Suspension Plasma Spraying Research Articles

Fabrication, characterization, and in vitro studies of Selenium-substituted hydroxyapatite coatings

Abstract The increasing demand for hydroxyapatite (HA) coatings with enhanced functionality have led to novel materials with compositions that are more closely resembling those of natural bone apatites. In the present study, selenium-substituted (Se–HA) powders with various Se quantities were prepared by chemical precipitation. By applying suspension plasma spray (SPS), the surface of Ti substrates was coated with corresponding Se-HA coatings. The microstructural and physicochemical properties of the powders and the coatings were studied. Analysis by x-ray diffraction indicates that SeO3 2− replaced the PO4 3− groups, affecting the crystal structure and crystallinity of HA. As the extent of Se substitution increases, the lattice volume expands and the crystallinity decreases. The synthesized Se-HA powders were confirmed to be calcium-deficient apatite through energy-dispersive x-ray spectroscopy. However, the high temperature of SPS accelerated volatilization of P, increasing the Ca/(P + Se) ratio of the coatings, whereas the chemical valence state of Se remained unchanged. The Se–HA coating exhibited a high bonding strength of >33 MPa, fully meeting the requirement of 15 MPa as coating implant materials. Dissolution behavior tests indicate that the Se–HA coatings had high solubility in comparison to the HA coating. As the substitution degree of Se increased, the dissolution rate also increased, which greatly enhanced the capacity to generate a bone-like apatite layer. In vitro cell experiments indicate that the Se–HA coatings exhibited excellent biocompatibility, and facilitated adhesion and proliferation of osteoblast MC3T3-E1, even in the presence of fluorine. Furthermore, antibacterial properties of Se–HA coatings were also indicated by inhibition of Staphylococcus aureus, which is the main cause of most infections after orthopedic surgeries. Thus, the Se–HA coatings have potential as implant coating materials for orthopedic applications.

Facile one-step fabrication of Li4Ti5O12 coatings by suspension plasma spraying

Spinel Li4Ti5O12 (LTO) is a promising anode material for solid state thin film batteries (SSTB) due to its almost-zero volume change and promising Li-ion mobility. However, preparing LTO anodes for SSTB demands tedious vacuum-based processing steps that are not cost effective. In this context, the present study embarks on evaluating the versatile suspension plasma spraying (SPS) approach to fabricate LTO coatings without using any binder. The microstructure and stoichiometry of the fabricated LTO coatings developed through the SPS route reveals retention of ∼76 wt.% of the spinel LTO from the starting feedstock, with minor amounts of rutile and anatase TiO2. The SPS experiments yielded varying thickness build up rates of the LTO coatings depending on the processing parameters adopted. The electrochemical data of the produced LTO based electrode tested in a half-cell through galvanostatic cycling show reversible lithiation and delithiation at expected potential, thereby validating the promise of the SPS technique for potential fabrication of SSTB components once fully optimized.

Surface preparation by femtosecond laser - An adhesion strength perspective for suspension plasma sprayed ceramic coatings

Surface preparation is very important for the adhesion of thermal sprayed coatings. In this work, the effect of surface preparation on the adhesion strength of suspension plasma sprayed (SPS) Al2O3 coatings is investigated. Aluminum (Al-2024) substrates were micromachined by femtosecond laser (FSL) and also mechanically blasted by conventional grit blasting for surface preparation prior to SPS coating. Surface morphology results showed laser-induced periodic surface structures (LIPSS) produced by FSL, whereas grit blasting produced random irregularities with peaks and undercuts. Surface chemistry analysis showed that the FSL-prepared substrates were functionalized by -OH and O, while the grit-blasted substrates were not functionalized. The prepared substrates were coated by the SPS process under two spray conditions, where one condition was selected to produce a dense coating and the other condition was selected to produce a porous coating. The dense coating showed poor adhesion regardless of surface preparation, while the porous coating showed good adhesion for both grit-blasted and FSL-treated substrates. The adhesion strength of the porous coating was evaluated using the ASTM C-633 pull test protocol. A significant improvement (4.5 factors higher) in adhesion strength was achieved for the FSL-prepared substrates compared to the grit-blasted substrates. The improved adhesion of the FSL-prepared substrates was assessed by surface chemistry and surface morphology analyses of the prepared substrates, as well as by further analysis of the failed samples after the adhesion test and splat analysis. Results from this research showed that FSL has potential as an effective surface preparation technique for SPS.

Investigation of the cooling hole blockage induced by different thermal spray TBC deposition processes

High-temperature turbine airfoils and combustion chamber walls in jet engines require sufficient cooling via cooling holes and thermal barrier coating systems (TBCs) to protect them from hot combustion gases. As the demand for greater efficiency and higher firing temperatures in jet engines increases, there is a corresponding need for more advanced film cooling methods, such as the use of more complex hole geometries. The use of Additive Layer Manufacturing (ALM) techniques allows the production of such intricate cooling holes, enhancing the flow of cooling air onto component surfaces. Conventional TBC deposition techniques, for example Atmospheric Plasma Spraying (APS) or Electron Beam Physical Vapor Deposition (EB-PVD), often lead to partial or complete blockage of cooling holes. This study compares the blockage of TBCs deposited on conventionally-sheet alloys with standard cooling holes and ALM alloys with more complex cooling holes using APS as a baseline process. Additionally, alternative plasma spray deposition technologies such as Suspension Plasma Spraying (SPS) and Plasma Spray-Physical Vapor Deposition (PS-PVD) were explored. The aim was to determine the effectiveness of these processes in preventing blockage compared to the traditional APS process. The experimental results showed that the formation of the coating, whether originating from splats or from the vapor phase, the feedstock particle size, and the cooling hole geometry can all affect the blockage. It was demonstrated that PS-PVD, with its vapor-induced deposition, is highly effective in minimizing blockage, regardless of the cooling hole geometry.

Thick Columnar-Structured Thermal Barrier Coatings Using the Suspension Plasma Spray Process

Higher operating temperatures for gas turbine engines require highly durable thermal barrier coatings (TBCs) with improved insulation properties. A suspension plasma spray process (SPS) had been developed for the deposition of columnar-structured TBCs. SPS columnar TBCs are normally achieved at a short standoff distance (50.0 mm–75.0 mm), which is not practical when coating complex-shaped engine hardware since the plasma torch may collide with the components being sprayed. Therefore, it is critical to develop SPS columnar TBCs at longer standoff distances. In this work, a commercially available pressure-based suspension delivery system was used to deliver the suspension to the plasma jet, and a high-enthalpy TriplexPro-210 plasma torch was used for the SPS coating deposition. Suspension injection pressure was optimized to maximize the number of droplets injected into the hot plasma core and achieving the best particle-melting states and deposition efficiency. The highest deposition efficiency of 51% was achieved at 0.34 MPa injection pressure with a suspension flow rate of 31.0 g/min. With the optimized process parameters, 1000 μm thick columnar-structured SPS 8 wt% Y2O3-stabilized ZrO2 (8YSZ) TBCs were successfully developed at a standoff distance of 100.0 mm. The SPS TBCs have a columnar width between 100 μm and 300 μm with a porosity of ~22%. Furnace cycling tests at 1125 °C showed the SPS columnar TBCs had an average life of 1012 cycles, which is ~2.5 times that of reference air-plasma-sprayed dense vertically cracked TBCs with the same coating thickness. The superior durability of the SPS columnar TBCs can be attributed to the high-strain-tolerant microstructure. SEM cross-section characterization indicated the failure of the SPS TBCs occurred at the ceramic top coat and thermally grown oxide (TGO) interface.

Reaction-sintered zircon-based nanostructured coatings obtained by suspension plasma spraying

Zircon (ZrSiO4) is an inexpensive and widely available material with excellent thermal properties that makes it an ideal candidate for thermal barrier coatings. Previous works have demonstrated the feasibility of obtaining coatings with a high retention of zircon by plasma spraying of ZrSiO4 and ZrSiO4/ZrO2 suspensions.Suspensions of ZrSiO4/Al2O3 and ZrSiO4/TiO2 were produced by dispersing a micrometric zircon powder into alumina and titania colloidal sols, optimising their colloidal stability and rheological behaviour. Optimised slurries were plasma sprayed onto metallic substrates, obtaining coatings with the typical morphologies obtained by suspension plasma spraying (SPS). Nanostructured coatings with nanoparticles embedded in the molten matrix were obtained at higher proportions of sprayed colloidal sol. The high retention of ZrSiO4 in the final coatings and the formation of new crystallographic phases of mullite and zirconium titanate by reaction of the by-products of zircon decomposition (SiO2 and ZrO2) and the Al2O3 and TiO2 colloids was demonstrated.

Suspension plasma sprayed ytterbium disilicate coatings: Phase stability and microstructural evolution in extreme environments

Suspension plasma spray (SPS) is a promising technique to deposit coatings with controlled microstructure. In this work, we explored this capability to produce ytterbium disilicate environmental barrier coatings with enhanced performance against steam and molten calcium-magnesium-aluminium-silicate (CMAS) corrosion. Steam exposure tests on the samples using steams with velocities of 1 m/s and 5 m/s at 1350 ᵒC for 96 h revealed that low-velocity steam caused silica volatilisation whereas the high-velocity steam caused both silica volatilisation and material erosion, yet no new cracks formed in the coating. CMAS degradation test for 5 and 240 mins at 1300 ᵒC on the coatings showed that the large aspect ratio of the splats facilitated reaction between CMAS and ytterbium monosilicate to form a dense layer that slowed further CMAS infiltration. These outcomes suggest that SPS has the proclivity to manufacture EBCs with improved resistance to steam and CMAS degradation.

High‐temperature oxidation and TGO growth behavior of Sr.9(Zr.9Yb.05Y.05)O2.85 thermal barrier coatings

AbstractHigh‐temperature oxidation (1050°C) of Sr.9(Zr.9Yb.05Y.05)O2.85 (SZYY) thermal barrier coatings (TBCs) by suspension plasma spraying (SPS) and growth behavior of thermally grown oxide (TGO) were investigated. When the TBCs were exposed to high temperature for a period of time (∼5 h), the BC oxidized and TGO inevitably formed between the bond coating (BC) and the ceramic top coating (TC). The high‐temperature oxidation behavior of the BC is generally manifested as the growth of TGO, which has four specific stages as follows: (1) formative oxidation stage (0‒10 h), (2) rapid oxidation stage (10‒50 h), (3) stable oxidation stage (50‒100 h), and (4) complex oxidation stage (100‒200 h). The main component of early TGO is α‐Al2O3. It has a very low oxygen ion diffusivity and provides an excellent diffusion barrier, which has a positive effect on preventing further BC oxidation. However, as the heat treatment time increased, the Al consumption and the formation of a CNS layer (NiO, Co3O4, and spinel) in the BC eventually led to coating failure. The working life of TBCs can be improved by improving the ceramic TC structure and the Al content of BC. SZYY‐TBCs have certain potential application value.

Influence of Yttria content in YSZ: An evaluation of water-based SPS coatings and spark plasma sintered pellets

The inherent phase instability of the state-of-the-art 7–8 mol% partially stabilised Yttria-Stabilised Zirconia (YO1.5, 8 YSZ, tetragonal) under a molten CMAS attack lacks the technological readiness needed to increase the gas inlet temperatures for more thermally efficient gas turbine engines. In this study, the concentration of Yttria in YSZ was systemically increased to impart CMAS resistance and their applicability via emerging Suspension Plasma Sprayed (SPS) coatings and Spark Plasma Sintered (SpPS) pellets under simulated conditions was evaluated. The fully stabilised higher Yttria YSZ compositions (21.4 mol% and 50.2 mol%, cubic) severely restricted the CMAS infiltration and interaction areas, with the later composition forming an apatite layer and the trans-granular cracking and chipping of YSZ into layers reduced with an increase in Yttria content. However, their application into water-based SPS coatings resulted in a complete coating failure following the high-temperature CMAS tests. During Furnace Cycling Test (FCT) tests, the 8 YSZ coating survived 34 thermal cycles compared to just one on the 50.2 mol% YSZ coatings. The premature delamination of the higher Yttria coating seems to have been caused by the spallation associated with horizontal cracks within the coating. The YSZ composition could be modified into CMAS-resistant chemistry; however, their applicability as a functioning TBC with inherent microstructural features, such as the Dense Vertically Cracked (DVC) coating strategy examined in this study, requires new coating design strategies that impart sustainable thermal cycling performance.

Protective layers of zirconium alloys used for claddings to improve the corrosion resistance

Abstract Zirconium alloys are used as a cladding material for fuel elements in nuclear reactors. In the case of severe accident conditions, the possible rapid oxidation of zirconium in steam or/and air may result in intense hydrogen generation and hydrogen–oxide mixture explosion. Advanced technologies for increasing the corrosion resistance of claddings are being investigated in two directions: (a) protective coatings on Zr alloys and (b) the use of new materials for claddings. Coatings with silicon may provide a more protective barrier than the ZrO2 films formed on an alloy cladding during nuclear plant operations. These coatings may also serve as a protective barrier during high-temperature accidents. The current work aimed at developing protective coatings with silicon on zirconium alloys. Multielemental Zr–Si–Cr coatings were formed on Zry-2 alloy using the physical vapor deposition (PVD) method. Long-term oxidation tests were carried out under the following conditions: 360°C/195 bar/63 days/water-simulating PWR water. Obtained results show the protective character of formed layers. The material in the form of silicon carbide grains covered with yttrium–aluminum garnet (SiC + YAG) was prepared using the sol–gel method. The formed powder is the main component for coating formation on Zr–1Nb alloy using the method of suspension plasma spraying (SPS).

Understanding the effect of bondcoat surface treatment on enhanced lifetime of suspension plasma sprayed thermal barrier coatings

Thermal barrier coatings (TBCs) are extensively used in gas turbine engines in power generation and aerospace applications. Improvements in TBC performance and lifetime are continuously pursued by the gas turbine industry. Suspension plasma spraying (SPS) has shown promising results in recent years as it could produce a porous columnar TBC microstructure exhibiting low thermal conductivity and high durability. Further improvements in lifetime and fundamental understanding of failure mechanisms would lead to their wider application.Lifetime of a TBC system is dependent not only on the topcoat microstructure and chemistry, but also on topcoat-bondcoat interface and bondcoat characteristics as they influence the growth rate of thermally grown oxide (TGO) layer as well as the mismatch stresses generated in the topcoat during operation. Moreover, in SPS TBCs, the column density and porosity in the topcoat are also affected by the bondcoat surface roughness which in turn affects TBC lifetime. In previous work, it was shown that bondcoat surface treatment by shot peening followed by light grit blasting can significantly enhance the cyclic lifetime of SPS TBCs.The objective of this work was to gain further insight into the lifetime improvements due to surface treatment of bondcoat. Commercial NiCoCrAlY powder was deposited by high velocity air fuel (HVAF) and high velocity oxy fuel (HVOF) spraying while SPS was used to deposit yttria stabilised zirconia topcoat. Before spraying the topcoat, the bondcoat samples were subjected to vacuum heat treatment, shot peening, and/or grit blasting. Residual stress measurements were performed by X-ray diffraction on samples with different variants of bondcoat treatments and compared with Almen strip tests. The lifetime was examined by thermal cyclic fatigue testing. The relationships between changes in bondcoat surface roughness, residual stress state and microstructure due to surface treatments, and resultant topcoat microstructure and lifetime were studied and discussed.

Processing-Microstructure-Properties of Columns in Thermal Barrier Coatings: A Study of Thermo-Chemico-Mechanical Durability.

Contemporary gas turbine engines rely on thermal barrier coatings (TBCs), which protect the structural components of the engine against degradation at extremely high operating temperatures (1300-1500 °C). The operational efficiencies of aircraft engines have seen significant improvement in recent years, primarily through the increase in operating temperatures; however, the longevity of TBCs can be potentially impacted by several types of degradation mechanisms. In this comprehensive study, a wide range of novel columnar suspension plasma sprayed (SPS) coatings were developed for their erosion, calcium-magnesium-aluminum-silicate (CMAS), and furnace cycling test (FCT) performance. Through a comprehensive investigation, the first of its kind, we achieved a range of SPS microstructures by modifying the spray parameters and measuring their microhardness, fracture toughness, column densities, and residual stresses using Raman spectroscopy. We were able to produce dendritic, lateral, branched, and columnar microstructures with a unique set of processing parameters. Coatings enhanced with a refined columnar microstructure, achieved by modulating the distance from the plasma torch, exhibited superior thermal cycling resilience. Conversely, the development of a columnar microstructure with dendritic branches, obtained by decreasing the robot's traversal speed during deposition, bolstered resistance to erosion and minimized damage from molten CMAS infiltration, thereby notably augmenting the coating's lifespan and robustness. The pursuit of the optimal columnar microstructure led to the conclusion that for each SPS coating, a general framework of optimization needs to be conducted to achieve their desired thermo-chemico-mechanical resistance as the properties required for TBCs are intertwined.

Fabrication and characterization of thermal barrier coatings for internal combustion engines via suspension plasma spray with high solid loading

Suspension plasma spraying (SPS) technique producing thermal barrier coatings (TBCs) with high porosity and good thermal shock resistance has great potential to improve the thermal efficiency of internal combustion (IC) engines. However, its wide usage is limited by the immature fabrication technology and low spraying efficiency. Therefore, this study optimized the SPS process with high solid loading and characterized the properties of the coating to obtain TBCs suitable for IC engines. Suspension composition optimization revealed that polyethylenimide (PEI) has the best dispersion effect, and a suspension with high solid loading of 35 wt% was obtained. Furthermore, the effects of the spraying distance, feeding speed and spraying power on the coating microstructure were investigated, and the porosity and thermal shock resistance of the coatings were characterized to determine the optimal spraying process. Thermal shock failure of SPS coatings primarily arises from the propagation of horizontal cracks originating from vertical intercolumn cracks. The SPS coating with a feathery columnar structure has the best thermal shock resistance. By optimizing the spraying process, a coating with porosity up to 24.16 %, bonding strength of 41.69 MPa, and good thermal shock resistance is successfully achieved.

SEM-Guided Finite Element Simulation of Thermal Stresses in Multilayered Suspension Plasma-Sprayed TBCs

This study presents novel insights into thermal stress development and crack propagation mechanisms in single- and multilayered suspension plasma-sprayed (SPS) coatings of gadolinium zirconate (GZ) and yttria-stabilized zirconia (YSZ), thermally treated at 1150 °C. By combining image processing with finite element simulation, we pinpointed sites of high-stress concentration in the coatings, leading to specific cracking patterns. Our findings reveal a dynamic shift in the location of stress concentration from intercolumnar gaps to pores near the top coat/thermally grown oxide (TGO) interface with TGO thickening at elevated temperatures, promoting horizontal crack development across the ceramic layers. Significantly, the interface between the ceramic layer and TGO was found to be a critical area, experiencing the highest levels of both normal and shear stresses. These stresses influence failure modes: in double-layer SPS structures, relatively higher shear stresses can result in mode II failure, while in single-layer systems, the predominant normal stresses tend to cause mode I failure. Understanding stress behavior and failure mechanisms is essential for enhancing the durability of thermal barrier coatings (TBCs) in high-temperature applications. Therefore, by controlling the interfaces’ roughness along with improving interfacial toughness, the initiation and propagation of cracks can be delayed along these interfaces. Moreover, efforts to optimize the level of microstructural discontinuities, such as intercolumnar gaps and pores, within the creaming layer and close to the TGO interface should be undertaken to reduce crack formation in the TBC system.

Tailoring the porosity level of the suspension plasma sprayed coatings using a dual suspension injection system

This study investigated the feasibility of tailoring the porosity in suspension plasma sprayed (SPS) coatings using a dual suspension injection system. Two titanium dioxide water-based suspensions with different particle sizes were injected into the plasma jet through two injectors located at different radial distances from the exit of the plasma torch. By varying the spray parameters, the fraction of unmelted particles in the coatings coming from the injector located farther from the torch changed. The total porosity was evaluated to range from approximately 16 % to 36 %, and the variation was related principally to the gaps between the unmelted particles. Among the selected spray parameters, the suspension feed rate and distance between the injectors were found to have the most significant effect on increasing the porosity. The samples were analyzed using SEM, XRD, and Raman spectroscopy.

Axial suspension plasma sprayed Ag-TiO2 coating for enhanced photocatalytic and antimicrobial properties

Ag-TiO2 coating has been extensively studied for its antimicrobial and photocatalytic applications. In this study, we developed a straightforward and efficient method with use of Axial Suspension Plasma Spray (ASPS) to deposit Ag-TiO2 coatings. In ASPS, a suspension containing AgNO3 solution and TiO2 particles (pure anatase) was prepared and plasma sprayed on SS304 stainless steel substrate to form the Ag-TiO2 coating. The microstructure, photocatalytic activity, and antibacterial property against E-coli (CFT073 and C1214) and Methicillin-resistant Staphylococcus aureus (MSRA, USA300) of the deposited coating were characterized. Results showed the deposited Ag-TiO2 is a composite coating consisting of anatase, rutile and Ag nanoparticles. The introduction of a small amount of Ag (up to 0.2at% of Ag/Ti in the coating) exhibited a significant increase in photocatalytic activity, achieving a rate at least twice as fast as that of the TiO2 coating without Ag in the methyl orange degradation test. Moreover, these Ag-TiO2 coatings demonstrated remarkable antimicrobial activity, completely inactivating E. coli CFT073, effectively inhibiting the growth of E. coli C1214 by four orders of magnitude and MRSA by nearly three orders of magnitude. The employment of ASPS, in conjunction with AgNO3 solution, presents a simple and effective approach for the production of nano Ag particles in a composite coating. This technique has great potential in surface modification on medical devices for anti-infective purpose.

Preparation of Y2O3 Coating by Suspension Plasma Spraying and Its Resistance to Plasma Etching

Preparation of Y₂O₃ Coating by Suspension Plasma Spraying and Its Resistance to Plasma Etching

Novel Effective Photocatalytic Self-Cleaning Coatings: TiO2-Polyfluoroalkoxy Coatings Prepared by Suspension Plasma Spraying.

Photocatalytic coatings can degrade volatile organic compounds into non-toxic products, which has drawn the attention of scholars around the world. However, the pollution of dust on the coating adversely affects the photocatalytic efficiency and service life of the coating. Here, a series of TiO2-polyfluoroalkoxy (PFA) coatings with different contents of PFA were fabricated by suspension plasma spraying technology. The results demonstrate that the hybrid coatings contain a large number of circular and ellipsoidal nanoparticles and a porous micron-nano structure due to the inclusion of PFA. According to the optimized thermal spraying process parameters, TiO2 nanoparticles were partially melted to retain most of the anatase phases, whereas PFA did not undergo significant carbonization. As compared to the TiO2 coating, the static contact angle of the composite coating doped with 25 wt.% PFA increased from 28.2° to 134.1°. In addition, PFA strongly adsorbs methylene blue, resulting in a greater involvement of methylene blue molecules in the catalyst, where the catalytic rate of hybrid coatings is up to 95%. The presented nanocomposite coatings possess excellent photocatalytic and self-cleaning properties and are expected to find wider practical applications in the field of photocatalysis.

Suspension High‐Velocity Oxy‐Fuel–Sprayed Dense Vertically Cracked and Suspension‐Plasma‐Sprayed Columnar Yttria‐Stabilized Zirconia Coatings: Calcia Magnesia Alumino Silicates Infiltration and Thermal Cycling Performance

The quest to increase the surface temperatures and resistance to the corrosive environment of thermal barrier coatings topcoats mean that newer coating design strategies are needed. In this study, a performance evaluation of suspension high‐velocity oxy‐fuel (SHVOF)‐sprayed dense vertically cracked (DVC) and suspension‐plasma‐sprayed (SPS) columnar structure (CS) topcoats is conducted. The calcia magnesia alumino silicate (CMAS) evaluation is conducted at 1300 °C for 30 min, whereas the furnace cycling tests (FCT) is conducted at 1135 °C for 45 min cycle dwell time. The CMAS infiltrates down to the bond coat layer, but does not induce partial or complete topcoat spallation on all studied topcoat layers. In terms of CMAS infiltration, the CMAS appears to be restricted along the vertical cracks. The FCT of the SPS CS structure indicates a failure largely at the thermally grown oxide (TGO)–topcoat interface, while the DVC topcoat layers indicate a mix‐mode failure, i.e., both material‐associated cracking and localized spallations at the TGO–topcoat interface. Overall, the SHVOF‐sprayed ethanol‐based DVC topcoat seems to offer a balanced trade‐off, i.e., a majority of the topcoat is still intact after 100 thermal cycles and exceeds the material durability and performance offered by the SPS CS structure.

Effect of suspension plasma spraying power on the microstructure and properties of Cr2AlC coatings

In this work, the microstructure evolution and mechanical properties of suspension plasma sprayed Cr2AlC coatings under different spraying powers were studied, and a self-protection model during oxidation was proposed. Due to the partial decomposition of Cr2AlC and its subsequent reactions with the surrounding H2O or O2 at high temperatures, the sprayed coating exhibits a heat-resisting shell, composed mainly of Cr2Al, carbides, oxides, and graphite, wrapping the internal Cr2AlC core against further decomposition. In addition, with the increase of spraying power, the content of Cr2AlC phase and the microhardness of the coating gradually increase, while the porosity and surface roughness decrease. The results indicate that suspension plasma spraying is a promising process for preparing Cr2AlC coatings.