US EPA

1756496 

Journal Article 

Fracture toughness and thermal resistance of polycrystalline diamond compacts 

Miess, D; Rai, G 

1996 

1 

Materials Science and Engineering A: Structural Materials Properties Microstructure and Processing
ISSN: 0921-5093
EISSN: 1873-4936 

209 

1-2 

270-276 

WOS:A1996UT95200042 

Polycrystalline diamond compacts (PCD) are being used
increasingly for oil and gas drilling and in machining of ceramics and hard non-ferrous
materials. Average diamond grain size and its distribution are used as one of the means to tailor
properties of PCD compacts. The diamond sintering process requires use of a tungsten carbide
cobalt disc placed onto diamond powder followed by high pressure and high temperature conditions.
During this process pseudo-eutectic, WC-Co liquid from the tungsten carbide disc is infiltrated
into diamond powder providing a liquid phase to facilitate inter-grain diamond bonding. The
amount and chemical composition with respect to carbon content of the liquid phase are dependent
on average diamond grain size and its distribution. Finer diamond sizes tend to have higher
sintered density than coarser sizes indicating a higher volume fraction of metallic content. The
role of residual metallic content of the diamond layer in conjunction with average grain size on
fracture toughness of the diamond layer was investigated. The fracture toughness was determined
using a diametral compression test. Larger grain PCD compacts having lower amounts of matallic
content were found to have a higher toughness than fine grained materials with higher amounts of
residual metallic phase. PCD compacts of different starting diameter grain sizes were subjected
to elevated temperatures under different gas environments and examined for their thermal
resistance. The results are explained in terms of total metal content of the diamond layer in
conjunction with the development of inter-grain diamond bonding. 

fracture toughness; thermal resistance; polycrystalline diamond compacts