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’ microstructure, diamond retention capacity and wear mechanism.

The shear strength and bearing characteristics of lunar soil have a strong connection with its compactness. The compactness varies significantly with depth and has an important effect on engineering activities on the lunar surface. In this study, lunar soil simulant samples of four compactness levels were prepared to explore the relationship between compactness and cone tip resistance in static cone penetration tests (CPTs). The compactness values at different depths were measured layer by layer, and CPTs were carried out. The results indicate that the cone tip resistance continuously increases with the increase in the penetration depth until it reaches a peak, and then remains constant for a certain depth. The cone tip resistance after the normalization of the overburden stress gradually increases and then decreases after reaching the peak. Models of the relationship between cone tip resistance before and after normalization and compactness were constructed using a regression algorithm. The variation in lunar soil compactness with depth can be determined by measuring cone tip resistance with this model. The research findings can provide a theoretical basis for in situ testing, site selection for lunar bases, and other related aspects on the lunar surface.

To explore a new formulation system of diamond bit matrix, three kinds of Fe-based pre-alloyed powder with low liquid phase content were utilized for the m

Various contents of carbon fibers (CFs) and potassium titanate whiskers (PTWs) were added to an Fe-based impregnated diamond bit (IDB) matrix to enhance its adaptability to percussive–rotary drilling. A series of mechanical tests were conducted successively to find the effects of the reinforcing materials on the properties of the Fe-based IDB samples. Then, the fracture surfaces of the samples were analyzed via scanning electron microscopy (SEM) and energy-dispersive spectroscopy, and the worn surfaces and abrasive debris of the samples were analyzed using a laser scanning confocal microscope and SEM. The results show that both the CF and PTW can effectively improve the hardness and bending strength of an Fe-based IDB matrix, and those parameters reached their maximum values at the additive amount of 1 wt%. However, the CF had a better enhancement effect than the PTW. Furthermore, the CF improved the impact wear resistance of the IDB matrix, with a minimum wear rate of 2.38 g/min at the additive amount of 2 wt%. However, the PTW continuously weakened the impact wear resistance of the IDB matrix with increases in its content. Moreover, the morphologies of the worn surfaces indicated that the minimum roughness of the CF-reinforced IDB matrix decreased significantly to as low as 4.91 μm, which was 46.16% lower than that without CF, whereas the minimum roughness of the PTW-reinforced samples decreased by 11.31%. Meanwhile, the abrasive debris of the CF-reinforced samples was more uniform and continuous compared to that of the PTW-reinforced samples. Overall, the appropriate addition of CF or PTWs can enhance the mechanical properties of Fe-based IDB matrices, which can be used on different formations based on their impact wear resistance.

Understanding rock behavior under cutting tools is critical for enhancing cutting processes and forecasting rock behavior in engineering contexts. This study examines the link between mechanical properties and indentation crater morphology of six rocks using a conical indenter until initial fracture. Through indentation testing, mechanical properties (indentation stiffness index k and hardness index HI) were assessed, and crater morphology was analyzed using a 3D laser profilometer. The rocks were categorized into three groups based on specific energy: Class I (slate, shale), Class II (sandstone, marble), and Class III (granite, gneiss). The morphological features of their indentation craters were analyzed both quantitatively and qualitatively. The linear model was used to establish the relationship between crater morphology indices and mechanical properties, with model parameters determined by linear regression. Key findings include: (1) Fracture depth, cross-sectional area, and contour roundness are independent morphological indicators, serving as characteristic parameters for crater morphology, with qualitative and quantitative analyses showing consistency; (2) Post-classification linear fitting revealed statistically significant morphological prediction models, though patterns varied across rock categories due to inherent properties like structure and grain homogeneity; (3) Classification by specific energy revealed distinct mechanical and morphological differences, with significant linear relationships established for all three indicators in Classes II and III, but only roundness showing significance in Class I (non-significant for cross-sectional area and depth). However, all significant models exhibited limited explanatory power (R² = 0.220–0.635), likely due to constrained sample sizes. Future studies should expand sample sizes to refine these findings.