Sol coating of metals

A method for improving adhesion between a metal and an organic resin, comprising the steps of:

• (a) coating the metal with a mixed organometallic sol coating, having about one part organometallic zirconium and about 2.0-3.4 part organometallic silane by volume in a water carrier stabilized with an effective amount of acetic acid;
• (b) covalently bonding the organometallic zirconium in the sol coating to the metal to form a metal-sol coating interface;
• and
• (c) covalently bonding the organometallic silane through a crosslinking functionality to the resin to form a resin-sol coating interface.

A method for enhancing corrosion resistance of and adhesion to a metal surface, comprising the step of applying a mixed metal sol to the surface by:

• (a) adding an effective amount of NH.sub.4 OH to deionized water in a mixing vessel, the NH.sub.4 OH being sufficient to disrupt Zr-acetate complex formation in the mixed metal sol;
• (b) separately adding glacial acetic acid in an amount sufficient to stabilize the rate of hydrolysis of an organozirconium to about 1 vol % of an organozirconium based upon the total sol;
• (c) adding about an equal volume of deionized water to the organozirconium-acetic acid mixture of step (b);
• (d) separate from the vessel, mixing about 2.0-3.4 vol % of an organosilane coupling agent based upon the total sol, the being either 3-glycidoxypropyltrimethoxysilane or 3-aminopropyltrimethoxysilane with deionized water;
• (e) adding the water-organozirconium-acetic acid mixture of step (c) to the mixing vessel;
• (f) adding the mixture of step (e) to the organosilane-water mixture of step (d) to make a combined sol;
• (g) diluting the combined sol with deionized water;
• and
• (h) applying the diluted sol to a metal surface.