Effect of KCl, NaCl and CaCl2 mixture on volume combustion synthesis of TiB2 nanoparticles

Article abstract of DOI:10.1016/j.materresbull.2011.05.013

Preparation of titanium diboride (TiB₂) nanoparticles was carried out by volume combustion synthesis. TiO₂, B₂O ₃ and elemental Mg were mixed with 0-60% salt mixture of KCl, NaCl and CaCl₂ with increment of 15% as a low melting temperature diluent. Compressed samples were synthesized in a tubular furnace at a constant heating rate under argon atmosphere. Thermal analysis of the process showed that the addition of the low melting temperature salts mixture led to a significant decrease in ignition and combustion temperatures. Synthesized samples were then leached by nitric and hydrochloric acids to remove impurities. The samples were examined by XRD, SEM and DLS analysis. The results showed the formation of fine deagglomerated particles with the addition of the salts mixture. The results revealed that 45% salts mixture had the smallest average particle size of about 90 nm.

Full text of DOI:10.1016/j.materresbull.2011.05.013

Materials Research Bulletin 46 (2011) 1377–1383
Contents lists available at ScienceDirect
Materials Research Bulletin
journal homepage: www.elsevier.com/locate/matresbu
Effect of KCl, NaCl and CaCl2 mixture on volume combustion synthesis
of TiB2 nanoparticles
*
Atiye Nekahi, Sadegh Firoozi
Mining and Metallurgical Engineering Department, Amirkabir University of Technology, 424 Hafez Ave., Tehran 15875-4413, Iran
A R T I C L E I N F O
A B S T R A C T
Article history:
Preparation of titanium diboride (TiB2) nanoparticles was carried out by volume combustion synthesis.
TiO2, B2O3 and elemental Mg were mixed with 0–60% salt mixture of KCl, NaCl and CaCl2 with increment
of 15% as a low melting temperature diluent. Compressed samples were synthesized in a tubular furnace
at a constant heating rate under argon atmosphere. Thermal analysis of the process showed that the
addition of the low melting temperature salts mixture led to a significant decrease in ignition and
combustion temperatures. Synthesized samples were then leached by nitric and hydrochloric acids to
remove impurities. The samples were examined by XRD, SEM and DLS analysis. The results showed the
formation of fine deagglomerated particles with the addition of the salts mixture. The results revealed
that 45% salts mixture had the smallest average particle size of about 90 nm.
Received 14 October 2010
Received in revised form 12 April 2011
Accepted 13 May 2011
Available online 20 May 2011
Keywords:
A. Inorganic compounds
A. Nanostructures
B. Chemical synthesis
C. Electron microscopy
D. Microstructure
ß 2011 Elsevier Ltd. All rights reserved.
1. Introduction
by an external source of heat and then a sudden reaction takes
place throughout the sample volume [5].
Titanium diboride is characterized by a high melting point,
hardness, and strength to density ratio, low specific weight, good
wear resistance, excellent thermal and chemical stability, and high
electrical conductivity [1–3]. Because of these outstanding
properties TiB2 ceramics have many technological applications
such as impact-resistant armour, wear components, cutting tools,
heating elements and cathodes in Hall–Heroult aluminium
smelting [3–6].
There are a number of methods for the synthesis of titanium
diboride particles such as carbothermic reduction of titanium and
boron oxides [2], boron carbide reduction of titanium oxide [1],
mechanical alloying of a mixture of elemental Ti and B powder [7]
combustion synthesis by direct reaction of Ti and B [8,9] or
oxidation/reduction of TiO2 and B2O3 with elemental Mg or Al
[4,5,10]. Among these methods, the combustion synthesis with
oxide constituent is a suitable and cost effective process, because of
its high speed, simple operation, generation of fine microstructure
and using low cost materials [10,11]. The heat of the reaction in
combustion synthesis is provided by the exothermic reaction of the
reactants. The generated heat propagates the reaction and reduces
the consumption of external energy [12]. In volume combustion
synthesis the whole sample is heated up to an ignition temperature
The properties of synthesized titanium diboride depend on
reactants particle size, green density [11] and added materials such
as diluents [4,11,13,14]. If the final product of the combustion
synthesis is used as a passive diluent in the starting mixture, the
combustion temperature decreases, however this process does not
usually lead into formation of a product with submicron particles
[15,16]. The effect of alkali metal salt diluents has also been studied
on the combustion synthesis [11,13,15,17]. Nersisyan et al. [17]
examined the addition of fusion salts of alkali metals as diluents for
the synthesis of some special ceramic powders in self-propagation
high temperature synthesis (SHS). They reported that the fusion
salts of alkali metals can greatly influence the SHS process by
lowering the particles aggregation and grain growth. Similar
results were obtained by Khanra et al. [13] on the effect of NaCl on
the combustion synthesis of TiB2. NaCl is considered to be an inert
phase in the synthesis reaction that lowers the combustion
temperature and creates an inhibiting layer on the forming
products. Formation of a layer on the particles is believed to
prevent particle coagulation and growth, hence forming smaller
particle size [11,13,15].
Several researches have studied the effect of NaCl diluent,
which has a relatively high melting temperature (800 8C) on the
synthesis of TiB2 [4,10,13]. A low melting temperature diluent can
change the VCS process by formation of a liquid phase during
ignition, hence changing the transport properties throughout the
synthesis reactions. Mixing the chlorides of alkali and alkali earth
* Corresponding author. Tel.: +98 21 64542961; fax: +98 21 66405846.
E-mail address: s.firoozi@aut.ac.ir (S. Firoozi).
0025-5408/$ – see front matter ß 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.materresbull.2011.05.013

1378
A. Nekahi, S. Firoozi / Materials Research Bulletin 46 (2011) 1377–1383
Table 2
metals substantially lowers their melting temperature. In this
study, a ternary mixture of some common and inexpensive inert
chloride salts of KCl/NaCl/CaCl2 near their triple point eutectic
temperature, as a low melting diluent was used. A ternary salt was
chosen because it provides a lower melting temperature. The effect
of this diluent on the mechanism of synthesis ignition, formation of
the by-products as well as the particle morphology and size has
been investigated.
Theoretical density and percent theoretical density of the samples with different
amount of salt mixture.
Percent salt
mixture
Theoretical densitya
Percent theoretical
density
(g cmꢁ3
)
0
15
30
45
60
2.31
2.27
2.25
2.23
2.21
68
73
74
77
79
P
2. Experimental
a
Theoretical density of the mixture (
r
m) was calculated as rm
¼
i ri f i, where
ri and fi are density and volume fraction of constituent i, respectively.
Titanium diboride was prepared from the mixtures of TiO2,
B2O3 (obtained from calcination of H3BO3 at 150 8C), and elemental
Mg as the reducing agent through volume combustion synthesis.
The properties of the starting materials are presented in Table 1.
The reactants of TiO2, B2O3 and Mg were weighed as mole ratio of
1:1:5.5, respectively, according to Reaction (1) [18]:
nitric acid at 80 8C to remove the by-products of the reaction. In
this process explained by Lok [19] aliquots of concentrated HNO3
was added. Stepwise leaching was used to minimize the
dissolution and loss of TiB2. In each step, one sixth of the
stoichiometric amount of nitric acid required to dissolve all the
produced MgO from Reaction (1) was added to achieve a minimum
pH of 2 in the solution. Each step continued until all the acid was
consumed and pH increased to about 7 and finally one extra
portion of hydrochloric acid was added to enhance the removal of
the by-products. Finally, the leached samples were analysed by
SEM to determine the particle dimensions and morphology,
dynamic light scattering (DLS) to measure the particle dimension,
and XRD to determine the phase constituents.
ꢀ
B2O3 þ TiO2 þ 5Mg ¼ 5MgO þ TiB2ð
D
G298 ¼ ꢁ1039 kJÞ
(1)
Excess amount of magnesium from the stoichiometric propor-
tion required for Reaction (1) was used to compensate a possible
evaporation of magnesium during synthesis. A mixture of 50 wt%
KCl, 25 wt% NaCl and 25 wt% CaCl2 (Table 1) was prepared, heated
in an alumina crucible to 850 8C to form of a fully liquid phase,
cooled to room temperature and then finely ground in a mortar.
The liquidus and solidus temperatures of the salt mixture were
determined by differential thermal analysis to be 521 and 490 8C,
respectively. The particle size of the salts mixture was below
3. Results and discussion
200
mm as determined by SEM micrograph. The salts mixture was
then added to the reactants in 0–60% weight ratio with 15%
increments.
3.1. Phase constituents of the combustion synthesis product
The precursor powders were dry mixed for 1 h and then
pressed in a form of 10–13 mm height, 17.2 mm diameter
cylindrical pellet. Theoretical density and relative density of the
pellets is presented in Table 2. The pellets were dried in a
tubular furnace at 150 8C for 1 h to remove the moisture from
the green samples. The dried pellets were then heated at a rate
of 15 8C/min under argon atmosphere to the ignition tempera-
ture. In situ differential thermal analysis (DTA) was performed
on samples during the synthesis in order to measure the ignition
temperature, maximum combustion temperature, and other
thermal effects during synthesis. Therefore, the temperature of
the reacting sample as well as the temperature of a pre-
synthesized reference sample was recorded simultaneously
during the process using two metal shielded K-type thermo-
couples with 2 mm diameter in contact with the samples. All
synthesis experiments were repeated once to confirm the test
results.
The XRD patterns of the unleached and leached samples with 0,
30 and 45% added salts mixture are shown in Figs. 1 and 2,
respectively. The XRD patterns of the unleached samples
confirmed the formation of MgO as the major compound and
TiB2 as one of the minor compounds. Based on Reaction (1), the
only products in the synthesis should be MgO and TiB2. However,
two other by-products, Mg3B2O6 and Mg2TiO4, were also detected.
Reactions (2) and (3) show the formation reactions of these two by-
products from the reaction of MgO with B2O3 and TiO2,
respectively. The XRD results show that the addition of the salts
mixture did not have a major effect in formation of these two by-
products [18]:
B2O3 þ 3MgO ¼ Mg3B2O6ð
D
Gꢀ
¼ ꢁ153:0 kJÞ
(2)
(3)
298
TiO2 þ 2MgO ¼ Mg2TiO4ð
D
Gꢀ
¼ ꢁ12:2 kJÞ
298
The synthesized samples were washed with distilled water to
remove the salts from the mixture. The phase composition and
morphology of the product were examined by X-ray diffraction
(XRD) and scanning electron microscope (SEM), respectively.
Thereafter, the synthesised samples were ball milled in a planetary
ball mill for 1 h and then subjected to a stepwise leaching with
XRD results of the leached samples (Fig. 2) confirmed that TiB2
was the main constituent and the leaching process removed a
major part of the impurities. MgO, which was the major product of
the synthesis, is present as a minor phase; and only a small amount
of Mg3B2O6 was detected in the leached samples. However, results
showed that Mg2TiO4 spinel phase, which was present as a minor
impurity in the as-synthesized sample, was the main impurity
after the leaching. This suggests that Mg2TiO4 is an acid resistant
compound and the current leaching method, which was effective
in protecting the valuable TiB2 product [19], was not successful in
removing all the impurities.
Table 1
Properties of the raw materials.
Reactant Purity (%) Particle size (
m
m) Manufacturer (catalogue no.)
Formation of the MgO, TiB2, Mg3B2O6 and Mg2TiO4 products
from the starting materials of 5 mole Mg, 1 mole TiO2 and 1 mole
B2O3 was predicted using FactSage [18] thermochemical software.
The simulation result in Fig. 3 showed that the only stable products
from room temperature up to about 2100 8C were MgO and TiB2.
Above 2100 8C, a gas phase consisted mainly of magnesium vapour
TiO2
H3BO3
Mg
>99%
99.5%
<0.2
Merck Chemicals (M808)
–
Surechem Products (B5102)
Merck Chemicals (8185060100)
Ghatran Shimi (6190)
>97%
>97%
>99.5%
>90%
<100
KCl
–
–
–
NaCl
CaCl2
Baran Chemical (26-37-39-45)
Merck Chemicals (1023791000)

A. Nekahi, S. Firoozi / Materials Research Bulletin 46 (2011) 1377–1383
1379
♦ TiB2
∗ MgO
• Mg2TiO4
∗
+ Mg3B2O6
∗
♦
♦
♦
•
•
♦
∗
∗
♦
+
•
+
♦
♦
+
+
+
+
+
•
•
+
+
+
+
+
+
+
a
∗
∗
∗
♦
•
+
+
+
♦
♦
+
+
+
♦
+
+
+
b
∗
♦
♦
+
•
+
+
∗
♦
•
+
+ +
+
+
♦
+
c
15
20
25
30
35
40
45
50
55
60
65
70
2 Theta (Deg)
Fig. 1. XRD patterns of the synthesized samples before leaching.
• Mg2TiO4
♦ TiB2
∗ MgO
+ Mg3B2O6
♦
♦
♦
•
♦
•
•
•
♦
∗
•
∗
∗
•
•
•
∗
+
+
+
+
+
+
+
+
a
b
♦
♦
♦
+
∗
•
♦
•
•
+
+
♦
♦
•
∗
+ ♦
•
•
+
♦
♦
♦
•
∗
•
•
+
+
+
+
c
15
20
25
30
35
40
45
50
55
60
65
70
2 Theta (Deg)
Fig. 2. XRD patterns of the leached synthesized samples.
600
a
a: 0%
b: 15%
c: 30%
d: 45%
e: 60%
400
200
0
b
c
d
e
-200
450
500
550
600
650
700
750
800
Reference temperature (°C)
Fig. 3. Predicted products weight with change of reaction temperature using
FactSage [18] thermochemical software.
Fig. 4. Differential thermal analysis of the samples with 0–60% salt mixture.

1380
A. Nekahi, S. Firoozi / Materials Research Bulletin 46 (2011) 1377–1383
was formed. Thermodynamics calculations showed that once there
was not enough magnesium available to reduce all TiO2 and B2O3,
Reactions (2) and (3) will proceed to form Mg3B2O6 and Mg2TiO4
compounds, respectively. However, if the formation of the gas
phase was prevented during the synthesis, i.e., the gas phase was
not included as a possible product in the simulation; results
showed that none of these two by-products form at equilibrium
conditions. Bigli et al. [5] reported that addition of 10–40% excess
Mg, which was used to compensate the evaporation of Mg, lowered
the content of Mg2TiO4 but had no effect on Mg3B2O6 content. This
suggests that insufficiency of magnesium due to evaporation is not
the only mechanism in formation of these two by-products. It is
possible that because of the very fast rate of the reactions,
thermodynamic equilibrium may not be attained and some MgO,
which is the main reaction product and abundantly available, react
with the remaining TiO2 and B2O3 and form these two by-products.
The same thermodynamic prediction was made for the sample
with the salts mixture and similar results were observed as for the
sample without the salts mixture. Hence, the thermodynamic
prediction was in agreement with the observation in Figs. 1 and 2.
Max. T
2800
2600
2400
2200
2000
1350
1150
950
750
550
350
150
Ignition T
Delta T
Adiabatic T
0
15
30
45
60
Wt% salts mixture
Fig. 5. Effect of salt mixture content on the ignition, maximum temperature of
combustion and their differences, as well as the adiabatic combustion temperature.
higher amount of salts mixture translated into a lower tempera-
ture increase during the combustion synthesis.
3.2. Thermal analysis of the combustion synthesis
Volume combustion synthesis is a reactive diffusion process,
where the ignition temperature is controlled by the rate limiting
step [20]. Ignition temperature depends on different parameters
such as the reactant particle size, heating rate, mechanical
activation, compaction pressure, relative density, formation of a
liquid phase and diluents [5,20–23]. Niyomwas et al. [24] and
Khandra et al. [13] separately performed a DTA of TiO2–B2O3–Mg
mixture. They both reported an endothermic effect at 650 8C due to
the melting of magnesium and then ignition occurred at about
685 8C. Khandra et al. [13] also reported that adding NaCl up to
20 wt% had no effect on the ignition temperature. Bigli et al. [5]
used the volume combustion synthesis of TiO2–B2O3–Mg mixture
to form TiB2 compound. They reported an ignition temperature of
690 8C; however after ball milling of the reactants, a more vigorous
reaction occurred at a much lower temperature of 220 8C. They
attributed this behaviour mainly due to the smaller particle size
and enhanced particle contact. Weimin et al. [14] also performed a
DTA of TiO2–B2O3–Mg system. They measured two exothermic
peaks; the first peak appeared at about 600 8C because of the
reaction of solid Mg and TiO2 and the second much larger peak at
about 645 8C due to the reaction of the rest of the Mg with B2O3 and
formation of TiB2. Since in these experiments, a different reactant
particle sizes, heating rate, and relative density were used, it is not
possible to determine the effect of each variable on the ignition
process. However, a comparison of these results suggest that the
particle size and contact area had a major role on the ignition
temperature and the maximum combustion temperature.
In this study, one smaller exothermic peak was observed before
the ignition in the samples with 0 and 15% salts mixture (Fig. 4).
This corresponds to a two-step synthesis process that based on
what described by Weimin et al. [14] indicates that the first
reaction occurred between Mg and TiO2 particles, in which the
latter had the smallest particle size among the reactants. The
second exothermic peak was due to the reaction of the liquid Mg
and the rest of the reactants and subsequently the formation of
TiB2. This suggests that formation of liquid magnesium was
necessary for ignition of the samples with 0–15% salts mixture and
also 15% salts mixture was not enough to significantly change the
ignition temperature. The samples with more than 15% salts
mixture showed only one highly exothermic reaction (Fig. 4) below
the melting temperature of magnesium indicating a one step
synthesis process, which suggests a fast reaction mechanism
between the oxides and solid magnesium in the medium of liquid
salts mixture.
Differential thermal (DT) results of the synthesis process are
shown in Fig. 4. Results showed two different types of behaviour
for the samples with no added salt and salts mixture. The samples
with 30–60% salts mixture had only one distinct exothermic peak
below the melting temperature of Mg (650 8C); however the
sample without added salt showed one small endothermic peak at
the melting temperature of Mg at 649 8C, one exothermic effect at
665 8C and ignition1 occurred at 785 8C. The behaviour of the
sample with 15% salts mixture was in between the two mentioned
behaviours. DT curves showed a small exothermic effect at 580 8C
and ignition occurred at 660 8C.
The effect of the added salts mixture on the ignition
temperature, maximum measured combustion temperature,
difference between these two, and adiabatic combustion temper-
ature is shown in Fig. 5. Adiabatic combustion temperature of
Reaction (4) with salts mixture addition between 0 and 60 wt% was
calculated using FactSage [18] thermochemical software.
5Mg þ TiO2 þ B2O3 þ nð0:5KClꢁ0:25NaClꢁ0:25CaCl2Þ
¼ 5MgO þ TiB2 þ nð0:5KClꢁ0:25NaClꢁ0:25CaCl2Þ
(4)
The results showed that the addition of the salts mixture
decreased the adiabatic temperature of the synthesis from 2827 8C
for the sample with no salt to 2400 8C for the sample with 60% salts
mixture. Thermal analysis results showed that the addition of salts
mixture from 0 to 60% resulted in a significant decrease in the
maximum combustion temperature from 1316 to 687 8C, accord-
ingly. It also showed a decrease in the ignition temperature from
786 to 499 8C for the samples with 0–60% salt addition,
accordingly. The maximum measured combustion temperature
was significantly lower than the theoretical adiabatic temperature
of the synthesis, which was mainly due to the heat losses to the
surroundings as well as the low response time of the shielded
thermocouple.
The addition of the salts mixture increases the heat capacity of
the reacting mixture and since an equal amount of heat is released
for all samples during the combustion synthesis,
a lower
temperature increase is expected. This corresponds well with
the reported difference between the maximum combustion
temperature and the ignition temperature in Fig. 5, in which the
1
The onset temperature of the major exothermic peak is the ignition
temperature.

A. Nekahi, S. Firoozi / Materials Research Bulletin 46 (2011) 1377–1383
1381
Fig. 6. SEM micrographs of the unleached samples with (a) 0%, (b) 15%, (c) 30%, (d) 45%, (e) 60% salt mixture and (f) 45% salt mixture at higher magnification.
The significant change in the ignition temperature of the
samples with the addition of salt was not in agreement with the
results from Khandra et al. [13]. They used uncompressed
powder with a relatively large reactant particle size2; hence
reaction did not occur for a self-sustaining thermal combustion
before the melting of Mg, and the addition of NaCl with a
relatively high melting temperature (800 8C) did not affect the
ignition process. However, in this study samples were com-
pressed and prepared with a smaller reactant particle size,
which increased the particles contact. Also, the addition of the
salts mixture increased the green density of the samples, which,
in turn, enhanced the heat transfer in the reaction medium [16].
The ignition temperature of the samples with 30% and more
salts mixture was in the melting zone of the salt mixture (490–
521 8C). As a result, formation of the liquid phase improved the
contact between the particles [25] and enhanced the heat
conduction and atoms diffusion, accordingly. Consequently, the
increased heat and mass transfer in the reaction medium
lowered the ignition temperature. The salt mixture completely
melted during the ignition and synthesis occurred in a medium
of liquid salt.
3.3. Particle size and morphology
Fig. 6 shows the SEM micrographs of the synthesised unleached
samples. The morphology of the sample with no added salt (Fig. 6a)
showed agglomerates of sintered product compounds. Some
agglomeration was still observed in sample with 15% salt mixture
(Fig. 6b); however it was less than what was observed in the
sample with no salt. Addition of more salt resulted in a complete
deagglomeration of the particles. Samples with 30, 45 and 60% salt
(Figs. 6c–e, respectively) consisted of fine disperse particles. Also,
some grain refinement was observed with the addition of the salt
and the smallest particle size was observed for the sample with
45% salt mixture (Fig. 6d). Fig. 6f shows TiB2 nanoparticles on MgO
matrix at higher magnification.
Grain refinement and deagglomeration is partly due to the
formation of a protective shell around the particles by the molten
salt mixture that prevented the particle growth during the
synthesis [26]. Also, the lower combustion temperature with the
addition of salt mixture resulted in
a lower tendency to
agglomerate. The deagglomeration of the particles is in good
agreement with results by Khanra et al. [13] who investigated the
combustion synthesis of TiB2 with addition of 0–20% NaCl to TiO2–
B2O3–Mg mixture.
2
Mg < 150
mm, B2O3 < 44 mm and TiO2 < 44 mm [13].

1382
A. Nekahi, S. Firoozi / Materials Research Bulletin 46 (2011) 1377–1383
Fig. 7. SEM micrographs of the leached samples with (a) 0%, (b) 30%, (c and d) 45% salt mixture.
The SEM micrographs of the leached samples with 0, 30 and 45%
experiments, i.e., smaller reactant particle size and densification
of the samples in this study. Given the substantial difference
between the particle sizes of the synthesis products in these two
studies, it may be concluded that the effect of the diluent is
secondary to the effect of the reactant particle size and the sample
green density. In other words, formation of nano-sized particles
was mainly because of using submicron TiO2 particles and high
green density of the particles.
salt mixture are presented in Fig. 7. Micrographs revealed a particle
dimension of about 100 nm for the samples with 0 and 30% salt
(Fig. 7a and b). A much lower particle size was detected for the
sample with 45% salt mixture (Fig. 7c) and individual particles at
higher magnification (Fig. 7d) were measured to be about 70 nm.
Fig. 8 shows the normalized cumulative particle size distribution
measured with DLS analysis. The measured particle sizes with DLS
analysis were slightly higher than what was observed in SEM
micrographs. The results showed the smallest average particle size
of about 90 nm for the sample with 45% salt mixture. The average
particle size of the samples with 0, 15, 45 and 60% salt mixture
were about 110 nm and the sample with 30% salt mixture had the
largest particle size of about 130 nm. Results did not confirm a
continuous decrease in particle size as reported by Khanra et al.
4. Conclusions
TiB2 nanoparticles were produced using volume combustion
synthesis of TiO2, B2O3 and Mg, with the addition of 0–60% salt
mixture of KCl, NaCl and MgCl2 as the low melting diluent. The
ignition and maximum combustion temperatures were substan-
tially decreased with adding the salt mixture from 0 to 60% to the
reactants, from 785 to 500 8C and 1316 to 687 8C, respectively. This
effect was attributed to the higher green density of the samples
with salt with a better contact between the particles, formation of a
liquid salt phase that improved heat and mass transfer between
the reactants.
[13]. They reported a particle size of about 65
mm for the sample
with no added salt, and 40 and 26 m for the samples with 10 and
m
20% NaCl, respectively. The disagreement between these results is
attributed to the different set of initial conditions of the
100
Mg2TiO4 and Mg3B2O6 by-products, which are not thermody-
namically stable once the reactants are present in stoichiometric
proportions, were also formed during the synthesis and addition of
the salt mixture did not have a significant effect on their formation.
The addition of the salt mixture resulted in the formation of
deagglomerated particles, which could be beneficial for the
purification of the products by leaching. Also, addition of the salt
mixture resulted in a small decrease in the particle average size
from about 100 nm for the sample with no salt to about 70 nm for
the sample with 45% salt mixture. Nevertheless, a continuous
decrease in the TiB2 particle size was not observed with the
addition of the salt mixture. Hence, it was concluded that the effect
of initial particle size and green density was more pronounced than
the effect of the diluent.
0% Salt
15% Salt
30% salt
45% Salt
60% Salt
50
0
50
100
150
200
250
References
Particle size (nm)
Fig. 8. Normalized cumulative particle size distribution of the leached sample with
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