Hardfacing with coated diamond particles

A welding rod for use in forming a layer of hardfacing on a substrate to protect the substrate from abrasion and wear, comprising:

• a hollow steel tube closed at each end;
• a plurality of coated diamond particles disposed within the hollow steel tube;
• each coated diamond particle having a diamond particle with a respective sintered coating of hard material encrusted on and metallurgically bonded with the diamond particle;
• a plurality of tungsten carbide particles mixed with the coated diamond particles;
• and
• loose material selected from the group consisting of cobalt, nickel, copper, tungsten, tungsten carbide, and alloys thereof mixed with the coated diamond particles and the tungsten carbide particles.

A method of hardfacing a surface of a substrate, comprising the steps of:

• encrusting a plurality of diamond particles by forming first metallurgical bonds between each diamond particle and respective hardfacing material to provide a plurality of individual encrusted diamond particles;
• sintering each encrusted diamond particle to establish a desired density for each encrusted diamond particle;
• placing the encrusted diamond particles in a hollow steel tube and sealing each end of the steel tube;
• progressively melting the steel tube to form molten metal having the encrusted diamond particles dispersed therein;
• and
• applying the molten metal and encrusted diamond particles to the substrate surface and solidifying the molten metal in contact with the substrate surface to form second metallurgical bonds between each encrusted diamond particle and an adjacent matrix portion and third metallurgical bonds between the matrix portion and the substrate.

A method of hardfacing a working surface of a substrate, comprising the steps of:

• encrusting a plurality of diamond particles by forming a plurality of first metallurgical bonds between a first hardfacing material and each respective diamond particle to form a respective hard material coating thereon;
• sintering the first hard material coating on each diamond particle to provide a desired density for the encrusted diamond particles;
• mixing the encrusted diamond particles with a second hardfacing material;
• applying heat to the mixture of encrusted diamond particles and the second hardfacing material to form molten hardfacing having the encrusted diamond particles dispersed therein;
• and
• applying the mixture of molten hardfacing and encrusted diamond particles to the working surface and solidifying the molten hardfacing in contact with the working surface to form a plurality of second metallurgical bonds between the second hardfacing material and the first hardfacing material and a plurality of third metallurgical bonds between the second hardfacing material and the substrate.