Effect of Oxide Stabilizers and Surface Metallization on the Wetting Behaviour of Silver Based Brazing Alloys onto Zirconia Substrates for Oil Well Drill Bits Application

摘要

Tricone drill bits with hard ceramic inserts are often used in oil well drilling operations. However, the cutting action and breakdown of the rock formation produces failures on the tricone bits, which mainly are related to wear, partial or total rupture of the drill bit body or ceramic inserts, thermal shock, and corrosion. Brazing is a well established technique to joint metal-metal, ceramic-ceramic and ceramic-metal materials. Wetting phenomena plays an essential role in the production of metal/ceramic interfaces if a liquid phase is present. Stabilized zirconia with yttria and magnesia can be an interesting material for hard ceramic inserts application on drill bits when oil well or the drilling fluid has acid characteristics. In this work, silver based brazing alloys were melted onto zirconia substrates under high vacuum. The effect of oxide stabilizers and the metallized surface on the wetting behaviour were studied. Better results were found for the yttria stabilized zirconia system using AgCu with 3% Ti as filler alloy.