Effect of shot peening on the oxidation behavior of thermal barrier coatings

Cyclic oxidation of an ultrafine-grained and CeO2-dispersed δ-Ni2Al3 coating

The promoted formation of an α-Al2O3 scale on a nickel aluminide with surface Cr2O3 particles

The effect of SMAT on pack boronizing of EN8 steel is addressed. SMAT induced plastic deformation, enabled nanocrystallization at the surface, reduced the grain size and increased the volume fraction of non-equilibrium gain boundaries, accumulation of defects and dislocations at the grain boundaries and within the grains. These features helped to promote the diffusion of boron. The present study demonstrates for the first time that SMAT treated EN8 steel can be boronized with a reasonable case depth at 923 K for 7 h. It also addresses the benefits of duplex treatment methodology to achieve the desired case depth and a dense boronized layer. Formation of an FeB phase along with an Fe 2 B phase for SMAT treated EN8 steel has also been reported for the first time. The findings of the study recommend that SMAT can be used as a pretreatment for boronizing of steel, provided necessary precautions are made on boron concentration, to control the volume fraction of the deleterious FeB phase.

Effect of surface mechanical attrition treatment (SMAT) on boronizing of EN8 steel

A theoretical model equation has been derived to relate the growth kinetics of silicide coating with the pack chemical composition and other processing conditions for siliconizing of Mo-TZM (Mo-0.5Ti-0.1Zr-0.02C) alloy to improve its oxidation resistance at high temperatures. A series of experiments conducted with varying pack Si (1-10 wt %) and NH 4 F (2-20 wt %) content, time (1-25 h), and temperature (800-1200°C) confirmed the validity of the model. MoSi 2 was the main coating layer formed during the siliconizing process. Optimum processing conditions were derived for doping of Al in MoSi 2 to form Mo(Si,Al) 2 in the outer layer of the coating.

P.K. Datta

Papers

Low-temperature formation and oxidation resistance of nickel aluminide/nickel hybrid coatings on alloy steels

Shot peening effect on aluminide diffusion coating formation on alloy steels at low temperatures