Metal pretreatment composition containing zirconium, copper, zinc and nitrate and related coatings on metal substrates

A metal pretreatment coating composition consisting of:

• 50 to 300 ppm of zirconium, 10 to 50 ppm of copper, 10 to 100 ppm of SiO2, 150 to 2000 ppm total fluorine, 10 to 100 ppm free fluorine, 600 to 7900 ppm zinc, and 10 to 10,000 ppm of an oxidizing agent.

A metal pretreatment coating composition comprising:

• 50 to 300 ppm of zirconium, 10 to 50 ppm of copper, 10 to 100 ppm of SiO2, 150 to 2000 ppm total fluorine, 10 to 100 ppm free fluorine, 600 to 7900 ppm zinc, and 10 to 10000 ppm of an oxidizing agent, and wherein the pretreatment composition contains only further metal ions selected from the group consisting of sodium, potassium, tin, vanadium and cerium, wherein said components are selected such that the coating composition is capable of depositing an amount of zirconium and a coating thickness on a metal substrate that are both less than an otherwise identical coating composition that is devoid of zinc under the same process conditions.