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Production of Nickel Silicide by Powder Metallurgy
A. Erol, Ş. Talaş
A. Kocatepe University, Technical Education Faculty, Afyon
Keywords: Nickel Silicide, Powder Metallurgy, Metal Matrix Composites, Electrodeless plating
Abstract. In this study, the reaction between SiC with chemically plated nickel on its surface has
been investigated. X-ray analysis gave the good number of lattice parameter for Ni3Si, a =
0.3522nm, and has good agreement with index. The surface layer of Ni diffuses into the SiC and
exothermically forms Ni3Si in a defined temperature range, producing free carbon which could be
deleterious to the properties. A reaction is evident at temperatures 900oC and 1350oC with
increasing trend. The mechanism of sintering which is shown to be a reaction sintered transient-
liquid phase method was determined by thermal analysis and metallographic techniques. The
strength, hardness and density properties of sintered Ni /Al (Liquid) + SiC composites are also
reported.
Introduction
The production of discontinuous reinforced composites has concentrated on the use of powder
metallurgy methods as well as on conventional melt casting techniques [1]. The mechanical
properties achievable through powder metallurgy are better than those attainable through liquid
state or spray deposition routes [2]. Due to the fact that smaller particle sizes can be used (0.1-
5µm), there is greater control of the distribution of the reinforcement. Greater levels of
reinforcement are achievable with maximum volume fractions in the region of 60% obtainable [3].
Ordered intermetallics such as aluminides and silicides are potential candidates for structural
applications at high temperatures and corrosive environments [4]. Their attractive properties include
relatively low densities, high melting points, good strengths and oxidation resistance at elevated
temperatures. Despite their attractive properties, intermetallic alloys have limited applications due
to their brittleness. The alloy design (microalloying and macroalloying) and processing techniques
(for instance, fabrication of single-crystal intermetallics and powder metallurgy methods, etc.) have
been employed to improve the structural applications of these materials [5]. Reactive sintering of
aluminides from elemental powder is similar to liquid phase sintering except the exothermic
synthesis reaction occurs between molten aluminum and the solid phase [6]. During reactive
sintering of nickel aluminides, molten aluminum reacts with solid nickel particles to form an
intermetallic compound.
In the present work, nickel aluminide matrix composites were produced by using powder
metallurgical techniques but instead of mechanical mixing of the powders, the SiC and aluminum
powder particles were chemically Ni plated to achieve a uniform Ni film. Development of chemical
Ni plating on SiC and Al powder mixtures and a transient liquid phase sintering process involving
short-times and relatively low temperatures were aimed here.
Experimental Procedure
Silicon carbide powders with a mean particle size of 10µm were produced by melting 4 g pellets of
a mixture of 99.99% pure silicon and graphite powders on the cooled copper heart of an arc furnace
Key Engineering Materials Online: 2004-05-15
ISSN: 1662-9795, Vols. 264-268, pp 1055-1058
doi:10.4028/www.scientific.net/KEM.264-268.1055
© 2004 Trans Tech Publications Ltd, Switzerland
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