Quantitative Study On The Matrix Materials Properties And Drilling Performances Of Electroplated Diamond Bit

As an important kind of electroplated diamond tool,electroplated diamond bit has been developed for forty years and its manufacturing technique has been highly improved.However,some problems still exist,such as there is an urgent need to construct a sophisticated evaluation system to characterize the relationship among diamond,matrix materials and rock formations;comprehensive understanding of the properties of the matrix material is lacked and no direct connection between the matrix properties and the bit working performance has been built;the understanding of the cooperative wear of diamond and matrix material is vague and lack of quantitative research.The purpose of this paper is to clarify the relationship between the matrix material properties and the performance of the bit,determine the decisive factors that affect the working performance of drill bits,provide theoretical basis for the selection and development of the matrix material and the optimum design of the bit and promote the application of electroplated diamond bits.In this paper,10 sets of plating solutions were designed for electroplated diamond matrix materials of nickel,cobalt and nickel cobalt alloy,and coating samples have been made.The differences of the microstructure,hardness,ductility coefficient and tensile strength of the three kinds of matrix materials were compared.The wear properties of the matrix materials were determined by the friction and wear test,and the effect of the mechanical properties of the matrix on the wear resistance of the matrix was analyzed.Then,10 electroplated diamond bits were made,and indoor micro drill experiments were carried out on rigid and medium abrasive granite.During this process,the drilling efficiency of drill bit was recorded.The laser scanning confocal microscope was used to compare the wear morphology,and the 3D point cloud data of the bit wear morphology were collected.Through the point cloud data processing and calculation,the matrix material consumption per unit drilling depth was obtained.Finally,through multiple linear regression statistical analysis method,the relationship between the properties of the matrix and the drilling performance of the bit was established,and the correlation degree between matrix properties and bit drilling performances were analyzed by grey correlation analysis.After a large number of experiments,the obtained conclusions are as follows:The hardness of the matrix material is closely related to the micromorphology of the matrix material;the finer the grain size,the greater the microhardness of the matrix material.The hardness of the matrix materials of nickel,cobalt and nickel cobalt alloy produced by plating solutions without any additives is the smallest.After adding the additives(valine,saccharin and so on),all of the nickel,cobalt,nickel-cobalt alloy matrix materials were refined and the hardness increased.The ductility of the matrix material is negatively related to the hardness.The ductility coefficient of the non additive nickel and nickel-cobalt alloy matrix is the largest.The ductility coefficient of the matrix materials are significantly reduced after adding additives,all not more than 2.The main mechanisms of friction and wear behavior of matrix material are surface fatigue wear and abrasive wear.The wear mechanism is determined by the hardness and ductility of the material,working conditions and friction couple materials.The wear resistance of non-additive Ni and Ni-Co alloy matrix materials is the weakest,and the wear resistance is enhanced after adding additives.While,the cobalt matrix materials all show low mass loss and strong wear resistance relatively.The correlation coefficient of matrix materials' hardness,ductility coefficient and tensile strength,and the wear resistance of matrix material is 0.800.The above matrix properties are not sufficient to accurately describe the differences in the wear resistance of the matrix materials.Among the three properties,tensile strength is the most important factor determining the wear resistance of the matrix,followed by hardness and ductility.The wear morphologies of the 10 groups of bits are significantly influenced by the hardness,ductility and wear resistance of the matrix materials.Wear morphologies of the non-additive nickel and nickel cobalt alloy diamond bits are dominated by ductility furrows which parallel to the sliding direction.Wear morphologies of the six group of bits manufactured from baths with additives are dominated by scratches with a metallic luster and obvious peeling pits.Compared with the same species of bits which produced form baths with additives,non-additive nickel,cobalt and Ni-Co alloy bits show higher drilling efficiency.The protrusion height of diamond is generally positively related to the drilling efficiency.The non-additive nickel matrix bit has the best adaptability to the hard dense and medium abrasive granite with the fastest drilling efficiency and matrix consumption rate.Its protrusion height of diamond is also the highest.The nickel-cobalt alloy bit produced form the electroplating bath with saccharin and 20g/L cobalt sulfate has the worst adaptability to the rock.The correlation between the matrix material properties and the drilling performances of the bit is highly significant,and the correlation coefficient is up to 0.988.The three most significant factors affecting the drilling performance are matrix wear rate per unit drilling depth,ductility and wear resistance.