Abstract:During geo-technical investigation, rock formation with different weathering degrees, and bouldery formation with different particle sizes and cementation can be encountered in drilling of the same borehole. The complexity of geological conditions may easily lead to such phenomena as bit bouncing, bit balling, resulting in low core recovery. To improve the adaptability and drilling efficiency of diamond bits, two kinds of diamond bits with heterogeneous structures were designed and manufactured according to the characteristics of geotechnical investigation. In the heterogeneous structure, every single cutter is divided into two parts: main and auxiliary working layers, which allows the diamond bit behaving like both the PDC bit in rock fragmentation and the impregnated diamond bit in drilling, improving the adaptability of the diamond bit to different formation. Field testing indicates that the new heterogeneous diamond bit can achieve 2.68m/h average rate of penetration, and 48.7m average bit service life in weathered rock and bedrock. Compared with ordinary electroplated diamond bits, the rate of penetration is improved by 21%, while the service life is more or less the same.

Abstract:The performances of superfine Fe-Co-Cu pre-alloyed powder SFP were tested, measured and analyzed. The sintered temperature of the powder decreased to 700 ℃, high relative density of fusion was proved to be 97%, in addition high hardness and abrasion resistance was achieved. The examination showed that the powder had less differ in size and better oxidation resistance than ultra-fine cobalt powder. Blending with other powder, different hardness and erosion resistance property could be achieved. In conclusion the pre-alloyed powder can match with the foreign products.