an automotive ball joint assembly includes a polymeric bearing disposed within a housing . the bearing includes an inner surface . a metallic stud includes a first end having a substantially spherical member and a second end having a shaft . the spherical member includes an outer surface capable of pivotal engagement with the bearing inner surface . a nickel - boron coating is applied to the outer surface of the spherical member to protect the spherical member against wear from friction , impact and corrosion .