A study on PDC drill bits quality

Abstract

The quality of innovating PDC bits materials needs to be determined with accuracy by measuring cutting efficiency and wear rate, both related to the overall mechanical properties. Therefore, a lathe-type test device was used to abrade specific samples. Post-experiment analyzes are based on models establishing coupled relations between cutting and friction stresses related to the drag bits excavation mechanism. These models are implemented in order to evaluate cutting efficiency and to estimate wear of the diamond insert. From here, an original approach is developed to encompass cutting efficiency and wear contribution to the overall sample quality toward abrasion. Four main properties of PDC material were used to define quality factor: cobalt content in samples that characterizes hardness/fracture toughness compromise, other undesired phase as tungsten carbide weakening diamond structure, diamond grains sizes and residual stresses distribution affecting abrasion resistance.

Discrete element thermomechanical modelling of rock cutting with valuation of tool wear

“…where F t is the friction force, v ir rt is the irreversible part of the relative tangential velocity, and 0 ≤ χ ≤ 1 is the part of the friction work converted to heat. Heat generated at the contact point is absorbed by the contacting particles (37) If the particles are of the same materials, it is assumed that the heat is absorbed equally by the particles:…”

Microstructures and thermal damage mechanisms of sintered polycrystalline diamond compact annealing under ambient air and vacuum conditions

“…2c presents the Co concentrates at the gaps among the diamond grains as well as the interface between PCD layer and WC-Co substrate. The Co phase in PCD layer is due to the infiltration of the Co from the WC-Co substrate during sintering [8]. Fig.…”

“…2c. The previous references [8,17] have indicated that W, with very low quantity, comes from thermal diffusion and infiltration during sintering process.…”

“…Moreover, PDC is considered as an excellent material for space drilling for its outstanding physical and chemical properties under vacuum condition [3][4][5][6]. However, a high temperature, during the processes of cutting and drilling, will accelerate the formation of thermal damage such as graphitization and micro-cracks [7][8][9], which rapidly leads to failure of PDC tools. Cobalt, as a binder existing in the gaps among diamond grains as well as the interface between PCD layer and WC substrate [8,10], plays a very important role in graphitizing and initiating of micro-cracks of diamond at high temperature (above 600°C) [11,12].…”

Evaluating the Wear of Polycrystalline Diamond Compact Drill Bit Cutters using Indentation and Scratch Tests

“…It is also reported that fine tungsten carbide grain size and a low level of cobalt content lead to higher hardness and good wear resistance, whereas coarse particles and high cobalt content produce low hardness and high wear rate (Mori, et al, 2003;Ndlovu, 2009). Yahiaoui, et al (2013) stated that the grain size and the content of cobalt are the most significant parameters of PDC cutters as high wear rate is associated with large particle size. Bellin, et al (2010b) reported that the increasing the cobalt content in the diamond layer and the substrate will increase the fracture toughness, whereas the wear resistance increases with lower cobalt content.…”