The structure and tribological properties of gradient layers prepared by plasma-based ion implantation on 2024 Al alloy

• Published in: Journal of physics. D, Applied physics Vol. 37; no. 3; pp. 392 - 399
• Main Authors: Liao, J X, Xia, L F, Sun, M R, Liu, W M, Xu, T, Xue, Q J
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 07.02.2004; Institute of Physics
• Subjects: Applied sciences; Contact of materials. Friction. Wear; Exact sciences and technology; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Nonmetallic coatings; Production techniques; Surface treatment; Atomic force microscopy; Interlayers; Ion implantation; Aluminium base alloys; Phase composition; Wear test; Titanium nitride; Diamond-like carbon; Hardness; Experimental study; Non metal coating; Inorganic compound; Knoop hardness; Transmission electron microscopy; Transition metal compounds; Depth profile; Microstructure; Raman spectrum; Concentration distribution; X-ray photoelectron spectra
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/37/3/014

Using plasma-based ion implantation, two types of gradient layers have been prepared on 2024 Al alloy. One is prepared by N-implantation then C-deposition, the other adds an interlayer composed of a Ti layer and a Ti-N layer between N-implantation and C-deposition. C-deposition is carried out at various implanting voltages or C sub(2)H sub(2)/H sub(2) ratios. The composition depth profiles of these layers were characterized by x-ray photoelectron spectroscopy. The structure, morphologies and microstructure of the C layers were studied using Raman spectroscopy, atomic force microscope and transmission electron microscope, respectively. The surface hardness was measured with a Knoop tester and a mechanical property microprobe. The dry ball-on-disc wear tests were performed in ambient air. The gradient layer without interlayer is composed of an N-implanted layer rich in AlN and a diamond-like carbon (DLC) layer (film), and the two layers are connected with a C-Al transition layer containing Al sub(4)C sub(3). The Ti layer rich in alpha -Ti and the N-implanted layer are connected by a Ti-Al transition layer containing TiAl sub(3), while the Ti-N layer rich in TiN and the DLC film are connected by a C-Ti transition layer containing TiC, TiCN, etc. Thus, the gradient layer with interlayers has optimized the gradient structure. DLC films are compact and amorphous, contain high sp super(3)/sp super(2) ratios and depend on the implanting voltage and the C sub(2)H sub(2)/H sub(2) ratio. Similarly, these gradient layers exhibit significant improvement in morphologies, surface hardness and tribological properties; the interlayer, the implanting voltage and the C sub(2)H sub(2)/H sub(2) ratio all have prominent effects on these properties.