For the sake of enhance the cutting performance of self-lubricating ceramic tools, in this paper, we prepared self-lubricating tool materials by adding CaF₂@Al₂O₃ coated powder with core–shell structured as solid lubricant, the cutting performance of ceramic tool materials were investigated through dry machining of hardened steel, and the wear mechanism was explored. The results showed that CaF₂@Al₂O₃ core–shell structured solid lubricant in the ceramic tool material was more effective than CaF₂ in improving the wear resistance. The addition of CaF₂@Al₂O₃ core–shell structured solid lubricant in the ceramic tool materials can reduce the cutting force and cutting temperature. Under the same cutting conditions, compared with Al₂O₃/TiC/CaF₂ ceramic cutting tool, the Al₂O₃/TiC/CaF₂@Al₂O₃ tool had lower surface roughness of workpieces, while the main cutting force and cutting temperature are reduced by 27.7 and 52.6 % respectively in the cutting process. The wear of the rake face included micro-chipping, crater wear and adhesive wear, while the wear of flank face included micro-chipping, adhesive wear and abrasive wear. The ceramic tool with CaF₂@Al₂O₃ core–shell structured solid lubricant obtained outstanding cutting performance.

Polycrystalline SiC coating on large-sized SiC ceramics was investigated for its application to SiC susceptors for use in severe environments in LSI processes. The proposed coating process is simple and special gases are not used. SiC coating on the SiC substrate is achieved by positioning the ceramics above Si melt maintained in a carbon crucible in a furnace constructed using carbon materials. First, we evaluated the effect on the SiC grain size and the thickness of the SiC coating of varying the temperature and the distance maintained between a 1-inch diameter SiC substrate and the melt surface. We found that 6H-SiC grains several micrometers in size were densely deposited on the substrate, and the grain size and thickness of the SiC coating increased with increasing temperature. Next, based on these results, we achieved crystalline SiC coating on both sides of a 6-inch diameter SiC substrate. The number of carbon or SiC particles released from the SiC ceramic surface was evaluated with a submerged particle counter, and this number was found to be reduced by 99 % or more with a sample coated at 1800 °C as compared to the uncoated product. A discussion of possible chemical reactions for crystalline SiC formation is presented here based on the analysis of chemical species in the furnace using quadrupole mass spectrometers.

ZnMgO:Al coatings were prepared by radio frequency (RF) magnetron sputtering on glass substrates, and the effects of the substrate temperature on the structural, electrical, and optical properties of ZnMgO:Al coatings were studied. The ZnMgO:Al coatings had a hexagonal wurtzite crystal structure oriented along the c-axis, regardless of the substrate temperature. Increasing the substrate temperature increased the grain sizes of the coatings and thus their Hall mobilities. The high substrate temperature also promoted the doping concentration efficiency of Al³⁺ ions, leading to enhanced carrier concentration. The optimal deposition was obtained at 400 °C, which led to the lowest resistivity (2.82 × 10⁻³ Ω cm) and 91 % transmission in the visible range. The optical bandgap increased to 3.632 eV as the substrate temperature increased to 400 °C. Wide bandgap, highly transparent, and conductive ZnMgO:Al coatings can be used as electrodes for ultraviolet photovoltaic applications.

We present a method for synthesizing brookite-type titanium dioxide (TiO₂) using an emulsion-assisted hydrothermal approach and a water-soluble titanium complex with glycolic acid as a complexing agent. In this study, stirred hydrothermal synthesis was used to synthesize water-in-oil emulsions with titanium glycolate complex in the aqueous phase. The resulting brookite-type TiO₂ was investigated using Raman spectroscopy for crystal polymorph identification, X-ray Diffraction to identify crystal polymorphs and crystallite size, Transmission Electron Microscope for primary particle size, and crystal shape, and Dynamic Light Scattering for TiO₂ secondary particle size in aqueous dispersion. The synthesized brookite-type TiO₂ was a needle-like crystal with a width between 20 and 30 nm and a length of more than 70 nm, growing in the b-axis direction at an angle of about 70° from the (120) plane. Furthermore, compared to the conventional synthesis method, the secondary particle size was smaller, and the dispersibility in water was improved. The results show that the brookite-type TiO₂ dispersion obtained using the emulsion-assisted hydrothermal method can facilitate the formation of uniform films and can be applied to the electron transport layer of organic perovskite solar cells.

36Pb(In_1/2Nb_1/2)O₃–30Pb(Mg_1/3Nb_2/3)O₃–34PbTiO₃ (36PIN–30PMN–34PT) ternary ceramics with morphotropic phase boundary (MPB) composition were fabricated by two-columbite precursor method. The effects of sintering temperature on phase formation, densification and electrical performance of PIN–PMN–PT ceramics were investigated in detail. It was found that the optimized sintering condition was 1240 °C for 5 h. The electric properties of the 36PIN–30PMN–34PT ceramics were dependent on sintering temperature. More importantly, the dielectric and piezoelectric constant increased as the sintering temperature increased. However, the increasing trends between electric properties and the sintering temperature were interrupted when the ceramics were sintered above 1260 °C as a result of PbO vaporization.

Ternary Au/Bi₂WO₆/BiOBr composites were skillfully prepared via a two-step synthetic route. The two-component Bi₂WO₆/BiOBr heterojunction was firstly fabricated by hydrothermal method, and Au nanoparticles (NPs) were further introduced and uniformly anchored on the surface of Bi₂WO₆/BiOBr, where the loaded Au NPs could be beneficial for improving visible-light absorption and adjusting photoinduced charge carriers in the heterostructure through surface plasmon resonance (SPR). In comparison with pristine Bi₂WO₆ and two-component Bi₂WO₆/BiOBr, the ternary Au/Bi₂WO₆/BiOBr composite exhibits a better photocatalytic activity for removal of rhodamine B (RhB) under visible light irradiation. The degradation efficiency of GTB-3 composite 1.9 times higher than that of the pure Bi₂WO₆ and 1.24 times than that of Bi₂WO₆/BiOBr. Trapping tests with different scavengers revealed that not hydroxyl radicals but superoxide radicals and photogenerated holes were highly responsible for the degradation process. The enhanced photocatalytic activity was ascribed to the synergetic effect of heterojunction effect (efficient separation of charge carriers), porous structure of Bi₂WO₆ (strong adsorption), SPR of Au.

An equation was derived to analyze carbonation phenomena in cement based on the Tomosawa theory, and it was applied to examine the difference between the cement content and degree of charcoal oxidation. Two types of fly ash cement based on ordinary Portland cement (OPC), high-alite cement (HAC), low-heat Portland cement (LHC), and moderate-heat Portland cement (MPC) were prepared, and the degree of carbonation was measured by acceleration examination. With these measurements, long-term carbonation was simulated using the new equation. Under the accelerated condition (CO₂ 5 %), when 18 % fly ash was added to Portland cement (OPC+FA18) and 18 % fly ash to HAC (HAC+FA18), the degree of carbonation in one month was examined relative to unmodified cement, and the carbonation rate increased by approximately 1.8 and 1.6 times, respectively. The degree of carbonation of MPC was approximately the same as that of OPC, but the carbonation of LHC was about three times greater. Therefore, fly ash cement (OPC+FA18, HAC+FA18) and LHC are more useful in the environment because these cements have a superior ability to prevent carbon dioxide release compared with that of OPC.

LiMn₂O₄ has been prepared by means of high-energy ball-milling of Li₂CO₃ and MnCO₃ followed by one-pot sintering. Milling at 800 rpm for 4 h with sintering at 700 °C for 12 h leads the enhanced cathode performance as 123.5 mAh g⁻¹ of initial discharge capacity under 1 C charge–discharge rate, retaining 95.1 and 91.6 % of capacity after 100 and 200 cycles, respectively. Mechanochemical reaction facilitates the sintering reaction to form the favorable microstructure homogeneously without second phase. Relaxation analysis showed that, at the charging around x = 0.2 for Li_xMn₂O₄, the sample prepared by optimal milling time varies mainly lithium concentration in Li-rich phase, while excessively milled sample alter the molar ratio of Li-rich and Li-lean phases. This indicates that optimal milling time allows the sample to undergo the less structural change at the charging, which enables the improved cycle performance.

In this work, based on the sol–gel and titration technology, an innovative method to prepare the yttria stabilized ZrO₂–Al₂O₃ composite beads which can greatly improve the bead properties is proposed. Using this method, the yttria stabilized ZrO₂–Al₂O₃ composite beads samples with different proportion of alumina component were prepared and tested. The density results show that the density of the ceramic beads is very close to the theoretical value, which implies that the new method can prepare the beads with high compactness and without containing pores. Vickers hardness results show that the hardness of the composite beads is higher than the zirconia beads without containing alumina. The SEM analyses show that the average grain size of the composite beads is about 180 nm, much smaller than that of the beads prepared by the conventional rolling process. X-ray diffraction results show that there is no monoclinic phase in the composite beads after sintering at 1250 °C. The EDS analyses show that the aluminum element exists in composite beads and the alumina grains are evenly distributed. Furthermore, the beads sintering temperature using this new process can achieve low-temperature which is about 1250 °C, much lower than that of the beads prepared by the conventional rolling process.

Silicon nitride ceramics have attracted increasing attention as insulated heat-dissipating substrates for power modules due to their high thermal conductivity and mechanical strength. However, there are very few reports on their dielectric breakdown strength, which was only evaluated for the substrates with thicknesses between 250 and 640 µm, though thinner substrates are preferable for attaining better performance of the module. In this work, dielectric breakdown of sintered silicon nitride substrates with thicknesses ranging from 285 to 15 µm was evaluated for the first time. Average breakdown strength increased from 36.38 to 103.80 kV/mm with decreasing thickness from 285 to 15 µm. It should be noted that the silicon nitride specimen had very high dielectric breakdown voltage of 1.5 kV even with a thickness as small as 15 µm.

The electronic structure of Pr-doped ZrSiO₄ is calculated using modified Becke–Johnson potential plus on-site Coulomb interaction (MBJ + U). The minimum energy gap of ZrSiO₄ calculated using the MBJ method is 5.8 eV, which is close to the experimental value. When a Pr atom replaced one of Zr atoms, strongly localized Pr 4f states appear in the forbidden gap of ZrSiO₄. By considering the on-site Coulomb interaction in addition to the MBJ potential, the empty Pr 4f states appear about 2 eV above the valence band maximum of ZrSiO₄. Compared with generalized gradient approximation (GGA), MBJ, and GGA + U approaches, MBJ + U better describes the position of empty Pr 4f states for Pr-yellow pigment.