Advanced Coating to Mitigate PDC Cutter Thermal Degradation in PDC Bit Manufacturing

Abstract

Abstract Polycrystalline Diamond Compact (PDC) cutters on PDC drill bits are the primary cutting elements to shear and scrape the formations during drilling process. In the PDC drill bit manufacturing, PDC cutters are attached onto drill bit with silver-copper-zinc alloys by brazing process. PDC cutters face the challenge of thermal degradation during this brazing process. This paper studies the development of an advanced coating on PDC cutter to mitigate its thermal degradation in the brazing process. The advanced coating is applied by physical vapor deposition process on PDC cutter. The coated cutter surface is checked by scanning electron microscope (SEM) for the coating integrity. Both the coated and uncoated cutters are brazed and debrazed to mimic the heating cycle of drill bit manufacturing. They are then tested in a vertical turret lathe to shear a rotating granite rock. The volume losses from the wear scars of the cutters after specific passes are compared among those the coated and uncoated PDC cutters. The SEM results show that coating is in good integrity on the PDC cutter surfaces. The coating is continuous, dense without porosity or microcrack. No obvious oxidation is observed after a high-temperature heat treatment at 740 °C, which was used to mimic the overheating brazing process, which is commonly encountered during bit manufacturing. Then, the vertical turret lathe test results show that the coating on the PDC cutters improves the wear resistance by 50% when compared with that of uncoated cutters, after the brazing and de-brazing simulation. This work presents a solution to the thermal degradation of the PDC cutters after brazing process by using an advanced coating process. With the improved wear resistance due to the coating protection, the life of drill bit and its rate of penetration (ROP) during the drilling process can be significantly improved. It is expected to save a lot of drilling time and cost for the drilling operation in the E&P sector.