CORROSION ISOLATION OF MAGNESIUM COMPONENTS
A vehicle component, such as a wheel, is formed of a magnesium alloy for weight reduction in an automotive vehicle. It is expected that the wheel will be attached to other vehicle wheel-related componenets that are formed of metal compositions (for example, steel or cast iron components) that may lead to the corrosion of the magnesium wheel. Such attachment surfaces of the magnesium wheel are oxidized to form an integral and durable oxide layer on the magnesium wheel. When the magnesium wheel is attached to vehicle wheel supporting components of other alloys, the oxide layer-coated surfaces of the magnesium wheel are electrochemically isolated from the non-magnesium materials to prevent oxidation of the wheel or attached components.
1 . A vehicle component formed of a magnesium-base alloy and having a component surface to be engaged in surface-to-surface contact by a second vehicle component of dissimilar metal composition in a vehicle multi-metal vehicle component, the multi-metal vehicle component to be exposed to air and water in vehicle use;
each contacting surface of the magnesium alloy component surface having an integral oxide coating that electrochemically isolates the magnesium alloy surface from a contacting surface of the second vehicle component.
2 . A vehicle component as recited in claim 1 in which the integral oxide coating has a thickness of at least 75 micrometers.
3 . A vehicle component as recited in claim 1 in which the integral oxide coating is an electrolytic anodic coating formed to a thickness of about 75 micrometers or thicker.
4 . A vehicle component as recited in claim 3 in which the integral oxide coating is decoratively colored.
5 . A vehicle component as recited in claim 3 in which the integral oxide coating comprises nano-sized filler particles.
6 . A vehicle wheel formed of a magnesium-base alloy and having wheel surfaces to be engaged in surface-to-surface contact by vehicle components of dissimilar metal compositions when the wheel is attached to a vehicle, each contacting surface of the magnesium alloy wheel having an integral oxide coating that electrochemically isolates the magnesium alloy surface from a contacting surface of a vehicle component.
7 . A vehicle wheel as recited in claim 6 in which the integral oxide coating has a thickness of at least 75 micrometers.
8 . A vehicle wheel as recited in claim 6 in which the integral oxide coating is an electrolytic anodic coating formed on the wheel surface to a thickness of about 75 micrometers or thicker.
9 . A vehicle wheel as recited in claim 8 in which the integral oxide coating is decoratively colored.
10 . A vehicle wheel as recited in claim 8 in which the integral oxide coating comprises nano-sized filler particles.
11 . A multi-metal vehicle component formed of a magnesium-base alloy component and having a magnesium alloy surface attached in surface-to-surface contact with a second component of dissimilar metal composition in a vehicle multi-metal vehicle component, the multi-metal vehicle component to be exposed to air and water in vehicle use;
each contacting surface of the magnesium alloy component having an integral oxide coating that electrochemically isolates the magnesium alloy surface from a contacting surface of the second vehicle component.
12 . A multi-metal vehicle component as recited in claim 11 in which the integral oxide coating has a thickness of at least 75 micrometers.
13 . A multi-metal vehicle component as recited in claim 11 in which the integral oxide coating is an electrolytic anodic coating formed to a thickness of about 75 micrometers or thicker.
14 . A multi-metal vehicle component as recited in claim 11 in which the magnesium-base alloy component is a wheel comprising an integral hub and rim and the hub of the wheel is attached to at least one vehicle component of dissimilar metal composition.
15 . A multi-metal vehicle component as recited in claim 11 in which the magnesium-base alloy component is a wheel comprising an integral hub and rim and the hub of the wheel is attached with non magnesium-base alloy lug bolts to at least one vehicle component of dissimilar metal composition.