Abrasion Resistant thin Partially Stabilised Zirconia Coatings by Sol-gel Dip-coating

摘要

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 4 200 h 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 crystallized at 673 K,and that it remains stable until ~1173 K.Optical microscopy of thin zirconia coatings showed that increased firing temperature facilitated the grain growth of zirconia.The mechanical properties (microhardness and abrasion resistance) of the coating-substrate system also increased with increasing the firing temperature and viscosity of the coating solution.