Analysis On Differences Of Contents And Structure Of Domestic And Foreign PDCs And Its Mechanism

Polycrystalline Diamond Compact (PDC) has been widely used in earth drilling, cutting of various materials such as non-ferrous metal and their alloy, hard metal alloy, graphite, plastics, rubber, ceramics. It's faced with polycrystalline diamond sintered from diamond powder. It has extremely high hardness, abrasion resistance and serving life. It's usually supported by tungsten carbide that has good toughness. The substrate provides good support for polycrystalline diamond and can be easily brazed to various tools. Presently PDCs are usually manufactured by HP-HT means. Domestic PDCs are inferior to foreign products. Domestic PDCs exhibit lower impact resistance, are more susceptible to delaminating, chipping and breakage.In the present research, scanning electron microscope (SEM), laser raman spectroscopy (LRS), X-ray photoelectron spectroscopy (XRS), X-ray diffraction (XRD) and electron probe micro analysis (EPMA) were utilized to investigate the difference in micro-structure and elements distribution between domestic and foreign PDCs. Combined with analysis on current manufacturing process, the mechanism for the difference was discussed. Scanning electron microscope (SEM), laser granularity analysis, atom emission spectroscopy (AES) and plasma emission spectroscopy (ICPAES) are also utilized to investigate the grain shape and impurities of key material-diamond power. Based on these work, some suggestions are presented to improve the performance of domestic PDCs.The present work suggests that our PDCs have following difference and could be improved by:I . Domestic PDCs contain more impurities such as Mo, Fe and Cr. They should be controlled by: 1. Improve the purification of diamond powder. 2. Improve the processing environment. 3. Change the material of shielding cup during sintering. 4. Improve the handling process and storage of diamond before sintering. Vacuum heat-treating and vacuum storage are recommended to eliminate impurities absorbed by diamond powder. 5. Standard for testing theimpurity content of diamond powder should be established.II. The direct diamond-diamond bonding between granules in domestic PDCs are poor. Accordingly more catalyst metal are left over, this weaken the strength of the whole PDC. Thus following measures should be adopted: 1 .Increase the pack density of micron diamond power to improve the pressure transmitting between diamond granules and decrease the distance between them. 2. Reduce the content of catalyst metal to prevent it from blocking the direct bonding of diamond granules and improve the thermal stability of PDCs.III. Measures should be taken to prevent uneven distribution of grain size in diamond blending.IV .Measures should be taken to lower the residual stress in PDCs by improving the structure of the interface between diamond and substrate.V .Improve the material of substrate to improve its adaptability to polycrystalline diamond.