Patent ID: 8250757

Claim:
A method for forming a corrosion resistant seal ring for a mechanical seal having first and second seal rings wherein one said seal ring is configured for mounting to a rotating shaft so as to rotate with said shaft about a shaft axis and the other said seal ring is configured for stationary mounting to a seal housing so as to remain stationary during rotation of said shaft-mounted seal ring, said first and second seal rings having respective end faces that define opposed seal faces which face axially toward each other in close opposing relation and rotate relative to each other during shaft rotation to define a sealing region which extends radially across said end faces and sealingly separates a process fluid chamber from a seal chamber disposed adjacent said seal rings, said first and second seal rings respectively being formed of different first and second seal ring materials which have respective first and second electrical conductivity levels which differ from each other, the method comprising the steps of: providing a seal ring having inner and outer diameters extending about a seal ring axis, said seal ring being formed of said first seal ring material so as to have an original conductivity level which is defined by original conductive properties of said first seal ring material such that said original conductivity level defines said first conductivity level, said first seal ring having said seal face disposed between said inner and outer diameters and exhibiting seal face properties wherein said original conductivity level extends across said seal face; treating said seal face of said first seal ring by a laser treatment process to modify the seal face properties of said first seal ring such that said original conductivity level is changed to a modified conductivity level over said seal face, said modified conductivity level being set proximate to said second conductivity level of said second seal ring to thereby minimize electro-corrosion between said seal faces of said first and second seal rings in mechanical seal applications prone to electro-corrosion; and said laser treatment process being applied to said seal face of said first seal ring such that said first seal ring has said modified conductivity level in a layer at said seal face and has said original conductivity level extending through the remaining axial thickness of said first seal ring, wherein said laser treatment process comprises the step of applying a laser beam over said seal face between said inner and outer diameters at a treatment energy level which substantially avoids ablation of said first seal ring material while changing said original conductivity level to said modified conductivity level.