Measuring Residual Strain and Stress in Thermal Spray Coatings Using Neutron Diffractometers

Background During thermal spray coating, residual strain is formed within the coating and substrates due to thermo-mechanical processes and microstructural phase changes. Objective This paper provides a comprehensive guide to researchers planning to use neutron diffraction technique for thermal spray coatings, and reviews some of these studies. Methods ENGIN-X at the ISIS spallation source is a neutron diffractometer (time-of-flight) dedicated to materials science and engineering with high resolution testing. The focus is on the procedure of using ENGIN-X diffractometer for thermal spray coatings with a view that it can potentially be translated to other diffractometers. Results Number of studies involving neutron diffraction analysis in thermal spray coatings remain limited, partly due to limited number of such strain measurement facilities globally, and partly due to difficulty is applying neutron diffraction analysis to measure residual strain in the thermal spray coating microstructure. Conclusions This technique can provide a non-destructive through-thickness residual strain analysis in thermally sprayed components with a level of detail not normally achievable by other techniques. Neutron sources have been used to measure strains in thermal spray coatings, and here, we present examples where such coatings have been characterised at various neutron sources worldwide, to study residual strains and microstructures.

Automated summary

This paper provides a comprehensive guide to using neutron diffraction technique for thermal spray coatings, focusing on the ENGIN-X diffractometer at the ISIS spallation source. The limited number of studies using neutron diffraction analysis in thermal spray coatings is partly due to global facility limitations and the difficulty in applying neutron diffraction to measure residual strain in the thermal spray coating microstructure. Neutron sources have been used to measure strains in thermal spray coatings, allowing for in-depth analysis of residual strains and microstructures.