With the development of heavy-duty gas turbines， its gas inlet temperature keeps increasing， and the traditional YSZ coatings could not service above 1200 ℃. The LaMgAl₁₁O₁₉（LMA） and YSZ coatings are fabricated byair plasma spray method， and the static oxidation tests are carried out at 1100 ℃ and 1300 ℃. The porosity， microstructure， and phase transformation process are investigated comparatively by SEM and XRD. The results show that the porosity of LMA coatings increases with the sintering time increasing at 1100 ℃ and 1300 ℃， while the porosity of YSZ coatings decreases obviously. The amorphous phase of LMA coatings is transformed rapidly at high temperatures. The needle-like grain at LMA coating fracture is formed， and the grain growth becomes platelet-shaped grains with the sintering time increasing， which improves the sintering resistance of LMA coatings. The results of YSZ coatings Rietveld refinement show that the content of the T′ phase decreases from 82.67% to 27.69% with the sintering time increasing to 1000 h at 1300 ℃. Meanwhile， the content of the C phase rises from 1.50% to 46.84%， and the M phase increases from 0.19% to 15.39%. This phase transformation causes volume transformation， which generates large residual stress，leading to the coating falling off.

Fe-based amorphous alloy coatings have emerged as a key area of research in the field of surface engineering due to its high strength， hardness， and exceptional wear and corrosion resistance. This paper provides a comprehensive review of the preparation， performance， and application status of Fe-based amorphous alloy coatings. It also summarizes the fundamental principles of amorphous alloy material design and typical Fe-based amorphous alloy coatings material systems. The focus is on three coating preparation technologies： thermal spraying， cold spraying， and laser cladding. Additionally， it compiles the research progress made in understanding the tribological properties and corrosion resistance of Fe-based amorphous alloy coatings. Furthermore， it briefly outlines the applications of these coatings in military， medical， industrial fields etc. Finally， it is pointed out that in-depth study of amorphous formation， the establishment of specialized material systems while matching the working environment， and the adoption of post-processing or more efficient preparation methods are the development trends for future research work in this field.

To explore the influence of acid salt spray corrosion on the abradability behavior of Al-BN coatings， the microstructure， surface hardness， bonding strength， and abradability of Al-BN coatings prepared by atmospheric plasma spraying before and after acid salt spray corrosion for 192 h are investigated.The results show that after acidic salt spray corrosion for 192 h， the surface of the Al-BN coatings forms a corrosion dense layer composed of Al， Al₂O₃， NaCl， and BN with the thickness of about 300-350 μm. The variance of average hardness and average bonding strength of the corrosion-dense layer increases compared to the as-sprayed coating. During the scraping process， the weak bonding areas of the corrosion-dense layer are prone to scraping off and adhere to the friction surface of the dual blade， which causes the incursion depth ratio（IDR）values of the Al-BN coatings to change from （11.43±0.46）% before acid salt spray corrosion to （-12.02±0.38）% after acid salt spray corrosion， resulting in the abradability scraping mechanism of the Al-BN coatings changing from the mixed form of plastic deformation and adhesive wear to the mixed mechanism of plastic deformation， adhesive wear， and scraping off adhesion， the friction coefficient increasing from 0.34±0.02 before corrosion to 0.55±0.03. Therefore， the acid salt spray corrosion has a negative impact on the abradability of Al-BN coatings.

As the turbine inlet temperature in aero-engines continues to rise， conventional thermal barrier coatings （TBCs） are becoming increasingly ineffective at blocking thermal radiation in the near-infrared wavelength range generated by high-temperature gases. The heat transfer of heat radiation can penetrate through the coating and directly heat the underlying metal substrate， thereby compromising the service life of hot-end components. In this paper， the authors’ experimental results are used to review recent developments in the design of novel TBCs materials and structures that combine thermal insulation with enhanced radiation suppression capabilities. A comparative analysis of the near-infrared optical properties of conventional TBCs is presented. The current methods aimed at improving the ability of coatings to mitigate radiative heat transfer are discussed. Particular attention is given to the issue of conventional YSZ-based inability of TBCs to effectively block infrared radiation in the shortwave infrared region. An analysis is conducted on the two fundamental approaches for reducing the infrared transmittance of TBCs， namely， improving the infrared reflectance or infrared absorptance of coatings. Additionally， a systematic summary of the strategies for tuning the infrared reflectance and absorptance of coatings， including influencing factors， underlying mechanisms， advantages， and limitations， is provided. Finally， future trends and breakthrough directions in the development of novel radiation-suppressing coatings， particularly in terms of material and structural design as well as the use of high-performance computational tools， are highlighted.

To investigate the effect of the spraying process parameters on the properties of NiCoCrAlYTa-Cr₂O₃-Cu-Mo high-temperature wear-resistant coating， the coating is prepared by atmospheric plasma spray （APS） process based on the orthogonal experiment. The range analysis method is used to study the primary and secondary relationships of the process parameters on the microstructure， hardness， and bonding strength of the NiCoCrAlYTa-Cr₂O₃-Cu-Mo coating， and the spraying process parameters are optimized. The optimized process parameters are that the argon flow rate is 50 L/min， the hydrogen flow rate is 12 L/min， the current is 500 A， and the spraying distance is 100 mm. With the optimized spraying process parameters， the microstructure of the coating is very dense， the porosity is lower than 1%， and the average bonding strength， hardness， and average oxidation speed during 50-100 h at 900 ℃ are 70.7 MPa， 543.7 HV， and 0.07302 g/（m²·h）， respectively. In addition， the friction coefficient and wear rate of NiCoCrAlYTa-Cr₂O₃-Cu-Mo coating are 0.248 and 2.12×10^-6 mm³/（N·m） at 800 ℃， exhibiting good friction and wear properties.

To investigate the effects of aluminizing coating on the surface integrity and rotational bending high cycle fatigue performance of DD6 alloy， the chemical vapor deposition method is used to aluminize DD6 fatigue samples after standard heat treatment. The cross-sectional microstructure and elemental distribution of DD6 alloy samples with aluminizing coating are analyzed using SEM and EDS， and the high cycle fatigue properties of the uncoated and coated samples are tested at 760 ℃ and 980 ℃， respectively. The results show that the surface area of the sample with aluminizing coating is mainly divided into two layers： inner and outer. The outer layer is mainly composed of the β-NiAl phase， and the inner layer is a diffusion layer， containing many solid solution strengthening elements. The aluminizing coating can slightly reduce the rotational bending high cycle fatigue performance of the alloy at 760 ℃ and 980 ℃ and has a significant impact on the fatigue life in the high-stress amplitude region and a small impact on the low-stress amplitude region. The coupling effect of surface roughness， oxidation damage， and element interdiffusion is the fundamental reason for the difference in fatigue life between uncoated and coated samples.

In order to obtain high quality aluminium oxide tritium barrier coatings， micro-arc oxidation （MAO）technology was used to prepare micro-arc oxidation coatings on the surface of 1060 pure aluminium by doping Cr₂O₃ and graphene as additives in the electrolyte， using phosphate as the main electrolyte component. The surface morphology， elemental distribution， physical phase composition， thickness，hardness， abrasion and corrosion resistance of the micro-arc oxidation coatings were characterized by scanning electron microscope，X-ray diffractometer，eddy current thickness gauge，Vickers hardness tester， friction and wear tester， and electrochemical workstation. The results show that the surface morphology of the micro-arc oxidation coatings prepared by adding 3 g/L Cr₂O₃ and 1 g/L graphene into the electrolyte is more dense， and the proportion of α-Al₂O₃ and γ-Al₂O₃ in the coatings increases， with the thickness reaching 25.3 μm，the hardness reaching 763.01HV， and the average friction coefficient of 0.4781.At the same time，the self-corrosion potential is -0.185 V， and the self-corrosion current density is 1.095×10^-9 A·cm^-2.

The electron beam-physical vapor deposition （EB-PVD） technology was employed to fabricate yttria-stabilized zirconia （YSZ） thermal barrier coatings at different electron beam currents （1.2，1.8，2.4 A）. The phase structure and microstructural morphology of YSZ coatings at different electron beam currents were analyzed and characterized. The thermal barrier coatings were also subjected to a 1150 ℃ thermal cycling life test. The failure behaviors of coatings were analyzed by the evolution of the microstructure. The results show that YSZ coatings at different electron beam currents all possess a non-equilibrium tetragonal phase structure. As the electron beam current increases， the columnar grain tip structure of the coating evolves from a triangular shape to a pyramidal shape and then to a ridge-like shape， with the column structure changing from a slender structure to a coarse structure， the dendrites decreasing， and the arrangement becoming more orderly. The thermal conductivity is lower slightly due to the appearance of ordered nanopores in the column of YSZ coatings. The YSZ coating prepared at 1.8 A demonstrates the most excellent thermal shock life of 895 cycles， approximately twice that of the YSZ coating prepared at 1.2 A and 1.3 times that of the YSZ coating prepared at 2.4 A. The slender columnar grain structure prepared at a low electron beam current is prone to sintering failure， while the coarse columnar grain structure prepared at a high electron beam current is prone to thermally grown oxide （TGO） layer stress accumulation failure. The columnar grain structure prepared at 1.8 A could balance the two types of failure behaviors， effectively extending the thermal cycling life of the YSZ thermal barrier coating.

Thermal barrier coatings， consisting of a metal bonding layer， ceramic surface layer， and thermal growth oxide， are widely utilized in turbine blades for aero engines as protective coatings. The LaZrCeO/YSZ double ceramic thermal barrier coating was prepared on a Ni-based superalloy matrix using EB-PVD technology. The composition， phase structure， and thermal cycle life of the thermal barrier coating were investigated by adjusting the deposition energy of the ingot. Furthermore， the failure mechanism of the thermal barrier coating under 1100 ℃ thermal cycle was analyzed. The results indicate that the Zr content in the LaZrCeO coating increases proportionally with the rise in ingot deposition energy， while maintaining a consistent La/Ce ratio. Additionally， the increase in evaporation electron beam leads to changes in coating phase structure from single fluorite phase to compound pyrochlore and fluorite phase structure， and finally to single pyrochlore structure. Thermal cycling tests at 1100 ℃ demonstrate that the average thermal cycle life of LaZrCeO/YSZ ceramic thermal barrier coating with composite pyrochlore and fluorite phase structure reaches 1518 cycles， indicating excellent thermal physical properties. As the thermal cycle progresses， the Al element in the bond coat diffuses outward to form a thermally grown oxide （TGO） layer， while the Cr element reacts with LaZrCeO and oxygen to generate LaCrO₃ and ZrO₂. At elevated temperatures， Ni and Co elements diffuse and react with oxygen to produce （Ni，Co）（Cl，Al）₂）O₄ compounds. The chemical reactions induce cracks in either the TGO layer or the interface layer， reducing the toughness between the metal bond layer and ceramic layer， and leading to thermal barrier coating failure.

NiCoCrAlYHf coating （HY5 coating） was prepared on DD6 alloy by vacuum arc ion plating method. After different diffusion temperature treatments， the ceramic coating was deposited by electron beam-physical vapor deposition（EB-PVD） method. The cyclic oxidation properties of thermal barrier coatings at different diffusion temperatures were investigated by analysing the phase composition and microscopic morphology of bond coating（BC） at different diffusion temperatures. The results show that the bond coating samples after diffusion treatment in a vacuum change from the single-phase structure of the deposited to the double-phase structure of the diffusively treated. The content of β-NiAl phase in the bond coating increases with the increase of diffusion temperature. After diffusion treatment， the coating surface is uniform and dense， gray-white and black phases are observed in the coating， the black phase is β-NiAl， and the gray-white phase is γ-Ni and γ'-Ni₃Al phases， which demonstrates that diffusion treatment can change the phase structure of the bond coating. The coating with 900 ℃ diffusion treated has the longest cyclic oxidation life， exceeding 400 h； the cyclic oxidation life of 1100 ℃ diffusion treated coating is less than 300 h. When the diffusion temperature is 900 ℃， the oxidation rate of the bond coating and the thermally grown oxide thickening rate are the lowest. It is not that the more β-NiAl phase content the better， but there is a threshold in the phase composition， increasing the β-NiAl phase content within the threshold can obtain better service performance.

The 316 stainless steel coatings with different thicknesses （SSC2， SSC4， SSC7， SSC10） were deposited on the magnesium alloy surface by using the HVOF method. The microstructures， deposition characteristics， residual stresses and immersion corrosion characteristics of the coating were investigated. The results reveal that due to the lower melting point and hardness of magnesium alloy， spray particles are prone to invade the substrate and melt its surface， causing particle escape or splashing， resulting in lower deposition efficiency； after depositing thinner coatings （SSC2 and SSC4）， the escape or splashing behavior of deposited particles reduces significantly， and the deposition efficiency increases； when the deposition thickness increases to SSC7 or above， the surface temperature of the deposition increases， particle splashing gradually increases， and the porosity and oxide content of the coating surface increase. Furthermore， as the coating thickness increases， the residual compressive stress of the coating decreases， the stress distribution becomes more uniform， and the number of penetrating pores in the coating decreases significantly， approaching zero. There are penetrating pores inside the SSC2 and SSC4 coatings， and the effective protection time is extremely short. The thick coatings （SSC7 and above） still have a protective effect after soaking in 3.5% （mass fraction） NaCl solution for 720 h.

Currently， the surface working temperature of second-generation or more advanced single crystal superalloy blade is above 1050 ℃， resulting in serious interdiffusion between coating and substrate. The interdiffusion not only consumes the beneficial elements of the coating and then reduces its service life， but also leads to the formation of secondary reaction zone in the substrate， which will seriously damage the high-temperature mechanical performance of the single crystal superalloy. Preparing diffusion barriers and designing the low inter-diffusivity coatings are effective ways to control the interdiffusion between thermal barrier coatings and single crystal superalloy substrates. Firstly，based on the latest international and domestic research progresses， the design principles， characteristics and classification of diffusion barriers were introduced briefly， and then the main problems and related research studies of metal diffusion barriers， ceramic diffusion barriers and active diffusion barriers were analyzed. Secondly， the application and latest progress of low inter-diffusivity coatings were reviewed， and the high-temperature protection properties and anti-diffusion mechanisms of nanocrystalline coatings， equilibrium coatings and γ′-based coatings were discussed in detail. Finally， the future development directions of different diffusion barriers and low inter-diffusivity coatings were pointed out.

With the rapid development of China’s manufacturing industry and the emergence of difficult-to-machine materials， there is an urgent need for cutting technology to continuously update and iterate， and the development of cutting tools has become a key factor in improving processing efficiency. In recent years， coating technology has become an effective way to improve the cutting performance of cutting tools. In particular， TiAlN coating has been widely used in cutting tools due to its good wear resistance and stability. However， the traditional TiAlN coated tools have made it difficult to bear the harsh conditions of thermo-mechanically-chemo multiple coupling. How to form solid solution strengthening and fine grain strengthening by element doping， for improving the cutting performance of TiAlN coated tools conveniently and efficiently， has become a research hotspot in this field. Given this problem， the action mechanism and preparation method of TiAlN coating were summarized， the microstructure and phase structure of the coatings obtained by different methods were analyzed， the limitations of TiAlN coating due to oxidation and phase transformation in high temperature were described， and the effects of doping Si， C， Cr， B and V elements on the microstructure， hardness， wear resistance， oxidation resistance and tool life of TiAlN coating were reviewed. Finally， the future development of TiAlN coated tools is summarized.

Achieving the best wideband stealth performance under the limited weight constraint is the goal pursued in stealth aircraft radar absorbing coating（RAC） application schemes design. To meet the need for the integrated application of various kinds of RACs on stealth aircraft， an automatic optimization method for the application programme of RAC was established. Firstly， the electromagnetic fields of the model under different frequencies， azimuths and polarizations were simulated based on the finite difference time domain method. The total electromagnetic field was obtained by normalization and weighted calculation of the electromagnetic fields.Then， the total electromagnetic field was divided according to the specific direction and quantity. Each partition was loaded with the corresponding RAC. The reflection coefficient of the RAC was calculated by the transfer matrix method to superimpose the effect of the RAC on the electromagnetic field. The near-far field transformation was performed on the total electromagnetic field after loading with RAC. In this way， fast computation of radar cross section （RCS） was implemented. Based on the improved simplex method and Karush-Kuhn-Tucker condition， an automatic optimization method is established. The objective function was reducing RCS of the target or reducing weight of the absorbing coating. Finally， taking traveling wave plate as an example， the application plan of three thicknesses of RACs was optimized. The goal of optimization was to reduce total weight of the coating. Compared with the 1.5 mm coating plan， the optimization program can reduce the weight by 50%， with the RCS of traveling wave plate increasing by on more than 1 dB. The optimization effect is remarkable.

Finite element simulation is one of the effective means to study the stress evolution of thermally grown oxides （TGO） at the interface of thermal barrier coatings （TBCs）， which can provide theoretical support for exploring the failure mechanism of TBCs. Advanced thermal barrier coating multifactor coupling test equipment was used to conduct thermal-mechanical coupling cycle tests and thermal cycling tests on circular tube specimens coated with TBCs， simulating engine operating conditions. Finite element modeling was conducted on TBCs containing real initial TGO morphology using finite element software ABAQUS， and the stress and deformation patterns of the coatings during tests were analyzed. The results show that without considering TGO and interface cracking， both the thermal-mechanical coupling model and the thermal cycle model exhibit an increase in Mises stress as the number of cycles increases. During the heating process， TGO is subjected to tension， while during the cooling process， TGO is compressed. The stress during the heating process is much lower than that during cooling to room temperature. After the same number of cycles， the stress values in thermal-mechanical coupling model are higher than those in the thermal cycle model. After 20， 45， 70 thermal cycles， the TGO stresses at room temperature reach 2.85， 3.65 GPa and 3.55 GPa， respectively. After the same number of thermal-mechanical coupling cycles；when cooling to room temperature，TGO stresses at the same position at room temperature reach 4.01 GPa， 5.0 GPa and 4.81 GPa， respectively. Compared with thermal cycles， under thermal coupling conditions， the TGO stress significantly increased after the same cycles when cooling to room temperature.

High-velocity air-fuel spray （HVAF） technology was used to prepare two kinds of Al-based amorphous alloy coatings with high porosity （HP） of 1.36% and low porosity （LP） of 0.86%. The effects of porosities on the corrosion behavior of Al-based amorphous alloy coatings were studied. The porosities and microstructures of the coatings were analyzed by scanning electron microscope （SEM） and X-ray diffraction （XRD） combined with three-dimensional X-ray tomography （3D XRT）. The corrosion properties of the coatings were studied by electrochemical testing system and contact angle measuring instrument. The passive film components of the two coatings were analyzed by X-ray photoelectron spectroscopy （XPS）. The results show that the self-corrosion current density （I _corr） and pitting potential （E _pit） of the LP coatings are 3.0×10^-6 A/cm² and -0.40 V， respectively. The I _corr and E _pit for HP coatings are 6.0×10^－6 A/cm² and -0.47 V， respectively， signifying that the LP coating has better resistance to the localized corrosion； the charge transfer resistance （R _ct） of LP coatings is about twice than that of HP coating； the LP coating has a larger contact angle， which proves that LP coating has better hydrophobicity and stronger corrosion resistance； the contents of RE₂O₃ in the passive film formed on the LP coating are larger， which further indicates that LP coating has better corrosion resistance.

Partially stabilized zirconia （7YSZ） with a mass fraction of 7±1% yttrium oxide is a widely used ceramic material for thermal barrier coatings. However， its phase stability， sintering resistance， and mechanical properties decreased during the long-time operation above 1200 ℃. A new type of Sc₂O₃-Y₂O₃ co-doped ZrO₂ thermal barrier coating ceramic material was proposed， and a molar fraction of 7.5%Sc₂O₃-x%Y₂O₃-（92.5-x）%ZrO₂（x=0，0.1，0.2，0.3） ceramics were prepared by solid-state reaction method. The effects of Y₂O₃ doping on the microstructural， phase evolution， and mechanical properties（including Vickers hardness， fracture toughness， elastic modulus and three-point bending strength）were explored by XRD， SEM， and other testing methods. The results show that the relative density of Sc₂O₃-Y₂O₃ doped ZrO₂ ceramics sintered at 1450 °C for 3.5 h is more than 97%， and the phase structure is composed of tetragonal phase. Compared with 6-8YSZ ceramics， Sc₂O₃-Y₂O₃ doped ZrO₂ ceramics exhibit similar Vickers hardness （13-14 GPa）， fracture toughness （6.5-7.0 MPa·m^1/2）， elastic modulus （211-214 GPa）and three-point bending strength（520-850 MPa）. Fracture mechanism shows a mixture of transgranular and intergranular fracture modes， in which transgranular fracture is dominant.This ceramic can be explored as a potential thermal barrier coating material for high-temperature applications.

Zr-Y modified silicide coating was deposited on TC4 alloy by the pack cementation process. The microstructure， friction and wear performance， and wear mechanisms of the coating were investigated. The results show that the Zr-Y modified silicide coating has a multi-layer structure， an outer layer consists of TiSi₂ and a small amount of ZrSi₂， a thin middle layer is TiSi， and an inner layer is a mixture of Ti₅Si₄ and Ti₅Si₃. The micro-hardness of the coating is much higher than that of the TC4 substrate and exhibits an obvious decrease tendency from the surface to the interior. The Zr-Y modified silicide coating possesses good anti-wear performance when wearing against GCr15 and Al₂O₃ balls at a high-temperature of 600 ℃. When wearing against GCr15， the wear rate of the coating is about 3.59×10^-5 mm³/（N·m）， which is about 36.6% of that of the TC4 substrate， and the main wear mechanisms are characterized by the adhesive of GCr15 on the coating surface and oxidation wear. When wearing against the Al₂O₃ ball， the wear rate of the coating is about 9.75×10^-5 mm³/（N·m）， which is about 18.9% of that of the TC4 substrate， and the wear mechanisms are fatigue wear， oxidation wear， and adhesion wear.

HfO₂ coatings with a thickness of approximately 8 μm were prepared on the refractory metals Mo surface by using chemical vapor deposition(CVD), and the reaction process of CVD HfO₂ was thermodynamically analyzed by HSC Chemistry.The microscopic morphology, self-oriented growth and nanomechanical properties of HfO₂ coatings were analyzed, and the bonding force of the coatings with the substrate and thermal shock resistance were tested. The results show that the HfO₂ coating is well bonded to the substrate, and no macroscopic flaking occurs on the surface of the coating after 100 cycles of thermal shock from 25 ℃ to 2000 ℃; the adhesion of the coating is about 23 N as determined by the scratch test; the average emissivity of the surface of the coating is 0.48 in the band of 2.5-5 μm, which improves the average emissivity of Mo in the band by nearly 5 times.

The TiC/IN625 coatings were prepared on 45 steel substrates by using extreme-high-speed laser cladding(EHLA) technology. The effect of different heat treatment temperatures(800, 1000 ℃ and 1200 ℃) on the microstructure, surface morphology, residual stress and corrosion resistance of TiC/IN625 coatings was analyzed. The results show that the coating segregation phenomenon is alleviated with the increase of heat treatment temperature. The distribution of Ti elements in the HT1000 coating is more uniform than that in the HT0 and HT800 coatings. The part Laves phase in the HT0 coatings starts to dissolve in the HT1000 coatings, releasing Nb elements that recombine with C and Ti elements to generate MC (M=Nb, Ti) carbides. The large-sized carbides in the microstructure of HT1200 coatings surface dissolve. The other elements, such as Ti and Ni, more homogeneously distribute and diffuse into the inter-dendritic region. The residual stress on the HT0 coatings surface is mostly expressed as residual tensile stress, with a maximum value of 362 MPa. The electrochemical corrosion tests indicate that the open-circuit potential is increased from －0.139 V for the HT0 coatings to －0.132 V for the HT1200 coatings. The charge transfer resistance (R_ct) of HT800, HT1000 and HT1200 coatings is also larger than that of the HT0 coatings, with an increase of 46.2%, 31.2% and 64.3% compared to the HT0 coating's 4.785×10⁵ Ω∙cm², respectively.

With the continuous development of the aerospace field, the service conditions of high temperature structural components such as metal and carbon materials are increasingly harsh. The service life of high temperature structural components can be effectively improved by preparing silicon-based ceramic coatings on the surface of high temperature structural components and giving them special properties through appropriate processes. In recent years, the polymer precursors conversion ceramic coating has gradually become a novel method for preparing inorganic coatings. The new approach has the advantage of excellent processability and functional scalability, which gets more and more attention from researchers. The research progress of high temperature resistant ceramic coatings based on silicon-containing polymeric precursors was reviewed in this paper. Firstly, the preparation of ceramic coatings from the polymers was introduced, including the influences of silicon-based polymer precursors, fillers, coating and pyrolysis process on the structure and properties of the obtained coatings. Then, the applications of polymer-derived ceramic coatings in high temperature protection fields, such as anti-oxidation, environmental barrier and thermal barrier coatings were discussed. Finally, The problems in improving coating performance and defect control of polymer ceramic coatings were pointed out, and the development direction of polymer ceramic coatings was prospected, for example, by introducing ultra-high temperature elements such as Hf, Zr, Ta into silicon-based precursors, improving the temperature resistance level of ceramic coatings, and developing new efficient ceramic technology to improve the existing efficiency and applicability.

With the development of modern science and technology, the demand for survivability of high-speed aircraft is constantly increasing. Its nose cone, wing, tail nozzle and other high-temperature components are easily exposed. In order to hide the high temperature parts of high-speed aircraft, the high temperature application of wave absorbing materials has attracted the attention of researchers. High temperature absorbing ceramic materials can realize the application in the above background. In order to provide the basis for analyzing and improving the problems of limited high temperature degree and narrow absorption bandwidth of ceramic absorbing materials, the absorbing mechanism of ceramic absorbing materials with high temperature resistance was described with the influence of temperature. The high temperature absorbing ceramic materials and coatings can be classified into carbide ceramics, nitride ceramics, oxide ceramics and polymer conversion ceramics. Based on this classification, the electromagnetic wave loss mechanism of ceramic absorbing materials and coatings, and their absorbing properties under high temperature conditions were summarized in this paper.In addition, it is pointed out that the future high temperature absorbing ceramic materials should improve the existing materials' low high temperature resistance and narrow effective absorption band width so as to strengthen its service ability.

In order to study the corrosion resistance of three different superhydrophobic coatings (MZS-1, MZS-2 and ZnO@ZIF-8) on AZ91D magnesium alloy surface in 5% (mass fraction) NaCl solution. The microstructure, wettability and corrosion resistance of the superhydrophobic composite coating were tested and characterized by field emission scanning electron microscope, static contact angle tester, electrochemical workstation and salt spray tester, respectively. The results show that the corrosion of the superhydrophobic coatings does not occur until 192 h after salt spray treatment among the three types of superhydrophobic coatings, and the corrosion of the MZS-1 superhydrophobic coating is the most serious. The surface pitting of the MZS-2 superhydrophobic coating doesn't occur until 240 h later, and the contact angle is still high after salt spray treatment, so the corrosion resistance of the MZS-2 composite coating is the best.The polarization curve tests indicate that the corrosion current density of three superhydrophobic coatings are still one order of magnitude lower than that of the metal matrix after salt spray treatment for 240 h, showing excellent corrosion resistance. The superhydrophobic coating can effectively increase the corrosion resistance of metal materials.It can effectively prevent the infiltration of corrosive ions and provide long-term protection for the matrix because of its water repellency.

In order to study and expand the application of Inconel718 alloy in high temperature environment, Co/TiN composite coating was prepared on its surface by laser cladding. Meanwhile, the tribological behavior of the coatings at room temperature (RT) and 600 ℃, and the oxidation resistance at 800 ℃ were investigated by XRD, SEM and EDS analysis, etc. The results show that the hardness of the composite coatings is 1.3-1.4 times higher than that of the substrate. The tribological properties of the coating are tested. When the TiN content is 4%(mass fraction, the same below), the anti-friction properties of the coating are the best. When 6%TiN added, the wear resistance of the coating is the best, and the wear rate can be reduced by 90.02%. In addition, the oxidation experiment shows that the Co/TiN composite coating has a certain oxidation resistance, and the oxidation rate is 8.7634 mg²·cm^-4·h^-1, which is not much different from the substrate.It shows that the composite coating can significantly reduce the wear rate at high temperature while retaining the oxidation resistance of the substrate, and the wear rate decreases with the increase of TiN. The wear mechanism analysis shows that the oxidation wear occurs on all coatings at 600 ℃, and the oxide film on the surface of the coatings also can reduces the wear rate at some extent.

SiC-based ceramic matrix composites (SiC-CMC) are an ideal material for aeroengines with high thrust/mass ratio.In order to prevent the corrosion of SiC-CMC by gas (rich in H₂O and O₂) in the engine, it is necessary to prepare environmental barrier coatings (EBCs) with excellent water and oxygen corrosion resistance, gas erosion resistance and thermal shock resistance. Among many factors that evaluate the performance of EBCs, the bonding strength between EBCs and SiC-CMC matrix is an important indicator, but the limit value of the bonding strength has not been clearly explored.In this paper, main factors to control the bonding strength were studied in order to reach the highest value, including the SiC-CMC matrix state, the tensile strength limit of single crystal Si, and the preparation process of the Si bonding layer, etc. In the SiC-CMC/EBCs system, the interface between the SiC fiber cloth is the weakest part of the bonding strength, followed by the Si bonding layer. The bonding strength limit is 15 MPa, which is the tensile strength limit of single crystal Si in the [400] crystal direction. The bonding strength of the Si layer using atmospheric plasma spraying (APS) or high velocity oxygen-fuel(HVOF) is similar, which is lower than that of mullite or Yb₂Si₂O₇ layer sprayed by the same process.

In order to explore the adaptability and failure mechanism of landing gear materials for amphibious aircraft in the marine environment. By preparing a high-speed flame sprayed WC coating on the surface of hot-rolled 300M high-strength steel, the corrosion behavior of the coating in an artificial seawater environment was studied using electrochemical testing, salt spray testing, tensile testing, fatigue testing, and characterization by SEM, EDS, XRD, and CLSM. The research results indicate that the WC coating undergoes significant passivation and exhibits good corrosion resistance in an artificial seawater environment with pH value 8.2, which is related to the passivation of Co in the coating under alkaline conditions. The long-term electrochemical impedance results indicate that the corrosion resistance of the coating increases after soaking for 28 days, which is related to the oxide formed by the surface binder. Compared with the 300 M substrate, the tensile strength of the sprayed material slightly increases, which is related to the residual stress releasing inside the coating. Its cracking in artificial seawater is mainly controlled by the anodic dissolution process. As the pre corrosion time increases, the fatigue life of the material significantly decreases. The corrosive medium from the environment enters the interior of the coating during the pre corrosion process, which increases the number of defects, causes premature failure of the coating, and leads to an increase in material fracture sensitivity. WC coatings have good corrosion resistance, and the release of residual stress during the tensile process slightly increases the tensile strength of the material. The coating fails prematurely after pre corrosion, which results in a reduced fatigue life of the material.

AlCrNiFeTi high-entropy alloy (HEA) with a diameter of 7 mm was prepared as electrode by vacuum arc melting method, and AlCrNiFeTi high-entropy alloy coating was successfully prepared on the surface of 304 stainless steel by using electric spark deposition technology. The microstructure and friction and wear properties of the coatings were studied by XRD, OM, EDS, SEM, microhardness tester and friction and wear tester. The results show that both the AlCrNiFeTi electrode and the coating are dominated by BCC1 and BCC2 simple solid solutions, and the microstructure of the electrode is typical of dendrites. The coating is formed by stacking and spreading of deposition points, and the surface is uniform and dense as orange peel, convex and concave, unfolding for sputtering pattern, and there is no macroscopic defects in the coating cross-section structure, and the thickness is about 59.67 μm.The maximal microhardness of AlCrNiFeTi coating is 587.3HV_0.2, which is about 2.45 times higher than that of the base material. As the load increases, the wear mechanism of the coating changes from oxidized wear and slight abrasive wear to abrasive and adhesive wear. When the friction load is 5 N, the wear rate is 1.213×10^-3 mm³/(N·m), and the friction coefficient is only 0.446. The wear rate of the coating decreases by about 28.3% compared with that of the substrate.

FeCoCrNiAl_x (x=0, 0.5, 1.0, mole ratio, the same below) coatings were prepared on the surface of TC4 titanium alloy by electric explosion spraying technology. The effects of Al content on the phase structure, surface morphology, microhardness and wear resistance of high-entropy alloy coatings were studied by means of XRD, SEM, EDS, microhardness tester and friction and wear test. The results show that the grain size of the coatings is nano-scale, and simple FCC, BCC and FCC+BCC solid solutions are formed. With the increase of Al element, the phase structure is gradually changed from FCC phase to BCC phase. The surface of the coatings is smooth and dense, without obvious cracks, and the elements are evenly distributed on the surface of the coatings, and no obvious segregation of elements is found. The scratch test shows that the average critical load for the failure of the FeCoCrNiAl_1.0 coatings is 37.2 N. The coating is metallurgically bonded to the substrate. The hardness and wear resistance of the coatings are positively correlated with the Al content. When x is 1.0, the average microhardness reaches the maximum value of 531.8HV, which is about 1.62 times that of the substrate. The FeCoCrNiAl_1.0 coatings have the smallest amount of wear, and the wear resistance is about 3.9 times that of the substrate. The wear mechanism is mainly abrasive wear.

In order to solve the protection problem of metal parts surface, the mixed metal coating was prepared on 45^# steel by cold spraying, and then synthesized into FeCrAlCu, FeCrAlCuNi, FeCrAlCuCo, FeCrAlCuNiCo HEA coating by induction remelting technology.The effect of the addition of Ni and Co on the phase composition, microstructure, hardness and wear resistance of the FeCrAlCu series HEA coating were investigated by XRD, SEM, EDS, TEM, microhardness tester and abrasive wear tester, etc. The results show that the coating of FeCrAlCu series HEA is composed of FCC+BCC phase, and the addition of Ni element can promote the formation of FCC phase, and the addition of Co element can promote the formation of B2 phase(AlCo).The microstructure of FeCrAlCu HEA coating is dendrite. With the addition of Ni and Co, the dendrite number in the coating increases and coarsenes obviously. When Ni and Co are added at the same time, the friction property of FeCrAlCuNiCo HEA coating is the best. The hardness of the coating is 565.5HV, the friction coefficient is 0.349, and the wear rate is 3.97×10^-5 mm³·N^-1·m^-1.

In order to solve the serious oxidation problem of the iron-based amorphous coating by arc spraying, the iron-based amorphous coating was prepared on the 20NiCrMo substrate by plasma transfer arc wire spraying(PTWS), and the parameter optimization experiment of four-factor three-level process was designed by the response surface method, and the mathematical model relationship between argon flow, hydrogen flow, working current, spraying distance and porosity was established. Then, the iron-based amorphous coating was prepared by using the optimal process parameters, and the surface, cross-sectional morphology, phase composition and hardness of the iron-based amorphous coating were analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD) and HV-1000A. The polarization properties of coating and substrate was tested by IM6ex type electrochemical workstation. The results show that the porosity of the coating will decrease with either the increase in argon gas and the decrease in spraying distance, or the decrease in argon gas and the increase in spraying distance, when the working current is constant. Under the optimal process parameters, Q_Ar=115 L/min, Q_H2=4 L/min, I=300 A, D=150 mm, d=12 mm, V_wire=60 mm/s, the porosity of the obtained iron-based amorphous coating is 2.14%, the average hardness is 960HV_0.1, the corrosion potential is -0.4841 V and the corrosion current was 3.716×10^-5 A·cm^-2, which indicate the coating has excellent corrosion resistance properties.

Ceramic matrix composites are desirable materials for the hot end components of high performance generation aeroengines due to their high temperature resistance, low density and excellent high temperature mechanical properties. However, when exposed to combustion environment, the ceramic matrix composites are subjected to serious water vapor corrosion. Thus, environmental barrier coatings are indispensable to apply to their surfaces to extend their service life.The rare earth silicate has become the primary candidate material for the new generation of environmental barrier coating materials because of its suitable thermal expansion coefficient with the substrate, outstanding water vapor corrosion resistance and high temperature stability. The characteristics, preparation techniques and typical service performance of rare earth silicates were reviewed in this paper, with focus on their classification, thermal/physical properties, as well as the damage and failure mechanisms during high-temperature corrosion processes. Finally, the research directions of high entropy design of multi-component rare-earth silicates and the design of new thermal/environmental barrier coating systems were proposed. This paper aims to provide useful references for the further application of rare earth silicate materials.

In order to enhance the physical barrier performance of polyaniline(PANI)/polyurethane(PU) coating against corrosive medium, the introduction of two-dimensional material in the coating is one of the effective methods. PU coating matrix was synthesized from 2, 4-diisocyanate (TDI) and 3, 3′-dichloro-4, 4′-diamino diphenylmethane(MOCA), and MXene@PANI was synthesized by intercalation reaction of PANI with Ti₃C₂T_x.Then protective coating of MXene@PANI/PU was obtained by adding MXene@PANI into PU. The results show that when the mass ratio of MXene/PANI is 1∶1, no obvious corrosion occurs on the surface of the MXene@PANI/PU coating after 60 days of salt spraying. The corrosion current is 3.709×10^-9 A·cm^-2, and the impedance modulus is 1.93×10⁸ Ω·cm². The reason is that MXene improves the electrochemical activity of PANI and thus enhances the electrochemical anticorrosion performance of PANI. On the other hand, MXene nanoplates as a two-dimensional barrier can prevent the corrosive medium from entering into the coating, which improves the long-term protective performance of the coating.

The continuous casting mould is the most crucial core component of the continuous casting production line，which undertakes the important tasks of cooling，heat conduction，abrasion resistance and high-precision forming of the billet surface during the high-speed vibration drawing process of the molten steel. Based on the engineering application practice of mould surface protective coatings in domestic steel plants， the advantages，disadvantages and developing trends of electroplated alloy coatings and thermal spray coatings on the surface of mould copper plate were summarized，as well as the main failure forms and formation mechanisms at different locations of mould surface after service under actual working conditions，providing the basis for optimizing the design of coating compositions and corresponding performance in different areas. Moreover，the service results and application advantages of the thermal spraying/vacuum diffusion composite technology developed by the project team in major domestic steel plants were introduced in detail. Finally，it was pointed out that thermal spraying technology will gradually replace electroplating technology and become the core technology of mold surface protection，and high entropy and medium entropy alloy coating has great application potential.

Implant infection is one of the most common and serious complications in orthopedics, and it is also an important reason for the failure of implant surgery. When bacteria form a biofilm on the implant surface, it is extremely difficult to be eliminated and attracts more bacteria and fungi. A large number of studies have shown that the use of surface modification technology can effectively reduce the adhesion and accumulation of pathogenic bacteria, thereby preventing peri-implant infection. The formation process of bacterial biofilm on the surface of orthopedic implants and the antibacterial mechanism of metal antibacterial agents were first analyzed. Then, some of the most widely used metal-based inorganic antibacterial coatings at home and abroad and their related preparation processes were reviewed, the problems and improvement methods in the application of these coatings were also discussed, and the development direction of inorganic antibacterial coatings in the future was prospected, such as synergistic antibacterial coatings and bone-promoting antibacterial coatings.

SiC fiber is one of the common reinforcements for ceramic matrix composite (CMC) due to its superior characteristics such as low density, high tensile strength, excellent high temperature resistance and oxidation resistance. The preparation of coating on the surface of SiC fiber can not only improve the mechanical properties, high temperature resistance, oxidation resistance and electromagnetic functional properties of the fiber itself, but also effectively improve the bonding properties of the interface between the fiber and the matrix to promote the fracture toughness and mechanical properties of the composite. The preparation methods of surface coatings on SiC fiber were firstly reviewed in this paper by elaborating on the basic processes and related research progress of etching, deposition, chemical vapor infiltration, and precursor derived methods, and the advantages and disadvantages of different preparation methods were compared. Then the effects of coatings on SiC fibers and their reinforced composite materials were reviewed. Finally, the development trend of surface coating on SiC fibers was briefly summarized. The combination of experimental research and computational simulation can be used to simulate the real service environment of SiC fibers coatings, and the performance of fibers under extreme service conditions can be improved by preparing thermal barrier composite coatings.

Plasma spray-physical vapor deposition(PS-PVD) technology which has many characteristics of the multi-structure regulation, provides the possibility for the preparation of thermal barrier coatings with high thermal insulation and long life. It is one of the key technology to realize the development of high performance aero-engine. The unique microstructure of PS-PVD columnar structure coatings has dual advantages of high thermal insulation and long thermal cycle life, and has broad application prospects in the field of thermal barrier coatings for aircraft engines. However, the process control of PS-PVD columnar structure coating is achieved on the basis of a large number of experiments, and there is a lack of relevant theoretical research. Moreover, the CaO-MgO-Al₂O₃-SiO₂(CMAS) corrosion failure problem faced by the columnar structure coating with high porosity restricts the use of the coating. The influence of deposition unit phase states on the coating structure was described from the structural characteristics of the coating, and the vapor deposition mechanism of columnar coating was revealed. Based on the phase transition of coating material in the jet, the essence of process parameters regulation was clarified. In addition, the corrosion mechanism of CMAS and the corrosion resistance mechanism of Al-modified coating were investigated. Finally, the structure control and performance improvement of PS-PVD coating and the application of PS-PVD technology in environmental barrier coatings and functional films were prospected.

Thermal barrier coating (TBC) materials are an important method to provide thermal protection and prolong service life for aero-engines and gas turbines. In recent years, various kinds of high-entropy (HE) rare earth oxides have emerged in the exploration of novel thermal barrier coating materials, in order to obtain thermal, mechanical, high temperature phase stability, sintering corrosion resistance and other properties better than single principal rare earth oxides through HE effect on the thermodynamics and kinetics of hysteresis diffusion effect, the structure of the lattice distortion effect and "cocktail" effect on the performance. The thermal, mechanical and other performances of HE rare-earth zirconates, cerates, hafnates, phosphates, tantalates, niobates, etc. were summarized and analyzed in comparison with the performance of the corresponding single phases to investigate the various factors affecting the performance. Finally, it was pointed out that in the future, it may be possible to combine experiments with first-principles calculations to select high-entropy ceramic thermal barrier coating materials with superior comprehensive performance; at the same time, extending high-entropy to complex components or medium-entropy ceramic thermal barrier coating materials is also an important development direction.

The BN coating was deposited on the surface of typical domestic SiC fibers by chemical vapor permeation (CVI) process, and the fibers were oxidized at 800-1200 ℃ for 1 h. The morphology, structure and composition of BN coated SiC fibers after oxidation were characterized. The property changes of BN coated SiC fibers after oxidation were evaluated by tensile strength of monofilament. The results show that when the oxidation temperature is lower than 1000 ℃, the BN coating and its oxide can effectively prevent the erosion of the inner SiC fibers by O₂, and when the temperature continues to rise, the SiC fibers are oxidized. With the increase of oxidation temperature, the surface oxide of BN coated SiC fibers goes through the process of α-B₂O₃→SiC_xO_y→amorphous SiO₂. The tensile strength of BN coated SiC fibers decreases with the increase of oxidation temperature. Direct exposure of BN coating to oxidizing environments reduces the oxidation resistance of SiC fibers. The failure source of fiber fracture first transitions from BN coating defects to B₂O₃ oxide layer defects and finally evolves into SiO₂ oxide layer porosity defects.

In order to reveal the correspondence between the microstructure and mechanical properties of in-situ TiC/Ti composite coatings by induction fusion coating, the nano-mechanical property variation patterns of different phase structures within the coatings were investigated by using the isolated nanoindentation test method, and the mechanical properties of the coating micro-zone structure were studied by using grid indentation test method. The isolated indentation results show that the nanoindentation hardness and elastic modulus of the in-situ TiC-reinforced phases are 21.3 GPa and 275 GPa, respectively, while the average nano hardness of the matrix phase in the α-Ti-rich and β-Ti-rich regions is 4 GPa and 6 GPa, respectively, and the average elastic modulus is 130 GPa and 155 GPa, respectively. The correspondence between the grid indentation and isolated indentation test results is good. The minimum peak obtained from the three-peak Gaussian fitting of the fractional nanoindentation test results represents the mechanical properties of the matrix phase of the coating, the middle peak reflects the comprehensive mechanical properties of the coating, and the maximum peak is lower than the real mechanical properties of the in-situ TiC reinforcement due to the influence of the reinforcement size and indentation position. Under the consideration of coating microstructure and reinforcement size, by reasonably setting the fractional indentation test conditions and selecting the appropriate test area, it can reveal comprehensive properties of the coating while obtaining real mechanical properties of different phase structures of in-situ TiC composite coatings.

To produce the porous coating on the inner wall of the pipe is an effective way to enhance heat transfer performance and improve heat exchange efficiency. The electric explosion spraying method was employed to produce the porous coating on the inner wall of the pipe. The surface morphology, roughness and pore distribution of the coating under different initial voltages were studied. The mechanism for the formation of the coating was investigated by the deposition energy and explosive products explained. The results indicate that the initial voltage of the electric explosion spraying influences the microstructure of coating. The optimal porous coating can be obtained when the initial voltage of the electric explosion spraying is 14.0 kV. The optimal porous coating is formed by the accumulation of the small particles. Moreover, the optimal porous coating is obtained, the surface area is 4.47 times that of the uncoated pipe and the porosity of the ideal coating is 57.8%. The uniform round porous coating is formed, when the initial voltage of the electric explosion spraying is 15.2 kV. The porosity of those coating is 40.3%. The formation of the coating depends on the energy deposited on the copper wire during the explosion. The energy deposited on the copper wire acts as the thermodynamic condition for the sprayed particles, determines the energy and particle size of the sprayed particles and the states of the sprayed particles collide with the surface of the base tube or the particles accumulate or form a molten pool. Finally, it influences the microscopic morphology of the coating.