Abstract: A diamond impregnated drill bit features layered encapsulation of the diamond grit where the innermost layer is hardest or most abrasion resistant while succeeding layers are generally softer and less wear resistant. This can be accomplished by manipulating several variables in the encapsulation layers such as particle size or hard particle concentration. The outer layers can have added binder to make them softer. The encapsulated grit can be sintered or pre-sintered to make it less friable when handled.

Abstract: Earth-boring tools and components thereof include a particle-matrix composite material having encapsulated diamond particles embedded within a matrix material. Diamonds in the particles comprise less than about 25% by volume of the composite material, the matrix material comprises less than about 50% by volume of the composite material, and encapsulant material surrounding the diamonds at least substantially comprises a remainder of the volume of the composite material. Methods of forming at least a portion of an earth-boring tool include embedding encapsulated diamond particles in a volume of matrix material to form a particle-matrix composite material. The composite material is formed in such a manner as to cause diamonds to comprise less than about 25% of the composite material, the matrix material to comprise less than about 50% of the composite material, and encapsulant material surrounding the diamonds to at least substantially comprise a remainder of the composite material.

Abstract: A diamond impregnated drill bit features layered encapsulation of the diamond grit where the innermost layer is hardest or most abrasion resistant while succeeding layers are generally softer and less wear resistant. This can be accomplished by manipulating several variables in the encapsulation layers such as particle size or hard particle concentration. The outer layers can have added binder to make them softer. The encapsulated grit can be sintered or pre-sintered to make it less friable when handled. As a result the encapsulated diamonds are retained in the matrix longer with higher protrusion to improve bit longevity and penetration rates.