Surface Modification Of 7075 Al Alloy Using Plasma Implantation And Deposition

The aluminum alloys have been utilized in manufacturing plastic mould. However, the applications of aluminum alloy molds are still limited due to their low hardness and poor wear resistance.This paper aims at fabricating excellent films onto the 7075 aluminum surface by nitrogen or carbon plasma based ion implantation to improve the wear and corrosion resistance, microhardness and so on. In this paper, the wear properties of the films was evaluated through the pin-on-disk test. The electrochemical test was used to analyze the corrosion behaviour. Grazing X-ray diffraction and X-ray photoelectron spectroscopy (XPS) were utilized to detect the surface structure and chemical composition of modified layers.The annealing temperature has a critical influence on surface hardness of 7075 aluminum alloys. The annealing treatment may decrease the surface hardness. When the temperature is lower than 120℃, the temperature effect is not evident. While the temperature reaches 300℃, the microhardness reduces to 64.2HV (before annealing, the microhardness of substrate is 180HV).Plasma ion implantation may induce the temperature elevation of treated samples due to self heating effect of ion implantation. With increasing the implantion time or pulsing frequency, the treatment temperature also increases. Thereby, the softening effect may be resulted in, as well. So it is difficult to improve the hardness of 7075 aluminum alloy by single PBII implantation. The microhardness, corrosion and tribological resistance of modified film can be improve by the nitrogen or carbon plasma implantation if the implanted temperature can be controlled.To achieve better surface properties, titanium was also deposited onto aluminum surface using the magnetron sputtering method before nitrogen or carbon plasma ion implantation. The results show that the hybrid treatment can enhance the properties of aluminum alloy remarkably. Hybrid treament combining nityrogen plasma implantation and titanium deposition can increase the microhardness to 281.4HV. Maenwhile, using carbo plasma implantation and titanium deposition, the hybrid processes may increase the...