Synthesis and Characterization of Copper Substituted Nickel Nano-Ferrites by Citrate-Gel Technique

Mixed Copper substituted Nickel nano-ferrites having the chemical formula Ni1-xCuxFe2O4 (where x = 0, 0.2, 0.4, 0.6, 0.8, 0.9 and 1.0) were synthesized by citrate gel technique. The crystal structure characterization and morphology were investigated by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). An elemental composition of the samples were studied by energy dispersive X-ray Spectroscopy (EDS). Lattice parameter, X-ray density, Volume of the Unit Cell and The values of the hopping length for octahedral (dB) and tetrahedral (dA) sites were calculated. The observed results can be explained on the basis of composition.

Characterization of Microstructure, Strength, and Toughness of Dissimilar Weldments of Inconel 625 and Duplex Stainless Steel SAF 2205

The dissimilar combinations of Inconel 625 and duplex stainless steel SAF 2205 obtained from manual GTA welding process employing ER2209 and ERNi CrMo-3 filler metals have been investigated. Formation of secondary phases at the HAZ of Inconel 625 and grain coarsening at the HAZ of SAF 2205 were witnessed while using these filler wires. The average hardness of ER2209 weldments was found to be greater than ERNi CrMo-3 weld. Tensile fracture was observed at the weld zones for both the fillers. Impact test trials showed brittle mode of fracture on employing ER2209 filler and mixed（ductile–brittle） mode of fracture while using ERNi CrMo-3 filler. Further optical microscopy and SEM/EDS analysis were carried out across the weldments to investigate the structure–property relationships.

Mechanical behavior of organo-modified Indian bentonite nanoclay fiber-reinforced plastic nanocomposites

The aim of the research was to examine the influence of organo-modified Indian bentonite （IB） nanoclay dispersed in vinyisster on the mechanical properties of nanoclaylvinylesterlglass nanocomposRes. Nanoclay was organically modified using cationic surfactant hexadecyltrimethylammonium bromide （HDTMA-Br） by cation exchange method and dispersed in vinylester using ultrasonication and twin screw extrusion. XRD of nanoclaylvinylester revealed exfoliaUon at 4 wt.% nanoclay indicating uniform dispersion in the polymer. DSC results showed improvement in glass transition temperature by 22.3% in 4 wt.% nanoclaylvinylester/glass when compared with that of vinylester/glass. Nanoclay/vinylester/glass with 4 wt,% nanoclay showed 29.23%, 23.84% and 60.87% improvement in ultimate tensile strength （UTS）, fiexural strength （FS） and interlaminar shear strength （ILSS） respectively when compared with those of vinylester! glass. The mode of tensile failure examined by SEM showed no agglomeration of nanoclay in 4 wt.% nanoclayNinylester/glass specimens.

Mechanical, thermal and fire nanoclay/vinylester retardation behaviours of nanocomposites

The dispersion of montmorillonite （MMT） in vinylester for preparing nanoclay/vinylester gel coat was reported. Two sets of MMT/vinylester specimens, namely Type I and Type 2, were prepared for comparative studies. Type I specimens were prepared using ultrasonication only, and Type 2 specimens were prepared using both ultrasonication and twin-screw extrusion. According to XRD and TEM results, Type 2 specimens showed lower levels of nanoclay agglomeration and higher levels o! exfoliation. DSC results showed that the glass transition temperatures of Type 2 specimens are higher than those of Type 1 specimens. TGA results showed that the residual weight of 4 wt.% MMT/vinylester of Type 1 was 7.38%, while the corresponding value of Type 2 was 13,5%, indicating lower thermal degradation in the latter. MMTt vinylester/glass and MMT/vinylester/carbon specimens were fabricated and tested for mechanical and fire retardation behaviours. Type 2 based nanocomposite laminates showed greater values of ultimate tensile strength, flexural strength, interlaminar shear strength, impact strength, horizontal burning rate, and vertical burning rate than Type 1 based laminates. SEM images of tensile fractured surfaces revealed that Type 2 based laminates have no or less agglomeration of nanoclay than Type 1 based laminates.