High-temperature sensors are widely used in high-temperature environments, such as industrial furnaces, aircraft engines, and energy equipment. Their core sensitive components must operate continuously in extreme environments ranging from hundreds to thousands of degrees Celsius. Detection accuracy directly determines the reliability of equipment monitoring. Zirconia ceramics, with their excellent and stable physical properties, are an ideal material for high-temperature sensor sensitive components. They withstand thermal shock, chemical attack, and mechanical stress in high-temperature environments, preventing material property fluctuations from interfering with the sensor's signal acquisition and transmission. Through structural stability, signal fidelity, and environmental adaptability, they provide key assurance for detection accuracy, resolving the pain point of conventional materials susceptible to failure and resulting accuracy degradation at high temperatures.
Zirconia ceramics' excellent thermal stability is fundamental to ensuring the detection accuracy of high-temperature sensor sensitive components. In high-temperature environments, drastic temperature fluctuations can easily cause thermal expansion and contraction, phase transitions, or thermal aging in the sensitive component material, leading to structural deformation or performance drift, affecting the accuracy of detection data. Zirconia ceramics, by adding stabilizers such as yttrium oxide and magnesium oxide, form a stable cubic or tetragonal crystal structure. This structure resists significant phase transitions over a wide temperature range (typically exceeding 1600°C), while maintaining an extremely low coefficient of thermal expansion. When zirconia ceramics are used as the substrate or core component of high-temperature sensor sensors, the components will not experience dimensional deviations or internal microcracks due to thermal deformation, even in the face of frequent temperature fluctuations during furnace heating and cooling, or transient temperature swings during engine start-up and shutdown. This ensures consistent contact between the sensor and the object being measured, as well as stable signal acquisition position, and avoids detection errors caused by structural deformation.
The chemical stability of zirconia ceramics prevents corrosion in high-temperature environments from damaging the performance of the sensor, maintaining long-term stable detection accuracy. High-temperature environments are often accompanied by hot gases (such as flue gas and fuel gas), molten liquids (such as molten metal and glass), or corrosive media (such as sulfides and nitrogen oxides). These substances can easily react chemically with the materials of sensitive components, forming impurity layers or corroding the component surface, leading to degradation of the component's electrical, thermal, or sensing performance, and thus detection errors. Zirconia ceramics, however, are inherently chemically inert and are not susceptible to these corrosive media at high temperatures. They are neither oxidized by hot gases to form a loose oxide layer nor wetted or dissolved by molten materials. For example, in industrial furnace flue gas detection sensors, zirconia ceramics can withstand long-term corrosion from the acidic substances in high-temperature flue gas, maintaining a clean surface and stable sensing performance. This ensures consistently accurate data for flue gas composition, temperature, and other parameters, and avoids accuracy degradation caused by chemical corrosion.
The excellent mechanical stability of zirconia ceramics reduces damage to sensitive components caused by mechanical stress at high temperatures, ensuring signal transmission integrity. Under high-temperature conditions, the strength and hardness of most materials decrease significantly. If sensitive components are subjected to equipment vibration, airflow, or minor collisions, they can develop microcracks or even structural damage, leading to interrupted signal transmission or distortion, compromising detection accuracy. Zirconia ceramics, however, maintain high flexural strength and fracture toughness even at high temperatures. Their hardness is far superior to that of ordinary metals or ceramics, making them resilient to external forces and impacts, even in high-temperature, vibrating environments. For example, sensitive components in aircraft engine high-temperature sensors must withstand the high-frequency vibration and airflow impacts of engine operation. Component housings or internal support structures made of zirconia ceramics maintain structural integrity at high temperatures, preventing mechanical damage that could loosen the connection between the sensitive component and the signal cable, ensuring stable signal transmission and reducing detection errors caused by signal interruption or distortion.
The stable electrical properties of zirconia ceramics provide the foundation for accurate signal output from sensitive components in high-temperature sensors that rely on electrical signals. Some high-temperature sensor components (such as oxygen sensors and temperature sensors) rely on the material's electrical properties (such as ionic conductivity and temperature coefficient of resistance) to detect parameters. If these electrical properties are unstable with temperature fluctuations, this can directly lead to output signal drift and reduce detection accuracy. Zirconia ceramics exhibit stable ionic conductivity at high temperatures. The oxygen ions in their crystal lattice migrate in an orderly manner at high temperatures, and their conductivity exhibits a regular and stable linear relationship with temperature, without random fluctuations. For example, in automotive exhaust oxygen sensors, zirconia ceramics sense oxygen concentration in exhaust gas through their oxygen ion conductivity. Their stable electrical properties ensure a precise correlation between conductivity and oxygen concentration, preventing random drift in the output signal due to temperature fluctuations. This enables the sensor to accurately determine exhaust gas composition, providing reliable data for engine fuel injection control and avoiding detection errors caused by unstable electrical properties.
The low and stable thermal conductivity of zirconia ceramics can reduce the impact of local temperature variations on the sensor on detection accuracy. The sensitive element of a high-temperature sensor must accurately sense the local temperature or temperature distribution of the object being measured. If the component material conducts heat too quickly or has unstable thermal conductivity, it can easily lead to temperature gradients within the component, causing temperature discrepancies between sensitive and non-sensitive areas, leading to measurement errors. Zirconia ceramics have a low thermal conductivity coefficient and remain stable at high temperatures, preventing drastic changes in thermal conductivity with rising temperatures.
When zirconia ceramics are used as a thermal insulation substrate for the sensitive element, they effectively block heat interference from the external environment, limiting the influence of the sensitive area solely on the temperature of the measured object, thus preventing temperature measurement deviations caused by stray heat conduction from the environment. Furthermore, the stable thermal conductivity ensures uniform temperature across the component, preventing variations in sensing performance due to localized overheating or overcooling, further improving the consistency and accuracy of measurement data.
In practical applications, the stable physical properties of zirconia ceramics not only improve the detection accuracy of high-temperature sensor sensitive elements, but also extend the component's lifespan, reducing the need for maintenance and replacement due to accuracy degradation. In industrial production, high-precision high-temperature testing helps companies precisely control production processes (such as kiln and metal melting temperatures) and improve product quality. In the aerospace sector, reliable high-temperature testing ensures the safe operation of critical equipment like engines, preventing accidents caused by testing errors. This dual advantage of "precision and durability" has made zirconia ceramics a core material for sensitive components in high-temperature sensors, promoting the stable application of high-temperature testing technology in various high-end fields and providing key material support for industrial upgrades and intelligent equipment.
