Yttria-stabilized zirconia (YSZ) coatings significantly extend the temperature resistance of metal pitot probes, adding up to 300°C to their usable range and making them viable for high-heat applications like gas turbine exhausts.Sensor Calibrationwelcome to click on the website to learn more!
YSZ coatings work by creating a thermal barrier, reducing heat transfer to the metal substrate. A 100μm YSZ coating on an Inconel 718 probe reduces substrate temperature by 250-300°C at 1000°C, allowing the probe to operate at 1000°C instead of the uncoated limit of 700°C. A gas turbine test found coated probes lasted 3x longer than uncoated ones at 900°C.
Coating adhesion is critical, achieved through plasma spraying with a bond coat (e.g., NiCrAlY) between the metal and YSZ. This bond coat reduces thermal expansion mismatch, preventing delamination. A thermal cycling test (20°C to 1000°C) showed probes with bond coats survived 500 cycles, compared to 50 cycles for direct YSZ application.
Porosity control (10-15%) allows the coating to expand without cracking, while keeping it dense enough to block hot gas ingress. Scanning electron microscopy (SEM) of failed coatings found those with <5% porosity cracked due to thermal stress, while >20% porosity allowed gas penetration.
YSZ-coated metal probes offer a cost-effective alternative to full ceramic probes, combining metal’s structural toughness with ceramic’s heat resistance. For applications between 700-1200°C—where uncoated metals fail and full ceramics are too brittle—YSZ coatings provide an optimal solution.