Analysis of abrasive blasting of DOP-26 iridium alloy

The effects of abrasive blasting on the surface geometry and microstructure of DOP-26 iridium alloy (Ir—0.3% W—0.006% Th—0.005% Al) have been investigated. Abrasive blasting has been used to control emissivity of components operating at elevated temperature. The effects of abrasive blasting conditions on surface morphology were investigated experimentally using surface profilometry. A simplified model was used to estimate the effects of process parameters on surface deformation and residual strain distribution. The surface geometry is found to be insensitive to the abrasive blast process conditions of nozzle pressure and standoff distance considered in this study. Modeling results suggest that the angularity of the abrasive particle has an important role in determining surface geometry and residual strains. Abrasive blasting causes localized surface strains and localized recrystallization, but it does not affect grain size following extended exposure at elevated temperature. The dependence of emissivity of the DOP-26 alloy on mean surface slope follows a similar trend to that reported for pure iridium.

► Experimental study and numerical model of abrasive blasting of DOP-26 iridium alloy.
► Increased particle velocity increases roughness but not slope.
► Surface slope is dependent on particle shape.
► Abrasive blasting results in local surface strains but no abnormal grain growth.
► Similar to pure iridium emissivity of DOP-26 alloy depends on surface slope.