New Journal of Glass and Ceramics, 2011, 1, 53-57
doi:10.4236/njgc.2011 .12009 Published Online July 2011 (http://www.SciRP.org/journal/njgc)
53
Research on the High Streng t h Glass
Ceramics/Mullite Ceramics Composites
Yijun Liu1,2, Jianfeng Huang1*, Xiufeng Wang1, Qiang Yang1, Yaqin Wang1, Peiwen Rao2,
Qinggang Wang2
1Key laboratory of Auxiliary Chemistry and Technology for Chemical Industry, Ministry of Education, Shanxi University of Science
and Technology, Xi’an, China; 2Guangdong Monalisa Industry Co. ltd, Foshan, China.
Received April 2nd, 2011; revised April 30th, 2011; accepted May 7th, 2011.
ABSTRACT
In order to improve the bending strength of mullite ceramic thin tiles, SiO2-ZnO-Na2O-Y2O3 glass was prepared on the
surface of the tiles. The influences of the thermal properties and thermal expansion coefficient of the glass and the sin-
tering temperature on the structure and the property of the composites were investigated by differential thermal analy-
sis (DTA), X-Ray Diffraction (XRD), Raman and scanning electron microscopy (SEM). The bending strength of the
composites was measured with an universal testing machine. Results show that the crystallization temperature of the
SiO2-ZnO-Na2O-Y2O3 glass is higher than that of SiO2-ZnO -Na2O glass. The corresponding crystallites show more
complex structure for the SiO2-ZnO-Na2O-Y2O3 glass. The thermal expansion coefficients of both glasses are lower than
the mullite ceramic tiles. The bending strength of the composites after sintering at 1150˚C was obviously improved by
10.7% to 106.2 MPa, compa red with the mullite ceram ic tiles.
Keywords: Glass Ceramics, Mullite Ceramics Thin Tile, Compo si tes, Bending Strength
1. Introduction
Large ultra-thin dry-pressing thin ceramic tiles have
many excellent properties, such as thinness, large size
(900 mm × 1800 mm × 5.5 mm), lo wer weight (only 1/3
- 1 /2 of regular c eramic wall and floor tile) and sa ving o f
sourc e mater ial a nd ener gy an d red ucing of d ust a nd gas.
It is becoming one of developing low-carbon green en-
vironmental new product advocated by all the countries
in the world [1]. However, the large ceramic thin tiles
still have ma ny pr ob lems d uri ng the co urse of pr ocessing
and application due to their large size and thinness, espe-
cially the poor mechanical strength of the product [2,3].
In order to solve this problem, thin mullite ceramic tiles
are developed to increase their strength greatly [4]. To
improve the strength of the mullite ceramics thin tile
further and get a good decoration effect, a kind o f mic ro-
crystal glass is prepared on the surface of the mullite ce-
ramics and a better result is achieved. Recently, the
theory analysis and practical application of microcrystal
glass composited to ceramic board has made rapid
progress [5]. Usually, ceramic tile is u sed as a matri x and
about 5 - 10 mm microcr ystal glass frit is added on its
surface. Then, it is sintered at high temperature and fi-
nally the glass/ceramic composites are obtained. It is
widely used as a decorating material on vestibule, post,
internal and external walls of stations, hotels, halls and
entertain ment facilities [6] .
In the present work, the following method to combine
microcr ystal glass with ceramic board is used. On the
surface of the large-size ultra-thin mullite ceramic tile
(900 mm × 1800 mm × 5.5 mm), ceramic glass of 1 mm
thickness is prepared. The strength of the ceramic tile is
greatly raised according to optimizing processing. The
influences of the thermal properties and thermal expan-
sion coefficient of the glasses and the sintering tempera-
ture of the composites on the structure and the property
of the composites were investigated.
2. Experimental
Details for the preparation of the mullite ceramic tile
(900 mm × 1800 mm × 5.5 mm) were reported in [4].
The raw materials were as follows: 50 wt % - 55 wt% fly
ash, 30 wt% - 35 wt% pyrophyllite, 10 wt % - 15 wt%
bauxite a nd 4 wt% AlF3.
Microcrystal glass was a sort of borosilicate glass and

Research on the High Strength Glass Cer amics/Mullite Ceramics Composites
54
the composition is shown in Table 1.
High purity silica, reagen t gra de b oric acid, zinc oxide,
sodium carbonate and yttrium oxide were used as source
materials and mixed in the above ratios, ball milled and
dri ed. Then, the mixture was gro und in a platinum cruci-
ble and kept it at 1 500˚C for 3 h. The molten glass trans-
formed from the mixture at high temperature and under-
went water quenching and a course of drying and ball
milling to produce a glass power with an average size
about 1 - 3 μm. These glass powder was distributed un-
iformly by distributor on the surface of mullite ceramic
tile and its thickness was kept at 1.2 mm. Next, the cov-
ered tile was placed in a furnace for a second sintering at
1000˚C - 1200˚C, causing the glass powder to remelt,
nucleate, cr ystallize and combinesolidly with the ceramic
base. After cooling down to the room temperature, the
large-size ultra-thin mullite glass ceramic tile was pre-
pared finally.
3. Characterization
Subsequently, the phase composition of the sample was
characterized by a Rigaku D/max-3C X-ray di ffracto me-
ter (XRD) and Raman spectroscopy. The thermal stabili-
ty and morphologies of the sample were analyzed by a
NETZSCH STA 409 PC/PG (DTA) and JSM-6390A
(JEOL) scanning electronic microscope (SEM) respec-
tivel y. T he characterization of the mechanical property of
the sample was measured by a universal material testing
machine (Taiwan Baoda Co. Ltd) and the testing of the
bulk density of the sintered sample was carried out by the
under wate r weighi ng me tho d and t hen t he po ro sity of th e
sample was calculated.
4. Results and Discussion
4.1. The Sintering Behaviors of the Ceramic
Glass Mulli te Board
Most research about microcrystal ceramic board show
that the range of the mullite crystallization temperature
of the cera mic thin tile is about 900˚C - 1200˚C with t he
content of mullite crystal increasing as the temperature
rise. The property of the sample is mainly dependent
upon the range of crystallization of ceramic glass and the
effective controlling. If the ceramic tile base and the
glass produce many more crystals, the mechanical prop-
erty of the composite tile would be greatly improved.
Table 1. The composition of SiO2-ZnO-Na2O-Y2O3 glasses/
mol% .
No. SiO2 B2O3 ZnO Na2O Y2O3
1 37 18 20 25 -
2 37 18 20 20 5
Figure 1 shows the DTA curves of the as-prepared
glasses. The endothermic peak observed at nearly 740˚C
is when Y2O3 was added into the glass, which might be
caused by the rebuliding of the structure in the course of
melting the glass. The exothermic peak at 880˚C might
have been caused by the crystallization of the glass
phase. The crystallization of glass can decrease the con-
tent of the glass phase which is not helpful to the densi-
fication of the composites, so increasing the crystalli-
zaion tempe- rature of the glass can improve the sintering
of the composites. It is proved that the addition of Y2O3
can increase the crystallization temperature of glass to
950˚C nearly the crystallization temperature of mullite
ceramic, which is ver y benefic ial to the opti mizat ion of it s
struct ure .
The porosity of the as-prepared glass/ceramic compo-
sites sintered at different temperatures was showed in
Figure 2. The addition of different glass on the surface
Figure 1. DTA curves of the as-prepared glasses (a. SiO2-
ZnO-Na2O; b. SiO2-ZnO-Na2O-Y2O3).
Figure 2. Porosity of the as-prepa red glasses/c eramics com-
posites sintered at dif f ere nt temperatures (a. SiO2-ZnO-
Na2O; b. SiO2-ZnO-Na2O-Y2O3).

Research on the High Strength Glass Cer amics/Mullite Ceramics Composites
55
of ceramic board had a great impact on the property of
the composites. When the SiO2-ZnO-Na2O-Y2O3 glass
was added on the surface of ceramic board, the density of
the composites reached its highest at 1050˚C with a cor-
responding porosity of less than 0.3%. Comparatively,
when the SiO2-ZnO-Na2O glass was used as the glass
coating, a temperature of 1100°C was required to make
the composites so dense. The higher crystallization tem-
perature of the SiO2-ZnO-Na2O-Y2O3 glass relative to
the SiO2-ZnO-Na2O glass might be the reason for this.
4.2. The Structure and Property of the
Glass/Ceramic Composites Board
Figure 3 shows the surface XRD patterns of the as-pre-
pared glasses. A weak bun peak can be observed on the
surface of the glass after sintering, which proves that the
crystal of the surface was either amorphous or the crystal
is was too small to generate the peak.
There were ZnB4O7 and ZnSiO4 peaks in the SiO2-
ZnO-Na2O-Y2O3 glass, which indicate the existence of
the crystal. In order to confirm the structure of the crys-
tal, the sample was analyzed by Raman spectroscopy.
The crystallization of B2O3 and SiO2 was found in the
SiO2- ZnO-Na2O glass through the testing (Figure 4),
though the intensity of those peaks decreases with the
increasing of the temperature. Additionally, the Raman
testing of the SiO2-ZnO-Na 2O-Y2O3 glass showed that
the presence Y2O3 crystals and the silicate melting struc-
ture of [Si2O7] and [SiO4] (Figure 5), proving that the
crystallites structure of Si O2-ZnO-Na2O-Y2O3 glass was
more complex and the addition of Y2O3 promotes the
crystallization of the galss.
Figure 6 shows the cross-section SEM images of the
glass/ceramic composites. Obviously, a well bonded and
Figure 3. Surface XRD patterns of the as-prepared glasses
(a. S iO2-ZnO-Na2O; b. SiO2-ZnO-Na2O-Y2O3).
Figure 4. Raman patterns of the as-prepared SiO2-ZnO-
Na2O glasses (a. 1200˚C; b. 1100˚C).
Figure 5. Raman pattern of the as-prepared SiO2-ZnO-
Na2O-Y2O3 glasses.
condensed glass layer on the surface of ceramic substrate
without holes and cracks was achieved, which indicated
the good match of the physical and chemical compatibil-
ity between the glass layer and ceramic base and that the
use of the glass and adoption of processing were reason-
able.
The thermal expansion coefficients of the ceramic
substrate and the glasses are displayed in Table 2. T her-
mal expansion coefficient of both SiO2-ZnO-Na2O glass
and SiO2-ZnO-Na2O-Y2O3 glass were less than that of
ceramic tile. Comparatively, the thermal expansion coef-
ficient of SiO2-ZnO-Na2O glass was closer to that ce-
ramic tile which is crucial to promote the strength of the
composites. During the course of cooling down, com-
pressive stress can be formed in glass layer and the wider
the difference in thermal expansion coefficient between
the glass and the ceramic tile is, the higher the compres-
sive stress is; too much compressive stress can lead to

Research on the High Strength Glass Cer amics/Mullite Ceramics Composites
56
(a) (b)
Figure 6. The cross-section SEM images of the glass/ceramic composites (a. SiO2-ZnO-Na2O/ceramics; b. SiO2-ZnO-Na2O-
Y2O3/ceramics ).
Table 2. T hermal ex pansion coefficient of the ceramics substrate and the glasses (× 10−6/K).
Temperature 40˚C - 400˚C 40˚C - 500˚C 40˚C - 600˚C 40˚C - 700˚C
SiO2-ZnO -Na2O-Y2O3 5.9885 5.9959 6.1207 6.5781
SiO2-ZnO -Na2O 6.2133 6.3438 6.8154 7.1873
Ceramic tile 6.7091 6.9815 7.6889 7.3512
cracks of the glass layer and deformation of the compo-
sites. Thus, it is necessar y to control the differenc e in the
thermal expan sion coefficients.
Figure 7 shows the relationship between the bending
strength of glass/ceramics composites and the sintering
tempe rature. The bending strength of the composites
increases with the sintering temperature, and when the
temperature was about 1180˚C, the bending strength of
the mullite cera mic tile reached the highest val ue of 95.9
MPa. After covering with the SiO2-ZnO -Na2O glass, the
bending strength was greatly improved to about 101.3
MPa and 5.2% enhanced. By comparison, when the
SiO2-ZnO-Na2O -Y 2O3 glass is coated on the surface of
the ceramic tile and sintered at the temperature of 1100˚C,
the bending strength peaked at 106.3 MPa and 10.7%
enhanced. This was not only caused by massive micro-
crystals of the glass layer, but also the lower compressive
stress formed in the glass layer. In addition, the crystal
structure of SiO2-ZnO-Na2O- Y2O3 glass was more com-
plicated and its high crystallization temperature was
helpful to improve the density of the composites during
the course of sintering, which reduced the sintering tem-
perature and sharply improved the strength of the com-
posit es.
5. Conclusions
SiO2-ZnO-Na2O glass and SiO2-ZnO-Na2O-Y2O3 glass
on the surface of large-size ultra -thin mullite ceramic tile
was successfully prepared by a distributing sintering
Figure 7. Relationship between the bending strength of
glass/ceramics co mpo s ites and the sintering temperature.

Research on the High Strength Glass Cer amics/Mullite Ceramics Composites
57
method. The crystallization temperature of SiO2-Zn O-
Na2O-Y2O3 glass was higher according to DTA analysis,
and the XRD and Raman analysis indicateed that the
crystallite structure of SiO2-ZnO-Na2O-Y2O3 glass was
more complicated with ZnB4O7, ZnSiO 4, B2O3, Y2O3 and
SiO2 crystal structures in the glass. The thermal expan-
sion coefficients of the SiO2-ZnO-Na2O-Y2O3 glass were
lower than the mullite ceramics tile, and the bending
strength of the composites after sintering at 1150°C was
obviously improved and reached 106.2 MPa and 10.7%
enhanced when compared with the mullite ceramic sub-
strate.
6. Acknowledgements
This work has been supported by the Graduate Innova-
tion Foundation of SUST.
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