engleski

Abrasion resistant thin partially stabilised zirconia coatings by sol-gel dip-coating

Thin partially stabilised zirconia coatings were prepared by dip-coating from sols. Zr(O-nC_4H_9)_4 was used as zirconia precursor in sol-gel synthesis, making use of yttria to stabilise the high-temperature zirconia modifications. The effect of synthesis parameters for sol, such as molar ratio of Zr(O-nC_4H_9)_4, 2, 4-pentadione, water and nitric acid on the stability of ZrO_2 sols was determined. The gelling time was largely extended from 0 to 4200 hours by increasing the molar ratio of 2, 4-pentadione to Zr(O-nC_4H_9)_4 from 0 to 0.8. The acid displayed a marked catalytic and, combined with 2, 4-pentadione, synergistic effects on the hydrolysis rate of Zr(O-nC_4H_9)_4. Crystallographic analysis showed that only tetragonal zirconia crystallizes at 400°C, and that it remains stable until ~900°C. Microscopy of thin zirconia coatings showed that increased firing temperature facilitates the grain growth of zirconia. The mechanical properties of the coating-substrate system also increased with increasing firing temperature and viscosity of the coating solution.

sol-gel ; dip-coating ; zirconia ; thin coatings ; tribology

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