MoS2对热压Fe基金刚石钻头胎体性能的影响研究

Effects of MoS2 on the matrix performance of hot-pressed Fe-based diamond drill bit

金刚石钻头是勘探工作中的常见破岩工具,但金刚石热稳定性较差,在钻进过程中会不断产生热量,干旱缺水条件下钻头自冷却对钻进效率的提高具有非常重要的意义。为降低干钻条件下钻头胎体与岩石界面间的摩擦因数从而减少钻进过程中金刚石的热损伤,在热压Fe基金刚石钻头胎体中添加二硫化钼(MoS2),研究MoS2含量对Fe基钻头胎体相对密度、洛氏硬度、抗弯强度以及与白刚玉砂轮干磨时的磨损量和摩擦因数的影响,并用扫描电子显微镜(SEM)和能谱仪(EDS)等测试仪器分析了抗弯强度和摩擦磨损试验后的试样断口和表面的形貌及物相成分。试验结果表明,在试验范围内,Fe基胎体相对密度与MoS2含量关系不大,但是与未添加MoS2的Fe基胎体相比,其相对密度提高了约2.5%,达98%以上。Fe基胎体洛氏硬度随着MoS2含量的增加先增大后减小,在MoS2体积分数为8%时胎体硬度最大,洛氏硬度HRB值达101.3。Fe基胎体抗弯强度随着MoS2含量的增加先增大后减小,在MoS2体积分数为2%时胎体抗弯强度最大,达1140 MPa。Fe基胎体磨损量随着MoS2含量的增加先减小后增大,在MoS2体积分数为4%时磨损量最小,为0.376 g。Fe基胎体与岩石界面间的摩擦因数则随着MoS2含量的增加而逐渐下降,在MoS2体积分数为10%时摩擦因数最小,为0.325。抗弯强度断裂试样断口形貌和物相分析表明,MoS2的加入降低了Fe基胎体显微组织的连续性。摩擦磨损试验后试样形貌分析表明,MoS2的加入降低了摩擦磨损过程中的粘着磨损和塑性变形。研究成果为减少干钻条件下金刚石磨损和热损伤,提高胎体耐磨性,延长钻头寿命奠定了理论基础。

Diamond drill bit is a common rock breaking tool in various exploration works,but the diamond in drill bit has poor thermal stability.As heat is constantly generated during the drilling process,the self-cooling of diamond drill bit under the condition of drought and water shortage is very important to improve the drilling efficiency.In order to decrease the friction coefficient between bit matrix and rock interface under dry drilling condition and reduce the thermal damage of diamond during drilling,molybdenum disulfide(MoS2)was added into the Fe-based diamond bit matrix,and research was performed for the effects of MoS2 content on the relative density,Rockwell hardness and flexure strength of Fe-based bit matrix,as well as the wear loss and friction coefficient during the dry grinding with white corundum grinding wheel.Besides,the morphology and phase composition on the fracture and surface of the specimens after flexure strength test and the friction-wear test were analyzed by the test instruments such as scanning electron microscope(SEM)and the energy dispersive spectrometer(EDS).The test results show that the relative density of Fe-based matrix has little relationship with MoS2 content within the test range,but the relative density of Fe-based matrix containing MoS2 is increased by about 2.5%to more than 98%compared with the Fe-based matrix without MoS2.The Rockwell hardness of Fe-based matrix increases at first and then decreases with the increasing of MoS2 content,and the HRB value is up to 101.3 at the MoS2 volume fraction of 8%.The flexural strength of Fe-based matrix also increases at first and then decreases with the increasing of MoS2 content,and the flexural strength is maximized to 1140 MPa at the MoS2 volume fraction of 2%.The wear loss of Fe-based matrix decreases at first and then increases with the increasing of MoS2 content,and the wear loss is minimized to 0.376 g at the MoS2 volume fraction of 4%.The friction coefficient between the Fe-based matrix and rock interface decreases gradually with the increasing of MoS2 content,and the minimum friction coefficient is 0.325 at the MoS2 volume fraction of 10%.The morphology and phase analysis of the fracture of broken specimen after flexural strength test shows that the continuity of Fe-based matrix microstructure is decreased with the addition of MoS2.Further,the morphology analysis of specimen after friction-wear test indicates that the adhesive wear and plastic deformation during frictional wear are declined with the addition of MoS2.Generally,the research results lay a theoretical foundation for reducing diamond wear and thermal damage,increasing the wear resistance of matrix,and prolonging the bit life under dry drilling conditions.