From Powder Metallurgy Technology

3.1. Introduction

The success of any powder metallurgical process depends to a great extent on the complete characterization and control of the metal powders. The method of powder production influences particle chemistry and structure, apart from the precise nature of particle size distribution. These properties also influence the behaviour of the powder during compaction and sintering, and the composition, structure and properties of the sintered material. In the present chapter, various characteristics of the powder, some interrelated, are considered. Table 3.1 gives a brief summary of principles involved in the characterization of various powder properties which shall be described in subsequent sections.

Table 3.1: Powder properties and methods of mesuring them

Particle size and size distribution

Sieve analysis: Permeability: Sedimentation electrical resistance; Light obscuration; Light scattering; Microscopy; Surface area.

Particle shape [external]

SEM; Shape parameters; Morphological analysis; Fractals.

Particle shape [external and internal]

Stereology; Mercury Porosimetry; Gas absorption.

Particle density

Pycnometry; Mercury porosimetry.

Specific surface area

Gas absorption; Permeametry.

Surface chemistry

X-ray photoelectron spectroscopy (ESCA); Auger electron spectroscopy; Secondary ion mass spectroscopy; Ion scattering spectroscopy.

Alloy phases and phase distribution

Optical metallography; Stereology; Electron microscopy; EDAX; X-ray diffraction.

Quality of mixing [segregation]

Macroregion:Variability coefficient (by chem.anal.); Microregion: Variability coefficient (2 nd comp. >5%); Homogeneity coefficient (2 nd comp. <5%); by metallography

3.2 Chemical Composition and Structure

The levels of impurity elements in metal powders can be very significant to both the processing and properties of the final product. It is necessary to know whether such elements are present...

Copyright Cambridge International Science Publishing 2002 under license agreement with Books24x7

Products & Services
Particle Analyzers
Particle analyzers are used to determine the physical makeup of individual particulates in aerosols, dispersion, emulsions, powders, and other samples.
Analytical Laboratory Services
Analytical laboratory services detect, classify and/or assay chemical, material, biological, geological and environmental samples.
Material Testing Services
Material testing services test, analyze, and certify a wide range of materials for purity, chemical compatibility, and environmental impact.
Nanoparticle and Powder Processing Services
Nanoparticle and powder processing services perform milling, crushing, classifying, screening, grading, atomizing, coating, or production of metal or chemical powders and nanomaterials on a contractual basis.

Topics of Interest

4.1 Annealing It is customary that the powder producer delivers the powder to the fabricator ready for mixing. The aims of annealing are: to soften the powder to reduce the residual amount of...

John W. McMurdy, Gregory P. Crawford and Selim Suner We have all the light we need, we just need to put it in practice. Albert Pike Biomedical spectroscopy and imaging are tools heavily relied upon...

Melene M. Keyser and Frans F. Prinsloo Sasol Technology R&D, KlasieHavenga Road 1, Sasolburg, 1947 Abstract This paper reports the loading of oxidized carbon nanofibers with cobalt employing a...

Y.F. Hsieh, S.L. Cheng and L.J. Chen 9.1 SCOPE OF THE CHAPTER This chapter will describe the fundamental principle of the analytical tools of materials characterisation and specially emphasise the...

The following abbreviations are used in this book: AC alternating current ASAXS anomalous small angle X-ray scattering BBL bottom blocking layer BC bond-centre BIS bremstrahlen isochromat...