Auger electron spectroscopy

Annealing (glass)

Diamond

Engineering

Metallurgy

Materials science

Coating

Nuclear physics

Differential scanning calorimetry

Polycrystalline diamond

Chemical engineering

Thermodynamics

Physics

Crystallite

Microstructure

Composite material

Sintering

Cobalt

Scanning electron microscope

Journal of Material Science and Technology

To improve the oxidation and graphitization resistances of the polycrystalline diamond (PCD), Ti coating was deposited on the diamond powders via magnetic sputtering method, which achieved a uniform TiC protection barrier in PCD during the sintering process. The phase compositions, microstructures and thermal stability of Ti-PCD were characterized by X-ray diffraction (XRD), Auger electron spectroscopy (AES), scanning electron microscopy (SEM) and thermal gravimetric-differential scanning calorimetry (TG-DSC). The results demonstrate that the oxidation and graphitization resistances of PCD are strengthened due to the existence of TiC phase, which acts as an effective inhibitor. The as-received inhibitor delays the oxidation and graphitization of PCD, elevating their initial temperature by ∼50 °C and ∼100 °C, respectively. During the annealing treatment of Ti-PCD, the priory oxidation of TiC, which produces TiO2 as an oxygen barrier, postpones the diamond oxide. Moreover, the TiC barrier also protects diamond grains from direct contact with cobalt, thus a lower cobalt-catalytic graphitization, and yields to an improved graphitization resistance of PCD. The enhanced oxidation and graphitization resistances of PCD are of significant importance for practical applications to elevated temperatures.

Enhanced oxidation and graphitization resistance of polycrystalline diamond sintered with Ti-coated diamond powders