A sol-gel method for forming durable, scratch-resistant coatings on glass substrates. Zirconia coatings, for example, are formed from a solution of zirconium oxychloride octahydrate in an organic, polar, aprotic solvent such as dimethylformamide. Annealed coatings, which optionally include an additive such as graphene, have a low coefficient of friction and can exhibit high hardness and hydrophobicity.