Lead zirconate titanate coating of tungsten carbide-cobalt to enable smart coatings

Smart coatings enable sensing and actuation functionality to be added to materials. Piezoelectric coatings, especially lead zirconate titanate (PZT), have been used on a wide range of metallic and semiconducting substrates. Tungsten carbide-cobalt (WC-Co) is extensively used in the metal processing industry due to its hardness and abrasion resistance. The ability to apply piezoelectric coatings close to a metal cutting edge would enable improved control of the cutting process resulting in improved quality and reduced power consumption in the manufacturing process. However, the WC is sensitive to oxidation at typical PZT processing temperatures presenting a challenge to the development of functional PZT films for this application. This paper reports the use of a low temperature solution-gelation (sol-gel) process to deposit high quality crystalline PZT (Pb_0.52Zr_0.48TiO₃) film onto a WC-Co substrate. Laser Doppler vibrometry showed significant piezoelectric activity with an effective d₃₃ coefficient of 19 pC/N. Both the dielectric constant and piezoelectric coefficient were lower than expected due to the formation of an insulating PbWO₄ oxide interlayer between the conducting WC-Co substrate and PZT. Accounting for this layer indicated a d₃₃ piezoelectric coefficient for the PZT of 85 pC/N. Crown