Machinable mica-based glass-ceramic

A glass-ceramic in the K₂O-MgO-Al₂O₃-MgF₂-SiO₂ system was prepared through the sol-gel and alkaline precipitation routes. The powders were hot pressed into workable discs. The glass-ceramic was found to be machinable with conventional tools. Its physical and mechanical properties compare favourably with commercial macor. A dependence of flexure strength on microstructure is also indicated.     

Neural networks and fuzzy logic-based spark advance control of SI engines

In SI engines, spark advance (SA) needs to be controlled to get Maximum Brake Torque (MBT) timing. Spark advance can be controlled either by open loop or by closed loop controller. The open loop controller requires extensive testing and calibration of engine, to develop look up tables. In closed loop controller, empirical rules relating variables deduced from cylinder pressure are used. One of such empirical rules is to fix location of peak pressure (LPP) at a desired value of the crank angle. In the present work, a combined neural network and fuzzy logic-based control scheme is designed for SA control to get MBT timing. The fuzzy logic controller is designed to maintain LPP of SI engine close to 16° ATDC. The controller works in conjunction with Recurrent Neural Network model for cylinder pressure identification. LPP is estimated from cylinder pressure curve reconstructed using neural network model and is used as feedback signal to fuzzy logic controller. The simulations have been carried out to test the performance of the combined neural network and fuzzy logic-based control strategy. The simulation results show that the proposed strategy can quite satisfactorily control LPP to its desired value.     

Microstructure and microhardness in alumina gel monoliths

Alumina gel monoliths prepared from aluminium isopropoxide through hydrolysis and chemical polymerization are porous, transparent, and consist of ultrafine particles. The monolithic xerogels exhibit lamellar, cellular and fractal microstructures which are found to arise due to instabilities during drying. Phase separation can occur during ageing and drying and influence the microstructure. The Vickers indentation hardness shows a power-law dependence on relative density.     

Direct Formation of Titanium Carbide via In Situ Carbothermal Reduction of TiO2/Carbon Cladding for Coating Application

Protection of Metals and Physical Chemistry of Surfaces - In situ direct formation of titanium carbide (TiC) was realized via tungsten inert gas (TIG) arc surface cladding using titanium dioxide...     

Influence of Syzygium cumini leaves extract on morphological,thermal, mechanical,and antimicrobial properties of PVA and PVA/chitosan blend films

In the present work, poly(vinyl alcohol)/Syzygium cumini leaves extract (PSN) and poly(vinyl alcohol)/chitosan/S. cumini leaves extract blend films were prepared by solution casting technique. The films were characterized by using scanning electron microscopy, atomic force microscopy, X‐ray diffraction study, Fourier transform infrared spectroscopy, thermogravimetric analysis, and universal testing machine. The results indicated that the appreciable physical interaction at lower concentrations of S. cumini leaves extract in the PVA and PVA/chitosan films contribute to the smooth uniform morphology, increased the degree of crystallinity, degradation temperature, and improved mechanical properties. Further, films were analyzed with water contact angle analyzer which illustrates that blend films were hydrophilic (PSN‐1) and hydrophobic (PCS‐1) in nature. However, blend films were also subjected to the antimicrobial study, which revealed that inclusion of S. cumini leaves extracts significantly enhanced the antibacterial activity in the PVA and PVA/chitosan film. With all of these results, fabricated blends can find potential applications in packaging material to extend the shelf life of foodstuffs. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46188.     

Optical properties of coloured transparent alumina gel monolith glasses

Optical properties of transparent alumina prepared through gel process at room temperature and coloured with dopants have been studied. The absorption bands, molar absorptivity, effect of concentration and the dependence of oxidation state of copper on the copper content and water content are similar to the random network glasses. The ultraviolet absorption edge at lower energies confirm the disordered nature of the transition phase aluminasγ andδ. The absorption bands in the visible suggest the octahedral symmetry of oxygen around aluminum.     

Crystallization of mica in the K2O-SiO2-MgO-MgF2 glass system

The growth of crystalline mica in K₂O-SiO₂-MgO-MgF₂ glass has been studied and characterised through various techniques, viz. differential thermal analysis (DTA), X-ray diffraction (XRD), microscopy (SEM), and microhardness tests. It is observed that the addition of titania has a stronger influence on the growth of mica crystallites as compared to variation in heat treatment schedules.     

Plasma-activated immobilization of biomolecules onto graphite-encapsulated magnetic nanoparticles

We describe the amino group surface functionalisation of graphite-encapsulated iron compound nanoparticles by radio frequency (RF) plasma processing followed by oxidized dextran immobilization. We have found that surface treatment using plasma represents an important step before biomolecules immobilization. After plasma treatment, the dispersion property of nanoparticles in dextran solution in water was significantly improved. The successful dextran immobilization was confirmed by X-ray photoelectron spectroscopy (XPS) and high resolution-transmission electron microscopy (HR-TEM) analyses followed by amino group derivatization using 4-(trifluoromethyl)-benzaldehyde (TFBA). As an evidence for covalent bonding between nanoparticles and dextran, the area percentage of deconvoluted CN peak at ～389.6 eV increased from 0% to 10.53 ± 1.30% with increasing the dextran concentration. The result is consistent with the evidenced decreasing of the free amino group percentage from 68.09 ± 5.10% to 14.73 ± 5.89% on the nanoparticle surface after dextran immobilization.     

Alumina-glassceramic composites

Alumina-glassceramic composites show good densification and uniformly distributed fine-sized particle microstructure owing to the liquid phase of the glassceramic at the sintering temperatures. The flexure strength decreases with increase in the glassceramic content. This is attributed to the dissolution of alumina at the interface resulting in a changed crystalline phase, glass coating around the matrix grains and the difference in thermal expansion. These aspects have been confirmed through expansion coefficient measurements. Paper presented at the poster session of MRSI AGM VI, Kharagpur, 1995