预合金粉末钎料对WC-Cu基孕镶金刚石钻头性能的影响OA

Objectives:With the wire line coring being widely used in deep rock core drilling,the drilling efficiency of diamond bits directly affects the efficiency of drilling projects.In view of the problem that diamonds are easily dislodged from the commonly used WC-Cu-based diamond bits when drilling in hard rock formations,resulting in low drilling efficiency,the effect of adding pre-alloyed powder brazing material on the properties and microstructure of WC-Cu based drill bits is investigated.Methods:Specimens and diamond composite specimens,containing 0-12%pre-alloyed brazing material and using 63#formulation as the base formulation,are prepared by hot press sintering method.The specimens are subjected to mechanical tests,wear ratio tests and XRD tests.In order to investigate the mechanism of action of pre-alloyed brazing material to improve matrix performance,the fracture of the specimen is observed with a scanning electron microscope.Drill bits are made with the ordinary matrix formula and the formula with the greatest increase in performance.Drilling tests are conducted to calculate rate of penetration and the wear of the working layer per unit footage to assess the application value of adding this brazing material.In order to study the changes in the wear condition of the matrix caused by the addition of pre-alloyed material,the morphology of the wear surface of the drill bit is observed with a body-view microscope and the number of diamonds was counted for each wear condition.Results:Mechanical property tests show that the addition of pre-alloyed powder to WC-Cu-based matrix can improve the mechanical properties of specimens.FCu14 and FAg737 additions at 8%resulted in the greatest enhancement of the mechanical properties of the specimens,with the highest rise in flexural strength of the matrix of 4.9%and the diamond composite specimens having an elevated wear ratio of 44.5%.The results of the XRD tests show that the pre-alloyed brazing material do not react with the constituents in the matrix to generate a new physical phase.Micro-morphological characterisation show that the addition of pre-alloyed powder brazing material is able to reduce the pores of the matrix.The pre-alloyed brazing material could achieve liquid-phase sintering and fill the gaps between the WC particles,which led to stronger toughness of the matrix.FAg737 pre-alloyed brazing material increases the hardness of the matrix through grain refinement.In the diamond composite material,the addition of pre-alloyed brazing material can make the diamond combine with the matrix more closely,and improve the mechanical holding force of the matrix on the diamond.The results of drilling test show that in hard granite formation,the rate of penetration of the drill bit with added pre-alloyed brazing material is increased by 98.4%and 97.3%,which is close to two times of the drilling speed of 63#formula drill bit.Observation of the wear surface of the drill bit shows that in the drill bit with pre-alloyed brazing material,the matrix supports the diamond in a tadpole shape,which results in a stronger holding force of the matrix on the diamond.On the cutting surface of the drill bit with pre-alloyed brazing material,the diamond spalling pits are obviously reduced,and the proportion of diamond that can play a role in cutting is larger,which effectively improves the drilling efficiency and makes the bit more difficult to slip.Conclusions:The addition of pre-alloyed brazing material to the WC-Cu-based matrix lead to liquid-phase sintering,which can fill the gaps between the WC particles and between the diamond and the matrix,thus increasing the toughness of the matrix and improving the mechanical holding power,which is reflected in the significant increase in the abrasion ratio of diamond composite specimens.The increase in matrix holding force contributes to the reduction of diamond shedding during the drilling process,and the diamond is able to perform more cutting,thus improving the drilling efficiency.