PZT materials withstand deep sea pressures

Paul Boughton

Test carried out by Morgan Advanced Materials on its range of lead zirconium titanate (PZT) materials for deep sea applications are proving they can withstand pressures greater than any they are likely to encounter in deep sea use with no loss of performance.

The tests involve a variety of ceramic formulations typically used in underwater applications, including both ‘soft’ and ‘hard’ PZT types. The objective was to better understand the behaviour of the materials and any changes in their electrical properties after tens or hundreds of exposures to very high pressures.

A pressure of 27,000psi (1,862bar) was applied to each ceramic type - equivalent to a depth of 18,500m underwater. This is beyond the maximum known deepest point in the ocean – the Mariana Trench, which at a depth of 10,994 m (± 40 m) exerts a pressure of 15,750psi (1,086bar), more than 1000 times the standard atmospheric pressure at sea level.

Results showed that Morgan’s PZT5A1 ‘soft’ and PZT401 ‘hard’ formulations suffered no signs of depolarisation at this pressure. Depolarisation has always been a concern for transducer design engineers, in the selection process of ceramic materials for deep sea applications and the traditional preference has been to use a ‘hard’ based ceramic material. However, these results confirm that a ‘soft’ product can now be specified delivering equal performance.