Nanomechanical Properties of Prepared-TiO2 Films Using Nanoindentation Technique
Nanoindentation was used to measure the hardness and Young’s modulus of prepared-TiO2 films. The thickness and refractive index of the TiO2 films were measured using ellipsometry with a monochromator. Scanning electron microscopy was used to determine the micrography of the TiO2 films. Pure TiO2 films were prepared from sols made by 3 % (w/w) of prepared-TiO2 suspension solution coated onto silicon wafers. After the dip-coating was completed, the coatings were further treated by various procedures, natural air-drying, water-vapor exposure, and calcinations. The prepared-TiO2 films were smooth and free of macro cracking. The grain sizes of these films were uniform and in the range of 50–100 nm and the films were of rutile structure. The prepared-TiO2 coatings exhibited more favorable porosity in water-vapor exposure than those under other conditions. The T-H2SO4 coatings exhibited higher hardness and modulus than those with T-H2O and T-NH4OH coatings after high temperature calcination. The values of hardness and modulus for T-H2SO4 coatings were 11.93 GPa and 226.25 GPa, respectively. Curves of hardness and modulus as a function of depth (0–2200 nm) of the coatings under calcination conditions show a peak at shallow contact depth within 100 nm and then demonstrate being rather constant. The hardness and modulus curve obtained from T-H2SO4 coatings in water-vapor exposure are rather constant.
L. C. Chuang and C. H. Luo, "Nanomechanical Properties of Prepared-TiO2 Films Using Nanoindentation Technique", Advanced Materials Research, Vol. 214, pp. 388-391, 2011