K. Endres et al., Enhancement of fracture strength of cutted plate glass by the application of SiO2 sol-gel coatings, THIN SOL FI, 351(1-2), 1999, pp. 132-136
The influence of SiO2 sol-gel coatings on the bending strength of soda lime
plate glass samples has been investigated by 3 point bending and double ri
ng bending strength measurements. The samples were prepared by manual glass
cutting and were coated with two different types of SiO2 coating: A TEOS c
oating (thickness of about 100 nm) was obtained from sols synthesized by ac
id catalysis of tetraethoxysilane and a MTKS coating (thickness of about 1
mu m) was obtained from a methyl modified nanoparticulate SiO2 sol. The coa
tings were applied by dipping and were densified at 500 degrees C for 1 h.
The fracture strength sigma(0) of edge coated plate glass (60 x 25 x 3.8 mm
), determined by 3 point bending test (according to EN 843-1), was increase
d after coating with TEOS from sigma(0) = 24 MPa to 40 MPa (67% increase).
The fracture strength increased to sigma(0) = 56 MPa (133% increase) on app
lying MTKS or a double coating of TEOS followed by MTKS. The evaluation of
these measurements using Weibull statistical analysis resulted in ill value
s of 4.1 and 4.2 for the TEOS and MTKS coating and 3.5 for double coating (
uncoated glasses nz = 5.7), respectively. These results combined with high
resolution secondary electron microscopy investigations led to the conclusi
on that the strengthening effect of the two different sol-gel systems is du
e to a partial flaw healing and clamping of the crack sides. (C) 1999 Elsev
ier Science S.A. All rights reserved.