Applying Plasma Immersion Ion Implantation technique to improve the surface properties of AA7005 Aluminum Alloy

• Main Authors: TIAN-YOU LIAO, 廖天佑
• Other Authors: Ye-Ee Wu
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/xefutd

碩士 === 國立臺灣科技大學 === 機械工程系 === 99 === The objective is to improve the surface property of the Al-Zn-Mg alloys by applying Nitrogen Plasma Immersion Ion Implantation (N-PIII) technique to modify the surface properties of the aluminum alloy. AA7005 aluminum alloy is used as the substrate material in this study. Effects of bias voltage of N-PIII process on the thickness, growth rate and microstructure of the modified layer was studied. The influences of pre-treatment and initial condition of substrate as well as the post-process heat-treatment on the microstructure and the surface characteristics of the modified layer were investigated and analyzed. At the first step, effects of bias voltage, 20 kV, 30kV and 40kV, on the thickness, growth rate and micro-structure of the modified layer were studied. Nano-indentation test and Glow Discharge Spectrometer (GDOS) test were conducted on the treated specimens to obtain the depth evolution profiles of the hardness and the depth profiles of nitrogen ions from the surface of specimen, respectively. Atomic Force Microscopy (AFM) were applied to measure the surface roughness of the treated specimens. The friction coefficient of the modified layer were measured by ball-on-disc method. The second step efforts were focused on studying the growth rate and the micro- structure of the modified layer, as well as the effects of post-process heat treatment on the surface properties of the modified layer. The depth profiles of Al and N were measured by Secondary Ion Mass Spectrometer (SIMS) to calibrate the GDOS results. Specimens being N-PIII treated were subjected to various heat treatments. Then, nano-indentation test, GDOS test, ball-on-disc test, and AFM were conducted on these heat-treated specimens to examine the effects of post-process heat treatment on the surface properties of the modified layer. Experimental results showed that the depth of nitrogen ion is related with the bias voltage. Until the level depth, the nitrogen ion can’t move into the deeply side of specimen. Specimen’s surface hardness was going up when we promote the ions dosage, and the hardness would increase double after the process of N-PIII. After the heat-treatment of T6, internal nitrogen ion in the specimen would diffuse to the external, and the wide of modified layer would be reduced. This phenomenon can promote the probability to form the aluminum nitride, and to get better surface property.