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In order to improve the service performance of Zr-4 alloy in nuclear industry and avoid introducing impurity elements， the micro-arc oxidation ceramic layer was prepared on the surface of Zr-4 alloy with Li2B4O7 as electrolyte.The effects of lithium tetraborate concentration on phase composition， microstructure， film thickness， hardness， roughness， wear resistance and corrosion resistance of micro-arc oxidation ceramic layer were investigated.Results showed that as the concentration of Li2B4O7 increased in the range of ρ(Li2B4O7)＝3～15 g/L， the conductivity of the electrolyte continued to increase， and the roughness of the ceramic layer continued to increase overall， which only slightly decreased when the electrolyte concentration changed from 6 g/L to 9 g/L.The thickness of micro-arc oxidation ceramic layer first continuously decreased in the range of ρ(Li2B4O7)＝3～9 g/L and then increased in the range of ρ(Li2B4O7)＝9～15 g/L.The hardness of the ceramic layer first decreased in the range of ρ(Li2B4O7)＝3 ～6 g/L， and then increased in the range of ρ(Li2B4O7)＝6 ～15 g/L.In addition， the ceramic layers were all composed of monoclinic zirconia (m-ZrO2).As the concentration of Li2B4O7 in the electrolyte increased， the porosity of the ceramic layer decreased and the micropore size changed little.The friction coefficient of the ceramic layer increased continuously in the range of ρ(Li2B4O7)＝3～12 g/L， and decreased when ρ(Li2B4O7)＝15 g/L.By comprehensive comparison， the ceramic layer with moderate thickness， good hardness， smooth and continuous surface， small porosity and pore size， good wear resistance and corrosion resistance could be obtained in the electrolyte with ρ(Li2B4O7) ＝ 15 g/L.

In this case ceramic layers from Metco ZrO2 and Al2O3 powders mixture (25/75; 50/50 and 75/25) were obtained through atmospheric plasma spraying (APS) after five passes on low carbon steel substrate. The sample surfaces mechanically grinded (160-2400) before and after ceramic layer deposition. Powder’s mixtures and the surface of ceramic thin layers were analyzed through: scanning electron microscopy (SEM). In order to understand the effect of surface wettability of the ceramic layers, before and after grinding the surface, three different liquids were used. Experimental results confirm the modification of the steel substrate surface characteristic from hydrophilic to hydrophobic when the ceramic layer was deposited. Surface free energy of hydration increases for all the samples with zirconia percentage addition before polishing process.

Piston performance has an important on vehicle reliability, efficiency, and exhaust emissions. Application of the thermal barrier coating is an effective method for preventing heat transfer from combustion chamber to the substrate. The numerical model of thermal barrier coating piston is established by using finite element method, and a comprehensive thermal-mechanical result is given to determine the influence of ceramic thickness on ceramic layer and substrate. Compared with uncoated piston, the maximum temperature of substrate decreased by 3.34%, 4.09%, 5.19%, 5.95%, and 6.69%, corresponding to ceramic thicknesses of 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, and 0.35 mm. The maximum thermal stress decreases from 78 MPa to 73 MPa. For ceramic layer of the thermal barrier coating piston, the maximum temperature appears at the top surface of the ceramic layer, while the maximum thermal stress occurs at the bottom of the ceramic layer. As the ceramics thickness increases from 0.15 mm to 0.35 mm, the maximum temperature of the ceramic layer increases from 322 °C to 377 °C, while the maximum thermal stress decreases from 95 MPa to 89 MPa. Thermal-mechanical coupled stress analysis shows that the maximum coupling stress occurs at the pinhole and its value does not change significantly. The thickness of the ceramic layer has little effect on the pinhole, but has a great influence on the ceramic layer. [ABSTRACT FROM AUTHOR]

• β Ti–Nb-Sn alloy comprise anatase, rutile, SnO and Nb 2 O 5 oxides after PEO-coating. • CP-Ti and β Ti–Nb-Sn presented basically the same thickness of the coating. • The thickness did not influence the microhardness and wear properties after PEO-coating. • After PEO-coating, the microhardness increased significantly for β Ti–Nb-Sn. • The wear volume for β Ti–Nb-Sn decrease after PEO-coating significantly compared to substrate. The plasma electrolyte oxidation (PEO) coating technique was used to fabricate a ceramic porous layer on the surface of β Ti-34Nb-6Sn alloy in a phosphate, calcium, and magnesium electrolyte (bioactive elements). The phase composition and microstructure of the substrate Ti-34Nb-6Sn (TNS) alloy was made by XRD essay and the PEO coatings were characterized by XRD and SEM analyses. The microhardness was done by Vickers microhardness and the wear assay was made by micro-abrasive wear technique. The oxide coatings can be effectively fabricated on the surface of this alloy. The pore size showed a variability and the maximum and minimum pore size values found were 2.98 µm and 0.42 µm. The PEO coatings comprised anatase and rutile TiO 2 , Nb 2 O 5 and SnO oxides. The hardness and wear properties were compared to the CP-Ti substrate. The hardness of the oxide surface coating increased significantly when compared to the metallic substrates. The wear resistance was improved after PEO-coating on CP-Ti compared to untreated material, and the treatment established the wear behavior of the TNS alloy. The improvement of the hardness, and wear resistance of the TNS alloy can be related to the oxides formed during the PEO treatment and can contribute to the development of biomedical devices advancing the biological properties when in contact with the bone tissue. [ABSTRACT FROM AUTHOR]

The possibility of deposition of Sm2O3–ZrO2–HfO2 and Sm2O3–ZrO2 ceramic layers by electron-beam evaporation of pressed rods is shown. The thermal conductivities of ceramic layers of various compositions are calculated. The stability of the chosen composition is shown at temperatures up to 1350°C. [ABSTRACT FROM AUTHOR]

In this case ceramic layers from Metco ZrO2 and Al2O3 powders mixture (25/75; 50/50 and 75/25) were obtained through atmospheric plasma spraying (APS) after five passes on low carbon steel substrate. The sample surfaces mechanically grinded (160-2400) before and after ceramic layer deposition. Powder's mixtures and the surface of ceramic thin layers were analyzed through: scanning electron microscopy (SE M). In order to understand the effect of surface wettability of the ceramic layers, before and after grinding the surface, three different liquids were used. Experimental results confirm the modification of the steel substrate surface characteristic from hydrophilic to hydrophobic when the ceramic layer was deposited. Surface free energy of hydration increases for all the samples with zirconia percentage addition before polishing process. [ABSTRACT FROM AUTHOR]

Bifunctional reactive polyhedral oligomeric silsesquioxane (POSS) of 3, 13‐divinyl octyphenyl silsesquioxane (DV‐DDSQ) and 3, 13‐dihydro octyphenyl silsesquioxane (DH‐DDSQ) were used as additive to modify ethylene‐propylene‐diene rubber (EPDM), and double vinyl groups or active hydrogen groups of bifunctional reactive POSS (brPOSS) underwent a cross‐linking reaction with the active hydrogen groups and double bonds of EPDM, to investigate the effect of brPOSS regulating functional reaction group on the properties of EPDM. Crosslinking density, mechanical properties, thermal stability and ablation performance of brPOSS modified EPDM were investigated, and the pyrolysis behavior and surface structure of modified EPDM was analyzed by X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Furthermore, the ablation performance of brPOSS modified insulation based on EPDM was investigated. The results showed that the tensile strength of EPDM/DV‐DDSQ and EPDM/DH‐DDSQ increased by 35.8% and 55.3% respectively compared with EPDM; the tear strength increased by 6.4% and 5% than that of EPDM. Moreover, the 5% initial thermal decomposition temperature based on thermogravimetric analysis (TGA) and mass (or linear) ablation rate ablative performance of brPOSS modified EPDM were optimized to a certain extent, and the ablative performance of brPOSS modified insulation based on is significantly improved, the mass ablation rate of DV‐DDSQ/insulation and DH‐DDSQ/insulation decreased by 35.4% and 41.6% respectively, and linear ablation rate decreased by 38.2% and 39.4% respectively. [ABSTRACT FROM AUTHOR]

A Ta-N ceramic layer on the surface of a Ta-2.5W alloy was synthesized by ion nitrocarburizing to improve its surface mechanical properties. Two processing parameters, temperature and holding time, were respectively investigated of the effects on the phase evolution of the ceramic layer. At 800 °C, only a single diffusion layer consisting of α-Ta (solution of nitrogen) was present. When temperature was raised to 900 °C and 1000 °C, a compound layer, mainly composed of θ-TaN phase, was formed to replace the upper part of the diffusion layer, resulting in the dramatic improvement of surface hardness. The thickness of compound layer increased with holding time and approached 20 μm for the sample processed at 1000 °C for 3 h, corresponding to the optimal microhardness properties. [ABSTRACT FROM AUTHOR]

Rapid crosslinking of silicone chains on the nanosilica surface during arc discharge is proposed as an efficient strategy to improve the tracking and erosion resistance of silicone rubber. Urethane-containing silane (URS) was synthesized by using (3-isocyanatopropyl) triethoxysilane, isopropyl alcohol and allyl alcohol via nucleophilic addition and trans-etherification. The suppression effect and mechanism of URS on the tracking and erosion of addition-cure liquid silicone rubber/silica (ALSR/SiO 2 ) nanocomposite were investigated. It was found that URS could significantly enhance the tracking and erosion resistance of ALSR/SiO 2 . When only 2.5 phr URS was added, all the ALSR/SiO 2 /URS specimens passed the inclined plane test at 4.5 kV and the erosion rate decreased from 3.44% to 0.25%. This might be because URS tightly constrained silicone chains on the SiO 2 surface by strong hydrogen-bonding interactions. During arc discharge, URS at the interphase enhanced the catalytic activity of platinum compound to promote the radical crosslinking of silicone chains absorbed on the SiO 2 surface. Hence, a compact and intact ceramic layer was quickly formed on the ALSR surface and protected the underlying materials from further arc ablation. Our finding provides a new method and theoretical basis for the design, preparation and application of the novel high-performance polymer insulating material. [ABSTRACT FROM AUTHOR]

Thermal barrier coatings (TBCs) protection is widely used to prolong the lifetime of turbine components. The outermost layer of TBCs is ceramic layer, whose function is heat insulation, and the main composition of the ceramic layer is ZrO. In this study, the micro-ZrO and the nano-ZrO doped with 10 wt% CeO as well as micro-ZrO and nano-ZrO were prepared by air plasma spraying (APS) to study the advantages of the addition of rare earth element. The effect of CeO on the phase transformation of ZrO was studied. The results show that there are few cracks in micro- and nano-ZrO doped with 10 wt% CeO, and rare earth oxides can affect the phase transformation significantly. The morphologies, hardness and elastic modulus of the four ceramic layers were also discussed. [ABSTRACT FROM AUTHOR]

W procesie wytwarzania odlewów wg metody modeli zgazowywanych na modele polistyrenowe (styropianowe), nakładana jest warstwa pokrycia ceramicznego. Pokrycie ceramiczne, które jest nanoszone na model zgazowywany powinno charakteryzować się określonymi| właściwościami fizykochemicznymi w tym: odpornością na termiczne, chemiczne i erozyjne działanie ciekłego metalu oraz odpowiednią przepuszczalnością gazów wytworzonych z zgazowywanego modelu polistyrenowego. W artykule przedstawiono wyniki badań własności, wytypowanych doświadczalnych powłok ceramicznych, nanoszonych na model polistyrenowy w procesie modeli zgazowywanych

Laser cladding of the Fe3Al+TiC pre-placed powders on titanium alloys can form the Fe3Al/Ti3Al+TiC ceramic layers, which improved the surface performance of the substrate. These ceramic layers have been researched by means of scanning electron microscope (SEM) and X-ray diffraction (XRD). Experimental results indicated that the Fe3Al/ Ti3Al+TiC ceramic layer can significantly improve the tribological property of the Ti-6Al-4V alloy surface. However, when the TiC mass percent was above 45 wt.% in the pre-placed coating, the microcrack was produced, and the wear resistance of the ceramic layer decreased. The Fe3Al/TiC laser-clad coating mainly consisted of the Fe3Al, Ti3Al and TiC phases etc., this phase constituent was beneficial in improving the wear resistance of the coating. [ABSTRACT FROM AUTHOR]

A ceramic layer was prepared on the surface of AlO/ZL109 composites by means of micro-arc oxidation (MAO) technique. The surface morphology and phase constituent of the ceramic layer were analyzed using scanning electron microscope and X-ray diffraction. The polarization curves of the composites before and after MAO treatment were measured and analyzed. The results showed that after AlO/ZL109 composites were treated using MAO technique in silicate solution, the ceramic layer formed, and it was composed of Al, Si, and mullite phase. Al and Si came from Al alloy matrix of the composites, and the mullite phase formed in process of MAO. AlO fiber in the composites affects the electric conductivity of the composites, the MAO reaction is promoted, and the ceramic layer forming on the composite material side is slightly thicker than that on the Al alloy side. After AlO/ZL109 composites were treated using MAO technique, the corrosion resistance of the composites is significantly improved. Graphical Abstract: A ceramic layer was prepared on the surface of AlO/ZL109 composites by means of micro-arc oxidation (MAO) technique. AlO fibers in the composites affect the electric conductivity of the composites during MAO and inhibit the inward growth of MAO ceramic layer. Therefore, the outward growth speed of the ceramic layer is quicker than the inward growth speed. [ABSTRACT FROM AUTHOR]

Abstract: Besides ‘bulk’ structural and functional ceramic, a third interesting group of inorganic or ceramic materials exists: particles used for medical applications like contrast agent as building blocks for photonic crystals, as thin or thick layers with controlled porosity or grain sizes showing interesting thermal or electrical behaviour or finally nanostructured ceramic with novel optical and mechanical properties. As high-tech ceramic this type of ceramic needs very well synthesised powders of high purity, defined sizes for the use of quantum effects and small size distributions. Very often, complex powders like core–shell particles with nanometer thin layers are needed to fulfil physical as well as biological demands. Additionally, powder processing is one of the key factors to reach outstanding structural and functional properties. Especially the stability of colloidal suspensions and the drying step during the film manufacturing are objects of the research because nanosized particles cause particular problems normally not observed with micron- or submicron-sized powders. Application of nanosized superparamagnetic iron oxide particles for molecular imaging and cancer treatment and results regarding the manufacturing of thin nanostructured layers for interesting physical (thermal conductivity) and medical (drug delivery) will be presented. [Copyright &y& Elsevier]

Abstract: A theoretical analysis has been carried out to study the efficient microwave processing of discrete food sample ceramic composite attached with ceramic (Al2O3 and SiC) plates. Continuous food sample with a specific thickness corresponding to smaller power absorption is replaced by two discrete samples and processed with ceramic composite. The effective power and temperature distribution are found to be function of discrete food sample ratios, type of microwave incidence and ceramic layer thickness. The effect of ceramic material on various discrete sample ratios have been studied via effective average power vs. thickness of ceramic (Al2O3 or SiC) intermediate for one side and both sides microwave incidence. It is found that power absorption is enhanced significantly for beef sample due to specific thickness of ceramic composite corresponding to one side microwave incidence. The power enhancement is lesser and the temperature difference or thermal runaway is larger for bread samples as compared to beef samples. The enhancement of heat absorption is larger for one side incidence as compared to both sides incidence with identical total intensity of microwave incidence. The role of discrete samples with ceramic composites is significant for highly lossy substances (beef) whereas the composites do not play significant role on optimal processing of low lossy substances (bread). [Copyright &y& Elsevier]

Ceramic/self-assembled monolayer (SAM) bilayer coatings can provide adequate protection for silicon devices, or act as a multipurpose coating for other electronic applications, due to synergistic effects by forming a hybrid coating structure. The organic SAM layer acts as a "template" for the growth of the ceramic layer, while the ceramic layer can provide protection from environmental and mechanical impact. Low-temperature solution-based deposition techniques, namely, an in-situ solution method (biomimetic) and a hydrothermal method, have been employed in this study. Specifically, phosphonate-based (diethyl phosphatoethyl triethoxy silane) SAMs were used as a template to generate a zirconia ceramic layer at low temperatures. Other organic templates such as -SiCl3-, -OH-, -HSO3-, or-CH3-terminated SAMs were also examined. The reactions to grow the ceramic film were found to be pH sensitive. The ceramic and SAM coatings were characterized by a variety of analytical techniques. A pathway for the formation of the ceramic coating is also discussed. [ABSTRACT FROM AUTHOR]

Laser drilling is a non-contact process that can be used to form small holes in a wide variety of materials with a high degree of precision and reproducibility. The advantages of being able to drill difficult materials, specifically superalloys and ceramics, are exploited in the laser drilling of cooling holes in thermal barrier coated superalloys. Plasma sprayed thermal barrier coatings (TBCs) consist of a partially stabilised zirconia top coat and a NiCrAlY bond coat, deposited on a Ni-superalloy substrate. Laser drilling was performed using a pulsed Nd:YAG laser (λ=1.06 μm), with a focussed spot power density of approximately 0.2 MW mm−2. Holes were drilled at both normal and inclined angles of incidence. The effect of drilling from the side of the metallic substrate, rather than the ceramic top coat, has been investigated. Laser-induced microstructural features, such as interfacial cracking, are reported. For the conditions used here, assist gas has a negligible effect on the volume of material removed per pulse, but does create additional features in the resolidified ceramic surrounding the hole. A spontaneous debonding technique was used, in conjunction with a finite difference process model, to investigate the effect of laser drilling on the interfacial toughness of plasma sprayed TBCs. Drilling was found to increase slightly the interfacial toughness of the TBC. This is attributed to the crack arresting effect of a resolidified ceramic layer that partially lines the hole. [Copyright &y& Elsevier]

In order to reduce the thermal load of the gas turbine blade, its surface is covered with an external ceramic layer of high thermal resistance. The main problem considered in our research is the selection of ceramics with a low value of specific thermal conductivity and its thickness of the layer. Obtained values should be chosen, such that the permissible metal temperature is not exceeded at the metal-ceramic boundary. It would result in the loss of mechanical properties. Therefore, for a given temperature distribution at the metal-ceramic boundary, the temperature on the inside of the blade and the initial temperature should determine the temperature function on the external surface of the ceramic. This is a Cauchy type problem. The paper considers the case of one-dimensional, unsteady flow. The influence of heat conduction ratio of the ceramic layer and thickness of the layer was investigated. The results showed, that the implementation of ceramic layer causes a decrease in temperaturee what improves the cooling of metal layer. The authors observed also that the thickness if ceramic layer is crucial – its value should be selected so that not to cause a loss of mechanical properties of metal layer. • The Cauchy problem type in the case of one-dimensional and unsteady heat flow. • Temperature distribution in the two-layer area with metal and ceramic layers. • Influence of ceramic layer properties on the temperature distribution. • Analysis of the relative deviation from the linear temperature in a ceramic layer. [ABSTRACT FROM AUTHOR]