Carbide ceramics (e.g., silicon carbide, silicon nitride) are valued in high-temperature flow measurement for their low thermal conductivity, but their extreme hardness makes machining difficult.Sensor Calibrationwelcome to click on the website to learn more!
Low thermal conductivity (10-30 W/m·K, 1/5 that of Inconel) minimizes heat transfer from the probe tip to internal sensors, critical in environments like glass melting furnaces (1200-1500°C). A furnace test showed a silicon carbide probe’s internal sensor maintained a 100°C lower temperature than an Inconel probe, reducing thermal drift by 60%.
This low conductivity also reduces tip temperature gradients, ensuring uniform pressure readings. In a plasma spray test, a silicon nitride probe had 2% lower measurement variation than a metal probe, where uneven heating caused hole expansion differences.
machining challenges include drilling holes (typically 0.5-2mm diameter) in materials with hardness exceeding 2000 HV. Diamond-tipped laser drilling is the only viable method, but it requires slow feed rates (0.1mm/s) to prevent cracking. A manufacturing study found laser power fluctuations >5% increased hole taper, leading to 3% pressure measurement error.
Surface finishing is another hurdle. Grinding to Ra <0.8μm requires diamond abrasives, as conventional tools wear rapidly. A rough surface (Ra >1.6μm) increases airflow disturbance, making it unsuitable for low-turbulence flow tests. Despite these challenges, carbide probes’ high-temperature performance justifies the manufacturing complexity in specialized applications.