CaF2/hBN自润滑Fe基孕镶金刚石钻头性能研究

Study on the Properties of Fe-based Impregnated Diamond Bits with CaF2

摘要:

针对地矿、油气行业面临的钻探新挑战，将材料科学领域的自润滑技术引入热压烧结孕镶金刚石钻头领域，以期实现钻头在高温井底工作环境中的自润滑功能，从而降低摩擦放热，防止金刚石热损伤，提高钻头使用寿命。本文作为自润滑孕镶金刚石钻头设计的初步尝试，通过对固体润滑添加剂的优选与试验，首先确定了氟化钙（CaF2）、六方氮化硼（hBN）两种固体润滑添加剂，以Fe基胎体为基体，通过热压烧结制备了具有不同浓度的固体润滑添加剂的自润滑孕镶金刚石钻头胎体试样，利用一系列仪器测定了其物理力学性能和摩擦学特性；制备了微型自润滑孕镶金刚石钻头，在微钻实验台上进行了钻进试验。试验结果表明：随着固体润滑剂含量的增加，两组自润滑钻头胎体试样的物理力学性能均有所降低，但幅度不同，CaF2组明显小于hBN组；两组胎体试样摩擦系数均显著降低；CaF2组胎体试样的磨损率先增后减，hBN组试样磨损率大幅增加；钻头进尺CaF2组有所提高，hBN组逐渐减小。

Abstract:

In order to cope with drilling challenges in mining, oil and gas industries, the self-lubricating technique in material science has been introduced into the design of hot press sintered impregnated diamond bits (IDB). Such attempt aims to endow IDB with the ability to self-lubricate, so as to reduce frictional heat, prevent diamond thermal damage and improve bit service life. This paper describes an initial design where CaF2 and hBN were selected as solid lubricant additives through optimization and experiments. They were added to Fe-based matrix to prepare two groups of self-lubricating IDB matrix specimens with different lubricant concentrations via hot press sintering. The specimens’ mechanical and tribological properties were tested by a series of testing machines, and the miniature IDB were made and bench-tested. The results show that with the increase in lubricant concentrations, both groups of specimens experienced decrease in their mechanical strengths; however, the degree of such decrease differed among two groups, with hBN group dropping more dramatically. The friction coefficients of both groups dropped significantly, and the wear rate of CaF2 group first rose and then dropped; whereas that of hBN group increased substantially. The drilling footage of CaF2 group rose slightly while hBN group decreased gradually.