Feasibility of Plasma Nitriding for Effective Surface Treatment of Pure Aluminum

Abstract

Cast aluminum with 99.99% purity was successfully plasma nitrided using nitrogen and hydrogen mixed gas. Pre-sputtering was carried out prior to plasma nitriding in order to eliminate surface oxide film. Sputtering and nitriding durations were varied from 3.6 to 18 ks and 72 ks to 252 ks, respectively. The samples were nitrided at 823 and 873 K to observe the effect of nitriding temperature. The nitrided samples were analyzed by GIXD, XPS, and TEM. Through GIXD and XPS results, formation of AlN was distinctly detected as a nitrided surface. Crosssectional microstructure of nitrided samples showed that AlN was formed with the thickness up to 3-5 mm. AlN formation is controlled by the diffusion process. The thickness of AlN layer was determined by the nitriding time and temperature. Partial degradation of AlN in the vicinity of the free surface occurred due to its reaction with moisture in air. Partial detachment of AlN layer occurred due to the residual thermal stress, which was caused by the difference in thermal expansion coefficient between AlN and substrate of Al.

Advanced Plasma Nitriding for Aluminum and Aluminum Alloys

“…The formation of AlN by normal plasma nitriding is controlled by diffusion process as had been reported in Ref. 16). Refs.…”

Wear of plasma-nitrided aluminum alloys

“…Two types of plasma nitriding are compared with respect to the formation behavior of aluminum nitride (AlN) layer: normal plasma nitriding [12][13][14] and precipitate-accommodated plasma nitriding [15,16]. Hardness profile is measured to describe the growth of AlN layer with increasing the nitriding time.…”

“…43.3 ks to attain E = 4.5 m [9]. Authors have developed the plasma nitriding for surface treatment of aluminum powder compacts and aluminum cast parts [11][12][13][14]. Although uniform AlN layer is formed by the normal plasma nitriding, its processing time must be much shortened and its process controllability must be further improved for reliable surface treatment of aluminum alloy, automotive parts.…”

Plasma-assisted surface treatment of aluminium alloys to combat wear

“…Other studies later explored the possibility of aluminium nitriding even without prior sputter cleaning (reinhold et al, 1998). Experimental results reported by Spies et al (2001) proved that the formation of aluminium nitride is possible on aluminium surfaces covered with an Al 2 O 3 film, and other investigators successfully carried out plasma nitriding of aluminium and its alloys without argon presputtering (Visuttipitukul et al, 2003).…”