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A gallium nitride (GaN)-based resonant step-up converter is proposed for the application in the satellite electric propulsion (EP) system. This converter consists of a full-bridge inverter, a resonant tank and a multi-stage Cockcroft-Walton (CW) voltage multiplier to provide a high gain. Additionally, the air-core transformer is introduced due to the megahertz switching frequency allowed by the GaN device. Thus, the limited magnetizing inductance of transformer and the remarkable junction capacitance of diode have to be carefully considered in the resonant tank design, especially after considering that this converter normally operates at the light load in the EP system. In this work, the 4-order LCLC resonant converter is investigated. The recommended parameter selection for the 4-order resonant tank is also provided. A 1.2-MHz, 23-V/2.5-kV, and 6-W prototype is demonstrated. It achieves a low harmonics distortion and a low power loss with the zero voltage switching (ZVS).

Corundum porous materials of particle-packing type with different contents of in situ formed LaAl11O18 were prepared using tabular corundum, reactive alumina and La2O3 powder as raw materials. The effects of the introduction of LaAl11O18 on the microstructure, phase composition and properties of the porous materials were investigated. The specimens were characterized by scanning electron microscopy, X-ray diffraction and mercury porosimetry. Results show that platelet-like LaAl11O18 is formed in situ by the reactions of La2O3 and Al2O3. With a certain amount of La2O3 added, the cold crushing strength, cold modulus of rupture and hot modulus of rupture (1400 × 0.5 h) of the specimens are increased, and the air permeability is improved simultaneously. However, upon further increasing the amount of La2O3 added, the mechanical properties and air permeability of the porous materials then decrease gradually owing to the increased numbers of pores and cracks in the bonding phase. The enhanced mechanical properties of the specimens with La2O3 added are attributed to the strengthening effects of plate-like LaAl11O18 in the bonding phase and to the activated sintering of both Al2O3 powder and corundum coarse aggregate for the diffusion of La3+ in Al2O3 lattice. In addition, the improved air permeability of the specimens should be related to the decreased content of pores in the bonding phase and the reduced number of interfacial cracks.

A GaN-based gate driver circuits have been successfully designed and fabricated using a commercially available 6-inch GaN-on-Si platform. The driver circuits consist of three-stage direct-coupled FET logic (DCFL) inverters featuring monolithically integrated depletion-mode (D-mode) and enhancement-mode (E-mode) high electron mobility transistors (HEMTs). At room temperature (RT), at a supply voltage of 4 V the single-stage DCFL fabricated on the same die exhibits a large gate swing (3.84 V) and large noise margins (logic-low noise margin (NML) of 1.55 V and logic-high noise margin (NMH) of 2.18 V), both of which are desirable for all-GaN IC applications. Meanwhile, the gate driver circuits were characterised up to 200°C on a PCB with a capacitance load of 1 nF in series with 4.7 Ω resistance to resemble the load condition. At 200°C, the gate driver circuits function well even at 5 MHz operation frequency. The turn on/off propagation delay and rise/fall time of the gate driver circuits are 5/40 and 22/18 ns, respectively. As far as the authors’ knowledge, this is the highest reported operation frequency for GaN-based gate driver circuits under such high temperature, making it very promising for high-temperature high-frequency all-GaN integrated circuit (IC) applications.

Coarse aggregates of shape-modified corundum (0.5–1 mm) were obtained by treating corundum particles in an intensive mixer, and the effect of shape-modified coarse aggregates on the pore structure and properties of the porous materials were investigated. After the shape modification process, the morphologies of the coarse aggregates became more regular, with increased circularities and decreased aspect ratios. This was not only conductive to accelerating the rearrangement of coarse aggregate particles during the press-forming process and obtaining a more tightly packed structure but also contribute to maintaining the structures of the pores from the stacking of coarse aggregate particles in the porous material. By using shape-modified coarse aggregates, the cold compressive strengths and bulk densities of the specimens were increased, while the apparent porosity was decreased. More interestingly, the Darcian and non-Darcian permeability coefficients of the specimens were enhanced despite the decreased apparent porosities.

Direct deposition of hydroxyapatite (HA) coatings on carbon/carbon(C/C) composites through hydrothermal electrochemical deposition (HED) were limited by the poor bonding strength. To overcome this problem，in this work, CaHPO4 (monetite) coating was firstly deposited on C/C using HED, and then converted into HA coating in a sodium silicate–containing solution by post-hydrothermal treatment. Effects of post-treatment temperatures on the chemical composition, structure, and bonding strength of the coatings were investigated. The results showed that obtained monetite showed a compact microstructure, and could react with the solution to produce a well-crystallized HA as well as amorphous silicate which contained some calcium and sodium ions. All the coatings were composed of rod-like crystals. The diameter of these crystals increased when the post-hydrothermal temperature was changed from 110 ℃ to 140 ℃, and then decreased at 155 ℃. The Si contents and the adhesive strength of the HA coatings showed a similar temperature dependence to the crystal size of the HA. 140 ℃ is determined to the optimal treatment temperature, at which the HA coating reached the highest critical load of 24.02 N, corresponding to the shear strength of 82.83 MPa. The bioactivity of the HA coating on C/C increased with the increasing post-treatment temperature.

Electrocrystallized calcium phosphate (CP) coatings generally show a porous structure on carbon/carbon composites (C/Cs) and poor adhesive strength that limit their application in orthopedics. To overcome this disadvantage, ultrasonic and ice bath were employed in the electrocrystallization process of preparing CP/gelatin coating with a thickness of 50 μm on C/Cs. The CP/gelatin coating was hydrothermally treated in aqueous ammonia and sodium silicate solutions, respectively, to obtain an ion-doped hydroxyapatite(HA)/gelatin coating on C/Cs. Results showed that the modified electrocrystallized process could achieve a compactly stacked flaky structure coating of brushite and gelatin on C/Cs, whose adhesive strength could reach a critical load of 6.3 N. HA/gelatin coating that contains nanoneedle crystals could be achieved after performing the ammonia hydrothermal treatment, but its adhesive strength decreased to 4.1 N. Further hydrothermal treatment of the HA/gelatin coating in the sodium silicate solution obtained a Na, Si-doped HA coating on C/Cs, which could reach a critical load as high as 7.72 N. This value is equivalent to shear strength of 47 MPa. The ion-doping and hydrothermal self-repair processes enhanced the adhesion strength of the Si,Na-HA coating on C/Cs. In vitro experiments showed that the Si, Na-HA/gelatin coating exhibited better cell compatibility than C/Cs and HA/gelatin coating.

The trend to move toward the solid-state and repetitive pulsed power supply requires the high-voltage, high-current, and high-speed semiconductor devices, which makes an insulated gate bipolar transistor (IGBT) preferred for this application. However, as a bipolar device, the IGBT is limited by the switching speed and switching loss. In this paper, the potential of silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET) for the pulsed power application is investigated. The surge current capabilities of 1.2-kV, 30-A commercial Si IGBT and SiC MOSFET are characterized and compared by the capacitor discharge experiment. In addition, the effects of various circuit parameters, including gate resistance, dc-link voltage, and dc-link capacitance, on the capacitor discharge process are investigated. It is found that the pulse current of SiC MOSFET is around two times of Si IGBT, which achieves good agreement with the datasheet. Using $di/dt$ to represent the discharging speed, the SiC MOSFET is 10 times faster than the Si IGBT. It is because the SiC MOSFET shows a lower ON-resistance in the saturation region resulted from the short-channel effect. This paper confirms the high-speed and high-current advantages of SiC MOSFET in the pulsed power application.

The LaF3-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 nanoparticles were synthesized via co-precipitation method followed by simple chemical deposition process. The crystal structure, particle morphology, and electrochemical properties of the bare and coated materials were studied by XRD, SEM, TEM, charge–discharge tests. The results showed that the surface coating on Li[Li0.2Mn0.54Ni0.13Co0.13]O2 nanoparticles were amorphous LaF3 layer with a thickness of about 10–30 nm. After the surface modification with LaF3 films, the coating layer served as a protective layer to suppress the side reaction between the positive electrode and electrolyte, and the Li[Li0.2Mn0.54Ni0.13Co0.13]O2 oxide demonstrated the improved electrochemical properties. The LaF3-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 electrode delivered the capacities of 270.5, 247.9, 197.1, 170.0, 142.7, and 109.5 mAh g−1 at current rates of 0.1, 0.2, 0.5, 1, 2, and 5 C rate, respectively. Besides, the capacity retention was increased from 85.1 to 94.8 % after 100 cycles at 0.5 C rate. It implied surface modification with LaF3 played an important role to improve the cyclic stability and rate capacity of the Li-rich nickel manganese oxides.

The FeF3-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 cathode materials were synthesized via a wet chemical process followed by a solid state reaction. The physical properties of the as-prepared samples were conducted using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results indicated that the surface of cathode particles was covered by FeF3 film (about 5–15 nm thick). Compared with the bare cathode, the FeF3-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 one delivered the higher coulombic efficiency, better rate capability, longer cycle life, and better structure stability. A high capacity retention of 95% (190 mAh g− 1) after 100 cycles at 0.5 C rate was obtained for the FeF3-coated Li[Li0.2Mn0.54Ni0.13Co0.13]O2 cathode. Besides, the results from cyclic voltammetry and electrochemical impedance spectra revealed that the noteworthy enhanced electrochemical properties of the surface-modified sample were due to the presence of FeF3 coating layer, which suppressed the side reaction between the Li[Li0.2Mn0.54Ni0.13Co0.13]O2 particles with electrolyte and further stabilized the Li[Li0.2Mn0.54Ni0.13Co0.13]O2 structure with cycling.

Growing attention has been paid to surface texture owing to its significance on bearing lubrication, load capacity and wear resistance. In this paper, in or der to learn more about the dynamic performance of journal bearings and the vibration of bearing ho usin g, a comparative experimental study between textured surface and non-textured surface journal bearing configurations is presented. The research was mainly divided into two parts. Firstly, the feature information of displacement under a range of loads from 0 N to 2500 N was obtained. Experimental measurements data of stiffness coefficients and damping coefficients under different static loads were calculated and analyzed respectively between the surface-textured and non-textured journal bearings. It can be learned that the values of fluid film stiffness coefficients and damping coefficients are increased via surface texture. Secondly, the vibration amplitude of bearing housing was measured. The experimental results show that appropriate texture distribution can certainly have better vibration damping effects according to acceleration amplitude. There is a good correlation under the relevant operating conditions compared with a theoretical model. The experimental results show that the appropriate texture distributed journal bearing provides a great improvement on stability than the non-textured journal bearing.

Monetite (CaHPO4) coatings were deposited on H2O2-treated carbon/carbon (C/C) composites by induction heating deposition (IHD) at electromagnetic frequencies ranging from 289 kHz to 438 kHz. The composition, microstructure and bonding strength of the monetite coatings on the C/C composites were investigated by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and large load scratch tester (LLST). The effects of the electromagnetic frequencies on the deposition kinetics of the monetite coatings on the C/C were also analyzed. The results showed that when the electromagnetic heating frequencies were 289 kHz, 319 kHz and 381 kHz, the monetite coatings presented similar compact morphologies, and critical loads of 38 N, 64 N and 25 N. The deposition processes of these monetite coatings were controlled by a surface reaction and their apparent activation energies were 20.26, 22.17, and 31.07 kJ/mol at 289, 319 and 381 kHz. But at 438 kHz, it showed a loose morphology and could be very easily scratched off, presenting a critical load of 0 N. The changes in the microstructure and adhesiveness of the monetite coatings were discussed at the different electromagnetic frequencies.

The humeral heads of rabbits were replaced with individualized C/C composite implants coated with hydroxyapatite (HA) via rotation plasma spraying. The effect of the implants was evaluated after 5 and 150 days by using histology, scanning electron microscopy, X-ray diffraction, and so on. Results showed that the coating interface of C/C composites facilitated phosphorite deposition and osseous tissue growth. Furthermore, the humeral bone and remaining bone tissues were morphologically similar and possessed enhanced bonding strength. These results indicated that individualized C/C composite implants with HA coatings enabled the humeral head to adapt to dynamic requirements and accelerate healing after bone transplantation.

The hot deformation behavior of Ti-6Al-4V alloy with transitional microstructure over temperature 800°C~950°C and strain rate ranges of 0.001~10s-1 has been studied by Gleeble-3500 hot working simulation testing machine. The flow softening of stress-strain curves is resulted from the spheroidization of transitional microstructure, dynamic recrystallization and superplasticity. Both temperature and strain rate are important factors affecting the deformation behavior. Flow instability induced by adiabatic shear bands occurs at 800-880°Cand 0.32-10 s-1. With the increasing of strain rate and decreasing of temperature, the degree of strain localization increases. The optimum working region of Ti-6Al-4V alloy with a transitional microstructure is at 820-910°C and 0.001-0.1 s-1.

A new chemical liquid vaporization deposition (CLVD) is used on carbon–carbon (C/C) composites to prepare hydroxyapatite (HA) coating. The heating frequencies of the CLVD and induction heating method are 330 kHz and 30 kHz, respectively. The phases, morphologies, and compositions of these coatings are characterized using scanning electron microscopy, X-ray diffraction, and electronic data systems; the adhesion of the coatings to the C/C substrates was evaluated by a scratch test. The results demonstrate that the critical loads of HA coatings prepared through CLVD and induction are 47 N and 18 N, respectively. Although these coatings have no significant phase differences, the CLVD HA coating has abundant CO32−, which improves the adhesion, multiplication, and differentiation of external osteoblasts.

SiC/SiO 2 nanochains were prepared by a simple chemical vapor reaction method and characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and UV–vis diffuse reflectance spectroscopy analyses. The visible-light photocatalytic activity of SiC/SiO 2 nanochains was investigated by the photocatalytic decomposition of Rhodamine B in the aqueous solution. The results show that the SiC/SiO 2 nanochain has equirotal beads of 650 nm and a uniform string with a diameter of 240 nm. The photo-response behavior of the SiC/SiO 2 nanochain can be expanded to visible-light region with a high absorbance. The photocatalytic activity of SiC/SiO 2 nanochains was found to be better compared to that of the SiO 2 -free SiC nanowires owing to the nanosized SiO 2 coating that can form activated hydroxyl groups and effectively separate the photogenerated electrons and holes.

SiC hollow spheres are obtained by a vapor–solid reaction using carbon spheres as templates. The prepared SiC hollow spheres are characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption, and UV–vis diffuse reflectance spectra. The visible-light photocatalytic activity is evaluated by photocatalytic decomposition of the methylene blue in aqueous solution. Results show that the diameter of SiC hollow spheres ranges from 200 to 300 nm and the shell thickness is about 50 nm. The SiC hollow spheres have a high surface area of 83.5 m 2 /g and exhibit a mesoporous structure characteristic. The photo-response of the SiC hollow spheres expand to visible-light region with band gap energy of 2.15 eV. The SiC hollow spheres exhibit a significantly enhanced photocatalytic activity due to their high surface area as well as large light-harvesting efficiencies.

A novel strategy for the preparation of Si-doped hydroxyapatite (Si-HA) coatings on H2O2-treated carbon/carbon composites (C/C) was developed. HA coating was prepared on C/C through chemical liquid vaporization deposition (CLVD)/hydrothermal treatment. HA coating was immersed in an H2SiO3 solution at an autoclave at 413 K for transformation into Si-HA coating. The effects of H2SiO3 mass contents on the phase, morphology and composition of the Si-HA coatings were studied through SEM, EDS,XRD and FTIR. Their bonding performance to C/C was measured through a scratch test. Under the optimal content condition, the in vitro skull osteoblast response behaviors of the Si-HA coating were evaluated. Results showed that SiO32− could enter into the HA lattice and occupy the PO43− sites. Doped SiO32− significantly improved the bonding performance of the HA coating to C/C in comparison with the untreated HA. The adhesive strength of the coatings initially increased and then decreased with increasing H2SiO3 content. Meanwhile, the cohesive strength of the Si-HA coatings was almost nearly identical. The Si-HA coating achieved at a content of 90% H2SiO3 exhibited the best bonding performance and its osteoblast compatibility in vitro was superior to that of the untreated HA coating on C/C through CLVD/hydrothermal treatment.

We present a method to fabricate diffractive optical elements (DOEs) with four phase levels by the Laser Direct Writing technology. One computation method is provided to optimize the step depth, which could improve efficiency of DOEs. The step depth and imaging results demonstrate the fabricated DOEs devices with good optical properties. The effective areas of the DOEs pattern are as large as 49 cm2, which could be replicated easily for mass production applications.

Fresnel mirror can greatly improve the compactness of imaging system, which has many advantages such as light, thin, and easy to integrate. Due to the limitations of the shape precision and the surface roughness by available fabrication technology, most Fresnel mirrors can only be used for illuminating and focusing areas. This paper presents a Fresnel mirrors ultra precision forming method, which can turn the Fresnel mirrors with an excellent imaging performance in visible light region. The surface roughness of the Fresnel mirror can be achieved as small as 1 nm, and the surface accuracy can be up to 0.23 lambda @ 632.8 nm after removing the spherical aberration, which make this kind of Fresnel mirror extremely promising for applications in ultrathin and light optical imaging system.

a monetite coating on H 2 O 2 -treated C/C composites was prepared by ultrasonic induction heating (UIH) technology. Subsequently, this coating was subjected to an ammonia hydrothermal treatment to form a undoped hydroxyapatite (U-HA) coating. Finally, the as-prepared U-HA coating was placed in a NaOH solution and hydrothermally treated to produce the other hydroxyapatite (Na-HA) coating. The structure, morphology and chemical composition of the two HA coatings were characterized by XRD, FTIR, SEM and EDS, the adhesiveness and local mechanical properties, e.g. nanohardness and Young's modulus of the two HA coatings to C/C composites was evaluated by a scratch test and nanoindentation technique respectively. The results showed that the two HA coatings had the alike morphology and crystallization. But, compared with the U-HA coating, the Na-HA coating was doped with Na ions, and gave a Ca/P ratio close to a stoichiometric hydroxyapatite, and thus showed a higher nano-indentation value, Young's modulus, and larger bonding strength. These results verified the strengthened effect of Na ion in hydroxyapatite coating on carbon/carbon (C/C) composities.

Modified wheat biochar and modified peanut shell biochar is immobilized carrier, studying its physical and chemical properties, and preparing immobilized microorganisms by adsorption method. The optimum conditions for the preparation of immobilized microorganisms were determined by orthogonal experiment. The effects of biochar types, adsorption time, the amount of biochar and the rotating speed on the amount of bacteria were studied. The results showed the physical and chemical properties of the two modified biochar were beneficial to the adsorption of microorganisms, and when the volume ratio of bacteria liquid and modified peanut shell biochar was 20: 1, stereo adsorption for 2 hours that the optimum immobilization rate was 72.38%.

Hydrothermal post-treatment was used to convert monetite coating fabricated by induction heating method on H2O2 treated C/C (HT-C/C) composites to an adherent HA coating. The monetite coatings were hydrothermally treated for 4 h at 373 K, 403 K, 423 K, and 453 K in a 50 mL autoclave. After hydrothermal post-treatment, the structure, morphology and the chemical composition of these HA coatings were characterized with XRD, FTIR SEM and EDS. A scratch test was conducted to measure the strength of the adhesion of the coatings to the HT-C/C substrate. The results showed that the degree of crystallinity and the Ca/P ratio of the HA coatings increased with increasing hydrothermal temperature. The submicron-level morphology and adhesion of the HA coatings were highly affected by the hydrothermal temperature. From the results, it can be suggested that 423 K was the best hydrothermal treatment temperature for the HA coatings which were transformed from the monetite coatings produced by the induction heating method on HT-C/C composites.

Monetite coatings on H 2 O 2 -treated carbon/carbon composites were prepared by induction heating deposition method and then converted to HA coatings by hydrothermal treatment in an autoclave with two different types of solutions, respectively NaOH aqueous solution and ammonia solution. The structure, morphology and chemical composition of the as-achieved HA coatings were characterized by XRD, FTIR SEM and EDS. The adhesion of HA coatings to the HT-C/C substrates was evaluated by a scratch test. The results showed that there are no obvious changes in the structure and morphology for the as-achieved HA coatings except to their compositions. The average critical load of the ammonia hydrothermally treated HA coatings is 10.9 N, while the NaOH hydrothermally treated HA coatings show the average one of 51 N, and the reason for it was suggested.

An adherent hydroxyapatite (HA) coating was applied onto H2O2-treated carbon/carbon composite (HT–C/C) substrate by induction heating and hydrothermal treatment techniques. Specimens of C/C were initially modified by immersed in an autoclave with 2 M H2O2 solution at 433 K, and then coated with monetite crystals by induction heating method. Subsequently, monetite coating on HT–C/C was converted to HA coating by hydrothermal treatment in an autoclave with the ammonia solution at pH of 10 at 433 K. The compositions, structures and morphologies of the coatings on HT–C/C were analyzed by EDS, SEM and XRD, and the adhesive strength of HA coating on HT–C/C was evaluated by a scratch test. The results showed that the coatings of monetite and HA display no significant changes in their morphologies before and after hydrothermal treatment. They have rectangular crystals stacking one another, and a strong adhesive interface has formed between the HA coating and HT–C/C substrate. The HA coating on HT–C/C was not scraped off until the applied load reached 13.12 N (i.e., shear stress of 61.4 MPa).

Y 2 BaCuO 5 nanocrystallites were prepared by a co-precipitation method with the aid of ultrasonic irradiation using Y 2 O 3 , CuCl 2 and BaCl 2 as source materials. The crystallization and morphologies of as-prepared nanoparticles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Results show that Y 2 BaCuO 5 monophase can be prepared at the calcining temperature up to 900 °C with NaOH and Na 2 CO 3 mixtures as precipitator. Particle size of Y 2 BaCuO 5 crystallites decreases with the increase of sonicating power. Around 30 nm Y 2 BaCuO 5 crystallites can be achieved when sonicating power is increased to 300 W.

Different compositions of yttrium silicates coatings were deposited on SiC-C/C by plasma spraying and an outer borosilicate glass was applied on the yttrium silicates coatings surfaces. The structure of the multi-layer coatings was characterized by XRD and SEM analyses. High temperature oxidation behavior of the multi-layer coatings coated C/C composites was investigated. Results show that SiC/2SiO2·Y2O3/1.5SiO2·Y2O3/ SiO2·Y2O3/glass multi-layer coating has better high temperature oxidation resistance, protecting carbon/ carbon composites from oxidation at 1 773 K in air for 164 h with the weight loss of 1.65%. The oxidation weight loss of the coated C/C with time accorded with parabolic rule in the temperature range 1 573 K–1 873 K; and the corresponding oxidation activation energy of the coated carbon/carbon composites is 132.2 kJ/mol.

A new type of oxidation-protective multi-composition coating for carbon/carbon (C/C) composites has been produced by a pack cementation technique in an argon atmosphere. XRD analyses shows that the phases of the composite coating are composed of Al 2 O 3 , mullite, SiC and Al 4 SiC 4 , and the bonding layer between the coating and C/C composites are composed of Al 4 C 3 , SiC and Al 4 SiC 4 . It is found by SEM surface observation and EDS area scanning analyses that the coating has two kinds of surfaces that are distinctly different in element content of Si and C. In the meantime, cross-section SEM observation of the coating also displays a dense microstructure. Oxidation test shows that the as-prepared coating characterized by excellent thermal shock resistance on the surface of C/C composites during exposure to an oxidizing atmosphere at 1773 K could effectively protect the C/C composites from oxidation for 41 h.

A SiC coating for carbon/carbon(C/C) composites was produced by a pack cementation technique in an argon atmosphere. The phase, microstructure and anti-oxidation property of the SiC coatings prepared from 1773 to 2273 K were investigated. It is found that the porous β-SiC coatings occur at 1773–1973 K while dense Si/β-SiC coatings generate at 2073 K and micro-cracked β-SiC/α-SiC coatings appear at 2173–2273 K. The thickness of the SiC coating increased with increasing temperature and oxidation tests at 1773 K in air showed that, based on observed weight changes, a preparation temperature of 2073–2273 K gave much improved oxidation resistance over that of coatings formed between 1773 and 1973 K.

In order to exploit the unique high temperature mechanical properties of carbon/carbon (C/C) composites, a new type of oxidation protective coating has been produced by a two-step pack cementation technique in an argon atmosphere. XRD analysis showed that the internal coating obtained from the first step was a gradient SiC layer that acts as a buffer layer, and the multi-layer coating formed in the second step was an Al2O3-mullite layer. It was found that the as-received coating characterized by excellent thermal shock resistance on the surface of C/C composites during exposure to an oxidizing atmosphere at 1873 K, could effectively protect the C/C composites from oxidation for 45 h. The failure of the coating is due to the formation of bubble holes on the coating surface.

Based on the determined metastable region by static beaker tests, this paper studied cation exchange resin in the treatment of recycling cooling water softening, compared to macroporous porous polymer materials resin white balls, cation exchange resins could be obtained as efficient induced crystallization of nuclear, and effluent achieved the circulating cooling water recharge water quality standard. The best experimental conditions for ion-exchange resin was: pH value for 9.24, the amount of Na 2 CO 3 (concentration 0.05mol/L)for 5.0 ml/L, the amount of resin for 40 g/L, mixing time for 20min, and mixing intensity for 200r/min. Ca2+ removal rate reached 94.8% and 94.8%, and effluent's calcium concentration were 0.52mmol/L. And average moisture content of crystalline product was 20.17%, the calcium ions in the carrier's average crystallization of 27.58mg/g.

In this paper, the design of miniaturized low-pass filter in a Low Temperature Co-fired Ceramic(LTCC) Technology is presented. The pass-band of the low-pass filter is from 900MHz to 1450MHz. The capacitor is constructed by multilayer MIM(Mental-Insulator-Mental) capacitor, and the inductor is fabricated by a narrow metal transmission line. The VSWR of input and output port is less than 1.6. The whole volume of final three-dimension model is 2.0mm×1.25mm× 0.90mm.

This letter outlines the design and manufacture of a UHF-band miniaturized band-pass filter realized by low-temperature cofired ceramic (LTCC) technology for super heterodyne microwave receiver applications. A distinct feature of this filter is the smaller size than conventional filter at such a low frequency and steady pass-band temperature electrical performance compared with surface acoustic wave filter. The band-pass filter with a central frequency of 750 MHz and a 40MHz pass-band is designed as a three-dimensional (3-D) structure based on distributed components. This filter has excellent out-of-band attenuation performance and it has 50.1 dB and 56.8 dB of attenuation at 550MHz and 950MHz respectively. The measured insertion loss is less than 2.7 dB at 750MHz, and the input/output VSWR is less than 2.0. The overall size of the miniaturized filter is only 4.5mm×3.2mm×1.5mm.

Carbon/carbon composite with hydroxyapatite (HA) coating is an attractive material in the dental and orthopedic fields, but the reported bonding strength between them was very poor. In this study, a compact crystalline HA coating on (NH(4))(2)S(2)O(8)-treated C/C substrate about 10 microm in width was obtained by hydrothermal treatment and induction heating. The microstructure, composition and morphologies of the as-prepared coatings were identified by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. A strong shear strength averaging 74.2 MPa between C/C substrate and HA was achieved and adhesion failures were observed more frequently than cohesion failures. The coating adhesion measured using a scratch test was 23 N and the reasons for this are discussed.

Manganese cobalt nickel complex oxide is a thermal-sensitive material with the property of semiconductor. In this paper, Mn1.74Co0.72Ni0.54O4 (MCN) thin film was prepared in air using metal-organic-deposition method at room temperature on Si substrate, and the crystallization synthesis of the MCN thin film was prepared using alcohol-thermal reaction. According to X-ray diffraction, field emission scanning electron microscope (FESEM) and the relationship between resistivity and temperature, effects of MCN thin film made by alcohol-thermal reaction on crystalline microstructure, surface morphology and electrical properties were investigated. X-ray diffraction pattern showed that the MCN thin film appears to be spinel structure with predominant spinel peaks. Field emission scanning electron microscope showed that the surface morphology of MCN thin film is crack-free and compact surface. The relationship between resistivity and temperature of the thin film Mn1.74Co0.72Ni0.54O4 was that the resistivity decreases with the increase in temperature. The room temperature(≈ 27℃) resistivity of the MCN thin film was 303.13 Ω·cm.