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1.
Titania-based ceramics with adjustable anatase-rutile fractions were obtained by milling of anatase, quartz and corundum precursors, uniaxial pressing and firing at 1100?°C. The influence of silica and alumina, combined with milling time and compaction pressure, was studied by design of experiments. The L9 orthogonal array with a three-level noise factor was employed. Firing of pure titania at 1100?°C yielded complete anatase to rutile transformation (ART), whereas stabilized samples show that an optimum amount of 9% silica and 33% alumina reduces phase transformation to only about 5?wt% rutile. An extended correlation matrix combined with analysis of variance (ANOVA) was applied to assess the combined effects of quartz, alumina, milling time and uniaxial compressing pressure on relative density, and anatase to rutile transformation. Results show absence of ART after milling, and controlled partial conversion of anatase to rutile after firing. Very good fitting was obtained by multivariate analysis on considering first and second order terms for dependence on silica contents and interactions between silica and each of the remaining factors, including milling time. This empirical dependence could be interpreted on a sound physicochemical basis, allowing the prediction of suitable compositions and processing conditions to obtain rutile-free samples by conventional ceramic processing, and to design ceramic samples with controlled fractions of anatase and rutile. 相似文献
2.
研究表明.在FL108作捕收剂条件下,硫酸铝强烈抑制金红石而使磷灰石上浮,采用“FL108+Al2(SO4)3”的浮选药剂制度,可实现两矿物的分离。通过分析Al3+和金红石表面Ti4+、磷灰石表面Ca2+的水解特性,还阐述了Al2(SO4)3的选择抑制机理。 相似文献
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4.
Single-crystalline iridium dioxide nanowires show the time-dependent universal conductance fluctuations (TUCFs) at cryogenic temperatures. The conductance fluctuations persist up to temperature T as high as nearly 10 K. The root-mean-square TUCF magnitudes increase with decreasing T, reaching approximately 0.1 e2 / h at 1.7 K. We ascribe these conductance fluctuations to originating from the conduction electrons scattering upon mobile defects (moving scattering centers). Our measured TUCF characteristics are satisfactorily explained in terms of the existing TUCF theory in its three-dimensional form. The extracted electron dephasing length Lφ(1.7 K) ≃90 nm is smaller than the diameter (≈ 180 nm) of our nanowires. 相似文献
5.
《Journal of the European Ceramic Society》2022,42(7):3313-3320
Glass-ceramic, which has negligible dielectric loss, high mechanical strength, excellent drop resistance, low CTE, and low density for lightweight design, is the best option for the back cover of mobile devices in the 5 G era. Herein, the effect of P2O5 on the phase separation and crystallization of MgO–Al2O3–SiO2-TiO2 glass-ceramics is studied. The incorporation of P2O5 in the glass structure leads to phase separation, in which the P and Mg-enriched phase was formed in the glass matrix, and promotes the increase of Tg. With the increase of P2O5 content, the precipitated crystals change significantly. First, the silicate crystals (Mg2SiO4) disappear, whereas the phosphate crystals (LiMgPO4) emerge when 2 mol% P2O5 is introduced. Second, titanate crystal (MgTi2O5) can not be observed when 4 mol% P2O5 is introduced. The Ti5O9 crystals appear simultaneously with LiMgPO4 crystals and transform to rutile TiO2 crystals at high temperature. Interestingly, the needle-like rutile TiO2 crystals, which is 300 nm long and 20 nm wide, have been found in a glass with 4 mol% P2O5. The large L/D ratio of needle-like crystals increases the hardness significantly from 6.08 GPa to 7.14 GPa. Similar to other fiber reinforced composites, this needle-like crystals provide a new strategy to improve the mechanical properties of glass ceramics. 相似文献
6.
《Journal of the European Ceramic Society》2017,37(2):801-810
A range of coatings from a water based suspension of anatase has been prepared by suspension high velocity oxy-fuel spraying with the aim to study effects of heat power of the flame on phase composition, microstructure and surface topography. Three most commonly used approaches of quantitative phase analysis have been scrutinized with respect to their applicability and as some of the coatings showed presence of preferred orientation and it was argued that quantitative Rietveld refinement is the most accurate method for phase composition determination. Coatings had a layered duplex anatase/rutile microstructure with fraction of rutile increasing exponentially with heat power. Spraying at the lower heat power led to a lower surface roughness and higher power resulted in surfaces with pronounced humps, which were distributed homogeneously on the surface. The emergence of humps is related to an increase in macroscopic surface area of up to 30% with respect to the flat coating. 相似文献
7.
《Ceramics International》2016,42(7):8038-8043
A rutile titanium dioxide nanostar over nanorods is synthesized by a simple and cost-effective hydrothermal deposition method onto conducting glass substrates. In order to study the effect of precursor concentrations on the growth of TiO2, the amount of Ti precursor is varied from 0.1 mL to 0.5 mL at the interval of 0.1 mL. These TiO2 thin films are characterized for their morphological, structural, optical and J–V properties using various characterization techniques. SEM images showed the formation of densely packed nanostars over nanorods for 0.3 mL titanium tetraisopropoxide (TTIP). XRD patterns show the formation of polycrystalline TiO2 with tetragonal crystal structure possessing rutile phase. Further, the TiO2 thin films are used for dye sensitized solar cells using N3-dye.The films were photoelectrochemically active and can be viewed as a promising application in DSSC with maximum current density of 1.459 mA/cm2 with enhanced photovoltage of 696 mV for the sample prepared at 0.3 mL TTIP. 相似文献
8.
提高胂酸对金红石浮选性能的研究 总被引:2,自引:0,他引:2
摘要通过对金红石矿石浮选研究发现:用苄基胂酸(BAA):非离子型表面活性剂(F2):离子型表面活性剂(E4)配比为l:l:002组成复合捕收剂(BF2/E4)浮选原生金红石矿石,结果粗精矿品位为75.41%,回收率68.25%;而单一BAA浮选金红石粗精矿品位为76.24%,回收率66.89%,这两者结果是很相近的。在捕收剂总用量不变条件下,复合BF2/E4中的BAA用量只有单一BAA用量一半,而且F2来源广,价格低,无毒。使用BF2/E4后,不仅提高了浮选作业回收率,而且该作业成本将降低1/3左右,环境污染也相应地减轻了。 相似文献
9.
《Ceramics International》2017,43(4):3761-3768
Nanofibers of titania and composite nanofibers of titania and multiwall carbon nanotubes were synthesized by electrospinning using a sol-gel process combined with activated carbon nanotubes. The relationships of treatment temperature, carbon nanotube content on the crystal phase, fiber morphology, and electric properties are reported. It is found that the rutile phase becomes more prominent at low heat treatment temperatures with an increase of carbon content in nanofibers, be it for higher amount of carbon due to reducing atmosphere or due to an increase in MWCNT. Atmospheric control and lower heat treatment temperatures enable crystalline nanocomposite fibers of anatase where the level of rutile is below the detection limit of XRD or Raman spectroscopy. This work provides a new path to fabricate electrospun TiO2/MWCNT nanocomposite nanofibers with limited C-induced rutile phase. 相似文献
10.