Effect of composition on abrasion-corrosion behavior of WC-based matrix material for impregnated diamond bits

To study the influence of the component (WC, Fe and 663Cu) contents on the abrasion-corrosion properties of impregnated diamond bit matrix, abrasion-corrosion tests, static corrosion tests and electrochemical tests were carried out in 20% NaCl slurry with pH value of 10. The surface morphology and corrosion products were observed and analyzed by SEM and Raman spectroscopy. The results show that mechanical wear plays a dominant role in abrasion-corrosion process in salt water environment, and pure corrosion has no obvious effect. However, the synergistic effect of these two components cannot be ignored. With the decrease in corrosion resistance of the matrix, the synergistic effect was more significant. Furthermore, the anti-corrosion property of the matrix deteriorated with the increase of WC and Fe contents, but the opposite was true for 663Cu. The dominant corrosive products have been detected as a mixture of oxides and hydroxy chloride. Due to the potential difference between different matrix components, Fe and other binder phases were formed as anode and WC as cathode in the process of abrasion-corrosion. The micro galvanic couple between WC and binder removed binder material preferentially. And WC particles were removed more easily under mechanical action after losing support from the binder. During the process of test, the exposure and passivation of the fresh surface will reach a balance. After the abrasion-corrosion test, the sample surface will be passivated rapidly.