The temperature at an interface is defined by two different parameters: 1. Flash temperature at the asperity contacts. 2. Nominal temperature which is the average temperature of the interface. Flash temperature is very important for the tribochemical wear and reactions. There are several flash temperature and nominal temperature models. You can  look for my paper (A Tewari, Wear 289 (2012)) for a brief review of these models. Full text is available on researchgate.

https://www.researchgate.net/publication/258226051_TRT_thermo_racing_tyre_a_physical_model_to_predict_the_tyre_temperature_distribution

Article TRT: Thermo racing tyre a physical model to predict the tyre...

Its not my area of expertise but ultrasonic scanning of the contact might be able to measure the temperature at the contact. As I say its not my area of expertise but might just help. 

Dear colleague,

You could try to estimate the temperature near the interface by mounting an embedded thermocouple. This is suited for a steady process, because the temperature must reach an equilibrium. So the measured temperature is the bulk temperature. To find the flash temperature, you can use an analytical model.

Best regards,

Viorel 

Dear Bhaumik,

As others colleagues told you, I suggest you use an embedded termocouple (one or more, depending on the shape and dimensions of your interested body, and use these collected data in the physical-math model technique know as Inverse Problems in Engineering (heat transfer model). With this technique you can reach very close to interested points on the interface.

On the other hand you can use the data generated by termocouple as a boundary conditions to Finite Elements Model to estimate the interface temperature in lot of interested areas.

In both suggestions the error for that estimative can reach around of 30%. It shows too high, however, you have an fine area difficult to reach!

Best wishes,

Wisley.

Dear Bhaumik,

I advise you to look at Martin Raynaud works about inverse heat conduction methods 

(example : Methodology for Comparison of Inverse Heat Conduction Methods M. Raynaud and J. V. Beck J. Heat Transfer 110(1), 30-37 (Feb 01, 1988) (8 pages)doi:10.1115/1.3250468)

Best regards,

Olivier

tHANK YOU ALL RESPECTED RESEARCHERS