ZnO-Bi₂O₃-MnO₂-Cr₂O₃ varistor ceramics doped with different amounts of silicon dioxide (SiO₂) were prepared by a conventional solid-phase sintering method. The phase composition and microstructure of the samples were investigated by X-ray diffraction and scanning electron microscopy. The electrical properties were measured by sourcemetry and inductance capacitance resistance, and the double Schottky barrier parameters were measured by a capacitance-voltage characteristic method. The results show that when the frequency is near 10⁵ Hz, the relative dielectric constant (ε_r) decreases rapidly since the polarization cannot change with the frequency of electric field, resulting in the corresponding loss peak. The loss peak (tanδ) firstly decreases and then increases with the increase of the doping amount, and its maximum tanδ is obtained witrhout SiO₂ and the minimum tanδ is achieved at 1.0% SiO₂. The value of tanδ at a frequency of 10⁵ Hz is reduced by doping SiO₂. The nonlinear coefficient firstly increases and then decreases with the increase of SiO₂ doping amount. The value of α reaches 43.36, the value of φ_b is 1.98 eV at 10 kHz, the donor concentration is 2.97×10²⁴ m^-3, and the leakage current I_L is 0.31 μA/cm² at SiO₂ doping amount of 1.0%.

The perovskite solid solution ceramics, (1-x)BaTiO₃-xDyFeO₃, were synthesized by a solid-state reaction method. The magnetic properties of different compositions at various temperatures were investigated. The effect of phase content on the magnetic behavior was analyzed. The results show that the magnetization and susceptibility in an applied field increase with increasing x value due to the increasing concentration of magnetic elements. The temperature-dependent static and dynamic susceptibilities follow the Curie-Weiss law, but the fitting parameters are different.

n(Ca²⁺)/n(Co²⁺)(n is mole) co-doped LaAlO₃ ceramics were synthesized by a solid-phase reaction technique. The effect of n(Ca²⁺)/nCo²⁺ doping ratio on the infrared radiation performance of LaAlO₃ ceramics (La_1-xCa_xAl_0.8Co_0.2O₃, 0.25≤n(Ca²⁺)/n(Co²⁺)≤2.00) was investigated, and the mechanism for improving infrared radiation property was analyzed. The result reveals that n(Ca²⁺)/n(Co²⁺) co-doped LaAlO₃ ceramics have a perovskite crystal structure. Increasing the doping ratio (0.25≤n(Ca²⁺)/n(Co²⁺)≤1.00) improves the emissivity in the wavelength range of 0.76-2.50 μm. The ceramic specimen with n(Ca²⁺)/n(Co²⁺) of 1.00 (La_0.8Ca_0.2Al_0.8Co_0.2O₃) has the maximum average emissivity (0.87). In the 2.50-14.0 μm band, the average emissivity of all n(Ca²⁺)/n(Co²⁺) co-doped LaAlO₃ ceramics is generally greater than 0.94. The improvement of emissivity can be attributed to the enhancement of free carrier absorption, impurity absorption and lattice vibration absorption. This novel infrared ceramic with a high emissivity has promising prospects for energy-saving applications of thermal equipment.

Diatomite porous ceramics prepared by a foam-gelcasting route were used as a matrix, and SiO₂ microspheres in-situ formed by a solvothermal method were used to modify the surface roughness of diatomite porous ceramics. Capstone FS-50 (CS-50) was used as a modifier to prepare SiO₂ microspheres and CS-50 co-modified superhydrophilic-superoleophobic diatomite porous ceramics (SSMDPC) for the use of continuous separation of oil/water emulsions. The effects of TEOS/NH₃·H₂O addition and CS-50 concentration on the microstructure and wettability of the obtained samples as well as the oil/water separation continuous performance and extreme environmental stability were investigated. The results show that the maximum oil contact angles in air and water of the prepared SSMDPC are 153° and 158° respectively at TEOS/NH₃·H₂O addition of 5%/2% and CS-50 addition of 5% respectively. The continuous separation flux and separation efficiency of SSMDPC for edible oil/water mixture and edible oil-in-water emulsion with a surfactant (5/95, mass ratio) are 162.3 kg·min^-1·m^-2 and 98.3%, 93.7 kg·min^-1·m^-2 and 91.3%, respectively. Moreover, SMDPC can still maintain stable hydrophilic and hydrophobic properties under corrosion conditions (i.e., pH value of 1, pH value of 14 and 1 M NaCl), even at -196 ℃ and 200 ℃, which has broad application prospects in oil-in-water emulsion.

The membrane materials of Ba_0.95Ce_0.8Y_0.2O_3-δF_0.10(BCYF_0.10) and Ce_0.8Y_0.2O_2-δ(YDC) ceramic powders were prepared by a sol-gel method. BCYF_0.10-YDC/BCYF_0.10-Ni double-layered asymmetric dense hollow fiber ceramic membrane was synthesized via co-spinning and co-sintering. The effects of spinning mixture composition and sintering temperature on the structure of hollow fiber membrane were investigated. The thickness of the dense layer, the interface between the two layers and the bending strength of the resultant hollow fiber membranes can be tuned by adjusting the ceramic powder loading in the inner and outer spinning solution. The thickness of the dense outer layer of the membrane is only 14.5 μm when the contents of ceramic powder in the inner and outer spinning solution are 65.7% and 44.4%, respectively. The two layers can be integrated well with the measured bending strength of 168.5 MPa. The prepared hollow fiber membranes were tested for hydrogen separation. At 900 ℃, when the feed gas (50% H₂+50% He) and the sweep gas (N₂) are controlled at 100 and 100 mL·min^-1, respectively, the hydrogen permeation flux of hollow fiber membrane is 0.54 mL·min^-1·cm^-2.

The ceramic green bodies with different structures can be formed via binder micro-jetting and bonding additive manufacturing technology. However, the density, strength and surface quality of the sintered ceramic bodies are low. The nanozirconia suspension was used as a jet solution to substitute a conventional organic binder, and the effect of nanozirconia suspension jet amount on the properties of additive manufactured zirconia ceramics after sintering was investigated. When the nanozirconia suspension jet amount increases from 0 to 175%, the line shrinkage and surface roughness of sintered zirconia ceramics decrease significantly, and the reduction rates are 6%-8% and 57%, respectively, while the relative density, flexural strength and hardness increase considerably, and the increase rates are 18.1%, 124.0%, and 187.0%. The nano-sized zirconia particles can fill in the pores of the zirconia powder layer after introducing the nanozirconia suspension, thus improving the green density and the sintering quality of the zirconia ceramic. This provides an effective method for rapid manufacturing complex and compact ceramic parts.

To improve the mechanical properties of B₄C ceramics, TiB₂ was generated in-situ in B₄C ceramics by a reaction sintering method with TiO₂ as a sintering aid to prepare dense B₄C ceramics, and the enhancement mechanism of its mechanical properties was analyzed. The results show that the density and flexural strength of B₄C firstly increase and then decrease and the fracture toughness increases with the increase of TiO₂ addition. The density of B₄C ceramics reaches 99.6% when the TiO₂ addition is 5% (in mass fraction) and the sintering temperature is 1 700 ℃. The optimum overall performance of B₄C ceramics (i.e., the Vickers hardness of 36.0 GPa, the fracture toughness of 4.38 MPa·m^1/2, the bending strength of 405 MPa) can be obtained when the amount of TiO₂ added is 15%. The in-situ TiB₂ inhibits the growth of B₄C grains, eliminates the stress at the crack tip, deflects and bifurcates the crack, and plays a role in grain refinement strengthening and toughening of B₄C ceramics.

Investigation on 3D printing of silica ceramic cores is crucial to the development of aviation level in China, but the related problems are high-temperature softening and structural anisotropy. Silica ceramic cores were fabricated by DLP light curing 3D printing technology using fused silica powder as a raw material and mullite powder as a modifier. The results show that the ceramic cores have a layer-packed anisotropic structure. The addition of a small amount of mullite powder promotes the sintering densification of ceramic powder and diffusion binding between printing layers. As a result, the structural anisotropy of ceramic cores is relieved, and the flexural strength is enhanced and tended to isotropy. For ceramic cores with 3% mullite powder, the high-temperature flexural strengths in horizontal and vertical printing are up to 18.5 MPa and 16.3 MPa, respectively, which can satisfy the demands for hollow blade casting.

Piezoelectric ceramics are used in the manufacture of ultrasonic motor because of its inverse piezoelectric effect. However, some problems of poor joint conductivity, easy aging and low connection accuracy caused by organic bonding in the manufacture of ultrasonic motor need to be solved. In this paper, the surface of PZT piezoelectric ceramics was metallized via magnetron sputtering to improve the weldability between PZT piezoelectric ceramic and TC4 titanium alloy. The results show that the bonding force between Ag and base metal is poor, and the unwelded position appears at the junction of Ag layer and base metal. The welding is easy to occur at the junction of Ti and Ag when Ti/Ag is a metallized layer due to the poor bonding force between Ag and Ti. Ni and solder can form Ni-Sn layer to improve the joint reliability when the metallized layer is Ni/Ag. A composite metal layer, that is, the base metal/Ti/Ni/Ag structure, was selected as a metallized layer on the base metal surface, and the typical microstructure of the joint was analyzed. The results show that the composite metal layer can improve the bonding strength between the metallized layer and the base metal and realize the effective bonding between the BASE metal of PZT ceramics and TC4 alloy. The microstructure of the interface is β-Sn/Ag₃Sn/β-Sn+Ni₃Sn₄/Ni₃Sn+Ni/Ti₂Ni/Ti₂Ni+α-Ti/PZT.

Hydroxy aluminum polycation was firstly prepared with AlCl₃·6H₂O and NaOH as raw materials, and then Al-pillared montmorillonite was prepared with hydroxy aluminum polycation as alumina source. A montmorillonite-based ceramic was fabricated via ball milling and hot pressing with Al₂O₃ and Al(OH)₃ as alumina sources. The effect of hot-pressing temperature on the mullitization and mechanical properties of montmorillonite-based ceramic was investigated. The results show that the mechanical properties of montmorillonite-based ceramics are improved by adding three kinds of alumina sources at the hot-pressing temperature of 1 100 ℃. The optimum flexural strength and fracture toughness of Al-pillared montmorillonite-based ceramics at 1 300 ℃ (i.e., 118.07 MPa and 2.30 MPa·m^1/2) can be obtained, which are increased by 41.0% and 74.2%, compared with original montmorillonite ceramics.