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Metal matrix diamond composite samples were fabricated by selective laser melting (SLM) at different forming parameters to investigate the feasibility and new challenges when SLM is applied to diamond tools manufacturing. The surface topographies, Rockwell hardness, compactness, microstructure, and diamond thermal damage of the samples were investigated in this study. The fabricated samples had high porosity and relatively low Rockwell hardness and compactness, and some ridge-shaped bulges and textures were observed at the edges and surfaces. Microstructure analyses showed that diamond particles were homogeneously distributed and metallurgically bonded within the metal matrix. The thermal damage pits on the diamond crystals along the scanning direction were the dominant damage type for SLM, which was completely different from conventional vacuum brazing and hot-pressing sintering. Although some challenges need to be further studied, our results demonstrate that SLM has great potential to propel the development of metal matrix diamond tools.

WC-Cu based hot-pressing diamond bit has been widely applied in all-hydraulic geological exploration, as well as deep and ultra-deep well drilling in the oil and gas industry. However, the effect laws and mechanisms of Cu and WC on the metal matrix composite need further study. Therefore, six WC-Cu based metal matrices were designed, and a series of samples with different dimensions were fabricated to conduct some specific physical and mechanical tests, namely, tests of relative density, Rockwell hardness, bending strength, impact toughness and abrasion weight loss. Additionally, the microstructure and diamond retention conditions of the WC-Cu based samples after bending strength test, as well as their wear morphologies after the pin-on-disc wear test, were analyzed by scanning electron microscope. Test results indicate that most of the physical and mechanical properties were improved with the increase of 663-Cu at first, and then monotonously declined. The increase of 663-Cu also shows an important influence on the samples&rsquo, microstructure, diamond retention capacity and wear mechanism.

Under the limitation of rockets carrying capacity, the rated torque and power offered by drilling rigs, Therefore, the optimizations of auger driller's structure size and drilling parameters are necessary to realize deep lunar coring drilling under qualified condition. Study results indicate that the bit inner diameter is determined by target sampling mass and the density of drilling objects. Outer diameters of the bit and the helical blades are determined by the required power and torque for auger driller's restart from its state buried. To utilize the accommodated capacity of cuttings and dissipating the heat produced by bit during drilling process as much as possible, the lead angle is recommended to be 15°∼20°. The helical blade width should be obtained after other drill pipe parameters are determined. Feeding rate should be determined at first, and rotation speed is decided by the auger driller's structure size and feeding rate. Rotational speed will be enough as long as it can satisfy the normal discharge of the cuttings, otherwise its increasing would significantly increase drilling power.