Synthesis and characterization of nano-sized α-alumina powder from kaolin by acid leaching process

2017 ◽  
Vol 146 ◽  
pp. 286-290 ◽  
Author(s):  
Sunipa Bhattacharyya ◽  
Pallavi Suhasinee Behera
2020 ◽  
Vol 3 (4) ◽  
pp. 1141-1145
Author(s):  
Alafara A. Baba ◽  
Veronica Y. Olowo ◽  
Mustapha A. Raji ◽  
Julius P. Akinribido

2011 ◽  
Vol 402 ◽  
pp. 243-248 ◽  
Author(s):  
Xing Bin Li ◽  
Chang Wei ◽  
Zhi Gan Deng ◽  
Min Ting Li ◽  
Cun Xiong Li ◽  
...  

A process has been developed at the laboratory scale for leaching of vanadium from a vanadium residue using mixed hydrofluoric and sulfuric acid solutions, and NaClO as an oxidant. The extraction studies were carried out using various acid concentrations, liquid/solid ratios, addition of oxidant, reaction temperatures and leaching times. The optimum leaching conditions were then determined. Characterization of the leach residues was carried out by SEM and EDS analysis. Results indicate that the silicates can be effectively destroyed by HF, and the vanadium contained in the vanadium-iron spinel can be leached by the mixed acid solutions. The addition of NaClO enhanced the leaching process by the oxidation of V3+(s) to V4+ and V5+. The leaching efficiency was also improved by raising the leaching temperature, prolonging the reaction rime and using a higher liquid/solid ratio. A vanadium recovery of 81.8% was obtained by the direct acid leaching process


Author(s):  
X. Zhang ◽  
Y. Pan ◽  
T.T. Meek

Industrial microwave heating technology has emerged as a new ceramic processing technique. The unique advantages of fast sintering, high density, and improved materials properties makes it superior in certain respects to other processing methods. This work presents the structure characterization of a microwave sintered ceramic matrix composite.Commercial α-alumina powder A-16 (Alcoa) is chosen as the matrix material, β-silicon carbide whiskers (Third Millennium Technologies, Inc.) are used as the reinforcing element. The green samples consisted of 90 vol% Al2O3 powder and 10 vol% ultrasonically-dispersed SiC whiskers. The powder mixture is blended together, and then uniaxially pressed into a cylindrical pellet under a pressure of 230 MPa, which yields a 52% green density. The sintering experiments are carried out using an industry microwave system (Gober, Model S6F) which generates microwave radiation at 2.45 GHz with a maximum output power of 6 kW. The composites are sintered at two different temperatures (1550°C and 1650°C) with various isothermal processing time intervals ranging from 10 to 20 min.


1996 ◽  
Vol 61 (10) ◽  
pp. 3572-3572
Author(s):  
Lawrence T. Scott ◽  
Atena Necula

2018 ◽  
Vol 2 (1) ◽  
pp. 7
Author(s):  
S Chirino ◽  
Jaime Diaz ◽  
N Monteblanco ◽  
E Valderrama

The synthesis and characterization of Ti and TiN thin films of different thicknesses was carried out on a martensitic stainless steel AISI 410 substrate used for tool manufacturing. The mechanical parameters between the interacting surfaces such as thickness, adhesion and hardness were measured. By means of the scanning electron microscope (SEM) the superficial morphology of the Ti/TiN interface was observed, finding that the growth was of columnar grains and by means of EDAX the existence of titanium was verified.  Using X-ray diffraction (XRD) it was possible to observe the presence of residual stresses (~ -3.1 GPa) due to the different crystalline phases in the coating. Under X-ray photoemission spectroscopy (XPS) it was possible to observe the molecular chemical composition of the coating surface, being Ti-N, Ti-N-O and Ti-O the predominant ones.


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