S.K. Sahoo

Progress of Red Mud Utilization: An Overview

Red mud is a solid waste residue of the digestion of bauxite ores with caustic soda for alumina production. Its disposal remains a worldwide issue in terms of environmental concerns. During the past decades, extensive work has been done by a lot of researchers to develop various economic ways for the utilization of red mud. This paper provides a review on the comprehensive utilization of red mud glo bally. The research progress of safe stockpiling of red mud is summarized. Enormous quantity of red mud is generated worldwide every year posing a very serious and alarming environmental problem. This paper describes the production and characterization of bauxite and red mud in view of World and Indian context. It reviews comprehensively the disposal and neutralization methods of red mud and gives the detailed assessment of the work carried until now for the utilization of red mud in different fields. The c hemical and mineralogical characteristics of red mud are summarized with their environmental concerns.

Dry Sliding Wear Behavior of Aluminium Matrix Composite Using Red Mud an Industrial Waste

The effect of fillers like red mud (RM) on dry sliding wear behavior of pure aluminium has been experimentally investigated. Pure aluminium of IE-07 grades from National Aluminium Company (NALCO), Angul of Odisha, India being collected with fillers in 10%, 15%, 20% and 30% based on weight were prepared using a stir casting technique. The dry sliding wear tests were conducted using pin-on-disc wear test machine. Tests were conducted for a sliding distance from 4.53×10m to 27.18×10m with wear track diameter 50mm-180mm. For each composition wear tests were conducted for different sliding speeds of 200 rpm (1.257m/s), 300 rpm (1.885m/s) and 400 rpm (3.141m/s) by applying normal loads of 10N, 20N and 30N. The wear rate and coefficient of friction were plotted against the normal load, sliding velocity and sliding distance for each filler composition. The results reveal that incorporation of red mud fillers leads to significant improvement in wear resistance of aluminium. The effect is the increase in interfacial area between aluminium matrix and red mud particles leading to the increase in strength appreciably. Research Article International Research Journal of Pure & Applied Chemistry, 3(1): 59-74, 2013 60

Characterization of Plasma Sprayed Pure Red Mud Coatings: An Analysis

The characteristics of plasma sprayed pure red mud coatings have been investigated. The red mud was collected as a waste from aluminium production. In order to understand the coating characteristics, pure red mud was plasma coated. After plasma spraying, the coated materials have been subjected to series of tests to determine coating thickness, adhesion strength, micro structural characterization of

Mechanical properties, wear behavior and crystallographic texture of Al–multiwalled carbon nanotube composites developed by powder metallurgy route

Aluminum (Al)-based metal matrix composites reinforced with multiwalled carbon nanotubes were developed by powder metallurgy route. The Al and multiwalled carbon nanotubes powder mixtures were consolidated under a load of 565 MPa followed by sintering at 550℃ for 2 h in inert atmosphere. Al–1, 2, and 3 wt.% multiwalled carbon nanotube composites were developed. In the present study, the microstructure, mechanical properties, sliding wear behavior, and crystallographic texture of various Al–multiwalled carbon nanotube composites were investigated. The multiwalled carbon nanotubes produced by low-pressure chemical vapor deposition technique and the various sintered composites were characterized using scanning electron microscope, high-resolution transmission electron microscope, X-ray diffraction, differential scanning calorimetry and thermogravimetric analysis, Raman spectroscopy, and Fourier transform infrared spectroscopy. A significant improvement in relative density, Vickers microhardness, and wear resistance of the composites up to addition of 2 wt.% of multiwalled carbon nanotubes was observed. The deterioration in these properties beyond 2 wt.% of multiwalled carbon nanotubes was possibly due to the agglomeration of multiwalled carbon nanotubes in the Al matrix. The tensile strength of Al–multiwalled carbon nanotube composites continuously decreases with the addition of multiwalled carbon nanotubes. The decrease in tensile strength can be attributed to the detrimental effect of Al4C3 formed at the interface of the Al matrix and the multiwalled carbon nanotubes which will cause premature failure of the composite. The addition of multiwalled carbon nanotubes altered the crystallographic texture of the composites. The residual stresses in the various composites were found to be compressive in nature and also show improvement up to addition of 2 wt.% multiwalled carbon nanotubes in the Al matrix.

An analysis of plastic flow through polygonal linearly converging dies: as applied to forward metal extrusion

Abstract An approximate method based on the upper bound theory has been presented in order to investigate into non-axisymmetric metal extrusion process. In this approach the deformation region is divided into a finite number of rigid tetrahedral blocks that slides with respect to one another. The proposed method is successfully adapted to the extrusion of T-section bars from round billet through straight taper die. Computation for the upper bound pressure is carried out for various process variables such as area reduction, die angle and interface friction. The theoretical predictions are compared with that of known experimental results and found to be well within engineering accuracy.

Effect of pre-annealing strains on annealing texture developments in commercially pure (CP) titanium

Hexagonal commercially pure titanium (cp-titanium) plates were subjected to unidirectional-rolling (rolling), accumulative roll-bonding (ARB) and cross-rolling in a laboratory rolling mill. Rolling and cross-rolling were carried out to impart 90% reduction in thickness and ARB processing was performed for six passes. The deformed plates were then subjected to annealing at 600 °C for a large range of soaking time starting from 0.17 min (10 s) to 30 min. It was observed that the samples were fully recrystallized after 5 min of annealing, irrespective of the rolling processes employed in this study. Also, the samples were seen to develop almost similar texture when annealing was carried out beyond 5 min of annealing time. However, before annealing, the texture development was seen to be different in the respective samples subjected to different rolling processes. The initial texture present in the deformed structure got strengthened during annealing of the samples under investigation. It was also observed that the texture development was insignificant in ARB-processed samples after annealing.

Three Dimensional Analysis of Combined Forward and Backward Extrusion-Forging Process Using DEFORM 3D

Combined extrusion-forging is used in the manufacturing of a wide range of engineering components. Due to the complexity of the forming process and because of so many process variables, it is difficult to predict the forming load required to manufacture a given component. It is very costly to conduct different trail runs to know the metal flow patterns, and for redesigning of tool and die setup, etc. The present paper deals with the Finite element analysis of combined forward and backward extrusion-forging process for the product shape socket wrench. Two types of socket wrenches, Square-square type and hexagon-square type have been taken for the present analysis. The modelling has been done by using 3D modelling software CATIA and simulation through the Finite element based package DEFORM 3D software. The forming load can be estimated by the results obtained from the Finite element analysis through DEFORM 3D software.

Improvement in mechanical properties of commercially pure titanium through reverse rolling

Abstract Commercially pure (cp) titanium plates were subjected to 90% reduction in thickness through UDR (unidirectional rolling) and RR (reverse rolling) in the cold-rolling route. These rolled plates were then annealed at 600 °C for 20 min. The plates processed through UDR and RR exhibited similar values of ductility, but the plates subjected to RR exhibiting a significant increase in their strength compared to those rolled through UDR. However, on annealing the yield strength of the RR plate was reduced slightly while its ductility improved. Relative growths of dislocation density in the samples appeared to be responsible for such differences in the mechanical properties of the samples.

Upgradation of bauxite by molecular hydrogen and hydrogen plasma

An approach was developed to upgrade the bauxite ore by molecular hydrogen and hydrogen plasma. A gibbsite-type bauxite sample was obtained from National Aluminium Company (NALCO), Odisha, India. The obtained sample was crushed and sieved (to 100 μm) prior to the chemical analysis and grain-size distribution study. The bauxite sample was calcined in the temperature range from 500 to 700°C for different time intervals to optimize the conditions for maximum moisture removal. This process was followed by the reduction of the calcined ore by molecular hydrogen and hydrogen plasma. Extraction of alumina from the reduced ore was carried out via acid leaching in chloride media for 2 h at 60°C. X-ray diffraction, scanning electron microscopy, thermogravimetry in conjunction with differential scanning calorimetry, and Fourier transform infrared spectroscopy were used to determine the physicochemical characteristics of the material before and after extraction. Alumina extracted from the reduced ore at the optimum calcination temperature of 700°C and the optimum calcination time of 4 h is found to be 90% pure.

Directional Properties of Cold Rolled Non-oriented Electrical Steel Sheets

Applications of cold rolled non-oriented (CRNO) electrical steels demand uniform magnetic property in all directions. The objective of the present study was to investigate the magnetic properties of CRNO steel in different directions. Four different sets of samples were made from CRNO steel sheets—(1) samples along the rolling direction, (2) samples at 30° to the rolling direction, (3) samples at 60° to the rolling direction and (4) samples at 90° to the rolling direction. The textural and magnetic properties were investigated using standard techniques. X-ray diffraction and electron backscattered diffraction were used for bulk- and micro-texture measurements respectively. Single sheet tester was used for core loss and magnetic permeability measurements. The results showed different textural and magnetic properties in all the CRNO samples. However, the properties were always better in rolling direction where the texture was more.