
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Table 1. Technological parameters of detonation spraying of NiCrAlY and YSZ coatings.
Table 1. Technological parameters of detonation spraying of NiCrAlY and YSZ coatings.
CoatingsRatio, O2/C2H2Barrel Filling Volume, %Spraying Distance, mmCoating Dose, µm/Shot
NiCrAlY0.97352002.3
YSZ2.529612001.7
Table 2. Sequence of layer application and number of shots in regime 1 (sample No. 1) and regime 2 (sample No. 2).
Table 2. Sequence of layer application and number of shots in regime 1 (sample No. 1) and regime 2 (sample No. 2).
LayerMaterialRegime I (Sample No. 1)Regime II (Sample No. 2)
Doser 1
(NiCrAlY)		Doser 2
(YSZ)		Doser 1
(NiCrAlY)		Doser 2
(YSZ)
Number of Shots
Substrate12Kh18N10T----
Layer 1NiCrAlY/YSZ51102
Layer 2YSZ/NiCrAlY3162
Layer 3NiCrAlY/YSZ2142
Layer 4YSZ/NiCrAlY2142
Layer 5NiCrAlY/YSZ1122
Layer 6YSZ/NiCrAlY1122
Layer 7NiCrAlY/YSZ1122
Layer 8YSZ/NiCrAlY1122
Layer 9NiCrAlY/YSZ1122
Layer 10YSZ/NiCrAlY1122
Layer 11NiCrAlY/YSZ1122
Layer 12YSZ/NiCrAlY1224
Layer 13NiCrAlY/YSZ1224
Layer 14YSZ/NiCrAlY1326
Layer 15NiCrAlY/YSZ120240
Table 3. Quantitative results of X-ray diffraction analysis.
Table 3. Quantitative results of X-ray diffraction analysis.
ParameterSample No. 1Sample No. 2
Space group:P42/nmcP42/nmc
Phase composition:100 wt.% tetragonal100 wt.% tetragonal
Lattice Parameters
a = b, Å:3.60823.6117
c, Å:5.14365.1539
Tetragonality1.0081.009
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Buitkenov, D.; Sagdoldina, Z.; Nabioldina, A.; Drenda, C. The Study of Tribological Characteristics of YSZ/NiCrAlY Coatings and Their Resistance to CMAS at High Temperatures. Appl. Sci. 2025, 15, 8109. https://doi.org/10.3390/app15148109

AMA Style

Buitkenov D, Sagdoldina Z, Nabioldina A, Drenda C. The Study of Tribological Characteristics of YSZ/NiCrAlY Coatings and Their Resistance to CMAS at High Temperatures. Applied Sciences. 2025; 15(14):8109. https://doi.org/10.3390/app15148109

Chicago/Turabian Style

Buitkenov, Dastan, Zhuldyz Sagdoldina, Aiym Nabioldina, and Cezary Drenda. 2025. "The Study of Tribological Characteristics of YSZ/NiCrAlY Coatings and Their Resistance to CMAS at High Temperatures" Applied Sciences 15, no. 14: 8109. https://doi.org/10.3390/app15148109

APA Style

Buitkenov, D., Sagdoldina, Z., Nabioldina, A., & Drenda, C. (2025). The Study of Tribological Characteristics of YSZ/NiCrAlY Coatings and Their Resistance to CMAS at High Temperatures. Applied Sciences, 15(14), 8109. https://doi.org/10.3390/app15148109

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