Eﬀect of hydrolysis of AlN particulates on corrosion behavior
of Al/AlNp composite in neutral chloride solution
, Biantao Wu, Mingyuan Gu
State Key Laboratory of MMCs, Shanghai Jiao Tong University, Shanghai 200030, China
Received 14 September 2005; received in revised form 21 December 2005; accepted 13 January 2006
The eﬀects of hydrolysis of the AlN particulates on corrosion behavior of Al/AlN
composite were examined by analyzing potentio-
static anodic current transient, cyclic voltammetry curves and potentiodynamic cathodic polarization curves. It is found that the degree
of hydrolysis of AlN particulates in the composite increase with the pre-hot water treatment time, which increase the occurrence of meta-
stable pits in the composite. In addition, hydrolysis of AlN particulates also aﬀects the electrochemical corrosion behaviors of the com-
posite, and makes Al/AlN
composite show intergranular corrosion behavior to some extent.
Ó 2006 Elsevier Ltd. All rights reserved.
Keywords: B. Corrosion; B. Mechanical properties; Al/AlN
Aluminum matrix composites reinforced with ceramic
particulates (AMCs) have attracted much attention for a
wide variety of aerospace and defense applications because
of their low density and improved mechanical properties.
In contrast to the extensive research into the development
of physical and mechanical properties of AMCs, few stud-
ies have been performed on their corrosion behavior. Cur-
rently corrosion studies on AMCs have focused on the
eﬀect of the reinforcement on the corrosion behavior .
Aylor and Moran  believed that the introduction of the
reinforcement results in the preferential attack at the rein-
forcement/matrix interface, which can be attributed to the
formation of crevices at the interfaces. This viewpoint was
also supported by Mcintyre et al. . However, other stud-
ies suggest that reinforcement additions do not substan-
tially aﬀect the corrosion behavior of the composites.
They only make surface corrosion morphology change to
some extent, and there is no change in the characteristic
potential for AMCs [4,5]. An acceptable viewpoint is that
whether the introduction of the reinforcement aﬀect the
corrosion behavior of the composites is related to the nat-
ure of the reinforcement .
As a new type of the ceramic reinforcement, AlN pos-
sesses more balanced thermal and physical property. From
the viewpoint of corrosion science, although they are poor
conductivity and there is no interfacial reaction between
the matrix Al and them, AlN particles hydrolyze easily
. This makes the corrosion behavior of Al/AlN
In this paper, the eﬀects of hydrolysis of the AlN partic-
ulates on corrosion behavior of Al/AlN
studied in 3.5 wt.% NaCl solution, and the inﬂuence was
mainly examined via SEM observation, potentiostatic cur-
rent transient technique and cyclic voltammetry technique.
The composites used were pure aluminum reinforced
with 55 vol.% AlN particulates, which were fabricated by
vacuum inﬁltration technique as explained elsewhere
[8,9]. The size of AlN particulates ranged from 3–30 lm
1359-835X/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
Corresponding author. Tel.: +86 21 62932106; fax: +86 21 62822012.
E-mail address: email@example.com (Z. Liu).
Composites: Part A 38 (2007) 94–99