Diopside Based White Porcelain Tiles

8/11/2019 Diopside Based White Porcelain Tiles

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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


2/4

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


3/4

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


4/4

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

Documents

Diopside Based White Porcelain Tiles