Search

The present study investigates the corrosion behavior of a Mg–Zn–Ca–La alloy. Results indicate that the corrosion resistance is enhanced by rolling deformation and subsequent annealing treatment significantly. The microstructure, distribution of second phase and grain orientation are the main factors affecting corrosion properties. The second phase with semi-continuous network in the as-cast alloy gives rise to the penetration of corrosion into the matrix. However, the dispersed second phase after deformation results in uniform corrosion. The formation of dense corrosion layer at the initial stage of corrosion is favorable for the improvement of corrosion resistance. The sample with 〈0001〉 plane oriented towards surface exhibits good corrosion resistance, which is ascribed to the homogeneous microstructure and strong basal texture.

The effects of aging treatment on corrosion properties of an extruded Mg-8.9Gd-2.8Y-1.8Zn-0.4Zr-0.2Ca (wt.%) alloy were investigated. The as-extruded alloy was consisted of un-dynamically recrystallized region containing lamellar long period stacking ordered (LPSO) phase and block-shaped LPSO phase, finely recrystallized grains and small amounts of Mg-RE phase. After aging treatment, part of lamellar LPSO phases was dissolved into the matrix and replaced by recrystallized grains. The size of recrystallized grain was increased from 1.8 μm for the as-extruded sample and to 3.5 μm for the peak-aged sample. Corrosion tests indicated that aging treatment effectively improved the corrosion resistance of the as-extruded Mg-8.9Gd-2.8Y-1.8Zn-0.4Zr-0.2Ca (wt.%) alloy. The lamellar LPSO phases with a low potential were preferentially corroded, and the homogeneous microstructure of the peak-aged sample effectively reduced the possibility of micro-galvanic corrosion. Hence, the peak-aged sample with a more homogeneous microstructure and small amount of lamellar LPSO phase showed a better corrosion resistance.

The present study investigated anisotropy in tensile behavior of an extruded Mg-4.50Zn-1.13Ca (wt.%) alloy through tensile testing along different tilt angles relative to the extrusion direction. Results showed that the as-extruded Mg-4.50Zn-1.13Ca (wt.%) alloy exhibited anisotropy in tensile behavior due to the formation of basal texture. Basal slip, prismatic slip and tensile twinning were the dominant deformation modes depending on the tensile direction. Prismatic slip was the dominant deformation mode for samples with small tilt angle (θ = 0° and 22.5°). Basal slip was activated when the tilt angle was increased, which also resulted in the decrease of yield strength. Tensile twinning was responsible for the yielding of the samples with high tilt angles (θ = 67.5° and 90°). The ductility was significantly reduced at high tilt angle, which was mainly attributed to the appearance of tensile twinning during tensile deformation.

Titanium nitride (TiN) is widely used in electrode materials in fast charging/discharging supercapacitors (SCs) due to its outstanding conductivity. However, the low capacitance of the TiN electrode limits its further application in the SCs. Therefore, the reasonable design of the TiN electrode with high electrochemical and mechanical properties is still a challenge. In this paper, the silicon nanowires/titanium nitride electrode (Si NWs/TiN) is prepared by depositing TiN onto the etched Si nanowires by direct current magnetron sputtering. The Si NWs are prepared by etching silicon in 4.8 M HF/0.02 M AgNO3 aqueous solution for different times (5 min, 15 min, 30 min, 60 min). The mechanism of the effect of etched silicon substrate morphology on the electrochemical performance of Si NWs/TiN electrode was studied. As the etching time increases, the differences of the TiN surface structure, lattice defects and surface chemical composition will change the capacitance performance and charge storage mechanism of the Si NWs/TiN electrode. The prepared Si30 NWs/TiN electrode exhibits an outstanding specific capacitance as high as 113.55 F g−1 at a scan rate of 5 mV s−1 with 0.5 M H2SO4 solution as electrolyte. The specific capacitance of the Si30 NWs/TiN electrode is as high as 7.5 times that of the electrode without etching at 100 mV s−1. The Si30 NWs/TiN electrode has an excellent cyclic stability performance, which the electrode has a decay rate of 12.4% after 2000 cycles. This indicates that the electrode has reliable stability. The electrode of the supercapacitor prepared by this method can open up a new way to expand the specific surface area of other transition metal nitride.

Thickness and specific surface area of the film electrode are critical parameters for supercapacitors. The relationship between the thickness and the specific surface area of the film directly affects the capacitance and electrochemical stability performance of super supercapacitors, which virtually affects the contact chance of ion in the electrolyte on the surface of electrode and the ion transport path of electrode. In this paper, the CrN thin films with a thickness of 200–3500 nm are prepared using direct current magnetron sputtering. Atomic force microscopy (AFM) technique is introduced to investigate the relationship between thickness and the specific surface area of the CrN films. The electrochemical performances of CrN electrode with the nanoporousper structure is analyzed in different electrolytes H2SO4, Na2SO4 and NaCl aquous solutions. The specific surface area of the film increases linearly with the film thickness increases. The areal capacitance is also linearly related to the specific surface area. The spurtted CrN film with a thickness of 3370 nm has a specific surface of up to 43.59 cm2 per cm2 footprint area. Its areal and volume capacitances reache to 53.92 mF cm−2 and 650 F cm−3 at 5 mV s−1, respectively. In addition, the areal capacitance of CrN film electrode with 655 nm possesses reaches to 40.53 mF cm−2 for 0.5 M H2SO4 solution, 32.69 mF cm−2 for 0.5 M Na2SO4 solution and 9.17 mF cm−2 for NaCl solution at a scan rate of 5 mV s−1. Furthermore, the CrN film electrode exhibits excellent capacitance retention of 95.3%, 93.8% and 89.9% in H2SO4, Na2SO4 and NaCl electrolytes, respectively, after 2000 cycles. Therefore, the sputtered CrN thin film is an potential electrode material for electrochemical supercapacitors.

The mechanical properties of an Mg–Zn–Ca alloy were significantly improved through extrusion deformation. High-density spheroidal Ca2Mg6Zn3 with a diameter ranging from 10 to 50 nm dynamically prec...

A nanobainitic matrix composing of nanoscale α phase and carbon-riched γ phase was obtained for the ductile iron by austempering treatment. The microstructure and properties of ductile iron were compared with GCr15. The microstructural characteristic gave rise to a good strength with an ultimate tensile strength higher than 1200 MPa, which was comparable and even superior to conventionally forged steels. The friction coefficient of the ductile iron was approximate 1/3 compared with that of commercial GCr15 under dry sliding wear condition, which was related to the existence of homogeneously distributed spheroidal graphite in ductile iron. The low friction coefficient and moderate strength resulted in a superior wear resistance of ductile iron with nanobainitic matrix by contrast to GCr15.

In this work, the Metal-rich phase Chromium Aluminum (CrAl)/Ceramic phase Chromium Aluminum Nitride (CrAlN) multi-layer coatings were prepared by Arc Ion Plating (AIP). The micro-structure and phase composition of CrAl/CrAlN multi-layer coatings were characterized, and the microstructure, mechanical properties, residual stress and fracture toughness of the coating were emphatically analyzed. It has been found out that the residual stress of the multi-layer coating was only −0.932 ± 0.065 GPa, which was significantly lower than that of the mono-layer coating for −1.569 ± 0.093 GPa. At the same time, it was also found that the preferred growth orientation of the coating changed from a mono-layer (111) to a multi-layer (200) crystal plane. The hardness of the multi-layer (22.74 ± 0.57 GPa) is slightly lower than that of the mono-layer (24.92 ± 0.5 GPa), and the adhesion strength (46.2 ± 3.8 N) is obviously higher than that of the mono-layer (37.4 ± 2.4 N), and the fracture toughness is also higher (8.7 ± 0.8 MPa m1/2). In addition, the mechanism of crack initiation and propagation in stress-induced coatings was studied in detail on the basis of the structure of micro-nano CrAl/CrAlN multi-layer coatings.

Directionally solidified Al2O3/SmAlO3 (SAP) eutectic ceramics were successfully prepared with an optical floating zone furnace. The crystallographic orientation and interfacial structures were investigated by electron backscattered diffraction and transmission electron microscopy. It was found that Al2O3 has one preferred growth direction but the SAP has two. The preferred growth direction of the directionally solidified Al2O3/SAP eutectic ceramics was 〈10 1 ¯ 0〉Al2O3 || 〈100〉SAP || 〈011〉 SAP. The near-coincidence site lattice models were proposed to interpret the intergrowth of the two SAPs. It was found that the two interfaces have nearly the same volume strain, validating the coexistence of both orientation relationships.

Titanium nitride (TiN) films were generated in the abnormal glow discharge (AGD) region and the glow-arc transition discharge (GATD) region by varying target current density (Ja) in an Ar/N2 atmosp...

Large size, high-density (99.97%) and well-organized Al2O3/Y3Al5O12 (YAG) eutectic ceramics were prepared by the modified Bridgman method. The evolution of the three dimensional microstructure and micropores were investigated. The diameter of the micro-pores and the porosity decreased during directional solidification. The average equivalent diameter of the micro-pores was 2.41 μm in the well-prepared eutectic ceramics. Most of the pores (98.07%) were smaller than 4 μm. These data are comparable to those prepared by the optical floating zone method. The as-grown eutectic ceramics were polycrystalline, but the interfaces were well-bonded and there were no amorphous phases in the microstructure. The misfits of the different crystallographic relationships were calculated, and the bottleneck of the single-crystal preparation was identified. These results could provide theoretical guidance for the preparation of large, single-crystal Al2O3/YAG eutectic ceramics by the modified Bridgman method.

Natural bio-ceramics have attracted extensive interests due to its high strength and high toughness, which can hardly be achieved in artificial ceramics simultaneously. In this work, the microstructure and properties of the wild boar's tusk enamel were investigated. The enamel was found to exhibit a hierarchical structure ranging from the hydroxyapatite (HAP) fibers (single or poly-crystals, nano-scale), enamel rods (micro-scale), enamel types (meso-scale) to enamel patterns (macro-scale). It is worth mentioning that the high-density and high-order hierarchical nanotwins were observed in the HAP fibers. The mechanical properties of the wild boar's tusk enamel showed strong anisotropy and were higher along the longitudinal direction than along the transverse direction. The mechanical properties varied from the dentin-enamel junction (DEJ) to the outer surface. The elastic modulus increased with the distance from the DEJ and then kept invariant. The nano-hardness increased in inner enamel but decreased in outer enamel. There was a peak of nano-hardness in inner enamel area. The fracture toughness showed an opposite tendency. It exhibited high values in inner enamel, but fell in the outer enamel zone. The irregular, decussating texture of the enamel, as well as the nanotwins/hierarchical nanotwins was considered as the main reason for its excellent mechanical properties. These unique structures of the wild boar's tusk enamel are expected to cast light on the design of medical materials and provide some guidelines to improve their mechanical properties.

Plasma electrolytic oxidation (PEO) was carried out on AZ91 and WE43 Mg alloys in phosphate electrolyte. The effects of β-phases on growth behaviors of PEO coatings formed on two Mg substrates were analyzed and compared. Results showed that PEO coatings developed heterogeneously in two Mg substrates due to the existence of β-phases. Before discharge breakdown, conversion film initially grew on α-Mg matrix and spread to β-phase (Mg17Al12) in AZ91 alloy, while it preferentially formed around β-phase (Mg14Nd2Y) rather than α-Mg matrix in WE43 alloy. This was attributed to the different reactivity of β-phases in two Mg alloys. After discharge breakdown, the micro-pores in PEO coatings grew on β-phases were larger in size as compared with that on α-Mg matrix. With the treated time, the inhomogeneous growth of PEO coatings disappeared gradually and PEO coatings became uniform. Finally, β-phases did not destroy the continuity of PEO coatings.

The dynamic precipitation behavior of a Mg-Zn-Ca-La alloy during deformation has been investigated. A large amount of fine precipitates was detected after deformation, indicating that dynamic precipitation occurred. The precipitates at the grain boundaries included Ca2Mg6Zn3 and Mg4Zn7, whereas the intergranular precipitates were mainly Mg4Zn7. Ca, which has a large atomic radius, preferred to segregate to grain boundaries, where it resulted in the formation of Ca2Mg6Zn3. Zn, which has a similar diffusion coefficient to Mg, resulted in Mg4Zn7 being distributed around the matrix. The stability of the Mg4Zn7 phase was enhanced in the as-extruded Mg-Zn-Ca-La alloy. The grain-boundary precipitates acted as effective obstacles to grain growth, giving rise to the formation of a refined microstructure. The intragranular Mg4Zn7 precipitates hindered the mobility of dislocations, improving the mechanical properties. Additionally, a high density of ultrafine nanoparticles was detected in the un-dynamically recrystallized (DRXed) region, being related to the high density of dislocations therein.

TiSiN-Ag composite coatings with different Si doping contents were prepared by multi-arc ion plating technology on 316L, TC4, and H65 copper substrates, respectively. The microstructure of the prepared coatings was characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy, respectively. The mechanical properties, electrochemical properties, and tribological properties were characterized by a micro-hardness tester, electrochemical workstation, scratch tester, and friction and wear tester, respectively. Results showed that the coatings with 8 wt.% Si doping content had a smaller average grain size, denser structure, excellent mechanical properties, and better anti-tribocorrosion performance than those with 5 wt.% Si doping content. The coating on the TC4 substrate with 8 wt.% Si doping content presented the best combination of properties and is a candidate for an anti-tribocorrosion material in seawater.

Severe shot peening (SP) was performed on the AZ31 and AZ91 Mg alloys to obtain a nanostructured surface layer. The microstructure, micro-hardness and corrosion behavior of AZ31 and AZ91 Mg alloys after SP treatment were studied using transmission electron microscopy, micro-hardness tester and corrosion tests, respectively. Results showed that SP treatment produced a plastic deformation layer with α-Mg grains at the nanometer scale in the surface of AZ31 and AZ91 Mg alloys. After SP treatment, the micro-hardness in the near surface region displayed an obvious increase for two alloys, owing to the combination of the grain refinement and the work-hardening. The corrosion resistance of AZ31 alloy was improved by SP treatment, because a relatively compact passive film formed rapidly on the nanostructured surface. Unfortunately, SP treatment played a minor role in enhancing the corrosion resistance of AZ91 alloy, because it had little effect on size and distribution of β-phases.

The weatherability of soluble lead flow battery is critical to its large-scale and safety application. In this work, physicochemical properties of PbO2 deposits are investigated at different temperatures, 50, 20, 0 and -20 °C. The deposit formed at low temperature has the higher discharge capacity than that formed at high temperature when they are discharged at the same temperature of 20 °C. With the temperature decreased from 50 to -20 °C, the relative content ratio of α-PbO2: β-PbO2 changes from 0: 100 to 33: 67. The non-stoichiometric ratio of Olattice: Pb in PbO2 deposits increases from 1.31 ± 0.15 to 1.67 ± 0.18. And particle sizes of PbO2 deposits become fine, from 4.29 ± 1.71 to 2.08 ± 0.93 µm, and their distributions become narrow. This indicates that physicochemical properties of PbO2 deposits can be improved by increasing activation overpotential through decreasing temperature. However, the cycling performance of batteries becomes worse at low temperature, even though the high activity PbO2 deposits is obtained after charge. It can be well explained from the limiting current-density and exchange current density of positive electrode significantly decreases with decreasing temperature.

Micro arc oxidation (MAO) coatings doped with graphene oxide (GO) were prepared on pure titanium by adding GO and sodium dodecyl benzene sulfonate (SDBS) into a sodium silicate solution. The as-deposited coatings were comparatively analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The binding forces of the MAO, MAO+GO and MAO+GO+SDBS three coatings were measured by a scratch tester. The mechanical property of the three coatings was analyzed using the nano-indentation technique. The corrosion resistance of the coatings was tested by the electrochemical system in 3.5% NaCl solution. The photocatalytic activity of the prepared samples was evaluated by determining the degradation of methylene blue (MB) solution. The results showed that compared to the MAO coating, the morphologies and phase compositions of MAO+GO and MAO+GO+SDBS composite coatings were significantly different. These two composite coatings all had superior photocatalytic activity. Especially, the MAO+GO composite coating still had enhanced binding force and excellent corrosion resistance. Furthermore, the relationship between the microstructure and the properties of these three MAO coatings was analyzed.

The microstructure and texture evolution of Mg-Zn alloy during recrystallization was investigated by EBSD in the present study. Deformed region, fine DRXed region and coarse DRXed region were obtained in Mg-Zn alloy during deformation. It was found that the texture intensity in DRXed region was weaker compared with the deformed region. The second phase at grain boundaries resulted in the formation of fine DRXed grains with weaker texture compared with the coarse DRXed region. Additionally, a remarkable grain-size driven textural transition from ⟨10.0⟩–⟨11.0⟩ texture to ⟨11.0⟩ texture were detected with the growth of DRXed grains. The recrystallized grains with small grain size showed a fiber texture distributing homogeneously between ⟨10.0⟩ and ⟨11.0⟩, while ⟨11.0⟩ fiber texture was predominant for the large recrystallized grains. It is suggested that ⟨11.0⟩ oriented grains grew faster than other oriented grains, which was ascribed to larger misorientation between ⟨11.0⟩ oriented grains and their neighboring grains.

In order to study the spontaneous escape behavior of silver in ion plating coatings and its inhibition mechanism, a series of silver-doped titanium nitride coatings were prepared by magnetron sputtering. The effect of cluster interface structure on the spontaneous escape behavior of silver in ion plating coatings were observed, and various thicknesses of homogenous silver-free barrier layers were explored to achieve the permanent retention of silver. Results showed that for silver-doped titanium nitride coatings prepared with the silver target current increased from 0.01 A to 0.2 A, more spontaneously escaped silver particles were observed at the cluster interface of the coating and were far from being crystallized into a layered structure. Approximately 500 nm pure titanium nitride surface cover could achieve the permanent retention of silver in titanium nitride coatings with a high dopant content of silver. The cluster interfaces of the titanium nitride coating interdigitated with each other to form a dendritic network structure. The interdigitated dendritic network structure blocked the spontaneous escape of silver and achieved the permanent retention of silver in the titanium nitride coating.

The hot deformation behavior and processing characteristics of Mg–3Zn–0.3Ca–0.4La (wt%) alloys were investigated by hot compression deformation. The results suggested that deformation parameters had significant effects on deformation behavior and dynamic recrystallization of the Mg–Zn–Ca–La alloy. The average activation energy of deformation was calculated to be 188.9 kJ/mol. The processing map was constructed and analyzed based on the dynamic material model, and the optimum hot working window of the alloy was determined to be the temperature of 350 °C and the strain rates between 0.001 and 0.01 s−1. Furthermore, the DRX kinetic model of the Mg–3Zn–0.3Ca–0.4La (wt%) alloy was established, which implied that incomplete dynamic recrystallization occurred for the Mg–Zn–Ca–La alloy in the present work. Microstructure analysis indicated that deformation parameters played a critical role on the microstructure optimization. The dynamically recrystallized (DRXed) region fraction and the DRXed grain size were increased with the increase of deformation temperature and decrease of deformation rates.

The microstructure of an Mg–Zn–Ca extrusion was investigated by transmission electron microscopy, and the interaction between dynamic precipitation and dynamic recrystallization was analyzed. The results showed that dynamic precipitation significantly affected the microstructure of the as-extruded Mg–Zn–Ca alloy. The pinning effects of precipitates on dislocations effectively prohibited dynamic recrystallization processes, while the grain boundary precipitate Ca2Mg6Zn3, inhibited the growth of dynamically recrystallized grains. Consequently, a bimodal microstructure with fine dynamically recrystallized (DRXed) grains and elongated deformed regions was obtained for the Mg–Zn–Ca extrusion. High-resolution transmission electron microscopy indicated that the intragranular precipitate MgZn2 had a crystal orientation relationship with α-Mg in the form of (0002)Mg//(10–13)MgZn2 and [1–100]Mg//[1–210]MgZn2, which was beneficial for strength improvement.

The present study compared the effects of minor addition of Ca and Ce on microstructure and mechanical properties of Mg-3Zn (wt. %) alloys. Results showed that Ce or Ca refined the microstructure and affected the texture obviously. Ca weakened the intensity of basal texture, whilst a non-basal texture was obtained for Ce containing alloy. Such texture modification are related to the solid solution of solution atoms and gave rise to the improvement of ductility. Compared with Ca, Ce was more effective to modify the texture and improve the plasticity.

In order to improve the tribological performance, a series of graphite-like carbon (GLC) films with different graphite target power densities were prepared by magnetron sputtering. The valence bond and microstructure of films were characterized by AFM, TEM, XPS and Raman spectra. The variation of mechanical and tribological properties with graphite target power density was analyzed. The results showed that with the increase of graphite target power density, the deposition rate and the ratio of sp2 bond increased obviously. The hardness firstly increased and then decreased with the increase of graphite target power density, whilst the friction coefficient and the specific wear rate increased slightly after a decrease with the increasing graphite target power density. The friction coefficient and the specific wear rate were the lowest when the graphite target power density was 23.3 W/cm2.

The single crystal of Al2O3/Y3Al5O12/ZrO2 ternary eutectic was prepared by an optical floating zone furnace. The crystallography and interfacial structure of the directionally solidified ternary eutectic were investigated by means of electron backscattered diffraction and transmission electron microscopy. We found that the preferred crystallographic orientation of the Al2O3/Y3Al5O12/ZrO2 eutectic crystal was { 11 2 ¯ 0 }〈 1 1 ¯ 00 〉Al2O3 ||{001}〈001〉Y3Al5O12 ||{001}〈001〉ZrO2. Most of the tiny ZrO2 locates dispersively between Al2O3 and Y3Al5O12. It can be concluded that interfacial energy between Al2O3-Y3Al5O12-ZrO2 played an important role in deciding the preferred crystallographic orientations of the Al2O3/Y3Al5O12/ZrO2 eutectic and the precipitation behavior of the ZrO2 phase.

An investigation on the corrosion protection and electrical conductivity films on metal bipolar plates can be achieved through magnetron sputtering. This work characterized the microstructures of TiN–Ag nanocomposite deposited at different temperatures with thermal stabilization. All the TiN–Ag films show adequate electrical conductivity with the interfacial contact resistance (ICR) of 4.81, 4.78, 4.52, 4.18 mΩ cm2 at the deposition temperature of 200 °C–350 °C on SS substrates, respectively, and corrosion resistance with the corrosion current density (Icorr) of 0.678, 0.526, 0.293, 0.596 μA cm−2. Additionally, the TiN–Ag film possesses the hydrophobic property with a static water contact angle of 106.7° at 350 °C. In summary, the TiN–Ag film on SS at 350 °C shows the potential application as metal bipolar plates of PEMFCs.

In this work, we prepared N-doped reduced graphene oxide/Co0.85Se (N-rGO/CS) microflowers through a two-step method. Since introducing N-doped rGO, the fabricated N-rGO/CS electrode with a high mass loading (~8.83 mg/cm2) exhibits high areal specific capacity of 0.522 mAh/cm2 (4.24 F/cm2) at 1 mA/cm2, and a long-term cycling stability (85.8% of capacity retention after 6000 charge-discharge cycles). This is mainly because N-doped rGO can increase specific area and electrical conductivity, enhance the electrochemical activity and effectively facilitate the electron/ion transport between the electrode and electrolyte. Besides, the quasi-solid-state hybrid supercapacitors (HSCs) assembled by the N-rGO/CS delivers a high volumetric specific capacity of 5.82 mAh/cm3 at 1 mA/cm2, excellent energy density of 4.65 mWh/cm3 under 10.5 mW/cm3 and eminement cycle stability (87.6% retention over 6000 cycles at 10 mA/cm2).

The microstructure and tensile property of extruded Mg–6Zn–1.5Ca (wt%) alloy were examined by means of electron backscattered diffraction, scanning and transmission electron microscopy. A bimodal microstructure featuring fine dynamically recrystallized (DRXed) grains with weaker texture and coarse-deformed region with strong basal texture and fine precipitates was achieved in the as-extruded Mg–Zn–Ca alloy, which resulted in a yield strength as high as 305 MPa and a moderate elongation to fracture of 8.6%. Dynamic precipitation was detected in the deformed region, which inhibited the dynamic recrystallization process. The texture intensity in the DRXed region was weakened compared with that in the deformed region, which was associated with the preferred nucleation during dynamic recrystallization. Such texture weakening effects gave rise to an obvious ductility improvement for the as-annealed alloy.

The present research investigated ageing treatment on dynamic recrystallization and texture in Mg-Zn alloy by optical microscopy (OM), transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD). Mg-6 wt.%Zn alloys were firstly solution and ageing treatment, and then the solutionized and peak-aged alloys were compressed at elevated temperature. The microstructure and texture were systematically investigated. Optical microstructure showed that ageing treatment prohibited dynamic recrystallization during deformation, which was because the precipitates inhibited dislocation movement and restricted the formation of deformation bands. The DRXed region and deformed region both contained typical basal texture with basal planes oriented perpendicular compression direction, but the recrystallized region showed a much weaker texture. The peak-aged alloy containing rod-shaped precipitates exhibited stronger texture intensity after dynamic recyrallization compared with the as-solutionized alloy, which was because the precipitates in the peak-aged alloy inhibited the lattice rotation of the newly formed DRXed grains or affected the microstructural evolution.

An Al2O3/Y3Al5O12 eutectic ceramic was prepared with a c-axis sapphire seed by an optical floating zone furnace. The crystallographic relationships in the initial and the steady growth sections of the as-grown eutectic ceramic were investigated by electron backscattering diffraction and transmission electron microscopy. The corresponding results were: {101}Y3Al5O12 || {112¯0}Al2O3 and {21¯1}Y3Al5O12 || {0001}Al2O3, respectively. The steady orientation of the latter one shows smaller planar disregistry. Interfacial strain played the decisive role in affecting the solidification behavior of the Al2O3/Y3Al5O12 eutectic ceramic. The stability of interfaces with minimum interfacial strain and better ionic charge balance in irregular microstructure prevail upon the constraint of the seed. These results might cast light for the interfacial design of the Al2O3/Y3Al5O12 binary eutectic ceramic. This article is protected by copyright. All rights reserved.

Molybdenum nitride (MoN x ) coatings with different nitrogen content were deposited by reactively sputtering molybdenum metal target with various N 2 flow rate. The structure of the coatings were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectrometry (XPS). The mechanical and tribological properties of the coating were evaluated by nano-indentation and ball-on-disc wear tests, respectively. The structural analysis showed that these coatings changed from bcc α-Mo phase to fcc γ-Mo 2 N phase, and then to fcc B1-MoN with the increase in N 2 flow rate. As the phase structure changed from α-Mo to γ-Mo 2 N, the MoN x coatings exhibit finer grain sizes and denser crystal structure, which have dramatic contribution on hardness enhancement. The γ-Mo 2 N coating exhibits the highest hardness with the value of 32.5 GPa. As phase structure further changed to B1-MoN coating, a slight decline of hardness can be observed. The γ-Mo 2 N structured coatings exhibited lower COF than that of mainly Mo structured MoN x coating or B1-MoN coating.

Amorphous Al2O3 coating with a thickness of 143 &mu, m was firstly prepared by anodic oxidation, then the amorphous Al2O3 was transformed into crystalline Al2O3 through applying micro arc discharge. The crystal structure of the Al2O3 coatings was analyzed with an X-ray diffractometer. Results indicated that the coating consisted of amorphous and crystalline Al2O3. The microstructure of the coating was characterized by scanning electron microscopy, which showed that the coating had a compact structure. The thermal conductivity of the coating was 23.7 W/m&middot, K, which is significantly higher than that of amorphous Al2O3 coating. The total and specific breakdown voltages of the coating were 3.85 kV and 26.92 kV/mm, which is suitable to apply for high power LED heat sink substrate.

Micro-arc oxidation (MAO) was performed on AZ31 and AZ91 Mg alloys to explore the relationship between Mg substrates and corrosion behaviors of resultant coatings. The microstructure and long-term corrosion performance of the two coatings were investigated. Results showed that MAO coating on AZ91 alloy provided a longer-term corrosion protection to substrate than that on AZ31 alloy, despite having similar microstructure and phase composition. However, once corrosion occurred, the corrosion area of MAO coating on AZ91 alloy enlarged at a faster rate compared to that on AZ31 alloy during immersion tests, and their corrosion morphologies were different. Based on the corrosion features of Mg substrates and MAO coatings, roles of substrates on the corrosion processes of coatings were analyzed.

Micro arc oxidation (MAO) coatings with green or black color were obtained on a 6061 Al alloy in a new Cr-containing electrolyte system. Compared to the white coatings obtained with traditional electrolytes, this black coating has the characteristics of self-sealing pores and different chemical compositions. The microstructure and composition of the different coatings were comparatively studied by field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS), respectively. The mechanical property, tribological behavior and corrosion resistance of the MAO coatings were systematically investigated using nano-indentation, tribological tester and electrochemical corrosion tests. The results indicated that the green MAO coating with a porous structure had Cr2O3 distributed into the Al2O3 ceramic coating with a little of K2Cr2O7 addition into the base solution, and the black MAO coating with a self-sealing microstructure contained Cr2O3 and CrO3 with a large amount of K2Cr2O7 addition into the base solution. The hardness values of the MAO coatings with an increase of Cr at% increased first and then decreased due to the compact structure and different compositions of the MAO coatings. Compared with the other MAO coatings, the self-sealing black MAO coating with a high Cr content showed greatly improved wear resistance and corrosion resistance for its special microstructure. Furthermore, the formation mechanism of these MAO coatings with Cr addition has been revealed and the relationship between microstructure and properties has been discussed.

Nanocrystalline Ti films were deposited by continuous dc magnetron sputtering (dcMS), pulsed dc magnetron sputtering (PMS) and cathodic arc evaporation (CAE) separately. Their structures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Mechanical and corrosion properties were studied via nanoindentation, microscratch test and electrochemical measurement. It was found that the dcMS Ti film exhibited a loose porous columnar structure with low film-substrate adhesion. Abundant macroparticles could be observed on the surface of CAE Ti film and it had a low film-substrate adhesion. On the other hand, the ion flux and ion energy of deposited particles in the PMS plasma were enhanced by increasing the average target power and decreasing the area of the sputter track as compared to those of the dcMS plasma. The high-power-density PMS Ti film exhibited a dense microstructure, fine grain size and smooth surface, with jointly enhanced corrosion resistance (corrosion current density of 0.04 μA · cm− 2) and film-substrate adhesion (critical load of 50 N).

Nanoaprticles(Nps)-Ag/TiO 2 multilayer films with different working pressures of Ag and inserted SiO 2 shell layers between Ag and TiO 2 were prepared by alternate magnetron sputtering. The formation of Ag nanoparticles embedded in TiO 2 matrix was confirmed by the XRD and TEM results. The optical absorption peaks assigned to the surface plasmon resonance (SPR) of Ag nanoparticles were observed in the wavelength range of 550–750 nm. With increasing working pressure of Ag, the SPR peaks show blue-shift due to the decreasing Ag Nps size and increasing spacing between them. Compared with the pure TiO 2 film, the Nps-Ag/TiO 2 and Nps-Ag/SiO 2 /TiO 2 film show significantly enhanced Raman scattering due to the strong local field induced by the SPR of Ag nanoparticles, and the enhanced photocatalytic activity of Nps-Ag/TiO 2 film is related with the improved charge separation by the embedded Ag nanoparticles.

The Mg–6 wt% Zn alloys microalloyed with different amounts of La were cast and extruded. The second phase in the as-cast Mg–Zn alloy is Mg4Zn7, which was replaced by Mg–Zn–La intermetallics with orthorhombic structure after La addition. Microalloying with La refined the grain size of dynamic recrystallization slightly, which was due to La solute atom in α-Mg alloy. Addition of La weakened the texture and gave rise to the formation of non-basal texture component, attributing to the existence of La in the form of solute atoms in matrix. The ductility was enhanced significantly by adding La to Mg–6 wt% Zn alloy, while the strength was reduced. Such phenomenon was related to the weakening texture of the La containing alloys. The Mg–6Zn–0.2La (wt%) alloy exhibited a superior ductility with the elongation-to-fracture up to 35%. However, with further increasing of La content to 1 wt%, the strength of the as-extruded Mg–Zn–La alloys was not improved but the ductility was reduced, suggesting that small addition of La is preferred for the improvement of mechanical properties.

In an appropriate electrochemical environment, the discrete thermal electron emission could be induced in the micro area due to the uneven distribution of electron flux on the anode surface. Thus an oxygen molecule could be ionized at the liquid-solid interface after collision, and then oxygen plasma with distribution characteristics would be formed. The plasma electrolytic oxidation (PEO) could happen at the liquid-solid interface. In this work, the low carbon steel was used to study the deburring process by PEO at a high frequency (70000 Hz) pulse DC mode. Its burr height H from 3.23 mm to 0.04 mm was removed to form a smooth surface within 6 min. The values of corrosion potential and current density for the untreated sample were −0.667 V and 6.735×10−5 A/cm2, respectively. But for the treated sample, the corrosion potential and current density were relatively lower, −0.354 V and 1.19×10−7 A/cm2. Therefore, PEO was expected to be a new deburring method of carbon steel for the material processing field.

Micro arc oxidation (MAO) coatings doped with graphene oxide (GO) were prepared on the 6061 Al alloy substrates in the electrolyte composed of an aqueous solution of sodium silicate (Na2SiO3·9H2O, 20 g L−1) and 100 mg L−1 GO. The microstructure, mechanical property and tribological behaviour of the MAO + GO composite coatings were comparatively investigated. Results indicated that GO was easily dispersed into the solution for MAO coatings preparation. Little of GO in the composite coating was observed by field-emission scanning electron microscopy and energy dispersive spectrometer. This composite coating with increased proportion of α-Al2O3 phase still exhibited a porous microstructure like MAO coating but with an improved binding force, mechanical property and tribological behaviour. Furthermore, the tribological behaviour of this composite coating sliding against with hard alloy steel (YG6), silicon nitride (Si3N4) and High-carbon chromium bearing steel (GCr15) had been analysed.

The effects of partitioning treatment on microstructure and mechanical properties of austempered ductile iron (ADI) were investigated in the present study. The microstructure of the ADI sample was composed of spheroidal graphite, nano-scale α phase, and high-carbon γ phase. During the partitioning process, the carbon atoms transported from α phase to γ phase, which resulted in the coarsening of α phase and the increase of carbon concentration in γ phase. The carbon concentration in γ phase was increased from 1.6 wt% for ADI to about 2.1 wt% for the sample after partitioning treatment. These microstructure variations resulted in an increase in plasticity by about 50% without sacrificing strength.

Optimizing the electrolytic composition is of practical interest to evaluate the flow battery's weatherability. In this work, the electrolytic composition is optimized for different temperature ranges according to the physicochemical characteristics of electrolyte from −30 °C to 50 °C. The solubility curves of lead methanesulfonate are obtained in methanesulfonic acid, and an equation is proposed among lead methanesulfonate's content, methanesulfonic acid's content and temperature. The conductivity and dynamic viscosity of electrolytes with different compositions can be enhanced by increasing temperature. The voltage efficiency of cell is improved with increasing temperature, but the coulombic efficiency has the maximum value around 30 °C. The high energy efficiency can be achieved by increasing the concentration of H+ below 0 °C or increasing the concentration of Pb2+ above 30 °C. The electrolytic composition of 1.5 M Pb2+ and 1.0 M H+ is suitable for the temperature range of −20 °C − 50 °C. It is also found that the concentration of H+ is demanded at least 0.17 mol/L for charging the battery.

The thin-film electrode for supercapacitors has broad prospects for providing high energy storage capacity. However, the microstructure of dense film resulting in poor ion access limits its capacitance still far below the theoretical value. Here, CrN thin film electrodes with good cycle performance can be prepared by tuning the porosity of the film at the nanoscale level. The atomic diffusion process and atomic peening effect that occur during the sputtering process of chromium nitride are the pivotal parameters for generating porosity and high specific surface area. During the controlled sputtering process, an increase in the nitrogen flow rate causes an increase in the porosity in each column (intracolumnar porosity), while an increase in temperature controlling the gap between two columns (intercolumnar porosity). When the nitrogen flow rate is 10 sccm and the deposition temperature is 250 °C the CrN film has the areal capacitance of 41.7 mF cm−2, 10 mV s−1 at the thickness of 950 nm. In addition, the CrN film has good electrochemical cycling stability, the capacity retention rate is still as high as 93.2% after 20,000 cycles. Therefore, the CrN film electrode has a promising application prospects in energy storage systems such as supercapacitors.

Highly conductive silver nanoparticles doped in graphite-like coating (GLC) can significantly optimize the conductivity of the film, while Ag and carbon could not form stable compounds, leading to rapidly escaping of Ag atoms to the surface of coatings. In this work, Ag doped GLC films deposited by magnetron sputtering technique at different temperatures (200–350 °C) are investigated. The results show that silver aggregates into nanowires along the carbon cluster interface in GLC at the deposition temperature of 350 °C and films show excellent hydrophobic property with the contact angle as high as 128.68°, interfacial contact resistance as low as 3.76 mΩ·cm2, and corrosion resistance improving remarkably, indicating that thermal stabilization under negative pressure can optimize film performance to make it as an excellent candidate for metal bipolar plates.

In lead methanesulfonate flow battery, with the charge/discharge cycling, some PbO2 drops into the electrolyte, decreasing the efficiency of the battery and limiting its service life. In this work, an aqueous solution of soluble lead trifluoromethylsulfonate is firstly proposed as a supporting electrolyte for the lead soluble flow battery. Its efficiency and the cycling stability can be improved. Compared with the Pb(CH3SO3)2/CH3SO3H electrolyte, the kinetics and reversibility of PbO2/Pb2+ are improved in the Pb(CF3SO3)2/CF3SO3H electrolyte. The charge voltage in the Pb(CF3SO3)2/CF3SO3H electrolyte is lower than that in the Pb(CH3SO3)2/CH3SO3H electrolyte at the same current density in the range of 10 - 60 mA cm−2. Moreover, the PbO2 layer deposited in the Pb(CF3SO3)2/CF3SO3H electrolyte is smooth and compact, no any PbO2 particles are observed to drop off from the positive electrode over tens of cycles. Pb particles are smaller than those deposited in the Pb(CH3SO3)2/CH3SO3H electrolyte. More impressively, the high columbic efficiency is dropped down to 80% after 244 cycles at a current density of 40 mA cm−2 by employing the Pb(CF3SO3)2/CF3SO3H electrolyte.

The phase constituents and mechanical properties of Cr/CrAlN and Cr/CrN/Cr/CrAlN coatings which prepared by Arc Ion Plating were investigated in this work. The stress variation of the coating process was investigated by the finite element method and the failure mechanism of the coatings was analyzed. The results suggested that the, Cr/CrN/Cr/CrAlN coating have fewer surface micro-particles, higher adhesion strength (86.7 ± 2.1 N), and lower residual stress (−1.665 ± 0.042 GPa) compared with Cr/CrAlN coating. In addition, the erosion resistance performance of the multilayer coatings is obviously higher than that of the uncoated specimen. According to crack growth and stress analysis, it is found that Cr/CrN/Cr/CrAlN coating has better longitudinal and transverse stress dissipation ability. During the impact of solid particles, high tensile stress is the main reason for the formation and propagation of brittle cracks in the coating. In addition, according to the plastic-brittle (DBT) transition of the Cr layer, it is inferred that the fracture failure mechanism of the coating is a joint mechanism of brittleness and toughness.

The tribological behavior of austempered ductile iron (ADI) obtained at different austempering temperatures is investigated. The microstructure of ADI is consisted of spheroidal graphite, retained austenite and acicular ferrite. The volume fraction of retained austenite and the thickness of acicular ferrite increase with increasing austempering temperature, which results in strength reduction but plasticity increasement. With the increase of austempering temperature, the friction coefficient changes little under low load (5 N) but decreases under high loads (10 N and 15 N), whilst the wear rate increases under low load (5 N) but changes little under high loads (10 N and 15 N). This wear behavior is attributed to the combined effects of hardness and friction coefficient. Additionally, adhesive and abrasive wear are main failure mechanisms for ADI under dry sliding wear condition.

In this work, different soluble lead electrolytes, lead methanesulfonate, lead trifluoromethylsulfonate and lead perchlorate are selected to investigate the characteristics of anodic electrodeposited materials. The charge current is large in Pb(CF3SO3)2/CF3SO3H electrolyte, followed by those in Pb(ClO4)2/HClO4 and Pb(CH3SO3)2/CH3SO3H solutions at the same positive electrode potential of 1.7 V vs. SCE. Physiochemical properties of PbO2, such as the particle size and its distribution, α-phase and β-phase, and the non-stoichiometry of PbO2 are investigated using SEM, XRD and XPS. PbO2 particles have a ball shape, which are electrodeposited in different electrolytes. Their sizes are 1.97 ± 0.84, 1.13 ± 0.35 and 1.78 ± 0.21 μm in Pb(CH3SO3)2/CH3SO3H, Pb(CF3SO3)2/CF3SO3H and Pb(ClO4)2/HClO4 electrolytes respectively. α-PbO2 has a larger grain size than β-PbO2 in those three electrolytes. PbOx (x = 1.72) with the highest oxygen content is obtained in Pb(CF3SO3)2/CF3SO3H electrolyte. Compared with other solutions, the reversibility of PbOx/Pb2+ exhibits the best in Pb(CF3SO3)2/CF3SO3H electrolyte, and the coulombic efficiency of 96.0 ± 0.4% is achieved.

The temperature adaptability of the lead methanesulfonate flow battery is evaluated from 253 K to 323 K. The energy efficiency reaches the maximum value of 85.7% at 313 K. The overpotentials of positive and negative couples decrease with increasing temperature, especially for the PbO2/Pb2+ couple. The high temperature can not only promote the diffusivity of ions, but also reduce the charge transfer resistance Rct and electrolyte resistance RL, which lower the electrode overpotential to improve the voltage efficiency. The coulombic efficiency of flow cell is mainly attributed to the reversibility of PbO2/Pb2+ half reaction, and the maximum value of 97.6% is achieved at 303 K. Many more defects and clusters appear on Pb and PbO2 deposited layers at low temperature. The particle size of PbO2 increases with increasing temperature, and the pure β-PbO2 can be obtained at 323 K. With the temperature increasing, the grain size of Pb is increased, and especially PbO2’s is apparently enlarged.