Investigation on a laser-assisted radiation thermometry technique

Area of Science:

• Thermophysics
• Optical Measurement Techniques
• Materials Science

Background:

• Accurate non-contact surface temperature measurement at high temperatures is crucial for industrial processes and material science research.
• Traditional methods like pyrometry often require prior knowledge of material emissivity, which can be difficult to determine accurately, especially for dynamic or oxidized surfaces.
• Existing techniques may also be limited by the need for physical contact or specialized sample preparation.

Purpose of the Study:

• To introduce and validate a laser-assisted radiation thermometry (LART) technique for high-temperature surface measurement.
• To demonstrate that LART can determine surface temperature independently of specimen emissivity.
• To assess the accuracy and applicability of LART in a relevant high-temperature material scenario.

Main Methods:

• Utilizing a modulated laser to induce a localized, transient temperature rise on the specimen surface.
• Detecting the resulting thermal radiation emitted from the surface at two distinct infrared wavelengths.
• Developing a theoretical model to infer surface temperature from the ratio of detected thermal signals, eliminating emissivity dependence.
• Conducting experimental validation on an oxidized Inconel 600 sample within a temperature range of 1120-1265 K.

Main Results:

• Theoretical analysis confirmed that surface temperature can be calculated irrespective of material emissivity.
• Experimental measurements on oxidized Inconel 600 showed excellent agreement with internal thermocouple readings.
• The LART technique achieved less than 3% difference compared to thermocouple measurements for surface temperatures above 1200 K.

Conclusions:

• The proposed laser-assisted radiation thermometry (LART) technique offers a robust solution for non-contact, emissivity-independent surface temperature measurement at high temperatures.
• LART demonstrates significant potential for applications in industries requiring precise thermal monitoring of materials under extreme conditions.
• The technique's accuracy and reliability, validated on Inconel 600, suggest broad applicability across various high-temperature materials and processes.