CHAPTER ONE
INTRODUCTION
- Background of Study
Powder metallurgy is a technique concerned with the production of metal powders and converting them into useful shapes. It is a material processing technique in which particulate material are consolidated to semi-finished or finished products. Metal powder production technique are used to manufacture a wide spectrum of metal powders designed to meet the requirement of a large variety of applications. Various powder production processes allow precise control of the chemical and physical characteristics of powders and permit the development of specific attribute for the desired application. Powder production processes are constantly being improved to meet the quality, cost, and performance requirements of all types of applications. Metal powders are produced by mechanical or chemical methods.
The most commonly used methods include water and gas atomization, milling, mechanical alloying, electrolysis and chemical reduction of oxides.
The type of powder production process applied depends on the required production rate, the desired powder properties and the properties desired in the final part. Chemical and electrolytic methods are used to produce high purity powders while mechanical milling is widely used for the production of hard metals and oxides. Atomization is the most versatile method for producing metal powders. It is the dominant method for producing metal and pre-alloyed powders from aluminium, brass, iron, low alloy steel, stainless steel, tool steel, super alloy, titanium alloy and other alloys.
Atomization [Mehrotra 1984] is a process in which a liquid stream disintegrated into a large number of droplets of various sizes. Basically atomization consists of mechanically disintegrating a stream of molten metal into the fine particles by means of a jet of compressed gases or liquids. It is an important process which finds wide applications such diverse field as spraying for insecticidal use, fuel injection in internal combustion engines, liquid spray drying, and liquid dispersion in numerous liquid-gas contact operations such as distillation, humidification and spray crystallization.
The technique of atomizing a metal melt, with fluid was connected with the production of metal powders. The basic principle involved in atomization of liquid consists in increasing the surface area of the liquid stream until it becomes unstable disintegrated. The energy required for disintegration can be imparted in several ways depending on the mode in which the energy is supplied.
The atomization process [Mehrotra 1984] can be classified into three main categories:
Pressure atomization.
- Mechanical atomization
- Chemical or centrifugal atomization
- Fluid atomization
The present work concentrated on the third type of atomization. The kinetic energy of a second fluid stream, being ejected from a nozzle is used for disintegrating of the liquid. The stream in a free fall is impacted by a high pressure jet of second fluid which is usually gas or water emerges either tangentially or at angle from nozzle. So that molten which in general, have high surface tension can be atomized by the fluid atomization technique.
- Aim and Objectives of the Study
- Aim of Study
The aim of this study is to design and fabrication a mini copula furnace and an atomizer for the production of powdered metal from waste aluminium cans.
- Objectives of Study
The objectives of the study include the following
- Determination of the volume of a single aluminium can using a weighing balance.
- Carrying out a material and energy balance to determine the mass aluminium to be melted, amount of fuel required and the required capacity of the furnace.
- Carrying out mechanical design of the mini-copula furnace required to melt the waste aluminium can.
- Fabrication of the proposed designed mini-copula furnace plant.
- Design of the atomizer for metal powder production.
- Fabrication of the designed atomizer.
- Analysis of the obtained aluminium powder metal.
- Problem Statement
Wide-spread application and high demand of powder metal in industrial and domestic processing activities and the littering-rate of aluminium cans all over the country which poses a serious adverse environmental condition, have grown at an alarming rate over the years. Therefore, the purpose of this project of this project is to design and fabricate a mini-copula furnace and an atomizer for the production of powder metal from waste aluminium cans which can be used for various domestic and industrial applications and also serves as a good environmental pollution control for the aforementioned waste.
- Scope of the Research Project
This research project focuses on the design and fabrication of a mini-copula furnace and an atomizer for the production of powder metal from waste aluminium cans through process atomization.
- Relevance of the Study
The importance of this study includes the following:
- To reduce the rate of environmental pollution (air, soil and water pollution) caused by littering waste aluminium cans.
- Meet up with the ever-growing demand for powder aluminium metal in automobile industry.
- To save energy and raw materials for the future industries.
- To provide raw material for metal matrix composites and wide applications in paint industries.
- To encourage researchers, think of ways of harnessing other waste materials.
- To increase the availability of solid fuels for rockers.
- It also serves as a reference material to any researcher on this field.
- Limitation of the Study
The factors hindering effective execution of this study are:
- Inadequate power supply for the operation of the fabricating machines.
- Inadequate fund
- Time towards successful completion of the project.
- Use of readily air as the atomizing fluid instead of costly pure nitrogen.
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