| 摘要 |
Various steel, downhole tools and components of drill string, including as examples, a PDC drill bit (10), a rotary rock bit (100), a cross-over sub (40), a stabilizer (51), a reamer or hole enlarger (70), and coring bit (120), are selectively treated to cause certain of their parts to be electro-negative with respect to steel, and certain other parts to either have the same electronegativity as steel, or to be treated electro-positive with respect to steel.
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