powder productıon and nano materıals - 6th International Powder ...

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6. ULUSLARARASI TOZ METALURJİSİ KONFERANSI ve SERGİSİ
th INTERNATIONAL POWDER METALLURGY CONFERENCE & EXHIBITION
EFFECT OF THE AlxNiy PHASES ON THE MECHANICAL PROPERTIES OF
THE AlCuSiMg/SiC(Ni)p COMPOSITES
judit PÁZMÁN * , Viktor MÁDAI ** , Zoltán GÁCSI * , Alíz MOLNÁR*, Árpád KOVÁCS*
* University of Miskolc, Institute of Materials Science, 3515 Miskolc-Egyetemváros, Hungary;
femjuju@uni-miskolc.hu; femtangz@uni-miskolc.hu; alizmolnar27@gmail.com; femkov@uni-miskolc.hu
** University of Miskolc, Department of Mineralogy and Petrology, 3515 Miskolc-Egyetemváros;
askcesar@uni-miskolc.hu
ABSTRACT
In our research work AlCuSiMg/SiC(Ni)p composite was produced by powder metallurgy. The reinforcing phase
(SiC) was surface coated by electroless nickel plating. The ceramic particles with inert surface had to be activated
by acidic pre-treatment or surface oxidation or palladium chloride activation before surface coating. The quality of
formed metal layer depends on the pre-treatment methods. The nickel layer of the silicon carbide particles and
matrix react together during the sintering, and Al x Ni y compound forms on the interface of AlCuSiMg-SiC. This compound
effects on the mechanical properties of the composite. In our research work the compressive yield point,
compressive strength and micro hardness were determined. The effect of the phase arrangement was studied
on the mechanical properties. The microstructure of the samples was examined by SEM, optical microscopy and
XRD.
keywords: Surface modification, Silicon carbide particles, Aluminium-nickel compounds, Powder Metallurgical
Composite
1.INTRODUCTION
To improve the interfacial bonding between the matrix and the reinforcing phase, the surface of the reinforcing
phase is coated with different metal layers. Mostly the particles are surface treated with copper [1-3] or nickel [4-6].
These metal layers can improve not only the interfacial bonding but the properties of the matrix. These metal layers
can be formed by different surface treating methods, for example by galvanization [7], mechanical alloying [8] or
electroless plating [9]. The last method can be used simply in a laboratory conditions and it provides equal layer
thickness, but the catalytic active surface is need to form the deposit. It is not simple to coat with metal the silicon
carbide particles. The surface of the silicon carbide particles must be activated before surface coating. Different
pre-treatment methods can be applied as a surface activation (Table 1), for example acidic pre-treatment, surface
oxidation or palladium chloride activation [10-11].
Table 1 The main parameters of the pre-treatment methods
Type of pre-treatment Chemical composition Applied parameters Mechanism
Acidic pre-treatment
Surface oxidation
Sodium hypophosphite
(NaH 2 PO 2 ∙H2O) 30 g/l
Lactic acid 98%
(CH 3 CH(OH)COOH) 20ml/l
In an air atmosphere in a
heat-treatment furnace
T=358K (85°C), 35
min.
At 1100°C for 3h
heat treatment,
oxidation
130
The development of a thin
hypophosphite layer can be
expected on the surface.
According to the Deal-Grove model,
a continuous, compact oxide layer
(SiO 2 ) develops on the surface of
ceramic particles.