About
Dr
Rakesh Bhaskaran Nair
Postdoctoral Researcher
DCU
Dr. Nair is a Postdoctoral Researcher in additive manufacturing at I-Form, based at Dublin City University (DCU). He completed his PhD in 2020 at Shiv Nadar University, India, where his research focused on the material degradation behaviour of high-entropy alloy claddings. Prior to joining I-Form, Dr. Nair worked as a postdoctoral researcher in Canada for three years, specialising in thermal spray coatings of advanced materials for harsh environments, particularly in aerospace gas turbine engine applications. His current research focuses on understanding the thermal history of materials processed via laser powder bed fusion (LPBF). He employs ex-situ high-speed pyrometry to develop calibration models and determine spectral emissivity, with the goal of enhancing process monitoring and quality control in metal additive manufacturing.
Technical Summary
Understanding the thermal history in Laser Powder Bed Fusion (LPBF) is crucial for determining the resulting microstructure and mechanical properties of printed parts. Accurate temperature measurements and thermal signatures are key to ensuring process repeatability and quality assurance of printed parts. In this study, non-contact pyrometry is used to analyse thermal signatures during LPBF; however, the radiance signals detected by the pyrometer are recorded as voltage rather than absolute temperature.
Dr. Nair’s research aims to develop calibration models correlating voltage and temperature for various LPBF powder materials. This is achieved using an ex-situ thermal station, where powders are heated under controlled temperatures and their voltage signals are captured by a high-speed pyrometer. The study explores the influence of particle size distribution, surface roughness, powder type, chemical composition, and morphology on radiance emission and spectral emissivity.
Additionally, his research includes investigating the microstructural of pre-alloyed samples during controlled heating—up to 1500°C—using an in-line optical microscope. This setup incorporates a FLIR thermal camera equipped with a microscope to visually capture microstructural changes in real time. The goal is to establish correlations between microstructural transformations, calibration model behaviour, and spectral emissivity, contributing to improved thermal modelling and process control in LPBF.