Abstract:
The present work is mainly focused on the macroscopic and microscopic examination of failed tungsten
carbide (WC-Co) drill bits to find the root cause of the inserts failure. Different failed WC-Co tool bits have
been observed macroscopically and found that the inserts have failed due to shear-off, cracks, and gradual
wear. The FE-SEM and AFM micrographs have been used to understand the different degradation and the
tribocorrosion mechanisms of WC-Co inserts. Typical shape change mechanisms of individual WC grains
have also been studied in detail with the help of FE-SEM micrographs, which have been influenced by the
tribocorrosion in the presence of the mining environment. Ultrasonic cleaning method has been used to
clean the inserts for the microscopic examinations. Various morphologies of fragmented WC grains have
been examined to understand the shape change mechanisms of WC grains. The different electrode potential
between the Co binder and the WC grains is the primary cause of the micro-galvanic form of corrosion.
Hence, in the present study the wear and corrosion mechanisms of WC-Co insert along with the possible
approaches to reduce the tribocorrosion have been discussed in detail. It was found that the proper
understanding of tribocorrosion mechanisms is essential for the selection, development, and advancement
of the suitable WC-Co tool materials.
