Saroj K. Singh

Processing and Characterization of Jute-Epoxy Composites Reinforced with SiC Derived from Rice Husk

This article depicts the processing and mechanical characterization of a new class of multi-phase composites consisting of epoxy resin reinforced with jute fiber and filled with silicon carbide (SiC) particulates. The SiC used as filler material in this work was prepared from rice husk through plasma-processing technique. The effect of filler in modifying the physical and mechanical properties of jute—epoxy composites has been studied. It is found that the incorporation of rice husk derived SiC modifies the tensile, flexural, and inter-laminar shear strengths of the jute—epoxy composites. The micro-hardness and density of the composites are also greatly influenced by the content of these fillers.

Sintering of Al–Zr based oxide ceramics using thermal plasma

Abstract A novel and low cost extended arc thermal plasma heating (EATPH) reactor [Roul et al., JMSP 6 (1) (1998)] has been used to sinter Al–Zr oxide ceramics within a few minutes in Ar atmosphere instead of a few tens of hours by conventional furnace heating. Critical experimental parameters such as plasma power (kW), plasmagen gas flow rate, sintering time and electrode spacing distance are optimized to achieve high density sintered materials. It is noted that sintering time is approximately reciprocal to plasma power. Higher plasma power with less sintering time can generate high-density homogeneous material without significant grain growth. XRD and SEM studies were carried out to characterize and evaluate the sintered materials. Surface morphology revealed uniform particle size distribution in long-range order, with no runway grain growth during this EATPH sintering process. This simple EATPH method provides an alternative and quick technique for tailoring high temperature ceramic materials over conventional sintering method due to fast heat and mass transfer kinetics inside thermal plasma reactor.

Studies on dielectric properties of Al–Zr oxide composites sintered by thermal plasma

Abstract High-density sintered product of Al x –Zr 100− x ( x =0, 10, 20,…100) composites were produced using low-cost extended arc thermal Plasma heating (EATPH) source. Dielectric properties of these samples were studied as a function of different frequencies and at different temperatures. Particle sizes and density of the plasma-sintered products were controlled by controlling the plasma power, sintering time and plasmagen gas flow rate during sintering. Morphology and structure of sintered Al–Zr samples were examined by SEM and X-ray diffraction (XRD) to understand the plasma-sintered induced dielectric properties. It is noted that frequency- and temperature-dependent dielectric constant and loss factors are the consequence of polarization of dipole moment, which varied with the variation of plasma-sintered particle size. It is also observed that surface charge polarization along with dipole screening play crucial role at higher frequencies and at higher temperature. Dipole pinning and depinning mechanism are proposed to explain this complicated dielectric behavior.

Performance Evaluation of Glass-Epoxy-TiC Hybrid Composites Using Design of Experiment

The present paper reports the processing and solid particle erosion behavior of a multiphase composite consisting of epoxy resin reinforced with E-glass fiber and TiC particles. The TiC powder synthesized from ilmenite employing DC extended thermal plasma technique has been used as the filler in these glass epoxy composites. It is observed that with increasing percentage of filler particles, there is significant improvement in hardness and erosion wear performance. It is also observed that, among all the factors, impact velocity is the most significant factor followed by TiC percentage and impingement angle, while erodent size has the least significance on erosion of the reinforced composite. Taguchis orthogonal arrays have been used to identify the controlling factors influencing the erosion wear rate.

Synthesis of low carbon boron carbide powder using a minimal time processing route: Thermal plasma

Abstract Boron carbide powder was synthesized by thermal plasma reduction of boric acid in presence of graphite with a very minimal processing time. Subsequently, the as-synthesized products were leached to minimize the impurities content. Based on the results of X-ray diffraction and Raman spectroscopy, the effect of leaching on phase purity and crystallinity was studied. X-ray photoelectron spectroscopy was performed to identify the chemical composition which highlighted the absence of the B–O bonding in the deconvoluted B 1s core-level spectrum. Finally, the temperature dependent thermal conductivity behavior of the leached materials was analyzed and presented.

Physico-chemical properties of di-(2-ethylhexyl) phosphoric acid with apolar solvents from ultrasonic studies

The ultrasonic velocity (U), viscosity (η) and density (ρ) values of binary mixtures of di-(2-ethylhexyl) phosphoric acid (D2EHPA) with three apolar solvents, namely benzene, carbon tetrachloride and n-pentane, were experimentally measured at 313.16 K. The acoustic impedance (z), isentropic compressibility (βs ), intermolecular free length (Lf ), free volume (Vf ), internal pressure ( ) and viscous relaxation time (τ) were computed using the experimental data. The excess functions have been calculated and discussed in terms of nature of binary interactions. The computed results of the excess functions have been fitted to a Redlich–Kister-type polynomial equation. The results of this study indicate that the molecular interaction in the case of D2EHPA + n-pentane is the strongest.

Studies on Carbothermal Reduction Nitridation of Alumina in Extended Arc Thermal Plasma

In this paper, carbothermal reduction and nitridation of alumina in an extended arc thermal plasma reactor operating in transferred arc mode is reported. The formation of hexagonal AlN (average particle size ∼5 to 7 µm) has been observed in 5 min of processing time. The reaction is completed around 25 min of processing time. The reaction mechanism at high temperature has been predicted based on the chemical equilibrium diagram. The phase analysis, morphology, and optical studies of plasma synthesized AlN powder are carried out by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Raman spectroscopy, respectively. The compositional analysis is carried out by electron probe micro-analyzer (EPMA) and energy dispersive X-ray analysis (EDAX).

Recovery of sillimanite from beach sand of Chhatrapur, Orissa, India and its thermal treatment for refractory application

Beach sands of Chhatrapur, Orissa, India comprise about 18% of heavy minerals, mixed with light minerals like quartz and feldspar. Sillimanite, which has refractory applications, accounts for 8% of these heavy minerals. Sillimanite was separated from garnet, monazite, zircon, rutile, ilmenite, magnetite, hematite and pseudo-rutile by combination of spiral, Wet High-Intensity Magnetic Separation (WHIMS) and flotation techniques. The cleaned sillimanite concentrate was then mixed with pure alumina powder in different proportions and treated in an indigenously developed plasma reactor for preparation of mullite refractory material. Out of the three products obtained, sillimanite alumina powder in the ratio of 75 : 25 was found to have the necessary physical and compositional properties suitable for refractory applications.

Solid particle erosion behavior of glass-epoxy composites filled with TiC derived from ilmenite

The present article reports the processing and solid particle erosion behavior of a multiphase composite consisting of epoxy resin reinforced with E-glass fiber and TiC particles. The TiC powder synthesized from ilmenite employing DC extended thermal plasma technique has been used as the filler in this glass epoxy composites. It is observed that with increasing percentage of filler particles, there is significant improvement in hardness and erosion wear performance. It is also observed that, among all the factors, impact velocity is the most significant factor followed by TiC percentage and impingement angle, while erodent size has the least significance on erosion of the reinforced composite. Taguchi’s orthogonal arrays have been used to identify the controlling factors influencing the erosion wear rate.

Synergetic Surface and Chemical Durability Study of the Aesthetically Enhanced Natural Quartz by Heat Treatment

The change in surface behavior of natural quartz stone before and after heat treatment with metal oxides such as: cobalt oxide (Co3O4) and copper oxide (Cu2O) under vacuum and open atmosphere has been investigated. The surface feature, bulk density and hardness value of quartz changed after heat treatment, converting to a high value product. Difference in crystallinity of quartz, pre- and post-heat treatment was obtained through X-ray diffraction (XRD) study. The electron probe microanalysis results clearly explicated the diffusion of metal ion in quartz matrix exposed under vacuum atmosphere but as coating on the surface under open atmosphere. The structural transformation of quartz after heat treatment has been observed from the XRD data and well corroborated with the nanoindentation results. Durability of such quartz to chemical hazardous environment was observed. Thus, this communication demonstrates the change in physical and chemical characteristics of natural quartz stone after heat treatment under different atmosphere.