Could this be described as a piezorubber (polymer) coating?
(Diagram unrelated to Sputnik or Russian defence industry).
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Russia's Sputnik news reports September 30, 2016 https://sputniknews.com/military/20160930/1045884198/submarine-antenna-sonar-stealth.html:
"New Antennas to Make Russian Submarines Invisible to Sonars"
"Russian submarines are going to be outfitted with new unique piezoceramic coating antennas capable of intercepting and distorting signals emitted by enemy sonars.
"Russian submarines are going to be outfitted with new unique piezoceramic coating antennas capable of intercepting and distorting signals emitted by enemy sonars.
The new invention, developed by [the] OceanPribor Concern and the Krylov Research Center, under the auspices of the Foundation for Advanced Research Projects, is essentially a polymer membrane designed to cover the entire hull of a submarine.
These new antennas are expected to be installed both on the next generation submarines and on the submersibles that are already employed by the Russian Navy.
A source in the [Russian] Defense Ministry, [who is] privy to the development of the new antenna, told Russian newspaper Izvestia that the work is proceeding as planned, and that testing is expected to begin soon:
"We’re talking about a polymer membrane based on lead, titanium and zirconium oxides that can both absorb and transmit a signal. Essentially, this piezorubber coating transforms the submarine’s entire hull into a hydroacoustic antenna," the source explained.
The project, designated as Korsas ('Corsair' in Russian) is being funded by the Foundation for Advanced Research Projects, with OceanPribor designing antennas and sensors, and the Krylov Research Center working on integrating the piezoceramic coating into submarines’ outer plating.
The operating principle of the new antenna is fairly simple: the membrane captures a sonar signal, analyzes and distorts it, and then sends it back. The project’s cornerstone is a unique piezoceramic capable of absorbing and distorting acoustic signals. According to the source, research and development is expected to be completed by the end of the 2017."