Method for forming a protective coating and substrates coated with the same

A substrate with a protective multicomponent coating, said coating formed by a process comprising the steps of:

• (a) applying a coating solution to the substrate, said coating solution comprising
• (i) a coating solvent;
• (ii) a SiO2 precursor comprising a silicon compound having at least one hydrolyzable group;
• (iii) a glass oxide precursor comprising a compound having an element selected from Group III or Group IV of the periodic table in the form of a salt, an alkoxide, hydroxide or an acid thereof;
• and
• (iv) a network modifier precursor comprising a compound containing an element selected from Group I or Group II of the periodic table in the form of a hydroxide, an acetate, or an alkoxide thereof;
• and
• (b) subsequently firing the substrate at a temperature greater than 450° C. to form the protective multicomponent coating on the substrate.

A multicomponent coating solution comprising:

• (i) a coating solvent;
• (ii) a SiO2 precursor comprising a silicon compound having at least one hydrolyzable group;
• (iii) a glass oxide precursor comprising a compound having an element selected from Group III or Group IV of the periodic table in the form of a salt, an alkoxide, a hydroxide or an acid thereof;
• and
• (iv) a network modifier precursor comprising a compound containing an element selected from Group I or Group II of the periodic table.