Superhydrophobicity of Bionic Alumina Surfaces Fabricated by Hard Anodizing

Bionic alumina samples were fabricated on convex dome type aluminum alloy substrate using hard anodizing technique. The convex domes on the bionic sample were fabricated by compression molding under a compressive stress of 92.5 MPa. The water contact angles of the as-anodized bionic samples were measured using a contact angle meter （JC2000A） with the 3μL water drop at room temperature. The measurement of the wetting property showed that the water contact angle of the unmodi- fied as-anodized bionic alumina samples increases from 90° to 137° with the anodizing time. The increase in water contract angle with anodizing time arises from the gradual formation of hierarchical structure or composite structure. The structure is composed of the micro-scaled alumina columns and pores. The height of columns and the depth of pores depend on the ano- dizing time. The water contact angle increases significantly from 96° to 152° when the samples were modified with self-assembled monolayer of octadecanethiol （ODT）, showing a change in the wettability from hydrophobicity to su- per-hydrophobicity. This improvement in the wetting property chemical modification. is attributed to the decrease in the surface energy caused by the

Optical and Electrical Properties of ZnO/CdO Composite Thin Films Prepared by Pulse Laser Deposition

有不同 CdO 内容的 ZnO/CdO 合成电影被脉搏激光免职技术获得。合成电影的结构、光、电的性质被 X 光衍射，光致发光和电的抵抗力大小分别地调查。结果证明紫外排放在在光致发光系列的一个经常的山峰位置。同时，他们的电的抵抗力减少到到 CdO 电影的价值的很低级的来临，它能被抵抗力的 Matthiessen 合成规则解释。在可见区域的低抵抗力和高发射度的怪癖启用对 optoelectronic 设备制造合适的这些电影。

A comparison study of Ce/La and Ca microalloying on the bio-corrosion behaviors of extruded Mg-Zn alloys

The influences of Ca and Ce/La microalloying on the microstructure evolution and bio-corrosion resistances of extruded Mg-Zn alloys have been systematically investigated in the current study.Compared with single Ca or Ce/La addition,the Ca-Ce/La cooperative microalloying results in an outstanding grain refinement,because the fine secondary phase particles effectively hinder the recrystallized grain growth.The coarse Ca2Mg6Zn3 phases promote the formation of Ca3(PO4)2 or hydroxyapatite particles during the immersion process and accelerate the dissolution of the corrosion product film,which destroys its integrity and results in the deterioration of anti-corrosive performance.The Ce/La elements can be dispersed within the conventional Mg7Zn3 phases,which reduce the internal galvanic corrosion between Mg matrix and the secondary phases,leading to an obvious improvement of corrosion resistance.Therefore,the Ca-Ce/La cooperative microalloying achieves a homogenous fine-grained microstructure and improves the protective ability of surface film,which will pave a new avenue for the design of biomedical Mg alloys in the coming future.

Effect of substrate temperature on structural properties and photocatalytic activity of TiO_2 thin films

Titanium dioxide (TiO2) films with anatase structure were prepared on quartz glass substrates by pulse laser ablating titanium (99.99%) target under oxygen pressure of 10 Pa at substrate temperature of 500-800 ℃. The structural properties of the films were characterized by X-ray diffractometry(XRD), X-ray photoelectron spectroscopy(XPS) and field emission scan electron microscopy(FESEM). The results show that, as the substrate temperature is increased from 600 ℃ to 800 ℃, the anatase structure of the films changes from random growth to (211)-oriented growth. The absorption edge tested by UV-Vis Spectrometer has a blue shift. The photocatalytic activity of the films was tested on the degradation of methyl orange. It is found that the film with random growth structure exhibits better photo-degradation efficiency than that with (211)-oriented growth structure.

Surface morphology and photoluminescence properties of ZnO thin films obtained by PLD

ZnO thin films on Si(111) substrate were deposited by laser ablation of Zn target in oxygen reactive atmosphere, Nd-YAG laser with wavelength of 1 064 nm was used as laser source. XRD and FESEM microscopy were applied to characterize the structure and surface morphology of the deposited ZnO films. The optical properties of the ZnO thin films were characterized by photoluminescence. The UV and deep level (yellow-green) light were observed from the films. The UV light is the intrinsic property and deep level light is attributed to the existence of antisite defects (OZn). The intensity of UV and deep level light depends strongly on the surface morphology and is explained by the surface roughness of ZnO film. A strongly UV emission can be obtained from ZnO film with surface roughness in nanometer range.

Tunable UV Absorption and Mobility of Yttrium-Doped ZnO using First-Principles Calculations

The electronic structures and optical properties of Y-doped ZnO are calculated using first-principles calculations.It is found that the replacement of Zn by the rare-earth element Y presents a shallow donor,and the Fermi level moves into the conduction band(CB).The high dispersion and s-type character of CB is expected to result in an increase in conductivity.Moreover,the absorption spectrum of the Y-doped ZnO system exhibits a slight blue shift with an increase of Y concentration,and a higher transparency in visible light is expected.Therefore,the Y-doping in ZnO would enhance the mobility and hence increase the electrical conductivity without sacrificing the optical transparency,which is essential for the improvement of ZnO's behavior and its performance in extension applications.

Optical and Electronic Properties of Wurtzite Structure Zn_(1−x)Mg_(x)O Alloys

Optical and electronic properties of Zn_(1−x)Mg_(x)O ternary alloys of wurtzite structure are calculated by using first-principles based on the framework of generalized gradient approximation to density functional theory with the introduction of the on-site Coulomb interaction.The use of the𝑈parameter on Zn-3d𝑑and O-2p𝑝orbits is obviously crucial,which can improve the GGA to predict the electronic properties and bandgap of the Zn_(1−x)Mg_(x)O(0≤𝑥≤0.25)system reasonably.It is further demonstrated that the bandgap widens with an increasing Mg concentration from 3.217 eV of ZnO to 3.877 eV of Zn0.75Mg0.25O.Therefore,the theoretical results show that Zn_(1−x)Mg_(x)O ternary alloys are potential candidates for optoelectronic materials,especially for UV photon emitters and detectors.

Poly(vinylidene fluoride)/Clay Nanocomposites by Melt Compounding

The crystalline structures, morphologies, and mechanical properties of poly（vinylidene fluoride）/clay nanocomposites were studied using X-ray diffraction（XRD）, transmission electron microscopy（TEM）, Fourier transform infrared spectroscopy（FTIR）, polarized optical microscopy（POM）, and tensile tests. The results of XRD and TEM show that organoclays are dispersed in the poly（vinylidene fluoride）（PVDF） matrix. A clay-induced crystal transformation from α-phase to β-phase of PVFD was confirmed by XRD and FTIR. Clay layers restricted the growth of spherulite. The tensile tests indicate that the tensile modulus and yield strength as well as the elongation at break decrease when clay is loaded.

Effects of Current Density on the Microstructure and the Corrosion Resistance of Alumina Coatings Embedded with SiC Nano-particles Produced by Micro-arc Oxidation

To improve the surface corrosion resistance of the alumina films fabricated by micro-arc oxidation （MAO）,Al2O3 coatings at different current densities （5,7 and 10 A/dm 2） were produced on aluminum alloys by adding SiC nano-particles into electrolyte during MAO process.The morphology and phase composition of the coatings were investigated by scanning electron microscopy （SEM） and X-ray diffraction （XRD）,respectively.Furthermore,the corrosion performance of the coatings was evaluated via a three-electrode system in a 3.5 wt pct NaCl solution.From the obtained morphology of alumina coatings,it was believed that the Al2O3 coatings embedded with SiC nano-particles were formed.The electrochemical impedance spectroscopy （EIS） plots and potentiodynamic polarization plots of the Al2O3 coatings with and without SiC nano-particles at different current densities reveal that the Al2O3 coatings with SiC nano-particles formed at 10 A/dm 2 showed the better corrosion resistance than the other coatings produced at 5 and 7 A/dm 2.

Effect of Ce/La microalloying on microstructural evolution of Mg-Zn-Ca alloy during solution treatment

The effect of Ce/La misch metal addition on the microstructural evolution of as-cast and as-soluted Mg-5.3Zn-0.5Ca（wt.%） alloys was systematically investigated. It was found that Ce/La could effectively refine the as-cast alloy and restrain grain growth during solution treatment, which was derived from the constitutional supercooling during solidification process and the formation of stable intermetallic compounds Ce Mg12 and Mg17La2. Furthermore, Ce/La microalloying and solution treatment resulted in an evolution from the original lamellar Ca2Mg6Zn3/α-Mg to the divorced eutectic structure. The thermal stability of Mg-Zn-Ca alloy could be effectively improved by Ce/La addition, because the low-melting-point binary Mg-Zn phase was transformed to Mg x Zn y-Ca-（Ce/La） phase with higher thermal stability and the amount of Ca2Mg6Zn3/α-Mg eutectic structure was reduced.

Joining of Zirconia and Ti-6Al-4V Using a Ti-based Amorphous Filler

Polycrystalline ZrO2-3 mol.%Y2O3 was brazed to Ti-6Al-4V by using a Ti47Zr28Cu14Ni11（at.%） amorphous ribbon at 1123–1273 K in a high vacuum. The influences of brazing temperature on the microstructure and shear strength of the joints were investigated. The interfacial microstructures can be described as ZrO2/TiO＋TiO2＋Cu2Ti4O＋Ni2Ti4O/α-Ti＋（Ti,Zr）2（Cu,Ni） eutectic/acicular Widmanst¨aten structure/Ti–6Al–4V alloy. With the increase in the brazing temperature, the thickness of the TiO＋TiO2＋Cu2Ti4O＋Ni2Ti4O layer reduced, the content of the α-Ti＋（Ti,Zr）2（Cu,Ni） eutectic phase decreased, while that of the coarse α-Ti phase gradually increased. The shear strength of the joints did not show a close relationship with the thickness of the TiO＋TiO2＋Cu2Ti4O＋Ni2Ti4O layer. However, when the coarse （Ti,Zr）2（Cu,Ni） phase was non-uniformly distributed in the α-Ti phase, or when α-Ti solely situated at the center of the joint, forming a coarse block or even connecting into a continuous strip, the shear strength greatly decreased.

Thermal Cycling Effect on the Wear Resistance of Bionic Laser Processed Gray Iron

Thermal fatigue and wear both seriously affect the service life of some working parts. Environmental temperature will modify the surface conditions and influences the result of wear. In this research, to come close to working conditions, specimens were tested by a combination of thermal cycles and wear. Different cycles of thermal fatigue was carried out first on the gray iron specimens and subsequently wear test was performed to evaluate the effect of these thermal fatigue cycles. In this case, bionic laser processing was used to enhance the wear performance. The results indicated that bionic laser processing reduces the negative effects from thermal fatigue, such as grain fragmentation and oxidation. Because the initiation and growth of cracks as well as oxidation are suppressed in bionic processed areas. Bionic specimens exhibit high wear resistance compared with the common one. The process described can be considered as an effective method to improve the performance of gray iron in combined thermal fatigue and wear service conditions.

Effects of substitution of Nd in a sand-cast Mg-2.5Nd-0.6Zn-0.5Zr alloy with x wt.% Sm(x=2.5, 4, and 6)

The microstructures and mechanical properties of a series of sand-cast Mg-Sm-Zn-Zr alloys under ascast, solution-treated and peak-aged states were thoroughly investigated. The OM, XRD, SEM and HRTEM were employed to characterize the microstructural evolution. The results indicate that substitution Nd in the conventional Mg-2.5 Nd-0.6 Zn-0.5 Zr alloy with different contents of Sm has comparative grain refinement effect and will fully change the dominant intermetallic phase. In addition, the substituted alloys perform clearly higher strength with comparative ductility at both as-cast and peakaged conditions and much greater aging hardening response than the referential alloy. It is obvious that the strength increments of this alloy are attributed to the changes of the eutectic intermetallic particles on grain boundaries.

Superhydrophobic Behavior and Optical Properties of ZnO Film Fabricated by Hydrothermal Method

ZnO film with claviform structure was synthesized on quartz substrates through a hydrothermal method at 90℃. The microstructure of the film is composed of clusters of submicrometer rods, which therefore endues the film with good superhydrophobicity. Meanwhile, the film with such tanglesome structure also shows highly crystalline quality testified by a strong ultra-violet （UV） emission and very low deep-level emission observed on the photoluminescence （PL） spectrum as well as high transparence of about 89% transmittance in visible light range.

TEM study of dislocations structure in In(0.82)Ga(0.18)As/InP heterostructure with InGaAs as buffer layer

In order to improve the quality of detector, In_x Ga_(1-x)As(x=0.82) buffer layer has been introduced in In_(0.82)Ga_(0.18)As/In P heterostructure. Dislocation behavior of the multilayer is analyzed through plane and cross section [110] by transmission electron microscopy(TEM) and high resolution transmission electron microscopy(HRTEM). The dislocations are effectively suppressed in In_x Ga_(1-x)As(x=0.82) buffer layer, and the density of dislocations in epilayer is reduced obviously. No lattice mismatch between buffer layer and epilayer results in no misfit dislocation(MD). The threading dislocations(TDs) are directly related to the multiplication of the MDs in buffer layer.

Microstructure and Mechanical Properties of an Extruded Mg-2Dy-0.5Zn Alloy

Microstructure and mechanical properties of an extruded Mg-2Dy-0.5Zn （at.%） alloy during isothermal ageing at 180℃ were investigated. Microstructure of the as-extruded alloy is mainly composed of α-Mg phase, 14H long period stacking order （LPSO） phase and small amounts of （Mg, Zn）=Dy particle phases. During ageing, the 14H LPSO phase forms and develops and its volume fraction increases with increasing ageing time. Tensile test showed that the peak-aged alloy exhibits similar yield and ultimate tensile strengths and elongation to failure at room temperature, 100℃ and 200℃, but excellent elevated temperature strengths at 300℃ as compared to the as-extruded and over-aged alloys. The analysis showed that the excellent elevated temperature strengths of the peak-aged alloy are attributed to the LPSO phase strengthening and the grain refinement strengthening, and the role of the LPSO strengthening is related to not only its amount, but also its morphology.

Rapidly Solidified Microstructure in Laser Alloyed Ni-Al Layer by TEM, STEM z-contrast and HRTEM Techniques

In the present study, laser alloying of electroless Nie P coating on aluminum substrate was conducted using Nd：YAG pulsed laser under the condition of 5.36 109W/m2 in power density and 3.0 mm/s in scanning speed. The rapidly solidified microstructure in the alloyed layer was studied. The results showed that the alloying element distributed in the alloyed layer is inhomogeneous. The dendrite containing relatively high Ni was identified as Al3Ni phase and the areas between the dendrites are rich in Al content. Featureless with cell structure in Al-rich areas was firstly displayed by z-contrast image. Amorphous structure was revealed to exist in Al-rich areas.