Challenges in Recovery of Valuable and Hazardous Elements from Bulk Fly Ash and Options for Increasing Fly Ash Utilization

Beneficiation of fly ash should require for ensuring the removal of reactive elements to reduce the effect of hazardous impact on our atmosphere and can fill the demand for resources such as metals and rare earths. In this chapter, we concentrate to describe the responsible factors involve in fly ash beneficiation that has a great contribution to our environment. The purpose of the current study is to know the recovery of different minerals; maximum removal of the contaminant, reactivity and neutralization capacity of acid mine drainage (AMD) with fly ash and development of the cost‐effective method of disposal of fly ash are achieved. Different beneficiation techniques of fly ash and utilization of fly ash are explained

Metallic Glasses: A Revolution in Material Science

Metallic glasses represent one kind of advanced material, very popular in recent decades. These materials are very adaptable like plastics for their manufacturability in very complex shapes. TPF (Thermoplastic forming) based processes seem very good method to process them. These materials can compete with plastics but have metallic properties. They behave as magnetic materials with less hysteresis loss and less eddy current loss making them suitable for transformer and MEMS (Micro-Electromechanical System) applications. These materials exhibit good corrosion resistance, hardness and toughness. Based on the property and application, metallic glasses are good rivals to plastics, metals and ceramics. Chemical composition and kinetics of supercooling of these materials are the areas where young researchers can focus attention with a view to their improvement

Wear: A Serious Problem in Industry

Wear is the damaging, gradual removal or deformation of material at solid surfaces. Causes of wear can be mechanical or chemical. The study of wear and related processes is known as tribology. Abrasive wear alone has been estimated to cost 1–4% of the gross national product of industrialized nations. The current chapter focuses on types of wear phenomena observed in the industries (such as abrasive wear, adhesive wear, fretting wear, fatigue wear, erosive wear and corrosive wear), their mechanisms, application of surface coating for the protection of the surface from the industrial wear, types of surface coatings, thermal spray coating, types of thermal spray coating and its application in industry to protect the surface from wear. The detail information about the wear phenomena will help the industries to minimize their maintenance cost of the parts

Superhydrophobic coatings for aluminium surfaces synthesized by chemical etching process

In this paper, the superhydrophobic coatings on aluminium surfaces were prepared by two-step (chemical etching followed by coating) and one-step (chemical etching and coating in a single step) processes using potassium hydroxide and lauric acid. Besides, surface immersion time in solutions was varied in both processes. Wettability and surface morphologies of treated aluminium surfaces were characterized using contact angle measurement technique and scanning electron microscopy, respectively. Microstructures are formed on the treated aluminium surfaces which lead to increase in contact angle of the surface (>150°). Also on increasing immersion time, contact angle further increases due to increase in size and depth of microstructures. Additionally, these superhydrophobic coatings show excellent self-cleaning and corrosion-resistant behavior. Water jet impact, floatation on water surface, and low temperature condensation tests assert the excellent water-repellent nature of coatings. Further, coatings are to be found mechanically, thermally, and ultraviolet stable. Along with, these coatings are found to be excellent regeneration ability as verified experimentally. Although aforesaid both processes generate durable and regenerable superhydrophobic aluminium surfaces with excellent self-cleaning, corrosion-resistant, and water-repellent characteristics, but one-step process is proved more efficient and less time consuming than two-step process and promises to produce superhydrophobic coatings for industrial applications

Enhancement of spray cooling by modify spray orientation and coolant characteristics

In the current work, using upward spray and NaCl added water, the Leidenfrost effect is significantly minimised in an ultrafast regime by cooling on a hot moving plate, and the heat removal enhancement rate is achieved at 2.15 times of water. The salt deposition on the steel augments CHF(Critical Heat Flux) and IHF(Initial Heat Flux) by bridging the droplet and hot plate's air gap and enhancing the momentum diffusivity. With NaCl added to water, the achieved corrosion rate is 0.79 mm/year lower than the SDS and Na2CO3 additives. The mechanical property analysis of the post-treated steel plate ensures significant tensile strength and hardness

A numerical study of the wall effects for Newtonian fluid flow over a cone

The effect of blockage ratio i.e. ratio of diameter of cone, d and flow channel, D on the drag coefficients due to Newtonian fluid flow over cone is studied numerically by solving the CFD equations in Ansys FLUENT. The drag coefficients (CD) as a function of Reynolds number (Re) and d/D are reported in the range of Re: 0.01–30,000 and d/D: 0.0015–0.9. The obtained CD values are higher for confined flow (high d/D) than unconfined flow. Validity of CDRe2=constant is ascertained for the confined Newtonian fluid flow over the cone. The variations of angle of separation and its effect on the drag coefficients are examined and justified. The comparative studies among the drag coefficients of sphere, cylinder and cone are carried out in terms of wall effect, re-circulation length and slope of axial velocity profile. The observations revealed the order of CD as cylinder > cone > sphere. The hydrodynamic interactions between wall and fluid medium are presented with the help of velocity contour plots. More asymmetric flow is observed around the particle at higher Reynolds number and for higher wall effect. The simulated results presented herein for unconfined flow are in good agreement with the literature data