1. APPLICATION OPPORTUNITIES OF DIFFERENT GLAZES TO AL 2 O 3 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

2. microCAD 2005 2 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

3. 10-11 March 2005 microCAD 2005 3 Materials – Composition 4 sorts of glazes 1: earthenware glaze material 2, 3, 4: porcelain glaze materials Wt %- 1 -- 2 -- 3 - - 4 - Al 2 O 3 13,9914,4913,227,32 SiO 2 61,569,0267,7385,56 K2OK2O4,762,1150,84 CaO9,568,6313,262,18 Fe 2 O 3 3,883,033,82,58 ZnO3,632,72 - - Na 2 O2,68 - - - MgO -2,72 - -

4. 10-11 March 2005 microCAD 2005 4 Materials – Grain structures 1 3 2 4 Inhomogenity, grain size 0,5 – 30  m

5. 10-11 March 2005 microCAD 2005 5 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

6. 10-11 March 2005 microCAD 2005 6 Unusable results Glazes marked 2, 3 and 4 did not develop perfect coatings Glaze skips Pinholes Too thin coating

7. 10-11 March 2005 microCAD 2005 7 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

8. 10-11 March 2005 microCAD 2005 8 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

9. 10-11 March 2005 microCAD 2005 9 Testing methods – Scratch test Starting load: 10 N Final load: 100 N Table speed: 10 mm/min Loading gradient: 10 N/mm

10. 10-11 March 2005 microCAD 2005 10 Results – Microhardness

11. 10-11 March 2005 microCAD 2005 11 Results – Scratch test

12. 10-11 March 2005 microCAD 2005 12 Results – Scratch test

13. 10-11 March 2005 microCAD 2005 13 Results – Roughness

14. 10-11 March 2005 microCAD 2005 14 Conclusions Nowadays glazing of technical ceramics exposed to heavy duty use is a current and important challenge. Nowadays glazing of technical ceramics exposed to heavy duty use is a current and important challenge. The quality of the ceramic glazes strongly depends on the density of the glaze liquids and the geometrical shapes and sizes of solid ceramic particles in the glaze slurries. The quality of the ceramic glazes strongly depends on the density of the glaze liquids and the geometrical shapes and sizes of solid ceramic particles in the glaze slurries. Using the ceramic glazes we can considerably reduce the roughness of the surfaces of the alumina technical ceramics, increasing with this the estimated life cycles of these valuable technical items. Using the ceramic glazes we can considerably reduce the roughness of the surfaces of the alumina technical ceramics, increasing with this the estimated life cycles of these valuable technical items. The scratch tests are necessary to reach the required hardness of the ceramic glazes and adhesive strength between the glazes and the alumina substrates. The scratch tests are necessary to reach the required hardness of the ceramic glazes and adhesive strength between the glazes and the alumina substrates.

15. 10-11 March 2005 microCAD 2005 15 Department of Physical Metallurgy and Metallforming Department of Physical Metallurgy and Metallforming Department of Mechanical Technology Department of Mechanical Technology Acknowledgement

16. Many thanks for your attention!