Black ceramic pigments for porcelain tile bodies produced with ...
Black ceramic pigments for porcelain tile bodies produced with ...
Black ceramic pigments for porcelain tile bodies produced with ...
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<strong>ceramic</strong> <strong>pigments</strong> <strong>for</strong> <strong>porcelain</strong> <strong>tile</strong> <strong>bodies</strong> <strong>produced</strong> <strong>with</strong> chromite ores and<br />
<strong>Black</strong><br />
oxide waste<br />
iron<br />
b Anadolu University, Department of Material Science and Engineering, Iki Eylül Campus 26550, Eskisehir, Turkey<br />
this study, two different natural chromite ores and iron oxide waste from the steel rolling industry were used as less expensive<br />
In<br />
raw materials <strong>for</strong> the synthesis of black <strong>ceramic</strong> <strong>pigments</strong> to be used in <strong>porcelain</strong> <strong>tile</strong> <strong>bodies</strong>. The effects of chromite<br />
alternative<br />
oxide waste ratios and calcination temperature on the pigment properties were investigated. It was found that<br />
ore-iron<br />
ore <strong>with</strong> a higher Cr 2 O 3 /FeO ratio can be used to synthesise black <strong>ceramic</strong> <strong>pigments</strong> when combined <strong>with</strong> the iron<br />
chromite<br />
waste. However, their color intensity was not as strong as commercial black <strong>pigments</strong> due to the presence of other phases<br />
oxide<br />
impurities coming from the chromite ores. When these <strong>pigments</strong> were used in combination <strong>with</strong> commercial black <strong>pigments</strong>,<br />
and<br />
natural and synthetic <strong>pigments</strong> find applications<br />
Inorganic<br />
coloring agents in glazes, <strong>ceramic</strong> <strong>bodies</strong> and <strong>porcelain</strong><br />
as<br />
[1]. Most of the synthetic <strong>pigments</strong> are prepared<br />
enamels<br />
metallic oxides or salts of the desired metals and<br />
<strong>with</strong><br />
must be of industrial chemical purity. However, this<br />
they<br />
them rather expensive. There<strong>for</strong>e, current trends are<br />
makes<br />
the use of less expensive natural raw materials<br />
towards<br />
and/or industrial wastes [6-9].<br />
[2-5]<br />
containing structures have been widely studied<br />
Chromium<br />
<strong>ceramic</strong> <strong>pigments</strong> [10, 11] <strong>for</strong> coloring glazes and <strong>ceramic</strong><br />
as<br />
due to their interesting properties including high<br />
<strong>bodies</strong><br />
resistance and chemical stability combined<br />
temperature<br />
suitable optical properties. Chromium-containing black<br />
<strong>with</strong><br />
<strong>pigments</strong> are either in the spinel or hematite<br />
<strong>ceramic</strong><br />
<strong>Black</strong> <strong>pigments</strong> based on the spinel system are<br />
structures.<br />
used to decorate glazed wall and floor <strong>tile</strong>s, since<br />
widely<br />
remain stable when mixed <strong>with</strong> glazes during high<br />
they<br />
firing. Spinel-based black <strong>pigments</strong> are based on<br />
temperature<br />
ferrochromite, (Fe,Co)(Fe,Cr) 2<br />
O 4<br />
or nickel ferrochromite,<br />
cobalt<br />
(Ni,Fe)(Fe,Cr) 2<br />
O 4<br />
compounds. <strong>Black</strong> <strong>pigments</strong> based<br />
the hematite system are synthesised by a traditional<br />
on<br />
state reaction method to obtain a (Fe,Cr) 2<br />
O 3<br />
solid<br />
solid<br />
and are mainly used in coloring <strong>porcelain</strong>-stoneware<br />
solution<br />
<strong>bodies</strong>. They are not suitable <strong>for</strong> glazes due to their<br />
<strong>tile</strong><br />
[12-14].<br />
instability<br />
many minerals contain chromium, chromite is<br />
Although<br />
author:<br />
*Corresponding<br />
: +90-222-2393750<br />
Tel<br />
+90-222-2393613<br />
Fax:<br />
btanisan@ogu.edu.tr<br />
E-mail:<br />
has a spinel crystalline structure and the theoretical<br />
ore<br />
composition is FeCr 2<br />
O 4<br />
(or FeO·Cr 2<br />
O 3<br />
as oxides).<br />
chemical<br />
the composition of chromite ores<br />
However, 2+ chemical<br />
be more generally written as (Mg,Fe )O·<br />
also could<br />
3+ 2 3<br />
owing to the partial natural substitution<br />
(Cr,Al,Fe 2+ ) 2+ 3+ O +3 , +3 , and Cr by Fe and Al in a lower<br />
Mg by Fe of<br />
[15, 16].<br />
proportion<br />
far as <strong>ceramic</strong> <strong>pigments</strong> are concerned, chromite is a<br />
As<br />
inexpensive natural pigment or a raw material<br />
potential<br />
of its high thermal and chemical stability among<br />
because<br />
oxides and is available on the market in a large<br />
natural<br />
[2]. Natural chromite has been used as a pigment<br />
amount<br />
coloring <strong>porcelain</strong> <strong>tile</strong>s, producing dark gray shades<br />
<strong>for</strong><br />
the fired <strong>tile</strong>. A mixture of 95 wt.% chromite and 5 wt.%<br />
on<br />
additions to a body at a certain amount was used to<br />
CoO<br />
black shades on the fired <strong>tile</strong> [17]. It is also reported<br />
get<br />
natural chromite combined <strong>with</strong> commercial black<br />
that<br />
reduced the cost of black coloring <strong>porcelain</strong>-<br />
pigment<br />
<strong>tile</strong>s [4]. However, chromite used in these studies<br />
stoneware<br />
neither calcined nor combined <strong>with</strong> hematite. Recent<br />
was<br />
on producing less expensive Fe-Cr <strong>pigments</strong><br />
investigations<br />
natural raw materials have shown that limonite and<br />
<strong>with</strong><br />
ores could be used to obtain brown <strong>pigments</strong><br />
chromite<br />
transparent and opaque glazes <strong>for</strong> wall <strong>tile</strong>s [2, 14].<br />
<strong>for</strong><br />
from dark brown to light brown, depending on the<br />
Colors<br />
temperature and chromite-limonite content,<br />
calcination<br />
obtained and present a good alternative to commercial<br />
were<br />
<strong>produced</strong> from pure oxides.<br />
<strong>pigments</strong><br />
oxides are the most widely used raw materials <strong>for</strong><br />
Iron<br />
production. The continually increasing importance<br />
pigment<br />
iron oxide-based <strong>pigments</strong> is due to their non-toxicity,<br />
of<br />
stability, wide variety of colors ranging from<br />
chemical<br />
orange, red, brown to black and low price [18].<br />
yellow,<br />
is reported that hundreds and thousands of tons of<br />
It<br />
J O U R N A L O F<br />
Journal of Ceramic Processing Research. Vol. 12, No. 4, pp. 462~467 (2011)<br />
Ceramic<br />
Processing Research<br />
Tanisan a, * and Servet Turan b<br />
a Belgin<br />
Osmangazi University, Department of Metallurgical and Materials Engineering, Meselik Campus 26480, Eskisehir, Turkey<br />
Eskisehir<br />
the consumption of the commercial <strong>pigments</strong> can be reduced, providing cost savings <strong>for</strong> coloration of <strong>porcelain</strong> <strong>tile</strong> <strong>bodies</strong>.<br />
Key words: <strong>Black</strong> <strong>ceramic</strong> pigment, Chromite, Iron oxide waste, Spinel, Color.<br />
Introduction<br />
the only commercial ore mineral of chromium. Pure chromite<br />
462
unusable solid waste containing from less<br />
practically<br />
15 to more than 90% iron are <strong>for</strong>med annually by<br />
than<br />
chemical, mechanical engineering and other<br />
metallurgical,<br />
plants [19]. There are several studies on the<br />
industrial<br />
of iron-chromium brown and/or black <strong>ceramic</strong><br />
synthesis<br />
<strong>for</strong> glazes and <strong>porcelain</strong> <strong>tile</strong> <strong>bodies</strong> from Fe-rich<br />
<strong>pigments</strong><br />
wastes. For example, cast iron foundry grinding<br />
industrial<br />
together <strong>with</strong> chromite [20], copper slag flotation<br />
waste<br />
<strong>with</strong> chromite, Cr 2 O 3 , ZnO and CoO [21], Fe-rich<br />
waste<br />
sludge generated during steel wiredrawing<br />
galvanizing<br />
Cr/Ni-rich sludge [22, 23] generated from Cr/Ni<br />
<strong>with</strong><br />
have been used.<br />
plating<br />
aim of this study is to produce (Fe,Cr) 2 O 3 black<br />
The<br />
<strong>pigments</strong> by using natural chromite ores and iron<br />
<strong>ceramic</strong><br />
waste from the steel rolling industry and to investigate<br />
oxide<br />
suitability <strong>for</strong> coloring <strong>porcelain</strong> <strong>tile</strong> <strong>bodies</strong> as a way<br />
their<br />
reduce their coloring cost. It is to be noted that (Fe,Cr) 2 O 3<br />
to<br />
<strong>ceramic</strong> pigment is the most extensively used pigment<br />
black<br />
materials<br />
Raw<br />
ores <strong>with</strong> different chemical compositions;<br />
Chromite<br />
chromite I (Kumas A.S., Turkey) and chromite II<br />
namely<br />
Chimica Mineraria S.P.A, Italy) and iron oxide<br />
(Laviosa<br />
and characterisation of <strong>pigments</strong><br />
Preparation<br />
chromite ores and iron oxide waste was<br />
As-received<br />
separately to the required particle-size by planetary<br />
ground<br />
ball-milling using distilled water and dried. Then,<br />
wet<br />
ores and iron oxide waste containing 30-100 wt.%<br />
chromite<br />
I ore and chromite II ore were mixed by wet<br />
chromite<br />
<strong>for</strong> 20 minutes and the slurries were dried<br />
ball-milling<br />
110 o C. This was followed by calcination firstly at 1200 o C<br />
at<br />
5 hours dwell time. This temperature was selected<br />
<strong>for</strong><br />
the previous studies on a similar system [24]. In<br />
from<br />
to see the effect of the calcination temperature on<br />
order<br />
products, a selected composition was also calcined<br />
reaction<br />
1100 o C and 1300 o C using the same dwell time. The<br />
at<br />
<strong>pigments</strong> were ground by planetary wet ball-<br />
calcined<br />
<strong>for</strong> 2 hours, filtered and dried at 110 o C in an oven.<br />
milling<br />
order to evaluate the color development, 3 wt.% ground<br />
In<br />
was added to a <strong>porcelain</strong> <strong>tile</strong> body composition,<br />
pigment<br />
from a <strong>ceramic</strong> factory (Toprak A.S, Eskisehir,<br />
supplied<br />
Table 1. Chemical composition of raw materials obtained by using XRF analysis (wt.%)<br />
was pressed into 4 cm diameter pellets at 40 MPa<br />
mix<br />
fired in an electric furnace at 1190 o C in 45 minutes<br />
and<br />
cold to cold.<br />
from<br />
compositions of the raw materials were determined<br />
The<br />
an X-ray fluorescence spectrometer (XRF, RIGAKU<br />
using<br />
Primus). A laser diffraction particle size analyser<br />
ZSX<br />
MASTERSIZER 2000G) was used to find<br />
(MALVERN<br />
the particle size distribution of the raw materials and<br />
out<br />
The crystalline phases in the samples were<br />
<strong>pigments</strong>.<br />
using an X-ray diffractometer (XRD, RIGAKU<br />
identified<br />
2200-Series). In the XRD analysis, metallic silicon<br />
Rint<br />
powder was used as a reference to determine the exact<br />
(Si)<br />
of the phases present and also to compare their<br />
d-spacings<br />
amounts.<br />
relative<br />
color parameters of fired <strong>porcelain</strong> <strong>tile</strong> samples<br />
L*a*b*<br />
<strong>with</strong> the <strong>pigments</strong> <strong>produced</strong> in this study were<br />
colored<br />
<strong>with</strong> an UV-Vis spectrophotometer (MINOLTA<br />
measured<br />
d). Measurements were recorded <strong>with</strong> a small<br />
3600<br />
and a standard D 65 light source. The color<br />
aperture<br />
L*, a* and b*, were measured according to<br />
coordinates,<br />
CIE-L*a*b* trichromatic system recommended by the<br />
the<br />
(Commission Internationale del’Eclairage) [25]. In<br />
CIE<br />
system, L* is the degree of lightness and darkness<br />
this<br />
the color in relation to the scale extending from white<br />
of<br />
= 100) to black (L* = 0). a* is the scale extending<br />
(L*<br />
green (−a*) to red (+a*) axis and b* is the scale<br />
from<br />
from blue (−b*) to yellow (+b*) axis. The<br />
extending<br />
difference (∆E*) was calculated according to<br />
color<br />
[(∆L*) 2 +(∆a*) 2 +(∆b*) 2 ] 1/2 . The values ∆L*, ∆a*<br />
∆E*=<br />
∆b* correspond to the difference of each parameter<br />
and<br />
of raw materials<br />
Characterisation<br />
compositions of the raw materials determined<br />
Chemical<br />
the XRF technique are given in Table 1. When<br />
using<br />
I and chromite II ores were compared, they both<br />
chromite<br />
similar amounts of Cr 2 O 3 , chromite I was<br />
contained<br />
to contain less FeO and consequently the Cr 2 O 3 /FeO<br />
found<br />
was higher <strong>for</strong> chromite I. There were also differences<br />
ratio<br />
MgO, Al 2 O 3 and SiO 2 contents in that chromite I was<br />
in<br />
in MgO and SiO 2 whereas chromite II was rich in<br />
rich<br />
2 O 3. The iron oxide waste was determined to contain<br />
Al<br />
97 wt.% Fe 2 O 3 (Table 1). XRD analysis showed that<br />
over<br />
iron oxide waste contained only the hematite phase<br />
the<br />
1(a)) and thus the iron oxide waste will be named<br />
(Fig.<br />
the “hematite waste” hereafter. XRD analysis also showed<br />
as<br />
<strong>Black</strong> <strong>ceramic</strong> <strong>pigments</strong> <strong>for</strong> <strong>porcelain</strong> <strong>tile</strong> <strong>bodies</strong> <strong>produced</strong> <strong>with</strong> chromite ores and iron oxide waste 463<br />
in <strong>porcelain</strong> <strong>tile</strong> production.<br />
Experimental<br />
waste from the steel rolling industry (Eregli Demir-Celik<br />
I<br />
Fabrikalar T.A.S., Turkey) were used as raw materials.<br />
recorded <strong>for</strong> the two samples that are being compared.<br />
Results and Discussion<br />
Turkey) by wet ball-milling. The dried <strong>porcelain</strong> powder<br />
Raw materials Fe 2 O 3 Cr 2 O 3 Al 2 O 3 SiO 2 FeO MgO CaO Others LOI<br />
Iron oxide waste 97.5 0.8 0.9 0.4 0.5<br />
Chromite I ore 42.5 8.4 7.4 17.7 17.8 1.8 1.0 3.4<br />
Chromite II ore 40.9 13.4 3.4 31.1 8.9 1.3 0.9<br />
(LOI is loss of ignition at 1000 o C)
oth chromites contained only spinel type phases<br />
that<br />
that chromite I also contained a minor amount<br />
except<br />
quartz (Fig. 1(b)). It is rather difficult to differentiate<br />
of<br />
composition spinel phases in chromites. However,<br />
different<br />
et al. [26] demonstrated that the iron present<br />
Sanchez-Ramos<br />
the spinel phase of chromite had a +2 valency and thus<br />
in<br />
the phase as the generic magnesiochromite<br />
identified 2+ spinel<br />
)(Cr,Al) 2<br />
O 4<br />
]. For this reason, the content<br />
[(Mg,Fe ferroan<br />
iron oxide is given as FeO in Table 1.<br />
of<br />
2 gives the particle-size distribution of each raw<br />
Table<br />
after planetary ball milling. The average particlesize<br />
material<br />
was around 7 µm and 90% of the particles are below<br />
25 µm. It is known that solid state reactions between<br />
about<br />
components primarily depend on the particle size: the<br />
two<br />
the particle size, the easier is the reaction between the<br />
finer<br />
However, milling into lower particle sizes by<br />
components.<br />
milling requires prolonged milling time that increases<br />
ball<br />
cost of processing.<br />
the<br />
of <strong>pigments</strong><br />
Characterisation<br />
XRD patterns of <strong>pigments</strong> <strong>produced</strong> <strong>with</strong> the use<br />
The<br />
different of chromite I and hematite waste<br />
of o amounts<br />
at 1200 C are shown in Fig. 2. When<br />
calcined mixtures<br />
I was calcined alone, the occurrence of a free<br />
chromite<br />
2<br />
O 3<br />
phase was evident together <strong>with</strong> predominant spinel<br />
Cr<br />
The free Cr 2<br />
O 3<br />
phase was not seen in the XRD<br />
phases.<br />
of the as-received raw material (Fig. 1(b)). This<br />
pattern<br />
Raw materials d 10 d 50 d 90<br />
patterns of <strong>pigments</strong> <strong>produced</strong> by calcining different<br />
XRD<br />
of chromite I-hematite waste mixtures at a constant<br />
amounts<br />
2+ the chromium-containing spinel [(Mg,Fe )·<br />
reveals that<br />
O 4<br />
] was separating to Cr 2<br />
O 3<br />
and another type<br />
2<br />
(Cr,Al)<br />
spinel at high temperatures. This phenomenon was also<br />
of<br />
by Sanchez-Ramos et al. [26] who demonstrated<br />
observed<br />
the Cr 2<br />
O 3<br />
segregates as a differentiable compound,<br />
that<br />
removed from the chromite spinel and remaining<br />
being<br />
in as magnesium, aluminium and iron oxides<br />
only o spinels<br />
C. In the compositions containing hematite<br />
800 above<br />
in addition to the presence of the spinel phases, the<br />
waste,<br />
free Cr 2<br />
O 3<br />
reacts <strong>with</strong> the hematite (Fe 2<br />
O 3<br />
) to<br />
generated<br />
a solid solution phase (Fe 1-x<br />
Cr x<br />
) 2<br />
O 3<br />
(Fig. 2). In the<br />
produce<br />
diagram of Fe 2<br />
O 3<br />
and Cr 2<br />
O 3<br />
, these oxides can be<br />
phase<br />
to a complete (Fe,Cr) 2<br />
O 3<br />
solid solution<br />
observed o generate<br />
the range of compositions up to 1400 C [27]. As<br />
all <strong>for</strong><br />
same amount of silicon (Si) was used in the samples<br />
the<br />
an internal standard, the intensity ratio of the solid<br />
as<br />
phase (Fe 1−xCr x<br />
) 2<br />
O 3<br />
(F) and Si (F/Si) can be used<br />
solution<br />
follow the development of the solid solution phase.<br />
to<br />
Fig. 2, F 110<br />
/Si 111<br />
ratio is 0.0, 0.48, 0.75 and 1.16 <strong>for</strong> the<br />
In<br />
of 100% chromite I, 80% chromite I-20% hematite<br />
mixtures<br />
60% chromite I-40% hematite waste and 40%<br />
waste,<br />
I-60% hematite waste, respectively. The highest<br />
chromite<br />
is observed in the 40% chromite I-60% hematite waste<br />
ratio<br />
indicating that this sample contains the largest<br />
sample,<br />
of the solid solution phase.<br />
amount<br />
XRD patterns of <strong>pigments</strong> <strong>produced</strong> <strong>with</strong> the use<br />
The<br />
different of chromite II and hematite waste<br />
of o amounts<br />
at 1200 C are presented in Fig. 3. The<br />
calcined mixtures<br />
phases were spinels and the solid solution phase<br />
main<br />
1−xCr<br />
x<br />
) 2<br />
O 3<br />
in all compositions. No free Cr 2<br />
O 3<br />
phase<br />
(Fe<br />
464 Belgin Tanisan and Servet Turan<br />
Table 2. Particle size distribution of ball milled raw materials (µm)<br />
Iron oxide waste 1.1 7.8 24.9<br />
Chromite I ore 0.9 7.1 23.0<br />
Chromite II ore 1.0 6.7 20.2<br />
Fig. 2.<br />
temperature of 1200 o C (CI : chromite I, H : hematite waste).<br />
Fig. 1.<br />
XRD patterns of iron oxide waste (a) and chromite ores (b).
3. XRD patterns of <strong>pigments</strong> <strong>produced</strong> by calcining different<br />
Fig.<br />
of chromite II-hematite waste mixtures at a constant<br />
amounts<br />
was observed in the pure chromite II after<br />
<strong>for</strong>mation<br />
in contrast to pure chromite I. This may be due<br />
calcination<br />
the higher amount of FeO content of chromite II which<br />
to<br />
the solid solution phase directly upon calcination.<br />
<strong>for</strong>ms<br />
the F 110 /Si 111 ratio (~0.8) was not changed substantially<br />
Although<br />
<strong>with</strong> the addition of hematite waste, the solid solution<br />
became rich in iron (see the shift of the solid solution<br />
phase<br />
to lower 2θ values, indicated by a dotted line in<br />
peaks<br />
3). Similar shift of 2θ values of the solid solution phase<br />
Fig.<br />
Fe 2 O 3 was also observed by Munoz et al. [24].<br />
<strong>with</strong><br />
both chromite I and chromite II containing compositions,<br />
In<br />
the highest amount of solid solution phase was<br />
when 40% chromite I and 60% hematite waste<br />
obtained<br />
used. There<strong>for</strong>e, to see the effect of temperature on<br />
were<br />
solid solution phase <strong>for</strong>mation, this composition was<br />
the<br />
constant and also calcined at 1100 o C and 1300 o C.<br />
kept<br />
XRD patterns of <strong>pigments</strong> <strong>produced</strong> from 40%<br />
The<br />
I and 60% hematite waste mixtures calcined<br />
chromite<br />
between 1100 o C and 1300 o C are compared in Fig. 4.<br />
at<br />
the same figure, a diffraction pattern of the commercial<br />
In<br />
pigment (Coded as CP-2) is also shown <strong>for</strong> comparison.<br />
black<br />
The XRD results showed that the samples calcined<br />
all temperatures contained (Fe 1−x Cr x ) 2 O 3 solid solution<br />
at<br />
spinel phases. The F 110 /Si 111 intensity ratios in Fig. 4<br />
and<br />
0.58, 1.16 and 0.86 at 1100 o C, 1200 o C and 1300 o C,<br />
is<br />
This indicates that the highest amount of<br />
respectively.<br />
solid solution phase was obtained at 1200 o C which was<br />
the<br />
at the beginning of the study to find out the<br />
selected<br />
composition <strong>for</strong> the <strong>for</strong>mation of the highest<br />
optimum<br />
of the solid solution phase. While the lower amount<br />
amount<br />
the solid solution phase at 1100 o C may be due to<br />
of<br />
reactions, its decreased amount at 1300 o C may<br />
incomplete<br />
due to the decomposition of the solid solution phase<br />
be<br />
by an increased vapour pressure of Cr 2 O 3 .<br />
possibly<br />
measurement<br />
Color<br />
measured L*a*b* values of colored <strong>porcelain</strong> <strong>tile</strong>s<br />
The<br />
4. XRD patterns of <strong>pigments</strong> containing 40% chromite I-<br />
Fig.<br />
hematite waste mixture calcined at different temperatures<br />
60%<br />
1100 o C and 1300 o C. An XRD pattern of black commercial<br />
between<br />
(CP-2) is also included <strong>for</strong> comparison purposes.<br />
pigment<br />
3 wt.% <strong>pigments</strong> (<strong>produced</strong> at 1200 o C according<br />
containing<br />
the procedure given above) are shown in Fig. 5. The<br />
to<br />
prepared <strong>with</strong> pure chromite I gives a yellowbrown<br />
pigment<br />
color which has L*a*b* values of 41.6, 3.0 and 5.2.<br />
an increasing hematite waste percentage in chromite<br />
With<br />
waste mixtures, L*a*b* values were all decreased<br />
I-hematite<br />
the lowest L*a*b* values of 35.9, 1.4 and 1.1, which<br />
and<br />
better black coloring, were obtained <strong>with</strong> the use<br />
indicate<br />
the 40% chromite I and 60% hematite waste composition.<br />
of<br />
These results are in line <strong>with</strong> the XRD spectra that<br />
use of 40% chromite I and 60% hematite waste gave<br />
the<br />
largest amount of the (Fe 1−x Cr x ) 2 O 3 solid solution phase<br />
the<br />
a concurrent decrease of the spinel phase intensity.<br />
<strong>with</strong><br />
commercial black <strong>pigments</strong>, coded as CP-1<br />
However,<br />
CP-2 (Itaca, Spain) both gave L*, a* and b* values of<br />
and<br />
33, < 1 and < 0.5, respectively (Table 3). This indicates<br />
<<br />
even the lowest L*a*b* giving composition (40%<br />
that<br />
I-60% hematite waste) is not good enough to be<br />
chromite<br />
as a replacement <strong>for</strong> a commercial black pigment.<br />
used<br />
may be attributed to the dilution effect of impurity<br />
This<br />
The other reason might be the difference in the<br />
oxides.<br />
size distribution of the pigment. However, please<br />
particle<br />
note that the particle size distribution of the synthesised<br />
also<br />
used in this study was very similar to the com-<br />
pigment<br />
black <strong>pigments</strong> (Table 4). In order to increase the<br />
mercial<br />
coloring, that is, to decrease L*a*b* values, 0.5 and<br />
black<br />
wt.% of a commercial black pigment (CP-2) was used<br />
1<br />
<strong>with</strong> 3 wt.% the pigment (40% chromite I-60%<br />
together<br />
waste composition) in a <strong>porcelain</strong> <strong>tile</strong> body.<br />
hematite<br />
was selected as the commercial black pigment to<br />
CP-2<br />
used together <strong>with</strong> the synthesised pigment in this<br />
be<br />
due to its better L*a*b* values (Table 3). The addition<br />
study<br />
the commercial pigment reduced the L*a*b* values as<br />
of<br />
in Table 3, approaching those of the pure commercial<br />
given<br />
This indicates that chromite I and hematite waste<br />
pigment.<br />
can be a cost-effective complementary to the<br />
mixtures<br />
<strong>Black</strong> <strong>ceramic</strong> <strong>pigments</strong> <strong>for</strong> <strong>porcelain</strong> <strong>tile</strong> <strong>bodies</strong> <strong>produced</strong> <strong>with</strong> chromite ores and iron oxide waste 465<br />
temperature of 1200 o C (CII : chromite II, H : hematite waste).<br />
commercial black <strong>pigments</strong> and help to reduce their usage.
5. The L*a*b* values of colored and fired <strong>porcelain</strong> <strong>tile</strong><br />
Fig.<br />
containing 3 wt.% pigment, prepared by calcining different<br />
samples<br />
of chromite I-hematite waste and chromite II-hematite<br />
amounts<br />
mixtures at a constant temperature of 1200 o C.<br />
waste<br />
3. CIE-L*a*b* and calculated DE* values of colored<br />
Table<br />
<strong>tile</strong> samples<br />
<strong>porcelain</strong><br />
Reference<br />
pigment<br />
Pigment<br />
(wt.%)<br />
CP-2<br />
(wt.%)<br />
a* b* DE*(1) DE*<br />
L*<br />
(2)<br />
and CP-2 : commercial black <strong>pigments</strong>, 40CI-60H designates<br />
(CP-1<br />
chromite I and 60% of hematite waste derived pigment)<br />
40%<br />
Pigment d 10 d 50 d 90<br />
and CP-2 : commercial black <strong>pigments</strong>, 40CI-60H designates<br />
(CP-1<br />
chromite I and 60% of hematite waste derived pigment)<br />
40%<br />
measured L*a*b* values of <strong>pigments</strong> containing<br />
The<br />
chromite I and 60% hematite waste calcined at<br />
40%<br />
between 1100 o C and 1300 o C are given in<br />
temperatures<br />
6. The L*a*b* values of <strong>pigments</strong> were influenced by<br />
Fig.<br />
calcination temperature. L* values decrease <strong>with</strong> a<br />
the<br />
calcination temperature, whereas the values<br />
decreasing<br />
a* and b* were considerably lower at a calcination<br />
of<br />
of 1200 o C in comparison to 1100 o C and<br />
temperature<br />
o C. These coloring observations are in line <strong>with</strong> XRD<br />
1300<br />
given in Fig. 4.<br />
data<br />
prepared <strong>with</strong> chromite II resulted in darker<br />
Pigments<br />
than those <strong>with</strong> chromite I where the chromite<br />
colors<br />
was higher (> 80%) (Fig. 5). This is due to the<br />
content<br />
of the solid solution phase even in the pure<br />
<strong>for</strong>mation<br />
II containing sample. However, at lower chromite<br />
chromite<br />
L*a*b* values of chromite II derived <strong>pigments</strong><br />
contents,<br />
not as low as chromite I derived <strong>pigments</strong>. The<br />
were<br />
black coloring of chromite I and hematite waste<br />
better<br />
6. The L*a*b* values of colored <strong>porcelain</strong> <strong>tile</strong> samples<br />
Fig.<br />
3 wt.% pigment, synthesised by calcining a 40%<br />
containing<br />
I-60% hematite waste mixture at temperatures between<br />
chromite o C and 1300 o C.<br />
1100<br />
466 Belgin Tanisan and Servet Turan<br />
CP-1 3 - 33.0 1.0 0.4 - 1.9<br />
CP-2 3 - 31.4 0.3 -0.3 1.9 -<br />
40CI-60H 3 - 35.9 1.4 1.1 3.0 4.8<br />
40CI-60H 3 0.5 34.5 1.4 0.9 1.6 3.5<br />
40CI-60H 3 1.0 33.8 1.0 0.2 0.8 2.5<br />
4. Particle size distribution of <strong>pigments</strong> (µm)<br />
Table<br />
CP-1 2.4 6.0 14.6<br />
CP-2 1.5 4.7 10.4<br />
40CI-60H 1.9 5.6 12.8
evidenced by lower L* and a* values, may be<br />
mixtures,<br />
to somewhat higher solid solution phase <strong>for</strong>mation in<br />
due<br />
I and hematite waste mixtures. This may be due<br />
chromite<br />
the exsolution of Cr 2 O 3 from chromite I, readily reacting<br />
to<br />
using less expensive chromite ores and hematite<br />
By<br />
black <strong>ceramic</strong> <strong>pigments</strong> suitable <strong>for</strong> <strong>porcelain</strong> <strong>tile</strong><br />
waste,<br />
coloring can be <strong>produced</strong>. A black color close to<br />
body<br />
black <strong>pigments</strong> was obtained after calcination<br />
commercial<br />
40% chromite I and 60% hematite waste mixture at<br />
of o C. The black coloring phase is the (Fe 1−x Cr x ) 2 O 3 solid<br />
1200<br />
phase. However, due to the presence of impurity<br />
solution<br />
of Al 2 O 3 , SiO 2 and MgO the color intensity is not<br />
oxides<br />
strong as commercial black <strong>pigments</strong> which are generally<br />
as<br />
<strong>with</strong> higher purity oxides. These <strong>pigments</strong>, when<br />
prepared<br />
<strong>with</strong> a small amount of commercial black<br />
combined<br />
can reduce the consumption of the more expensive<br />
<strong>pigments</strong>,<br />
<strong>pigments</strong>, providing cost savings <strong>for</strong> black<br />
commercial<br />
of <strong>porcelain</strong> <strong>tile</strong> <strong>bodies</strong>.<br />
coloration<br />
would like to thank Eregli Demir-Celik Fabrikalari<br />
We<br />
Kumas A.S. and Laviosa Chimica Mineraria S.P.A<br />
T.A.S,<br />
the supply of raw materials. One of us (B. Tanisan)<br />
<strong>for</strong><br />
likes to thank Anadolu University, Material Science<br />
also<br />
Engineering Dept. <strong>for</strong> the use of their facilities and<br />
and<br />
Pervin Dag <strong>for</strong> her help.<br />
Miss<br />
T. Manfredini and F. Bondioli, Ceramic Ind. 150[2] (2000)<br />
1.<br />
53-58.<br />
E. Ozel, I. Küçük and S. Turan, Silicates Ind. 68 (2003) 25-28.<br />
2.<br />
A.B. Corradi, C. Leonelli, T. Manfredini, P. Pozzi and M.<br />
3.<br />
American Ceram. Soc. Bull. 72[5] (1993) 63-69.<br />
Romagnoli,<br />
F. Bondioli, A.M. Ferrari, C. Leonelli and T. Manfredini,<br />
4.<br />
Eng. Proc. 18[2] (1997) 44-58.<br />
Ceram.<br />
V.M. Pogrebenkov and M.B. Sedel’nikova, Glass and<br />
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59(2002) 396-399.<br />
Ceramics.<br />
G. Costa, M.J. Ribeiro, T. Trindate and J.A. Labrincha, Bol.<br />
6.<br />
(1994) 63-69.<br />
73[12]<br />
F.J. Berry, N. Costantini and L.E. Smart, Waste Manage.<br />
8.<br />
(2002) 761-772.<br />
22<br />
R.I. Lazau, C. Pacurariu, D. Becherescu and R. Ianos, J.<br />
9.<br />
Ceram. Soc. 27 (2007) 1899-1903.<br />
Eur.<br />
T.S. Lyubenova, M. Ocana and J. Carda, Dyes and Pigments.<br />
10.<br />
(2008) 265-269.<br />
79<br />
R. Munoz, N. Maso, B. Julian, F. Marquez, H. Beltran, P.<br />
11.<br />
and E. Cordoncillo, J. Eur. Ceram. Soc. 24[7]<br />
Escribano<br />
2087-2094.<br />
(2004)<br />
J. Calbo, M.A. Tena, G. Monros, M. Llusar, R. Galindo and<br />
12.<br />
Badenes, American Ceram. Soc. Bull. 84[12] (2005)<br />
J.A.<br />
10-14.<br />
J. Calbo, S. Sorli, M. Llusar, M.A. Tena and G. Monros,<br />
13.<br />
Ceram. Trans. 103[1] (2004) 3-9.<br />
Brith.<br />
E. Ozel and S. Turan, J. Eur. Ceram. Soc. 23 (2003) 2097-2104.<br />
14.<br />
H.B. Xu, Y. Zhang, Z.H. Li, S.L. Zheng, Z.K. Wang, T. Qi<br />
15.<br />
H.Q. Li, J. Cleaner Production. 14 (2006) 211-219.<br />
and<br />
M.F. Gazulla, A. Barba, M.P. Gomez and M. Orduna,<br />
16.<br />
and Geoanalytical Research. 30[3] (2006)<br />
Geostandards<br />
237-243.<br />
G. Biffi, “Porcelain Stoneware Production Manual Method<br />
17.<br />
Use” (Gruppo Editoriale Faenza Editrice S.p.A. Italy, 1999).<br />
of<br />
O.K.R. Montedo, F.M. Bertan, R. Picolli, D. Hotza and A.P.<br />
18.<br />
de Oliveria, Qualicer. (2004) 11-13.<br />
Novaes<br />
A.N. Epikhin and A.V. Krylova, Russian Journal of Applied<br />
19.<br />
76[1] (2003) 20-22.<br />
Chem.<br />
S. Turan, Y. Inceefe and E. Ozel, Key Eng. Mater. 264-268<br />
20.<br />
2473-2476.<br />
(2004)<br />
E. Ozel, S. Turan, S. Çoruh and O.N. Ergun, Waste Manage.<br />
21.<br />
24 (2006) 125-133.<br />
Res.<br />
G. Costa, V.P. Della, M.J. Ribeiro and J.A. Labrincha, American<br />
22.<br />
Soc. Bull. 87[7] (2008) 9101-9107.<br />
Ceram.<br />
G. Costa, V.P. Della, M.J. Ribeiro, A.P.N. Oliveria, G. Monros<br />
23.<br />
J.A. Labrincha, Dyes and Pigments. 77 (2008) 137-144.<br />
and<br />
R. Munoz, M. Martos, C.M. Rotaru, H. Beltran, E. Cordoncillo<br />
24.<br />
P. Escribano, J. Eur. Ceram. Soc. 26[8] (2006) 1363-1370.<br />
and<br />
C.I.E (1978) Recommendations on uni<strong>for</strong>m color spaces,<br />
25.<br />
difference equations, psychometric color terms.<br />
color<br />
No.2 to CIE publication No.15 1971.<br />
Supplement<br />
S. Sanchez-Ramos, A. Domenech-Carbo, J.V. Gimeno-<br />
26.<br />
J. Peris-Vicente and F.M. Valle-Algarra,<br />
AdelantadoÅ,<br />
Acta. 476 (2008) 11-19.<br />
Thermochimica<br />
A. Muan and S. Somiya, J. Am. Ceram. Soc. 57 (1960)<br />
27.<br />
<strong>Black</strong> <strong>ceramic</strong> <strong>pigments</strong> <strong>for</strong> <strong>porcelain</strong> <strong>tile</strong> <strong>bodies</strong> <strong>produced</strong> <strong>with</strong> chromite ores and iron oxide waste 467<br />
Soc. Esp. Ceram V. 46[1] (2007) 7-13.<br />
7. N. Ay, M. Çak and A. Kara, American Ceram. Soc. Bull.<br />
I<br />
<strong>with</strong> the hematite waste to <strong>for</strong>m the solid solution phase.<br />
Conclusions<br />
Acknowledgements<br />
References<br />
204-209.