The short answer is yes since1:
Amorphous silica is, in general, a good electric insulator
but exhibits a finite dc electrical conductivity, especially
when impurity alkali ions are contained
You will also find more info and specific references on that paper(ref. 1). For sure tests will be needed depending on the service conditions (it seems that porosity is also a critical aspect of the insulation properties).
It will also work well for improving the corrosion resistance of an existing coating. From the abstract of this paper2:
To improve the corrosion resistance of phosphate coatings, the
phosphated hot-dip galvanized (HDG) sheets were post-sealed with
sodium silicate (water glass) solutions. The results show that after
the silicate post-treatment the pores among zinc phosphate crystals
are sealed with the films containing Si, P, O and Zn, leading to the
formation of the continuous composite coatings on the surface of HDG
steel. The corrosion resistance of the composite coatings depending on
concentration of sodium silicate and post-sealing time is greatly
improved by the silicate post-treatment.
- Minoru Tomozawa, Chapter 3 - Amorphous silica, Editor(s): Hari Singh Nalwa, Silicon-Based Material and Devices, Academic Press, 2001,
Pages 127-154, ISBN 9780125139090, DOI: 10.1016/B978-012513909-0/50005-2
- Bi-lan Lin, Jin-tang Lu, Gang Kong, Synergistic corrosion protection for galvanized steel by phosphating and sodium silicate post-sealing,
Surface and Coatings Technology, Volume 202, Issue 9,
2008, Pages 1831-1838, ISSN 0257-8972, DOI: 10.1016/j.surfcoat.2007.08.001.