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8/11/2019 Diopside Based White Porcelain Tiles
1/4
SPAI
i\
QU L
DIOPSIDE B
SED
WHITE PORCELAIN TILES
Ka ra and M Ca va e
Tubi
tak
Ceram ic Resea rch Ce ntre
nado lu Un ivers ity, Iki Eylu l Karnpusu, Eskise hir / Turkey
IN
TR
ODUCTION
In th is s tu
dy
, a p
or
celain tile bod y con ta in ing a substantial
am
o
unt
of a lkal ine ea rth
elemen ts was formulated to form di opside
cr
ystals and / o r
wo
llastonite crystals if
required ) d uring firing. It is thought th at less pure r
aw
mate rials, especia lly clays
conta in ing iro n oxide can be used w ith ou t substa ntia lly degrad ing the whi teness of the
tile sin ce di opside can d issolve iron in its lattice by su
bs
titu ting for magnesium.
EXPERIMENT L
The p
or
ce lain body wa s fo r
mu
lated by using a frit , Ukra in ia n clay, qua rtz, a lbite,
ca lcite and a lte r
ed
ma
gn
es ite . The com
pos
itio nal r
an
ge of the b
od
y is g ive n in Tabl e I. The
tri t was added in o rde r to facilita te easy sin te ring d
ur
ing fas t firi ng . Although any type
of fri t can be used , a d iopsid e forming fri t was d evelop
ed
in o rder to ob ta in max imum
d iopside formation d ur ing fir ing. The frit con ta ine d 5iO CaO, ~ g and
Kp .
Indus tria l
melting of the fri t was c
arri
ed ou t in a ro ta ry furnace at I-tOOC.
65 75
AhO,
7 12
CaO
16 12
M O
4-10
Na,O
13
K,O
13
Fc,O,
TiO
0300 35
The crys ta lline phas
es
th at dev
eloped
durin
g firi
ng
of the bod y were cha racte rised
by X-ra y d iii raction XRD) and sh rinkage behav iour was fo llowed by a di la tometer. The
micros truct u re of the s in tc rc d po rcela in ti le was investig
ated
using scann ing electron
microscope. For ind us trial p ro
du
ction trials, 30 tons o f spra y d ried g ranules we re
Io II
8/11/2019 Diopside Based White Porcelain Tiles
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ill U U
~
prepa red and 330x330 mm and 300x600 mm size tiles were pressed at 40 MPa . These tiles
were sintered at a pe
ak temperatur
e of 2 O C in an
indu
stri al rolle r kiln f
or
55 min and
65 min for 330x330
mm
and 300x600
mm
size tiles, respectively.
RESU LT S
The XRD spectrum of the frit after crystallisation at 11 30 C in a fast fir ing furnace
and that of the p
or
celain tile after sintering at 12
O
C are given in Fig.
1.
Frit crystallises
mainly to d iopside but some am
ount
of cristobalite also occu rs (Fig. l a ). The po rcelain tile
body contains diopside and
qua
rtz as main
pha
ses
but
a trace of cris tobalite is also pres
ent
(Fig. Ib).
bl
.,
I
__ _
;J
1 . . - A l
v J \
\ - f t
r lco
eCCjorlllill \ f fit aftt'r crystal/isatiol/ at 50C (iJ) tilt por
e nn
tilt'aftt siutt'rillS at
5
C.
.e
o
Time h )
t c
r - - - - - - - - - - - - - -
---
2
-- - - -
- - - - - - - - - - - - - - - - - - - - - - ----- -to
8
u oo
1200
100 0
f5
80 0
00
w
c.
. 0
E
ace
0
0
Figure 2. Shrillkas t' bchm. tlu r
th
di0l':,idl' pMedai .
1\,.. 102
8/11/2019 Diopside Based White Porcelain Tiles
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Fig. 2 sho ws the shrinkage be
havio
u r of the
bod
y. There are two vol ume expansions:
on e is a t 573C and the other s tarts at about 1000C and con ti nu e s until the o
nset
of
shr
i
nkage
at
lI2
0C. The
expa
ns ion
see
n at 573C is d ue to the
well
kn o
wn u-{
qu artz
transforma tio n whereas that sta r ting at lOOO C is thought to res ult from the vo lume
expansion du e to the forma tion of d iopsidc from the reaction of a m ixture of qu ar tz,
magne sium and calcium oxides. The am ou nt of vo lume expans
ion
due to diop side
form
atio
n is
O.
5j{. Bef
or
e thi s vo lume ex
pa
nsion , 0.3% volume sh r inkage is a lso ev i
denc
ed
at
aro
und 900 C in Fig. 2.
This
is att ribu ted to d i
opsid
e crystallisa tion from the frit. The
di opside crystals formi ng from the frit ac t as seeds for furthe r d iopside formation from the
reaction of quartz magnesium and ca lcium oxides . Total linear shrinkage was observed
to be 9.5%. The SEM mi
crograp
h of the sintered tile after lig
ht
e tching w ith HF is s
how
n
in Fig . 3. Diopside
and
quartz cr
ysta
ls
are embedde
d in a
glassy
ma trix. T
he
size o f the
d iopsi
de
cr
ystals
is less than I .
L1m
. Some
pro
perties o f the po rcela in tile p roduced on an
ind ustrial sca le are listed in Tab le 2.
Dry strength (kg/em
13
Fired strength (kg/em
(ISO 10545-4) 615
Water absorption (%)( ISO 10545-3) O
O
:
Thermal expansion coefficient (ISO 10545-8)
76xlO-l
Deep abrasion resistance {mm ) (ISO 10545 -6)
131
Chemical resistance (ISO 10545-13)
UIIA
Colour
a- -0.56. b- 5.47
The
fire d st ren gt h of th e new tile is somew ha t higher than that of com
merc
ial
porce lain tiles, wh ich lies be tween 500-550 kg / cm. Th is can be a ttributed to a large
am oun t of di opside formati on in the compos it
ion
.
Whi
teness of the tile is
also qui
te high .
In order to observe the effectiveness of di
op
side crys tals on wh iten
ess
, a d iopside forming
compos ition and a trad itional porcelain tile composit
ion
we re prepared w ith the same
a
moun
t
of
1 1.
,0
,
(0.33
t
,) and TiO, (0.32
7
8/11/2019 Diopside Based White Porcelain Tiles
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ll
U U
CASTELLO SI AI:-I)
valency of 2. [ron ions with --2 valency do not cause colouring. De
ep
abrasion resistance
is also better than that of commercial
por
celain tiles whi ch varies
betw
een 139-147 rnrn
.
Similarly to the mechanical p roperties a large amount of diopside crystals imp roves
abrasion resistance
ON LUS ONS
A
dio
pside based new porcelain tile has been developed . This new tile can be
produced with high whiteness compared to conventional tiles when the same amount of
impu rities is present in the composition. Thus relatively impure raw materials can be
tolerated when producing tiles with high whiteness. The n
ew
tile is mechani cally stro
nger
with high er abras ion resi
stan
ce. D
epend
ing on the CaO / MgO ratio in the starting
composition d iopside diop side-wollastoni te and woll astonite conta ining tiles can be
produced.
Po ; 1M
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