APPLICATION OPPORTUNITIES OF DIFFERENT GLAZES TO
AL2O3 TECHNICAL CERAMICS
Nikoletta PUSKÁS
Dr. László A. GÖMZE
Ildikó LUKÁCS
University of Miskolc, Department of Ceramics and Silicate Engineering
microCAD 2005
Miskolc
10-11 March 2005
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Introduction
How develop the smoothness of the technical ceramics?
Experiments and investigations at the Department of Ceramics and Silicates Engineering
Using of porcelain and earthenware glazes
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Materials – Composition
4 sorts of glazes
1: earthenware glaze material
2, 3, 4: porcelain glaze materials
Wt % - 1 - - 2 - - 3 - - 4 -
Al2O3 13,99 14,49 13,22 7,32
SiO2 61,5 69,02 67,73 85,56
K2O 4,76 2,11 5 0,84
CaO 9,56 8,63 13,26 2,18
Fe2O3 3,88 3,03 3,8 2,58
ZnO 3,63 2,72 - -
Na2O 2,68 - - -
MgO - 2,72 - -
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Materials – Grain structures
1
3
2
4
Inhomogenity, grain size 0,5 – 30 m
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Materials – Technology
Densities of glaze suspensions: 1: 1450 g/l 2: 1250 g/l 3: 1350 g/l 4: 1275 g/l
Firing temperature: 1270 °C
Dipping
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Unusable results
Glazes marked 2, 3 and 4 did not develop perfect coatings
Glaze skips
Pinholes
Too thin coating
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Further examinations
Further examinations, using glaze material marked 1 in different densities: 1350 g/l 1450 g/l 1500 g/l
Different dry material content alumina substrates made by casting: Porous Medium Compact
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Testing methods – Microhardness measurement
Applied loading force: 2 N Time of loading: 10 sec
Medium compact bodies with different density of glazes
Different compact base ceramics with 1350 g/l density glaze
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Testing methods – Scratch test
Starting load: 10 N Final load: 100 N
Table speed: 10 mm/min Loading gradient: 10 N/mm
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Results – Microhardness
HVM values of middle compact samples glazed with different density glaze materials
619 617
600
580
590600
610
620
1350/m 1450/m 1500/m
signs of samples
HV
M
HVM values of different compact samples glazed with 1350 g/l density glaze material
621 619
601
590
600
610
620
630
1350/c 1350/m 1350/p
signs of samples
HV
M
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Results – Scratch test
Critical load values of middle compact samples glazed with different density
glaze materials
58
6259
545658606264
1350/m 1450/m 1500/m
Signs of samples
Cri
tic
al
loa
d
(N)
Critical load values of different compactness samples glazed with
1350 g/l density glaze material 79
6259
50556065707580
1350/c 1350/m 1350/pSigns of samples
Cri
tic
al
loa
d (
N)
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Results – Scratch test
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Results – Roughness
Roughness values of glaze coatings and base ceramics
00,5
11,5
22,5
Al2O3 PorcelainRa
rou
gh
nes
s va
lue
roughness of theglaze
roughness of thebase ceramic
roughness of theglaze
roughness of baseceramic
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Conclusions Nowadays glazing of technical ceramics exposed to heavy Nowadays glazing of technical ceramics exposed to heavy
duty use is a current and important challenge.duty use is a current and important challenge. The quality of the ceramic glazes strongly depends on the The quality of the ceramic glazes strongly depends on the
density of the glaze liquids and the geometrical shapes and density of the glaze liquids and the geometrical shapes and sizes of solid ceramic particles in the glaze slurries.sizes of solid ceramic particles in the glaze slurries.
Using the ceramic glazes we can considerably reduce the Using the ceramic glazes we can considerably reduce the roughness of the surfaces of the alumina technical ceramics, roughness of the surfaces of the alumina technical ceramics, increasing with this the estimated life cycles of these valuable increasing with this the estimated life cycles of these valuable technical items.technical items.
The scratch tests are necessary to reach the required hardness The scratch tests are necessary to reach the required hardness of the ceramic glazes and adhesive strength between the of the ceramic glazes and adhesive strength between the glazes and the alumina substrates.glazes and the alumina substrates.
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Department of Physical Department of Physical Metallurgy and MetalMetallurgy and Metalllforming forming
Department of Mechanical Department of Mechanical TechnologyTechnology
Acknowledgement
Many thanks for your attention!