Investigation of a Simultaneous Silicon-Modified Pack Aluminizing Method on Pure Nickel Using Quartz and RHA

Abstract

This research aims to study the simultaneous silicon-modified pack aluminizing method using silica (SiO2) from Rice Husk Ash (RHA) which contains 99.45% SiO2 in comparison with commercial SiO2 in the form of quartz. Samples can thus be categorized into two groups: quartz-doped and RHA-doped. Simultaneous silicon-modified pack aluminizing of pure nickel was performed at 1000°C for 4 hours under an argon atmosphere. The pack used in this research was prepared from aluminum (Al), ammonium chloride (NH4Cl), alumina (Al2O3) and silica (SiO2, i.e. quartz and RHA) powder at ratios of 29:2:60:9 by weight, respectively. Post aluminized samples were characterized by glancing incident-angle X-ray diffractometer (GIXD). Quantitative analysis of the layer was performed using energy dispersive spectroscopy (EDS). A scanning electron microscope (SEM) was employed to observe the resulting microstructure. It was found that simultaneous silicon-modified pack aluminizing can be successfully performed by doping RHA and quartz into the pack. The aluminized layer consists of Ni2Al3 and NiAl3 with a small amount of silicon. RHA was found to be more effective than quartz as a silicon source providing a higher amount of silicon in the aluminized layer. Moreover, using RHA successfully forms a silicon-rich interdiffusion layer beneath the typical aluminized layer.