Nitrogen plasma source ion implantation for corrosion protection of aluminum 6061-T4

Abstract

It is established that nitridation of aluminum (Al) 6061-T4 by plasma source ion implantation (PSII) can dramatically enhance the pitting corrosion resistance of this alloy in marine environments (i.e., chlorine-ion-bearing aqueous solutions or humid atmospheres). Corrosion tests and microstructure analyses establish that the mechanism for successful passivation against chloride-induced pitting corrosion involves the formation of a multilayered microstructure, including the presence of a continuous layer of aluminum-nitride (AlN). Important process variables are the implantation voltage and the nitrogen dose (or total implantation time), as these two variables establish the implanted nitrogen concentration. Too high or too low an implanted nitrogen concentration will not yield the continuous AlN layer required for good corrosion resistance. PSII is attractive for this application as it provides for uniform, conformal implantation of irregularly shaped objects without masking, beam rastering, or object rotation.

Plasma-based ion implantation and deposition: a review of physics, technology, and applications

“…Much work focused on improvement of components made from stainless steel [86][87][88][89][90][91][92][93][94][95][96][97][98][99], tool steel [6,19,45,[100][101][102][103][104][105][106][107][108][109], tungsten carbide [110], nickel alloys [6,111], chromium [112], pure aluminum [113,114] and titanium and aluminum alloys [20,49,[115][116][117][118][119][120][121]. Möller and coworkers [122] describe PBII of nitrogen as "favorable boundary conditions for the efficiency of diffusive surface treatment."…”

An XPS study on the influence of nitrogen implantation on the passive layers developed on different tempers of AA7075 aluminum alloy

“…One way of improving the superficial properties of aluminium alloys is ionic implantation, and one of the more common implanted elements is nitrogen. The effect of N-implantation on wear resistance of pure aluminium and aluminium alloys has been already proved, [1,2] nevertheless, from the point of view of corrosion resistance, its performance is not clearly established (since it is highly dependent on the implantation conditions, type of selected alloy and test media [3,4] ). As corrosion properties are highly dependant on the passive layer formed on the alloys, it is necessary to understand the induced modification during the implantation process, in order to explain the corrosion behavior of the implanted alloys.…”

Influence of N+implantation on structure, morphology, and corrosion behavior of Al in NaCl solution

“…[17][18][19] Ion implantation modifies the sample surface and the interaction of the incident ions with sample atoms may lead to surface hardness and corrosion resistance of the sample surface. [20][21][22][23][24][25][26] In this process high temperatures are not required, while the bulk of the sample remains intact. Considering that in ion implantation one can control the ion fluence and the accelerating potential, hence conditions for tailoring the surface morphology are provided.…”