Organosilicon sols undoped and doped with Zr⁴⁺ ions were prepared by a sol-gel method. These sols were then coated on a modified α-Al₂O₃ support by a dip-coating method. Silica composite membrane was prepared via calcining. The surface morphology of each film during the preparation was characterized by scanning electron microscopy. The prepared silica composite membranes were used for the dehydration of isopropanol by pervaporation in order to examine the effects of operating temperature and initial water content on the dehydration performance of the membrane, and the effect of acidic environment (pH=2) on its performance was also investigated. The experimental results show that silica composite membrane pervaporates 85% (in mass) isopropyl alcohol solution at 75 ℃, its flux is 1 kg/(m²h) and the water content of permeate is 99.4% (in mass). The membrane can maintain a good separation performance at different temperatures and initial water contents, so that it has a good hydrothermal stability. The membrane can maintain a stable separation performance in acidic environment (i.e., pH=2) for a long time, thus having a great acid resistance.

Diamond-like carbon (DLC) regarded as a typical solid lubricant has been dramatically restricted by internal weak thermostability, which further shortens the intrinsic service life and obstructs its industrialization. While working at elevated temperatures, the carbon matrix of DLC changes along with the deterioration of its superior tribological performance. In this paper, the latest progress on thermal stability and thermal wear mechanism of DLC film were reviewed and future research direction was proposed as well, aiming to provide technical reference for the studies on high-temperature service performance of DLC film.

In order to adhere diamond film onto stainless steel surface, a Cr/Cr-Si film was selected as an interlayer and deposited via magnetron sputtering. Diamond film was deposited via hot-filament chemical vapor deposition. All the samples were investigated by X-ray diffraction, scanning electron microscopy and Raman spectroscopy, etc.. The results show that Cr-Si layer is composed of Cr(Si) solid solution, and the diffusion rate of Fe atoms decreases when Si content is 12.7% (in mole). The diamond film is dense and strongly adhere onto the stainless steel surface.

Sm³⁺ doped SrBi_8-xSm_xTi₇O₂₇(SBT-BIT-xSm³⁺, 0≤x≤0.50) inter-growth bismuth layer-structured ceramics were prepared by a conventional solid-state method. The effect of Sm³⁺ doping on the structural, electrical and photoluminescence properties of SBT-BIT-xSm³⁺ ceramics were investigated. All the samples show a single inter-growth bismuth layer-structure. Based on the results by the Rietveld analysis and Raman spectroscopy, the lattice distortion decreases. The dielectric loss (tanδ) decreases and piezoelectric constant (d₃₃) increases with the increase of Sm³⁺ doping content. SBT-BIT-xSm³⁺ ceramic with x of 0.30 exhibits an optimum electrical behavior, i.e., d₃₃=16.3 pC/N, and tanδ=0.90%. Moreover, Under a near ultraviolet excitation at 407 nm, a most intense red orange emission appears at 598 nm in SBT-BIT-xSm³⁺ ceramics. The optimized emission intensity was obtained when x=0.15 for SBT-BIT-xSm³⁺ ceramic. The results show that Sm³⁺ doped SBT-BIT-xSm³⁺ inter-growth bismuth layer-structured ceramics have potential applications in the field of optoelectronic multifunctional devices.

Na_0.5Bi_4.5-x(Sm_0.5Ce_0.5)_xTi₄O₁₅ (NBT-x(Sm, Ce) bismuth-layered lead-free piezoelectric ceramics were fabricated by a solid-state synthesis method, and the influence of (Sm_0.5Ce_0.5)³⁺ additive on the structure and electrical/photoluminescence properties of samples was investigated. For the ceramics modified by (Sm_0.5Ce_0.5)³⁺ dopants, the phase structure and microstructure have little changes. The electrical properties of ceramics are enhanced. As x=0.008, the remnant polarization 2P_r reaches 13.33 μC/cm², and a high Curitemperature T_C is 640 ℃. After (Sm_0.5Ce_0.5)³⁺ doping, the ceramics show a bright orange photoluminescence. The more intense emission band at 597 nm appears under an excitation at 407 nm, corresponding to the ⁴G_5/2→⁶H_7/2 energy level transition. As a multifunctional material, (Sm_0.5Ce_0.5)³⁺-modified NBT piezoelectric ceramics have promising application prospects in optoelectronic devices, sensors, etc..

The ZnO-Pr₆O₁₁-Co₂O₃-Cr₂O₃-La₂O₃ varistors were prepared by solid state sintering method. The effect of La₂O₃ doping on the microstructure, varistor property, and dielectric characteristics of the ZnO varistor ceramics were studied in detail. The results show that the ZnO varistor has the best overall performance with La₂O₃ content of 1.5% (in mole fraction), the grain size is the smallest and uniform, the breakdown voltage E_1Ma is the highest (752 V/mm), the nonlinear coefficient is large (12), the grain boundary capacitance is the largest (276 pF), and the loss tangent is relatively low.

In order to evaluate the absorbing properties of B₄C ceramic absorber, B₄C powder was fabricated via combustion synthesis with carbon black and boron oxide as raw materials, and Mg as a reductant. The microstructure of the products was characterized by X-ray diffraction, scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The samples for dielectric test were prepared with B₄C powder as an absorber and paraffin as a binder, respectively. The complex permittivity of samples containing different amount of B₄C absorber was tested by a rectangular waveguide method at X band (8.2 GHz-12.4 GHz), and the reflection loss values were calculated based on the transmission line theory. The results show that the impurities such as MgO and Mg₃B₂O₆ can be removed by pickling. The grain size of the product is 0.4-1.0 μm with an oblique hexagonal structure. The real and imaginary parts of the complex permittivity increase with the increase of the content of B₄C powder. When the content is 50% (mass fraction), the real and imaginary parts are 19.33 and 10.40, respectively. The calculated results show that the optimum electromagnetic wave absorption performance can be obtained at B₄C powder content of 33%. The minimum reflection loss value is -21.1 dB when the thickness is 2.3 mm, and the effective bandwidth reaches 2.95 GHz. It is indicated that B₄C powder could be a promising candidate as a high-temperature microwave absorber.

In this paper, new lead-free luminescent ferroelectric materials, (Bi_0.5Na_0.5)_0.935-xSm_xBa_0.065Ti_1-xSb_xO₃ (BNT-0.065BT-xSmSb) ceramics, were prepared by introducing Sm/Sb. The influence of Sm/Sb on the phase structure, microstructure and electrical functions of BNT-0.065BT was systematically studied. BNT-0.065BT-xSmSb ceramics presented a pure perovskite phase structure. Doping with Sm/Sb induced a ferroelectric to relaxor phase transformation and thus promoted strain improvement. When x=0.004, the unipolar strain was 0.31% (70 kV/cm), equivalent to a large signal d₃₃^*(S_max/E_max) of 443 pm/V. Moreover, studies on the luminescence properties showed that BNT-0.065BT-xSmSb ceramics exhibited bright orange-red luminescence under 407 nm excitation. The luminescence intensity increased as the Sm/Sb doping concentration increased. The main emission peak was a strong red emission peak located near 599 nm, corresponding to the ⁴G_5/2→⁶H_7/2 transition. As multifunctional materials, BNT-0.065BT-xSmSb ceramics showed great latent capacity for optical-electrical integration and coupling device applications.

B₄C-TiB₂ multi-phase ceramics were prepared in a pressureless vacuum sintering-furnace at different temperatures with TiB₂ added into B₄C matrix as a second phase substance, and C and Si as sintering aids. The density, hardness, bending strength and fracture toughness of the samples were determined. The influences of composition ratio of B₄C-TiB₂ and sintering temperature on the microstructure and mechanical properties of the multiphase ceramics were investigated by X-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy. The toughening mechanism of ceramics was discussed. The results show that the optimum density and comprehensive mechanical properties of the multiphase ceramics (i.e., the relative density of 94.59%, the Rockwell hardness of 87.62, the bending strength of 182 MPa, and the fracture toughness of 3.97 MPa·m^1/2 can be obtained at a sintering temperature of 2 200 ℃ and TiB₂ content of 30%. The TiB₂ particles can effectively nail the grain boundary, inhibit the growth of B₄C grains and play a role in fine-grain strengthening. The TiB₂ and laminated graphite phase hinder the crack growth, thus improving the fracture toughness.

A Si₃N₄ ceramic foam having a shell with the thickness of 500 μm and the thickest portion of 693 μm was prepared by a reaction sintering method with a pre-embedding powder. The shell sintered at 1 400 ℃ for 6 h appears a staggered crystal columnar structure. The length of the crystal column in the shell increases slightly when the nitriding temperature is 1 450 ℃. Prolonging the nitriding time to 10 h can transform the microstructure of shell into a coarse crystalline column structure, thus reducing an aspect ratio of the crystal column. The shell has a ceramic foam with a certain degree of elasticity (i.e., Young's modulus of elasticity is 117-352 MPa), and increases the compressive strength of the sample by 47%. In addition, the presence of shell has little effect on the porosity, density and thermal conductivity of ceramic foam.