Pack aluminization has been rapidly developed and widely used in many fields
due to its superior properties of coating. Surface is the only part of the component
which has to coexist with external environment. Majority of engineering failures
originate from the surfaces and components degrade in service leading to failures such
as fatigue, wear, corrosion and oxidation. The present study deals with the surface
modification of steel base through diffusion of aluminium by aluminium pack
cementation for improving wear and corrosion resistance. The material chosen for
study is medium carbon steel. Effect of varying weight percentage (wt.%) of halide
activator (NH4Cl) at different diffusion temperatures and times on the microstructure
and microhardness of aluminized specimens was studied. Taguchi robust design
technique using MINITAB13 was used to rank several factors that may affect the
microhardness and microstructure in order to formulate the optimum conditions. The
Taguchi orthogonal array L9 (33) was used for experimental design with three level of
consideration for each factor. The respone (Microhardness) was analyzed based on the
Taguchi’s signal-to-noise ratio. The use of 4%wt. of (NH4Cl) at 5hr and diffusion
temperature of 700oC seems to be the optimum condition, where the surface hardness
could be increased to 1000Hv when aluminized. X-Ray diffraction studies have been
confirmed the presence of aluminides in the surface layer, which could be instrumental
in the significant increase in the surface hardness.