Role of Rate and Temperature on Fracture and Mechanical Properties of PCD

Abstract

Polycrystalline diamond compacts (PDC) cutters are widely used in oil and gas well drilling and a different format of the same material is also used in high speed turning. During the cutting process these tools experience very high temperatures and impact loads which lead to their sudden fracture. In this work the mechanical and fracture properties of two different grades of PCD test specimens, i.e. the Young’s modulus and fracture toughness, are measured under a range of test conditions such as temperature and loading rate, which correspond to the actual drilling conditions. The fracture is found to propagate in a highly dynamic manner, where the results show the examined properties of PCD specimens to vary with the loading rate and temperature. The study performed leads to a greater understanding of PCD behaviour, and aims to provide guidance for improved material design.

Thermal decohesion model validity for polycrystalline advanced ceramics

“…where α = a / h, Pin is the breaking load and f(α) is a fitting function of α as outlined in (Petrovic et al, 2011).…”

“…The low-rate three point bend flexural tests were performed using a standard screw-driven tensile testing machine (Petrovic et al, 2009;Petrovic et al, 2011). The plane strain fracture toughness is determined by the load at initiation method according to ASTM E1820-01 fracture standard:…”

The mechanical properties of polycrystalline diamond as a function of strain rate and temperature

“…tensile strength, transverse rupture strength, compressive strength, impact strength, fracture toughness and elastic constants as described below. The quasi-static Young's modulus of two grades of PCD has been determined at room temperature in [3]. Clearly, however, the availability of fracture and mechanical properties of PCD at low rates and low temperatures is not sufficient to satisfy industrial and academic needs, due to their irrelevance to in-service drilling conditions.…”

High Rate and High Temperature Fracture Behaviour of Polycrystalline Diamond

“…Strain gauges used were of MicroMeasurements type ZC-NC-G1262-120, which are free filament kanthal alloy gauges bonded by ceramic adhesive and with the measurement range of up to 1150°C. Figures 1a and 1b for G6 and G30 material, respectively, and compared with previously published quasistatic results [3]. At least three repeats at each combination of rate and temperature were conducted.…”

“…The fracture toughness of PCD was evaluated at a temperature of 600°C and 3 different dynamic loading rates: 0.3 m/s, 1 m/s and 5 m/s. The load at initiation method was used in the analysis, as previously explained in [3,4], which is sufficiently accurate even for the dynamic tests as the specimens were instrumented with the minute strain gauges close to the crack tip from which the load was extracted. Strain gauges used were of MicroMeasurements type ZC-NC-G1262-120, which are free filament kanthal alloy gauges bonded by ceramic adhesive and with the measurement range of up to 1150°C.…”