Abstract: A composition for surface treatment of aluminium, aluminum alloys, magnesium or magnesium alloys and the treating solutions being diluted to the desired concentration are defined. The composition contains (1) compound A containing at least one metal element selected from the group consisting of Hf(IV), Ti(IV) and Zr(IV), (2) a fluorine-containing compound of sufficient amount to make fluorine exist in the composition in an amount of at least 5 times the molarity of the total molarity of the metal contained in the above-mentioned compound A, (3) at least one metal ion B selected from the group of alkaline earth metals, (4) at least one metal ion C selected from the group consisting of Al, Zn, Mg, Mn and Cu, and (5) nitric ion and the mol concentration of compound A is 0.1-50 mmol/L as the metal element of Hf(IV), Ti(IV) and Zr(IV). A metal treated with the treating method of the present invention solution has an excellent resistance to various corrosive environments.

Abstract: A composition for surface treatment of aluminium, aluminum alloy, magnesium or magnesium alloy and the treating solutions being diluted to the desired concentration are defined. A said composition of this invention containing (1) compound A containing at least one metal element selected from the group consisting of Hf(IV), Ti(IV) and Zr(IV), (2) fluorine containing compound of sufficient amount to make fluorine existed in the composition at least by 5 times of molarity to the total molarity of metal contained in above mentioned compound A, (3) at least one metal ion B selected from the group of alkaline earth metals, (4) at least one metal ion C selected from the group consisting of Al, Zn, Mg, Mn and Cu, and (5) nitric ion and the mol concentration of compound A is 0.1-50 mmol/L as metal element of Hf(IV), Ti(IV) and Zr(IV). The metal treated with the treating method applying the present invention solution has excellent resistance to various corrosive environments.