Ceramic Films Research Articles

Mechanical and electrical properties of sodium potassium niobate ceramic coating by plasma spraying

Potassium sodium niobate ceramics are environmentally friendly piezoelectric ceramics with excellent electrical properties. It is the most promising green piezoelectric ceramic for current applications. Currently, ceramics are needed in the form of thin films or coatings for brakes, sensors, etc. Most of the current ceramic films are prepared by physical vapor deposition and chemical vapor deposition. However, the ceramic layers prepared by the above methods are thin. The thickness of the ceramic layer has a large influence on its mechanical and electrical properties. The coatings prepared by thermal spraying are thicker, but there is no in-depth study about the relationship between the coating thickness and the mechanical and electrical properties of the coating. In this article, four different thicknesses of coatings were prepared by plasma spraying technology, and the relationship between the mechanical and electrical properties of the coatings and the thickness was studied and discussed. The results show that the coating microhardness and residual compressive stress values reach the maximum and the dielectric and ferroelectric properties are optimal when the coating thickness reaches 300 μm. The study of the connection between coating thickness and coating mechanical and electrical properties provides a theoretical study for the application of the coating in practice.

The Preparation and Modification of Strontium Titanate Ceramic Films for High‐Performance Flexible Supercapacitor

AbstractBased on previous research, the perovskite‐type SrTiO3 can be considered as a potential energy storage material because of its good electrical conductivity properties and oxygen‐vacancy structure. In this work, Ce‐doped SrTiO3 nanofibers film with excellent flexibility was successfully fabricated by using electrospinning and conventional sintering route at 600 °C. For the series of the SrCexTi1‐xO3 (SCTO‐x) films (0≤x≤0.5), although the corresponding nanofibers structure could remain intact, their lattice structure transferred from cubic into tetragonal phase with the increase of Ce doing amount. Moreover, the electrochemical measurement results shown that the working electrode fabricated by SCTO‐0.3 sample as active materials exhibited the best electrochemical performance possessing with a maximum specific capacitance value of 2895 mF ⋅ cm−2 at 3 mA ⋅ cm−2 (1809.4F ⋅ g−1 at 1.875 A ⋅ g−1).Therefore, a symmetrical flexible device was assembled by two SCTO‐0.3 electrodes with 1 M Na2SO4 solution, showing a good energy density of 89.5 Wh ⋅ kg−1 (at power density of 1250 W ⋅ kg−1). However, while the super‐concentrated electrolyte (1 M Na2SO4+66.7 wt % sucrose) was instead of the 1 M Na2SO4 solution in the fabrication of the device, it could display higher energy density (151 Wh ⋅ kg−1 vs. 1600 W ⋅ kg−1), good cycling stability and better mechanical flexibility. Herein, this work may provide a new potential electrode material for flexible energy storage device design.

Densification of BaZr0.9Y0.1O3‐δ ceramic thin films by an infiltration and co‐sintering approach

AbstractThe proton conductivity of Y‐doped BaZrO3‐based ceramic (BZY) films is highly dependent on the preparation process, especially thermal treatment. In order to further improve the electrochemical properties of BZY thin films, a novel sintering method was introduced to enhance the densification of such refractory materials. BaZr0.9Y0.1O3‐δ (BZY10) was used as a composition in this case study and the concept is realized using chemical solution deposition (CSD) derived porous cathode and anode films as auxiliary layers underneath the BZY10 films, which are CSD derived as well. After co‐sintering at 1200°C for 4 h, BZY10 films with a high degree of densification were attained, accompanied by average grain sizes of 300–350 nm. The grain sizes are comparable to common results found in BZY10 pellets sintered at 1600°C for more than 6 h. However, the densification conditions are much better. For the porous NiO/BZY10 composite films, the in‐plane conductivity is enhanced to about 2 × 10−4 S/cm at 600°C, which is quite close to that (10−3 S/cm) of optimized BZY bulk materials. The compatible stack structures and the remarkably low sintering temperature are applicable to the fabrication of proton‐conducting solid oxide fuel and electrolyzer cells.

Effect of Na2SiO3 concentration on corrosion resistance and wear resistance of MAO ceramic film on the Al‐Mg‐Sc alloy

AbstractAlthough Al‐Mg‐Sc alloy was widely applied to aviation aerospace field, they were vulnerable to local corrosion and wear in the process of long‐term service in severe environmental conditions. In this paper, micro‐arc oxidation (MAO) ceramic films on Al‐Mg‐Sc alloy substrate were prepared in electrolyte solutions with different Na2SiO3 concentrations, and the corrosion resistance and wear resistance of the MAO samples were studied. The experimental results of potentiodynamic polarization (PDS) and long‐term immersion tests indicated that the MAO ceramic film prepared in 10 g/L Na2SiO3 electrolyte solution had the best corrosion resistance, as manifested by no obvious cracks, serious collapse and corrosion products on the sample surface and no deep cracks and corrosion paths in the cross‐sectional area. The increase of Na2SiO3 concentration in electrolyte solution also improved the wear resistance of MAO ceramic film, as manifested by low wear depth (10 μm)and width (1 mm) of the MAO ceramic film prepared in 10 g/L Na2SiO3 electrolyte solution against GCr15 steel ball. Studies in mechanisms suggested that as the Na2SiO3 concentration in the electrolyte increased, the MAO ceramic film became denser, which could prevent the penetration of corrosive medium, promote the generation of the anti‐wear layer with SiO2 as the main component to enhance the wear resistance. MAO ceramic film formed in Na2SiO3 electrolyte solution provided good protective performance for Al‐Mg‐Sc alloy in the corrosion and wear conditions, which had a broader application prospect.

A hybrid piezoelectric and triboelectric nanogenerator with lead-free BZT-BCT/PDMS composite and PVA film for scavenging mechanical energy.

A hybrid piezo/triboelectric nanogenerator (H/P-TENG) is designed for mechanical energy harvesting using polymer ceramic composite films; polydimethylsiloxane/Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (PDMS/BZT-BCT) and polyvinyl alcohol (PVA). A lead-free BZT-BCT piezoelectric ceramic was prepared via solid-state method and blended into PDMS to form a series of polymer-ceramic composite films, ranging from 5% to 30% by weight. The films were forward/reverse poled with corona poling and their electrical properties were compared to non-poled samples. The H/P-TENG constructed with forward-poled 15 wt% BZT-BCT in PDMS achieved the highest open-circuit voltage, V oc of 127 V, short-circuit current density, J sc of 67 mA m-2, short-circuit charge density, Q sc of 118 μC m-2, and peak power density of 7.5 W m-2, an increase of 190% over pristine PDMS-based TENG. It was discovered that incorporating BZT-BCT into the PDMS matrix improved the triboelectric properties of PDMS. The overlapping electron cloud (OEC) model was used to explain the enhancement and the effect of poling direction of the PDMS/BZT-BCT composite used in H/P-TENG, providing fundamental knowledge of the influence of piezoelectric polarisation on contact electrification.

Corrigendum to “Structural evolution and mechanical properties of multi-element (TiCrZrVNb)C high entropy ceramics films by multi-arc ion plating” [Ceram. Int. 48(13) (2022) 19191–19197

Corrigendum to “Structural evolution and mechanical properties of multi-element (TiCrZrVNb)C high entropy ceramics films by multi-arc ion plating” [Ceram. Int. 48(13) (2022) 19191–19197

Cost-effective screen printing approach for Ce/Nd-doped ZnAl2O4 films: tuning crystallinity induced by the substrate.

Near-infrared (NIR) emitting phosphors are currently receiving considerable attention owing to their high demand in various applications, such as light detection and ranging (LiDAR), short-range communications, security, biosensing and night vision lighting applications. The miniaturization of photonic components demands the integration of thin films into exploitable devices. In this context, NIR emitting ZnAl2O4:Ce/Nd films of hundreds of nanometer thickness are synthesized using a scalable and cost-efficient approach to screen printing. Cerium co-doping is responsible for the Nd emission in the NIR through energy transfer by exciting the films under UV excitation at around 360 nm. Through the proper design of ink, dense Nd/Ce doped ZnAl2O4 ceramic films were produced using polycrystalline alumina. The use of polycrystalline alumina substrates opens up new opportunities because this ceramic is a cheap and well-known substrate for optoelectronic packaging. During manufacturing, as a direct effect of predominant crystal growth over the polycrystalline alumina substrate, an increase in emission intensity is achieved. The results obtained by X-ray photoelectron (XPS) and X-ray absorption near edge spectroscopy (XANES) serve to determine the oxidation state of Ce. The findings of this study indicate that a higher concentration of Ce4+ promotes NIR emission. This study may contribute to a better understanding of film production processes of films based on the ZnAl2O4 matrix and guide future studies on films for NIR emitters.

Chemical expansion of CeO2−δ and Ce0.8Zr0.2O2−δ thin films determined by laser Doppler vibrometry at high temperatures and different oxygen partial pressures

The chemical expansion of ceria (CeO2−δ) and ceria-zirconia (Ce0.8Zr0.2O2−δ, CZO80) thin films is investigated by high-temperature laser Doppler vibrometry (LDV) at temperatures from 600 to 950 °C. The films are deposited on single-crystalline 8 mol-% yttria-stabilized zirconia substrates, which act as pumping cells to adjust oxygen non-stoichiometry in the thin films. Oxygen deficiency causes film expansion, leading to mechanical strain that bends the sample. The total displacement, i.e., the sum of bending and film-thickness change, is determined contact-less by LDV. A differential laser Doppler vibrometer (D-LDV) is realized to enable measurements on a very long time scale, which is necessary due to the long equilibrium times of the ceramic films. These displacements are compared to those acquired with a commercial single-point laser Doppler vibrometer (SP-LDV) for motions above 1 Hz. Here, both devices yield similar results. CZO80 films are found to bend a substrate much more than ceria films under similar experimental conditions. A model describing the displacement of the sample is derived from the Stoney model and applied to calculate deflections using literature data. The displacements at the center of the CZO80 sample measured with the SP-LDV increase from 0.18 nm at 10 Hz and 600 °C to 32.7 nm at 0.1 Hz and 800 °C. For ceria, the displacements range from 1.6 nm (10 Hz, 800 °C) to 79.4 nm (0.1 Hz, 900 °C). The D-LDV enables the detection of quasi-static displacements at very low frequencies. The ceria sample exhibits 218 nm at 0.001 Hz and 800 °C.

The Effect of Couple Doping Gd and Co on The Physical Characteristics of LaFeO3 Thick Film for Acetone Gas Sensor Application

The acetone gas sensor is one type of sensor being researched for its application because it detects the presence of diabetes in sufferers. Gas sensors with high sensitivity and low operating temperature have been extensively investigated for this purpose, and this research is focused on the same purpose. Synthetization and characterization of LaFeO3 with co-doping Gd2O3 and CoO thick film ceramics for acetone gas sensor was conducted. LaFeO3 was made using the co-precipitation method with 2.5% CoO for each and 0%, 2.5%, and 5% Gd2O3 variation to the LaFeO3. The LaFeO3 thick film was prepared using the screen-printing technique and calcined at 800°C for two hours. The analysis of crystal structure characterization using X-Ray Diffraction (XRD) resulted in LaFeO3 with co-doping Gd2O3 and CoO thick film ceramics having the same cubic crystal phase with smaller lattice parameters and crystallite sizes after doping were added. The results of morphology structure characterization using Scanning Electron Microscopy (SEM) showed the grain size of the LaFeO3 with co-doping 2.5% CoO and 0%, 2.5%, and 5% Gd2O3 samples to support the analysis of electric property characterization later on. The electric property characterization showed that LaFeO3 with various Gd2O3 concentrations, as part of co-doping with 2.5% CoO, resulted in higher sensitivity compared to the lacking of Gd2O3 one. In order, the maximum sensitivity values of each Gd2O3 concentration are 2.74, 3.06, and 8.76 when exposed to 270 ppm acetone gas at 310°C. Gd2O3, as part of co-doping in LaFeO3 with CoO 2.5%, has successfully increased the sensitivity to the gas sensor yet still can not meet the expectation towards the operating temperature, which is still high compared to other references.

A Review on coating of steel with nanocomposite for industrial applications

The current review goal to provide a thorough understanding of the nanocom- posite coating of steel for industrial applications. Based on findings from recent research, we will go into detail here about the several coating mate- rials, deposition methods, and the challenges associated with creating the best coating for steel. The two primary categories in which this article has been prepared are. In the first part, anti-corrosion coating, ceramic film, chemical vapour deposition, carbon nanotube, graphene has been presented with lat- est research. The second part focuses on industrial application of the current research including aerospace, automotive and petrochemical industry.

Thin-Film Platinum Resistance Temperature Detector with a SiCN/Yttria-Stabilized Zirconia Protective Layer by Direct Ink Writing for High-Temperature Applications.

In situ temperature monitoring of curved high-temperature components in extreme environments is challenging for a variety of applications in fields such as aero engines and gas turbines. Recently, extrusion-based direct ink writing (DIW) has been utilized to fabricate platinum (Pt) resistance temperature detectors (RTDs). However, the current Pt RTD prepared by DIW technology suffers from a limited temperature range and poor high-temperature stability. Here, DIW technology and yttria-stabilized zirconia (YSZ)-modified precursor ceramic film packaging have been used to build a Pt RTD with high-temperature resistance, small disturbance, and high stability. The results indicate that the protective layer formed by the liquid phase anchors the Pt particles and reduces the agglomeration and volatilization of the Pt sensitive layer at high temperature. Attributed to the SiCN/YSZ protective layer, the temperature resistance curve of the Pt RTD in the range of 50-800 °C has little deviation from the fitting curve, and the fitting correlation coefficient is above 0.9999. Interestingly, the Pt RTD also has high repeatability and stability. The high temperature resistance drift rate is only 0.05%/h after 100 h of long-term testing at 800 °C and can withstand butane flame up to ∼1300 °C without damage. Moreover, the Pt RTD can be conformally deposited on the outer ring of aerospace bearings by DIW technology and then realize on-site, nondestructive, and real-time monitoring of bearing temperature. The fabricated Pt RTD shows great potential for high-temperature applications, and the novel technology proposed provides a feasible pathway for temperature monitoring of aeroengine internal curved hot-end components.

A Two-Dimensional Guidance Strategy to Fabricate Perovskite Gadolinium Aluminate Ceramic Film

Gadolinium aluminate is an effective host for doping with various ions, and it can emit various colors. However, it is not easy to prepare transparent ceramics of gadolinium aluminate using traditional methods, although transparent ceramics are very suitable for solid lighting. In this work, a two-dimensional guidance strategy has been successfully carried out for perovskite-structured aluminate ceramic film. Through the two-dimensional interfacial reaction, GdAlO3:Eu3+ (GAP:Eu3+) transparent ceramic films were successfully fabricated using nanosheets exfoliated from layered gadolinium hydroxide, a rare earth source. The final films were tested by characterization techniques, including XRD, SEM, TEM, FT-IR, PLE/PL spectroscopy, temperature-dependent PL spectroscopy, and luminescence decay analysis. The perovskite film of transparent ceramics can be obtained by calcining LRH nanosheets on the substrate of amorphous alumina at 1550 °C in air with a reaction time of 2 h. During the interface reaction, temperature-dependent element diffusion takes the dominant role, and increased reactants take in the reaction with increasing calcination temperature. The grain for ceramic film is only 2–5 μm, which is much smaller than that for bulk ceramic. This is mainly due to the lower temperature and the interface diffusion. Ceramic film has a high transmittance larger than 90% at the visible range. Upon UV excitation at 254 nm, the film exhibits intense emission at the red wavelength range. The outcomes described in this work may have wide implications for transparent ceramics and layered rare-earth hydroxides.

Microwave Plasma Assisted Aerosol Deposition (μ-PAD) for Ceramic Coating Applications

To improve plasma and chemical resistance on various vacuum components used for semiconductor manufacturing equipment, various ceramic coating techniques have been applied. Among these methods for ceramic coating, the well-known atmospheric plasma spray (APS) is advantageous for providing thick film (100 µm or more) deposition. However, there are problems associated with the phase transition of the coating film and poor film quality due to formation of voids. To solve these problems, the aerosol deposition (AD) method has been developed. This method provides nice ceramic film quality. However, the coating rate is quite slow and has difficulty producing thick films (>30 µm). To overcome these limitations, microwave plasma-assisted aerosol deposition (μ-PAD) is applied at low vacuum conditions without the AD nozzle. This method uses a microwave plasma source during the AD process. After enduring a long-term durability test, as a trial run, μ-PAD has been applied on the actual process site. With the Al2O3 powder, μ-PAD shows a coating rate that is 12 times higher than the AD method. In addition, the formation of a thicker film (96 µm) deposition has been demonstrated. On the other hand, the coating film hardness, porosity, adhesion, and withstand voltage characteristics were confirmed to be less than the AD method.

Microstructure evolution and fracture mechanism of the interfacial region between MAO ceramic film and Al-Mg-Sc alloy substrate

Surface ceramics on Al-Mg-Sc alloy with micro-arc oxidation (MAO) was attracting increased attention in industrial field. The mechanisms concerning high bonding strength between MAO ceramic film and metal substrate were not yet clear. In this study, MAO ceramic films were constructed on Al-Mg-Sc alloy surface to reveal the microstructure evolution and fracture mechanism of the metal/ceramic interfacial region. The results indicated that the interfacial region exhibited an Al-Mg-Sc/Al 2 O 3 composite laminated structure mainly composed of Al 2 O 3 . The Al substrate near the interface presented fine grained structure, only a few grains grow along <001> and <101> plane, while almost all the grains were oriented along <111> plane. The fracture mechanism of the interfacial region in the tensile process was a mixed mode of ductile and brittle fracture.

Recent advances in composite films of lead-free ferroelectric ceramics and poly (vinylidene fluoride) (PVDF) for energy storage capacitor: a review

Recent advances in composite films of lead-free ferroelectric ceramics and poly (vinylidene fluoride) (PVDF) for energy storage capacitor: a review

Orientation controlled microstructure and mechanical properties of TiN-Cu nanocomposite films

Adding soft metal phases into transition metal nitrides to generate nanocomposite structures can considerably tune the mechanical properties of films. We prepared TiN-Cu nanocomposite films with different orientations on MgO (100) and (110) substrates; the hardness of the film with 〈110〉 orientation was 40.4 GPa, while the 〈111〉-oriented film hardness was 28.1 GPa. This significant difference in hardness was attributed to orientation affecting Cu segregation at grain boundaries (GBs) to form different thicknesses of amorphous layers. This study opens a new avenue for tuning the mechanical properties of ceramic thin films.

Pressureless sintering of LRH nanoplates on amorphous alumina for near‐infrared GAP:Mn4+ transparent ceramic film

AbstractTransparent ceramics have become a research hotspot in the preparation of fluorescent materials in recent years, because of their excellent physical and chemical properties and high transparency. Gadolinium aluminate, as a stable matrix material, is often doped with various active ions to obtain luminescence with different colors. However, it is very difficult to fabricate gadolinium aluminate transparent ceramics by a traditional method, although they are the charming solid lighting materials. Here, we developed a pressureless sintering method to prepare GdAlO3:Mn (GAP:Mn) transparent ceramic films, which were prepared by spin coating layered rare‐earth hydroxide (LRH) on amorphous alumina substrate and sintering at 1550°C for 2 h. Through the interface reaction, the Al2O3 reacted with Gd2O3 to form mesophase Gd4Al2O9 below 1550°C. However, the final products are GdAlO3 at 1550°C. The GAP:Mn4+ film exhibits a high transmittance of about 90%. Under UV excitation at 310 nm, the ceramic film outputs deep red and NIR emissions, which are both arising from the 2Eg–4A2g transition of Mn4+. Due to the electron traps arising from unequal valence substitution, the ceramic film exhibits a negative thermal quenching phenomenon. The ceramic film has a good luminescence thermal stability, because its emission intensity at 150°C maintains over 72% that at room temperature. This work may pave a new way to fabricate transparent ceramics using LRHs.

Effect of Annealing Time on the Cyclic Characteristics of Ceramic Oxide Thin Film Thermocouples.

Oxide thin film thermocouples (TFTCs) are widely used in high-temperature environment measurements and have the advantages of good stability and high thermoelectric voltage. However, different annealing processes affect the performance of TFTCs. This paper studied the impact of different annealing times on the cyclic characteristics of ceramic oxide thin film thermocouples. ITO/In2O3 TFTCs were prepared on alumina ceramics by a screen printing method, and the samples were annealed at different times. The microstructure of the ITO film was studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results show that when the annealing temperature is fixed, the stability of the thermocouple is worst when it is annealed for 2 h. Extending the annealing time can improve the properties of the film, increase the density, slow down oxidation, and enhance the thermal stability of the thermocouple. The thermal cycle test results show that the sample can reach five temperature rise and fall cycles, more than 50 h, and can meet the needs of stable measurement in high temperature and harsh environments.

Formation of palladium nano-gap on self-cracked WO3 for hydrogen gas sensors

In the event of a hydrogen leak accident, an explosion occurs at a concentration of 4% or more in the atmosphere, so, the technology to accurately measure the hydrogen detection near the 5% area is very important. Among the various hydrogen detection methods, a hydrogen sensor using a fine pattern of Pd with excellent ability to absorb hydrogen is very suitable for this purpose. In this study, in forming a micropattern of Pd metal, a technique for easily fabricating Pd micropatterns was proposed by utilizing micro-cracks generated in the process of forming a ceramic thin film on a polymer substrate. It showed very accurate detection capability at the 1–5% hydrogen concentration level, and it is expected that it can be easily applied to various curvature environments as it is manufactured on a polymer substrate.

Synthesis and characterization of the ceramic refractory metal high entropy nitride thin films from Cr-Hf-Mo-Ta-W system

High entropy alloy and nitride coatings from the Cr-Hf-Mo-Ta-W system were deposited by reactive magnetron sputtering from elemental segmented targets. The study aimed to investigate the effects of deposition parameters on the microstructure and mechanical properties of this novel multicomponent material. Samples without nitrogen flow and under different nitrogen flows were prepared in two series of samples prepared at ambient temperature and at 750 °C. The proportion of metallic elements varied with increasing nitrogen flow. The nitrogen content revealed saturation below 50 % under high flow. The thin films showed a different microstructure depending on the deposition conditions, from a single nanocrystalline bcc phase (a = 3.174 Å) in the metallic sample prepared at 750 °C without nitrogen flow, through an amorphous structure under low nitrogen flow to a major nanocrystalline NaCl-type fcc nitride phase (a = 4.186–4.268 Å, in agreement with the ab-initio predicted values) in samples deposited under high nitrogen flow. The cross-section morphology of the amorphous sample was very homogeneous, while the samples with a major fcc nitride phase showed a typical columnar morphology. Overall, the films revealed hardness and Young's modulus up to 20.3 GPa and 471 GPa, respectively, for the fcc nitride coating. The experimental values of Young's modulus were in good agreement with the values of directional [100] Young's modulus obtained by ab-initio calculations. The results of our research showed that coatings consisting of bcc and fcc phases could be produced by magnetron sputtering with interesting mechanical properties such as high Young's modulus. Moreover, the results contribute to the understanding of the influence of the nitrogen flow on the microstructural features such as crystallite size, vacancies in the lattice, and lattice parameter change.