| The thesis introduces the development history and classification of diamond drill bits,as well as the types and problems of the impregnated diamond bit crown.In order to solve the problem of high sintering temperature and poor comprehensive mechanical properties of traditional bit crown,this paper carried out experimental research on prealloyed bit material?ultrafine Fe-Ni prealloyed powder?.The prealloyed bond material with WC as the skeleton phase and a corresponding impregnated diamond composite material were prepared.The effects of sintering temperature and WC addition on the properties of composites were investigated by mechanical properties testing and microscopic characterization.A diamond drill bit was prepared by selecting a bit crown formula with good test results,and compared with the conventional 63#formula bit for indoor drilling test.research shows:?1?The sintering process of the ultrafine Fe-Ni prealloyed powder at 700°C and750°C is insufficient,resulting in low density,hardness and bending strength,and over-fire at 950°C and 1000°C.?2?When the sintering temperature is 800°C,the pressure is 15 KN,and the temperature is kept for 4 min,the material has high compactness,the relative density is 97.75%,and the hardness and bending strength also reach the highest of 24HRC and 2114.87MPa.?3?When the sintering temperature is above 800°C,the hardness and flexural strength decrease with the increase of temperature,mainly because the grain size increases with the increase of temperature,and the defects such as pores also increase.?4?With the increase of WC content,the relative density of pre-alloyed carcass samples showed a downward trend,mainly due to the increase of WC and the increase of voids caused by WC segregation in the sintered system.?5?The hardness of the prealloyed bond sample increases first and then decreases with the increase of WC content.When the WC content is 40%,the hardness is28.2HRC,which is 17.5%higher than that without WC.On the one hand,the hardness is increased due to the higher hardness of the WC,and the probability of the indenter contacting the WC becomes higher,and on the other hand,due to the dispersion-like strengthening effect of the WC particles.The hardness cannot continue to rise and the decrease is mainly due to the increase in the porosity of the prealloyed carcass.?6?The flexural strength of the prealloyed carcass sample decreases with the increase of WC content.When the WC content is less than or equal to 40%,it can meet the needs of preparing diamond composite materials.The main reason for the decrease in bending strength is that the interface bonding ability of the skeleton material WC and the Fe-Ni binder is a simple mechanical inlay.?7?The prealloyed agglomerate has good comprehensive performance when the WC content is 20%40%.Under the selected process parameters?800°C,15kN?,the diamond can be packaged in a good way,and the comprehensive performance requirements are excellent.Material;when the WC content is 30%,the diamond-impregnated composite has the highest wear resistance.?8?Under the same conditions,the pre-alloyed diamond-impregnated diamond drill bit with 30wt%WC as the skeleton material has a mechanical drilling speed of6.04cm/min,and the per working layer consumption is 2.4mm·m-1.Although the diamond-impregnated diamond drill bit with 63#formula has a mechanical drilling speed of 3.16cm/min,and the per working layer consumption is 0.9mm·m-1.The drilling speed of the pre-alloyed impregnated diamond drill bit increased by 91.14%,making it suitable to be used in hard and medium abrasive rock.Due to its lower sintering temperature?800°C?,the manufacturing cost of the drill bit can be saved,so the pre-alloyed diamond-impregnated diamond drill bits have broad prospects in the future. |
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