Compressive behaviour of thin catalyst layers. Part I - Experimental study

Abstract In this study, the effect of compression is investigated experimentally on deformation and porosity of catalyst layers (CLs). Compression tests are performed on five CL samples with various microstructures using a thermomechanical analyzer and a custom-made machine Tuc-Ruc (Thickness under compression-Resistivity under compression). The results indicate that CLs have a linear behaviour with no plastic deformation at pressures less than 2 MPa even after 12 cycles. However, CLs showed plastic deformation, work hardening, and elastic shakedown under cyclic compression up to 5 MPa. In this pressure range, the material becomes stiffer and Young's modulus has increased by 50–113% after 8 loading cycles. Moreover, the material “settles down” after 6 cycles showing no further significant plastic deformation at higher pressures (up to 5 MPa). This behaviour suggests that CLs enter elastic shakedown region since after several cycles, plastic strain diminished, and they behave elastically afterwards. The compression tests on five samples yield Young's modulus of 30–45 MPa for pressures up to 2 MPa and Young's modulus of 37–70 MPa for pressures up to 5 MPa. The reason for slight change in Young's modulus is that the microstructure of CL changed, and the porosity decreased at higher pressures.