WEAR PROPERTIES AND CHARACTERIZATION OF LASER-DEPOSITED NI-BASE COMPOSITES ON 304 STAINLESS STEEL

The amorphous phase (AP) and nanocrystalline particle (NP)-reinforced composite coating was fabricated by laser cladding (LC) of the Ni45-WC mixed powders on the 304 stainless steel. An LC technique favored APs as well as NPs to be formed due to their rapid cooling and solidification characteristics, so the wear resistance of the Ni-base coating was improved. Microstructures and wear resistance of the fabricated composite coating were studied extensively. The test results showed that the microhardness and wear resistance of this LC coating were enhanced under the actions of NPs, APs and the ceramics. The study of the laser synthesis of NPs provided a theoretical basis for improving the LC technique.

Impedance spectroscopic and dielectric properties of nanosized Y2/3Cu3Ti4O12 ceramic

Yttrium Copper Titanate ( Y 2/3 Cu 3 Ti 4 O 12) nanoceramic is structurally analogous to CaCu 3 Ti 4 O 12 (CCTO). X-ray diffraction (XRD) of Y 2/3 Cu 3 Ti 4 O 12 (YCTO) shows the presence of all normal peaks of CCTO. SEM micrograph exhibits the presence of bimodal grains of size ranging from 1–2 μm. Bright field TEM image clearly displays nanocrystalline particle which is supported by presence of a few clear rings in the corresponding selected area electron diffraction (SAED) pattern. It exhibits a high value of dielectric constant (ε′ = 8434) at room temperature and 100 Hz frequency with characteristic relaxation peaks. Impedance and modulus studies revealed the presence of temperature-dependent Maxwell–Wagner type of relaxation in the ceramic.

Hydriding Characterization of La2Mg17-Ni Composite Materials by Mechano-Synthesis

In order to improve the hydrogen storage performance of La2Mg17 alloy, with high energy ball-milling in argon atmosphere prepared La2Mg17-Ni composite materials, and mixed in a little NbF5. Through automatSubscript textic control Sieverts equipment tested hydrogen absorption kinetic characteristics of sample. X-ray diffraction (XRD) analyzed the microstructure of material after hydrogenated, and estimated the phase composition of hydrogenated powder material. The results showed that hydrogen storage properties of composite materials improved significantly because of the mechanical ball-milling approach, and the hydrogenated capabilities also increased dramatically with rising of temperature. Further explained the material hydriding property is largely ameliorate because of the Ni powder and NbF5 prompted amorphous or nanocrystalline particle formation, but temperature controlling the generation of new hydride phase is as well the reason of hydrogenated performance to advance.

Synthesis and Characterization on Fe-doped In2O3 Nanoparticles

ABSTRACTPure and Fe-doped In2O3 nanocrystalline powder was synthesized using a solution chemistry route based on the Sol-Gel process, which is a simple and inexpensive technique and produces long-time stable stock solutions. The X-ray diffraction patterns revealed the formation of nanocrystalline particle size with well-crystallized cubic bixbyte structure. The average crystal size was calculated from XRD patterns using Debye-Scherrer's equation for the (222) peak and found to be 8 nm. This observation agrees well with the particle size estimated from transmission electron microscopy (TEM). The observed Raman peaks in the doped materials are shifted towards the lower frequency up to 15 cm−1 and we did not observed any additional new Raman modes with Fe doping. This clearly indicates that Fe ions are indeed occupying interstitial/substitutional sites in the host In2O3, in agreement with XPS measurements. Magnetic properties were studied using superconducting quantum interface device magnetometer (Quantum design MPMS XL-7). Preliminary magnetic measurement results suggest the incorporation of the dopants in the diamagnetic In2O3-host structure.

Nanocrystalline Particle Coatings on α-Alumina Powders by a Carbonate Precipitation and Thermal-Assisted Combustion Route

We have suggested ultrafine particle coating processes for preparing nanocrystalline particle coated α-alumina powders by a carbonate precipitation and thermal-assisted combustion route, which is environmentally friendly. The nanometric ammonium aluminum carbonate hydroxide (AACH) as a precursor for coating of alumina was produced from precipitation reaction of ammonium aluminum sulfate and ammonium hydrogen carbonate. The synthetic crystalline size and morphology were greatly dependent on pH and temperature. By adding ammonium aluminum sulfate solution dispersed the α-alumina core particle in the ammonium hydrogen carbonate aqueous solution, nanometric AACHwith a size of 5 nm was tightly bonded and uniformly coated on the core powder due to formation of surface complexes by the adsorption of carbonates, hydroxyl and ammonia groups on the surface of aluminum oxide. The synthetic precursor rapidly converted to amorphous- and γ-alumina phase without significant change in the morphological features through decomposition of surface complexes and thermal-assisted phase transformation. As a result, the nanocrystalline polymorphic particle coated α-alumina core powders with highly uniform distribution were prepared from the route of carbonate precipitation and thermal-assisted combustion.