Powder Metallurgy Technology
Giving particular emphasis to those processes which are of industrial significance, this useful text provides detailed coverage of metal powder production, compaction, sintering, hot consolidation, and much more.
TABLE OF CONTENTS Powder Metallurgy Technology
Chapter 2: Metal Powder Production
Overview
The subject of metal powder production is a very extensive one. In this chapter the description of most important principles and processes is given, which are of technological significance. The significant manufacturing methods may be classed as follows:
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Chemical methods
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Physical methods
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Mechanical methods
Virtually any material can be made into a powder by one or more of these methods. The exact method chosen must be related to the type of application and the desired properties and structure of the final product.
2.1. Chemical Methods
For detailed description of basic thermodynamics and kinetics aspects readers are referred to follow standard text1 as an introductory guide. These methods can be further classified as chemical reduction and decomposition.
2.1.1 Chemical Reduction
Chemical reduction involves chemical compound most frequently an oxide, but sometimes a halide or other salt of the metal. This may be carried out:
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from the solid state - as in the reduction of iron oxide with carbon or of tungsten oxide with hydrogen.
Sponge iron powder produced by the H gan s process is a typical example of this production method. This is a batch process in which the ground ore does not move during reduction, but is static in contrast to other direct reduction processes which are continuous. The H gan s process is based in the use of quite pure magnetite (Fe 3O 4) ores found in northern Sweden. The iron ore is reduced with a carbonaceous material. Figure 2.1 shows the steps involved in producing such powder.
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