Research Of The Plasma Ion Immersion Implantation And Deposition On 7A04 Aluminium Alloy

Aluminum-based alloys are widely used in the automotive and aerospace industries due to their high strength-to-weight ratio, low density, and good formability. But sometime the relative poor wear resistance, lower hardness and poor pitting corrosion resistance restricts their application. In this study,7A04 aluminium alloy was treated by nitrogen plasma immersion ion implantation (PIII), and DLC were deposited on 7A04 aluminium alloy by plasma immersion ion implantation and deposition (PIII&D). PHI nitriding technology at different N2 partial pressure has been applied to improve 7A04 aluminium alloy properties. The effect of different gas pressure and different interlayers on the structures and properties of DLC films has been investigated.The microstructure and composition were characterized with X-ray photoelectron spectroscopy (XPS). Raman spectroscopy was ultilized to characterize the structure of the DLC film. The adhesion strength were examined by nano-scratch test. Ball-on-disc wear test was performed to evaluate the tribological properties of the the two different modificated layers, and the micro-hardness was measured by HXD-1000TM. The corrosion resistance was measured in a 0.9% NaCl solution at room temperature.The results indicate that the nitriding layer with good wear resistance and pitting corrosion resistance was synthesized on 7A04 aluminium alloy using plasma immersion ion implantation and nitriding technology. The gas pressure influenced the properties of the nitriding layer, when the value of the gas pressure was 0.2Pa, the nitriding layer has the best performance, But the hardness of the aluminum alloy decreased for the high temperature during the process of implantation. The microhardness and wear resistance were evidently improved by nitrogen plasma immersion ion implantation and the artificial aging duplex treatment.DLC films have been deposited on 7A04 aluminium alloy substrates by high voltage and low frequency plasma immersion ion implantation and deposition technology. The film-cohesion and wear resistance became poor with the increasing of the gas pressure, but the micro-hardness and corrosion enhanced due to the thickness raised. Compare the DLC films on bare 7A04 aluminium alloy, the samples with interlayers the microhardness, wear resistance and adhesion force were evidently improved, the ones with Si interlayer have the best adhesion force, and the ones with TiN interlayer have the highest hardness. The DLC films fabricated using low voltage and high frequency plasma immersion ion implantation and deposition technology, the adhesion force decrease, but the micro-hardness and wear resistance increase with the C2H2 fraction in the C2H2-Ar gas mixture. The adhesion force and wear resistance increase with the bias voltage.