The large-scale synthesis of Si3N4 nanobelts from quartz and graphite on a graphite-felt substrate was successfully achieved by catalyst-assisted carbothermal reduction-nitridation. The phase composition, morphology, and microstructure of Si3N4 nanobelts were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, energy-dispersiv...

Multiphase (MP) monoclinic and cubic Y2O3 nanoparticles, 40 nm in diameter, were densified by spark plasma sintering for 5–15 min and100 MPa at 1000 C, 1100 C, and 1500 C. Densification started with pressure increase at room temperature. Densification stagnated during heating compared to the high shrinkage rate in cubic single-phase reference nanopowder. The limited densification of the MP nano...

We have fabricated advanced metal–insulator–metal (MIM) capacitors with ultra-thin (200 Å) remote-PECVD Si3N4 dielectric layers having excellent electrical properties. The breakdown field strength of MIM capacitors with 200-Å-thick Si3N4 was larger than 3.5 MV/cm, which indicates the excellent quality of the deposited Si3N4 film. The main capacitance per unit area extracted by radio frequency (...

The chemical dry etching of silicon nitride (Si3N4)and silicon nitride (SiO2) in a downstream plasma reactor using CF4, O2, and N2 has been investigated. A comparison of the Si3N4 and SiO2 etch rates with that of polycrystalline silicon shows that the etch rates of Si3N4 and SiO2 are not limited by the amount of fluorine arriving on the surface only. Adding N2 in small amounts to a CF4 /O2 micr...

Using intermediate, liquid-forming compositions in the approach focuses on the Si3N4–R2O3 binary, where R2O3 is any (Y,La)2O3–AlN system as additives, fully dense Si3N4 ceramrare-earth oxide (or Y2O3) used singly or severally. After sinics with high strength at high temperature have been tering, this composition forms -Si3N4 and some refractory rareobtained by pressureless sintering. The cerami...

Excellent Fe3Si-Si3N4-SiC composites were successfully prepared with FeSi75 and SiC as main starting materials by nitridation reaction(at 1300°C for 8Hrs). The material properties were studied; the ferrosilicon nitridation mechanism was analyzed through chemical thermodynamics; phase composition, microstructure, corrosion resistance of products were also investigated. The results are shown that...

In the present work, passive oxidation kinetics of silicon nitride α-Si3N4 and (α+β)-Si3N4 powders at different temperatures from 1000 to 1200 °C were evaluated. Oxidation these was carried out improve wettability pressureless infiltration AZ91E Mg-alloy. The kinetic constant (kp) values oxide layer depth calculated. constants kp, 9.11e-16 6.35e-16 kg2/m4s 4.25 nm 3.69 nm, for (α+β)-Si3N4, resp...

The catalytic effects of chromium (Cr) on the direct nitridation of silicon (Si) and morphology of nitridation product were investigated. Cr dramatically improved the conversation of Si to silicon nitride (Si3N4). The complete conversion was achieved at 1350 °C upon addition of 1.25 wt% Cr. This temperature was much lower than that required in the case without using a catalyst. Meanwhile, Cr pl...

Sedimentation studies have been carried out to optimize the dispersion conditions of aqueous alumina nanopowder suspensions with or without dispersants (ammonium salt of polymethacrylic acid or rhamnolipids at 15%). Different dispersant dosages, solid loadings, pulp densities and pH values were examined. The iso-electric point (IEP) of the alumina nanopowder was found to be pHiep= 9.2. The expe...

TiO2-doped SnO2 nanopowder is synthesized via a sol-gel method and characterized by atomic force microscopy and X-ray diffraction. Using this nanopowder, we have fabricated a novel semiconductor gas sensor that is sensitive to UV light illumination. We find that gas-sensing properties of TiO2-doped SnO2 sensor can be enhanced significantly under the exposure of UV light. The sensor exhibits a h...