Influence of the Carbon Allotropes on Dilatometric Properties …
643
the phase composition of the made materials, depend on the type of used allotropic
carbons, their content in the initial mixture, and on the degree of its degradation
under mechano-chemical synthesis [11–13, 28–30].
In this work, we briefly consider, on the basis of literary data, the role of carbon
forms in determining the characteristics of some intermetallic composites Further,
we present data on their temperature behavior, mainly on dilatometric characteristics, and then describe the results of our own studies of the effect of temperature on
the characteristics of Fe–Cu nanocomposites with the addition of multiwall carbon
nanotubes (MWCNT). There, as above, the focus will be on the study of dilatometric characteristics. The conditions and details of the procedure and the compositions those ensure the control of characteristics of the resulting composites were
defined early by us, as we were the first who successfully used MWCNT for Fe–Cu
composites production [31–33].
2 Impact of Impurities on Properties of the Fe-Based
Composite Materials
It is known that the composition of P/M steels plays an important role in the
microstructure and physical properties of sintered parts [25]. The different levels of
alloying elements prealloyed into base powders change the hardenability of the material. Copper and graphite are very important additives. Reasonably, start considering
with a simple system, namely Cu–C.
Studies of the various carbon allotropic forms influence on the formation of
the structural-phase composition of copper-based composites have particularly been
performed in the work [30]. The composites Cu–C 60/70 and Cu–C g (in proportion
Cu-25 at.% C, 30 g by weight) were prepared by MA in planetary ball mill AGO-2S
in inert atmosphere P Ar = 0.1 MPa, with drums made of hardened stainless steel,
and balls 8 mm in diameter made of ball-bearing steel. The rotation speed of disc and
vial were 890 and 2050 rpm, respectively. It has been found there that the kinetics of
solid-state reactions in the copper–fullerite (Cu–C 60/70 ) and copper–graphite (Cu–C g )
systems obtained in process of the MA depend on deformational stability and oxidation–reduction properties of fullerite and graphite. It has been also shown that partial
destruction of fullerene molecules in the Cu–C 60/70 sample results in the formation
of an amorphous fullerite-like phase, copper oxide Cu 2 O, and supersaturated solid
solution Cu(C, O). Total destruction of fullerene molecules in the system Cu–C 60/70
results in the formation of supersaturated solid solution Cu(C), just like in the case
of the composite Cu–C g . Main obtained results can be understood from the grafice
abstract published in the paper (Fig. 1) [30].
Main attention in that study was focused on the copper–carbon composites because
of good conductivity of both constituents, which makes it possible to use Cu–C g
materials as current-collecting elements of sliding electrical contacts. At the same
time, the search was directed on for the improvement of the characteristics such as
643
the phase composition of the made materials, depend on the type of used allotropic
carbons, their content in the initial mixture, and on the degree of its degradation
under mechano-chemical synthesis [11–13, 28–30].
In this work, we briefly consider, on the basis of literary data, the role of carbon
forms in determining the characteristics of some intermetallic composites Further,
we present data on their temperature behavior, mainly on dilatometric characteristics, and then describe the results of our own studies of the effect of temperature on
the characteristics of Fe–Cu nanocomposites with the addition of multiwall carbon
nanotubes (MWCNT). There, as above, the focus will be on the study of dilatometric characteristics. The conditions and details of the procedure and the compositions those ensure the control of characteristics of the resulting composites were
defined early by us, as we were the first who successfully used MWCNT for Fe–Cu
composites production [31–33].
2 Impact of Impurities on Properties of the Fe-Based
Composite Materials
It is known that the composition of P/M steels plays an important role in the
microstructure and physical properties of sintered parts [25]. The different levels of
alloying elements prealloyed into base powders change the hardenability of the material. Copper and graphite are very important additives. Reasonably, start considering
with a simple system, namely Cu–C.
Studies of the various carbon allotropic forms influence on the formation of
the structural-phase composition of copper-based composites have particularly been
performed in the work [30]. The composites Cu–C 60/70 and Cu–C g (in proportion
Cu-25 at.% C, 30 g by weight) were prepared by MA in planetary ball mill AGO-2S
in inert atmosphere P Ar = 0.1 MPa, with drums made of hardened stainless steel,
and balls 8 mm in diameter made of ball-bearing steel. The rotation speed of disc and
vial were 890 and 2050 rpm, respectively. It has been found there that the kinetics of
solid-state reactions in the copper–fullerite (Cu–C 60/70 ) and copper–graphite (Cu–C g )
systems obtained in process of the MA depend on deformational stability and oxidation–reduction properties of fullerite and graphite. It has been also shown that partial
destruction of fullerene molecules in the Cu–C 60/70 sample results in the formation
of an amorphous fullerite-like phase, copper oxide Cu 2 O, and supersaturated solid
solution Cu(C, O). Total destruction of fullerene molecules in the system Cu–C 60/70
results in the formation of supersaturated solid solution Cu(C), just like in the case
of the composite Cu–C g . Main obtained results can be understood from the grafice
abstract published in the paper (Fig. 1) [30].
Main attention in that study was focused on the copper–carbon composites because
of good conductivity of both constituents, which makes it possible to use Cu–C g
materials as current-collecting elements of sliding electrical contacts. At the same
time, the search was directed on for the improvement of the characteristics such as