Diamond exposed on the surface of an impregnated diamond bit (IDB) is the key to breaking rock. The exposure conditions of the diamond affect the drilling efficiency and life of the bit. However, scant attention has been directed towards investigating the diamond exposure mechanism of IDBs, particularly under varying drilling process conditions. In this study, drilling experiments were conducted on granite under rotary and rotary-percussive drilling conditions using a self-developed drilling test platform. The evolution of diamond emergence on the surface of the IDB under two drilling technology conditions was evaluated; the typical characteristics of diamond wear and their causes were discussed. The results indicate that under rotary drilling conditions, the primary evolution process of diamond on a slippery IDB surface follows the sequence of Emerging→Whole→Blunt (Flat). The exposed diamond tends to be predominantly blunt and fractured, and a slippery IDB cannot be resharpened by increasing the weight-on-bit. The evolution process of a diamond under rotary-percussive drilling conditions encompasses Emerging→Whole→Fractured→Pull out, and the diamond on the surface of the bit is primarily fractured. Diamond emerges from the matrix in the form of points, lines, and planes, with different emergence states affecting its wear and failure modes. The main form of wear in diamonds is mechanical wear, which is dominated by abrasive and fatigue wear. The proportion of fractured diamonds was notably higher under rotary-percussive conditions than in rotary drilling conditions. The tail of the diamond under rotary-percussive drilling conditions was shorter than that under rotary drilling conditions. The impact effect in rotary-percussive drilling enhances the bit-rock contact, facilitating matrix wear and diamond emergence. These results provide valuable insight for optimizing the IDB design and refining drilling technology.

中文翻译：

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钻井工艺对孕镶金刚石钻头磨损演变的影响


暴露在孕镶金刚石钻头（IDB）表面的金刚石是破碎岩石的关键。金刚石的暴露条件影响钻头的钻井效率和寿命。然而，人们很少关注 IDB 的金刚石暴露机制的研究，特别是在不同的钻井工艺条件下。本研究利用自主研发的钻孔试验平台，在花岗岩上进行了旋转式和旋转冲击式钻孔条件下的钻孔实验。评估了两种钻井技术条件下 IDB 表面金刚石出现的演变；讨论了金刚石磨损的典型特征及其原因。结果表明，在旋转钻井条件下，IDB光滑表面上金刚石的初级演化过程遵循新兴→整体→钝（平）的顺序。裸露的金刚石往往是钝的和破碎的，并且光滑的 IDB 不能通过增加钻压来重新磨利。旋转冲击钻进条件下金刚石的演化过程为出土→整体→破裂→拔出，钻头表面金刚石以破裂为主。金刚石以点、线、面的形式从基体中出现，不同的出现状态影响其磨损和失效模式。金刚石的磨损主要形式是机械磨损，其中以磨粒磨损和疲劳磨损为主。在旋转冲击条件下断裂金刚石的比例明显高于在旋转钻井条件下。旋转冲击钻进条件下的金刚石尾部比旋转钻进条件下的金刚石尾部短。 旋转冲击钻进中的冲击效应增强了钻头与岩石的接触，促进胎体磨损和金刚石的出现。这些结果为优化 IDB 设计和改进钻井技术提供了宝贵的见解。