Methods for making antireflection coatings for heat-treatable inorganic substrates

Antireflection coatings are used for a variety of substrates, particularly glass. Broad band antireflection coatings are typically designed to minimize reflection throughout the visible range of the spectrum. There are many ways to apply such coatings to glass, including dip coating using sol gel techniques and more costly vacuum techniques such as sputtering. The invention includes a bilayer antireflection coating, multilayer antireflection coatings, and a method for making a multilayer antireflective coated substrate. The bilayer and multilayer coatings include layers having metallic oxides, at least one layer in each of such coatings having as a material with an index of refraction at least about 1.90, a layer comprising oxides of zirconium such that when subjected to heat treatments, such as tempering, the coatings substantially retain their optical properties. The coatings further include layers having materials of low index of refraction which include oxides of aluminum which provide coating stability and increased precursor storage life. In the method, the layers are applied by successive dip coating techniques using solvent-based solutions and the resulting coatings can be used to coat large sized substrates which can be later cut, trimmed and/or otherwise shaped and later heat treated with substantial retention of optical properties.