Research status and development trend on wear of impregnated diamond bits

Significance Impregnated diamond bits (IDBs) have been widely used in various hard rock drilling activities, especially deep drilling. Drilling process with IDBs relies on diamond edge wrapped by metal matrices to break the rock formation, which means the wear pattern of the diamond bit reflects the interaction between bits and rock, as well as the existence form of broken particles, which directly determine the drilling efficiency and service life of the drilling tools. But up to now there have not been so much in-depth study on its wear mechanism and analysing method in geological drilling. Progress and Analysis Therefore, this paper reviews the research literature on IDBs wear in the field of geological drilling, summarizes the abnormal bit wear problem according to engineering project experineces and industrial standards. Firstly, based on the experiences of geological drilling activities and industry standards, different types of abnormal bit wear of drill bits were summarized. Then, the evaluation methods of drill bit wear were introduced from the aspects of wear images and drilling signals. The wear mechanism and influencing factors of the drill bit in the drilling process were sorted out from three aspects: The overall drill bit, diamond, and metal matrix. In addition, mainstream methods of controlling drill bit wear performance were listed, and the research progress of wear analysis equations was introduced, besides, how machine learning methods can assist in the study of drill bit wear was discussed. Conclusion and Prospect Thus, IDBs have great potentials in deep hard rock drilling, and their wear performance is the key influnencing the whole drilling activity. To this end, research directions such as artificial intelligence assisting data analysis, microscale computational simulation, additive manufacturing, and material processing modification were analyzed and discussed, aiming to explore advanced methods for monitoring, analyzing, and regulating the wear of diamond drill bits, so as to meet the needs of remote monitoring and controlling in drilling activities such as geological deep drilling and extraterrestrial drilling

Effect of sintering pressure on the performance of Fe-based pre-alloyed bit matrix with low liquid phase

The hot-pressing sintering experiments were carried out under the conditions of sintering temperature of 950 ℃, holding time of 5 mins and different sintering pressures. The effects of sintering pressure on the properties of three kinds of low liquid phase Fe-based pre-alloyed bit matrix and one traditional Fe-based bit matrix were compared and studied, including the hardness, the bending strength, the relative density, the diamond embedding strength of the matrix, the thermal damage of diamond. as well as the microstructure and the morphology of drill bit matrix. The results show that with the increase of sintering pressure, the indentation hardness, the bending strength and the relative density of blank matrix with low liquid phase gradually increase, but the hardness and the bending strength of traditional Fe-based pre-alloyed blank matrix increase at first and then decrease, and the relative density increases. For the matrix containing diamonds, the bending strength of low liquid phase and traditional Fe-based matrix increases with the increase of sintering pressure. When the sintering pressure is 20 MPa, the bending strength of the diamond containing matrix with low liquid phase tends to be stable, while the bending strength of the traditional Fe-based matrix containing diamond decreases slightly. At the same time, with the increase of sintering pressure, the homogeneity of the low liquid phase matrix is enhanced, but the thermal damage of the diamond is gradually aggravated. According to the analysis of the mechanical properties and the fracture morphology of the matrix, the optimal sintering pressure is 20MPa. At this time, the hardness and the bending strength of the low liquid phase Fe-based pre-alloy matrix can meet the requirements of impregnated diamond bits

Effect of Carbon Fiber and Potassium Titanate Whisker on the Mechanical and Impact Tribological Properties of Fe-Based Impregnated Diamond Bit Matrix

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

Texture and High Yield Strength of Rapidly Solidified AZ31 Magnesium Alloy Extruded at 250 °C

In this study, commercial AZ31B magnesium alloy was used to compare the differences between the microstructure, texture, and mechanical properties of conventional solidification (as homogenized AZ31) and rapid solidification (as RS AZ31). The results demonstrate that a rapidly solidified microstructure leads to better performance after hot extrusion with a medium extrusion rate (6 m/min) and extrusion temperature (250 °C). The average grain size of as-homogenized AZ31 extruded rod is 100 μm after annealing and 4.6 μm after extrusion, respectively, but that of the as-RS AZ31 extruded rod is only about 5 μm and 1.1 μm, correspondingly. The as-RS AZ31 extruded rod attains a high average yield strength of 289.6 MPa, which is superior to the as-homogenized AZ31 extruded rod, and is improved by 81.3% in comparison. The as-RS AZ31 extruded rod shows a more random crystallographic orientation and has an unconventional weak texture component in 112¯1>/202¯1> direction, which has not been reported yet, while the as-homogenized AZ31 extruded rod has an expected texture with prismatic 101¯0>/1¯21¯0>//ED