Abstract: A method to apply a high performance overlay to a metal substrate of a rock bit to render the substrate surfaces of the rock bit more resistant to erosion, corrosion and substrate cracking while performing in an earthen formation is described. The method comprises the steps of bombarding the surfaces with a thermal spray of entrained fine particles of a cermet based composition at a velocity in excess of 3,000 ft/per sec. The resultant coating of the cermet based composition has a tensile bond strength in excess of 20,000 psi that results in an increase of the strain to fracture of the rock bit surface. The hard overlay has a resistance to severe service environments of high strain and shock tolerance as well as a higher load carrying capacity.

Abstract: An improved O-ring seal for rock bit bearings is formed from a resilient elastomeric composition comprising a multiplicity of low friction wear resistant particles distributed uniformly throughout the composition. The low friction wear resistant particles can have a rounded or non-rounded configuration. The low friction wear resistant particles located near the surface of the O-ring are exposed through wear of the elastomeric component to form wear pads that contact adjacent rotating rock bit sealing surfaces. The wear pads serve to reduce the break-off friction between the adjacent sealing surfaces and minimize the occurrence of stick-slip, thereby enhancing the service life of the O-ring seal and rock bit.