Self-Propagating High-Temperature Synthesis of Functionally Graded PVD Targets with a Ceramic Working Layer of TiB2-TiN or Ti5Si3-TiN

Two- and three-layer functionally graded PVD targets with a working layer (sputtering surface) based on TiN-TiB₂ or TiN-Ti₅Si₃ formation via the technology of forced SHS compaction were considered. It was shown that rather wide (up to 1 mm) transition diffusional zones providing firm adhesion of the layers were formed between the working, intermediate, and third layers. The compositions TiN + TiB₂ + 20%Cu and TiB₂ + 50%Cu were found to be optimum for the intermediate (damping) and third layers of the three-layer PVD targets. The specific features of phase and structure formation of the two- and three-layer products with the working layer based on TiN-TiB₂ and TiN-Ti₅Si₃ were elucidated. Variation of the chemical oven mass exerted a noticeable effect of reduction of the residual porosity and enlarging of the grains of the product phases owing to prolongation of the time for secondary structure formation. The relationship of the hardness of the layers in the functionally graded target on the chemical oven mass allow prediction of the properties of the resultant graded material systems.     

论现代陶艺创作中的偶然性

偶然性和事物发展过程的本质虽没有直接的关系,但它的发生却极大的影响了现代陶艺的整体面貌。本文通过对现象之后的必然性的规律的分析,论述了偶然性因素在现代陶艺创作中的运用及其意义。     

灰铸铁与Al_2O_3副的摩擦磨损研究

本文在Ｍ－２００环－块磨损试验机上研究了工程陶瓷Ａｌ_２Ｏ_３与灰铸铁配副在空气、蒸馏水、乳化液和油润滑条件下摩擦磨损特性，并与０．８％Ｃ钢（Ｔ８）做比较，探讨铸铁中石墨对磨损行为的影响．结果表明：随着空气、蒸馏水、乳化液和油这一润滑顺序，Ａｌ_２Ｏ_３陶瓷和铸铁副的摩擦系数和磨损量都逐渐降低，但下降幅度逐渐减小．在空气和蒸馏水润滑下，铸铁中石墨能起固体润滑剂作用，而在乳化液和油润滑下，石墨不能发挥其固体润滑剂作用．     

The effect of heat treatment on colemanite processing: a ceramics application

Boron oxide (B₂O₃), water content, particle size, and specific surface area are important parameters in colemanite (2CaO3B₂O₃5H₂O) in the production of glasses especially of E-glass, boron carbide (B₄C) and borides (CaB₆, LaB₆, SiB₆, LiB₆, MgB₂, TiB₂, and TaB₂ etc.) which are used in ceramics applications. Calcination, a thermal treatment method, is known to affect these parameters significantly. In this study, differential thermal analysis (DTA)-TG, X-ray diffraction (XRD), SEM, BET and chemical analysis were performed on Turkish colemanites before and after calcination. The results are compared in order to elucidate the influence of calcination on processing. An application in the ceramic industry for the production of CaB₆ is demonstrated. Results indicate that the raw colemanite could be processed through calcination in the temperature range of 400 and 600 °C without milling. Calcination is shown to have a significant impact on colemanite similar to that of the milling process. As a result, colemanite was upgraded to ∼58 wt.% B₂O₃ for <250 μm yielding a specific surface area of 2.8 m²/g. This is higher than that of milled colemanite. Because of the crystal water of colemanite, CaB₆ is not produced from uncalcined colemanite, but easily produced from colemanite calcined at 600 °C.     

Effect of pH on the precipitation of hydroxyapatite on silica gels

Silica-HAp composites have been produced with particle size ranging from several nm to few μm, through control of the pH of the solution, which also controls morphology. A calcium ions reservoir has been made available as a Ca/EDTA soluble complex allowing the production of HAp at low temperature and short periods of time (hours). The presence of silica seems to promote the formation of HAp under these conditions. Electronic Publication     

陶瓷废渣的再生利用技术及方向

阐述了当前陶瓷废渣所带来的环境危害以及利用现状，提出了以超细技术为基础，通过深加工，创新出陶瓷废渣利用的一条新的路子，同时提出了新的发展方向。     

Dielectric anomaly in LiCa2V5O15 ceramics

A polycrystalline sample of LiCa₂V₅O₁₅ (LCV) was prepared using a mixed oxide method at low temperature (i.e., at 630 °C). X-ray structural analysis shows the single-phase formation of the compound in the orthorhombic crystal system at room temperature. A study on the surface morphology of the compound showed uniform grain distribution on the surface and in the bulk of the sample with less porosity. A dielectric anomaly suggests that the compound has a transition temperature at 274 °C. The activation energy, calculated from the temperature dependence of ac conductivity (dielectric data), of the compound was found to be 0.67 eV at 10 kHz. The nature of the variation of conductivity and value of activation energy in different regions, suggest that the conduction process is of mixed type (i.e., ionic-polaronic and space charge generated from the oxygen ion vacancies).     

Optimized microwave dielectric properties of Co- and Ca-substituted Mg0.6Zn0.4TiO3

The system of (1 − y)(Mg_0.6Zn_0.4)_1−xCo_xTiO₃-yCaTiO₃ was investigated to optimize its microwave dielectric properties by adopting appropriate contents of Co and Ca and by controlling sintering conditions. The effect of Co substitution was to enhance densification and Qf value, while the addition of CaTiO₃ resulted in increases of dielectric constant and TCF. As an optimal compositions, 0.93(Mg_0.6Zn_0.4)_0.95Co_0.05TiO₃-0.07CaTiO₃ successfully demonstrated a dielectric constant of 23.04, a Qf of 79,460 GHz and a TCF value of +1.4 ppm/°C after firing at a relatively lower sintering temperature of 1200 °C. The increase of sintering temperature beyond 1200 °C tended to degrade overall microwave dielectric properties presumably due to Zn volatilization as evidenced by the presence of a Zn-deficient phase (MgTi₂O₅) at 1400 °C. An attempt to establish the correlation between microstructure characteristics and dielectric properties was made in this dielectric system where the extensive range of firing temperature up to 1400 °C was evaluated.     

Synthesis and characterisation of chromium lutetium gallium garnet solid solution

The chromium lutetium gallium garnet system has been studied. Samples with 2xCaOxCr₂O₃(3 − 2x)Lu₂O₃5Ga₂O₃ (x = 0.025, 0.05, 0.075, 0.1, 0.2 and 0.3,) and xCr₂O₃(3 − x)Lu₂O₃5Ga₂O₃ (x = 0, 0.05, 0.075 and 0.3) compositions have been prepared in Ca,Cr:LGG and Cr:LGG systems, respectively. Samples were prepared by ceramic method, fired at 1250 °C/6 h and characterised by XRD, lattice parameters, UV-vis-NIR spectroscopy, CIE L^*a^*b^* measurements and SEM/EDX. Results indicate that Ca,Cr:LGG and Cr:LGG solid solutions are obtained. In Cr:LGG system only Cr(III) is stabilised in octahedral positions substituting for Lu(III) and Ga(III). Both Cr(III) and Cr(IV) are present in Ca,Cr:LGG. The calcium is a charge compensator to stabilise Cr(IV) and this is the predominant oxidation state up to x = 0.075 composition. From this composition, Cr(III) becomes more stabilised in garnet lattice. Cr(IV) occupies generally tetrahedral and dodecahedral sites substituting for Ga(III) and Lu(III), while Cr(III) is in octahedral site substituting for Ga(III).     

Order-disorder phase transitions and high-temperature oxide ion conductivity of Er2+xTi2−xO7−δ (x = 0, 0.096)

The Er_2+xTi_2−xO_7−δ (x = 0.096; 35.5 mol% Er₂O₃) solid solution and the stoichiometric pyrochlore-structured compound Er₂Ti₂O₇ (x = 0; 33.3 mol% Er₂O₃) are characterized by X-ray diffraction (phase analysis and Rietveld method), thermal analysis and optical spectroscopy. Both oxides were synthesized by thermal sintering of co-precipitated powders. The synthesis study was performed in the temperature range 650-1690 °C. The amorphous phase exists below 700 °C. The crystallization of the ordered pyrochlore phase (P) in the range 800-1000 °C is accompanied by oxygen release. The ordered pyrochlore phase (P) exists in the range 1000−1200 °C. Heat-treatment at T ≥ 1600 °C leads to the formation of an oxide ion-conducting phase with a distorted pyrochlore structure (P2) and an ionic conductivity of about 10⁻³ S/cm at 740 °C. Complex impedance spectra are used to separately assess the bulk and grain-boundary conductivity of the samples. At 700 °C and oxygen pressures above 10⁻¹⁰ Pa, the Er_2+xTi_2−xO_7−δ (x = 0, 0.096) samples are purely ionic conductors.