http://nopr.niscair.res.in/handle/123456789/3969 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/3979 Title: Synthesis, characterization, curing and thermal studies of phosphorylated epoxy resins <br/> <br/>Authors: Durga, Geeta; Singh, Darshan; Kukreja, Parveen; Narula, A K <br/> <br/>Abstract: Phosphorous containing two epoxies tris (glycidyloxy) phosphine oxide (TGPO) and tris (glycidyloxy) phosphine (TGP) are synthesized and their structure are characterized with the help of FTIR, ¹HNMR, ¹³CNMR, and ³¹PNMR spectroscopy. Synthesized TGPO/TGP is blended with DGEBA, which after curing with diamine curing agents, viz., 1,4-phenylene diamine (P), 3,4’-oxydianiline (O), 4,4’-diaminodiphenyl sulphide (DS), and 1,5-diamino naphthalene (N) resulted in several phosophorylated epoxy polymers. Curing reactions and reactivities of polymers are studied via DSC, which revealed that TGP is relatively more reactive towards diamine curing agent than TGPO. Further, among the diamines phenylene diamine (P) is most reactive curing agent towards both the epoxies as compared to other diamines. Thermal gravimetric analysis (TGA) was used to study the thermal behaviour and weight loss behaviour of cured epoxy resin. The phosphorous containing epoxy resin shows lower weight loss temperature and higher char yield (~23-36) and LOI (~27-32) values than that of Bisphenol-A based epoxy resin (char yield~10-12 & LOI~21-22), which confirms the effectiveness of phosphorylated epoxy resins as flame retardant. <br/> <br/>Page(s): 133-139 http://nopr.niscair.res.in/handle/123456789/3978 Title: Study of surface morphology in DC and pulse plating of silver alloy <br/> <br/>Authors: Shanthi, C; Barathan, S; Jaiswal, Rajasrisen; Arunachalam, R M <br/> <br/>Abstract: The objective of this work is to make a comparative study of dc and pulse plating of silver on silver alloy. The dc and pulsed electro deposition of silver on silver alloy is analyzed from an alkaline cyanide bath with brightener. Pulse duty cycles of 20 to 80%, at frequencies 10, 25, 50 and 100 Hz with peak current densities of 3.21, 3.75 and 4.55 A/dm² are employed. The influences of peak current density on the thickness and current efficiency of the plating process are studied. The surface morphology is characterized by SEM and XRD. Less porosity and fine grains are formed by pulse plating compared to that formed by dc plating. <br/> <br/>Page(s): 128-132 http://nopr.niscair.res.in/handle/123456789/3977 Title: Size dependent modifications in the physical properties of chemical solution deposition and pulsed laser deposition grown La_0.7Ca_0.3MnO₃ manganite thin films: A comparative study <br/> <br/>Authors: Markna, J H; Vachhani, P S; Shah, N A; John, J; Rana, D S; Malik, S K; Kuberkar, D G <br/> <br/>Abstract: Grain-size dependence of electronic transport and magnetoresistance (MR) properties of nanostructured La_0.7Ca_0.3MnO₃ (LCMO) manganite thin films grown using pulsed laser deposition (PLD) and chemical solution deposition (CSD) have been compared in the context of the grain size, surface and strain modification due to the different synthesis techniques used as well as due to substrate induced magnetic anisotropy. CSD grown LCMO thin films shows the grain size ~70 nm while grain size ~150 nm is exhibited by PLD grown films resulting in an appreciable change in the strain and low temperature magnetoresistance (LTMR). In CSD grown film, nanostructured grains exhibit sharp magnetic orientation in the absence of strain resulting in the observation of large maximum TCR value ~10.1% K^-1at 235 K as compared to PLD grown film (TCR value ~2.7% K^-1 at 194 K). Epitaxial thin films grown by the CSD technique are strain free and possess nanostructured grains size resulting into better physical properties as compared to PLD grown LCMO films. <br/> <br/>Page(s): 123-127 http://nopr.niscair.res.in/handle/123456789/3976 Title: An experimental investigation into the machinability of GGG-70 grade spheroidal graphite cast iron <br/> <br/>Authors: Korkut, Ihsan; Yavuz, Kadir; Turgut, Yakup <br/> <br/>Abstract: In this study, machining tests of the bearing necks of crank shafts produced from GGG-70 grade ductile iron (DI) are carried out. Coated cemented carbide inserts are used in the machining tests. The tests are carried out at four different cutting speeds (250, 275, 300 and 325 m/min), three different feed rates (0.15, 0.25 and 0.30 mm/rev) and two different depth of cuts (0.5 mm and 2 mm). The effects of these parameters on the surface roughness and the cutting force are investigated. Increasing cutting speed is found to deteriorate the surface roughness. The best average surface roughness values are obtained at 250 m/min which is the lowest cutting speed. Main cutting forces increased with increasing feed rate and depth of cut. <br/> <br/>Page(s): 116-122