The generating of a functional film by multiply nitriding of aluminum using the In situ reduction reaction.

人们对铝（Al）作为汽车或机器零件等闪电材料很感兴趣。然而，由于Al的硬度和耐磨性分别不如钢，因此不适用于滑动部件。在之前的研究中，使用低于铝熔点的商业纯铝（JIS-A1050）在氮气气氛中形成氮化铝（AlN）层，在桶中松散填充平均直径0.1 mm的氧化铝粉末和平均直径0.2 mm的铝镁合金粉末，以化学和/或物理激活Al衬底表面。本研究通过离子渗氮和桶形渗氮，研究了桶形渗氮中AlN层的形成机理，并对改性层的硬度进行了控制。在铝氮化之前，存在潜伏期。在这段时间内，光学显微镜观察到在靠近表面的横截面上出现了白色区域，电子探针分析仪（EPMA）也观察到镁（Mg）的存在。Mg似乎是从填充的Al-Mg合金粉末中渗透扩散出来的。经过这一步，AlN部分在Al衬底表面生成，并与衬底表面均匀生长。氮化层厚度随渗氮时间的延长而增大。在筒状渗氮后，对部分试样进行离子渗氮联合处理。在复合渗氮工艺中，改性层的厚度小于单筒渗氮。通过选择桶状渗氮周期与离子渗氮周期的比值，可以控制改性层的硬度。采用φ0.8 mm氧化锆（ZrO_2）丝作为标记物，鉴别氮化层中扩散物的种类。用手压机将金属丝压入铝基板表面。氮化后有三种可能的导线位置。首先，(a)如果氮扩散到氮化层，则标记线将停留在氮化表面；第二，(b)如果Al扩散到氮化层，则标记线将在氮化层和衬底之间徘徊；第三，(c)氮和Al都扩散，则标记线将驻留在氮化层中。通过基板渗氮前后的截面光学显微照片，标记停留在氮化层表面，可见氮层是通过氮向氮化层扩散而生长的。少

An Aluminum (Al) has been interested as a material for lightning such as automotive or machine parts. However, it is not applicable in sliding parts since the hardness and wear resistance of Al are respectively inferior to steel. In previous study, an aluminum nitride (AlN) layer was formed in nitrogen atmosphere using the commercial glade pure Al (JIS-A1050) below the melting point of Al in barrel which was loosely filled with average diameter 0.1 mm alumina powder and average diameter 0.2 mm aluminum-magnesium alloy powder for activating the Al substrate surface chemically and/or physically. In this study, the mechanism of formation of AlN layer in barrel was examined and the hardness of modified layer was controlled using ion nitriding with barrel nitriding.Before the Al is nitrided, the incubation period exists. In this period, at the cross section near the surface the white region is observed by the optical micro scope and also the existence of magnesium (Mg) is observed by Electr … More on Probe Micro Analyzer (EPMA). It seems that Mg is infiltrated and diffused from the filled Al-Mg alloy powder in barrel. After this step, the AlN is partially generated at the surface of Al substrate, it grows even with substrate surface. The AlN layer thickness increases proportionally to the root of nitriding time in barrel. After the barrel nitriding, the ion nitriding was combined for some specimens. In the combined processes, the thickness of the modified layer is less than that obtained by barrel nitriding alone. By choosing the ratio of the barrel nitriding period and the ion nitriding period, the hardness of the modified layer can be controlled in respect.In order to identify the diffusion species in the nitride layer, φ0.8 mm zirconia (ZrO_2) wire was used as a marker. The wire was squeezed into the surface of Al substrate with a hand press. There are three possible wire positions after nitriding. First, (a) if the nitrogen diffuses to the nitride layer, the marker wire will stay on nitride surface, second, (b) if the Al diffuses to the nitride layer, it will wander between the nitride layer and the substrate, third, (c) both nitrogen and Al diffuse then the marker will reside in the nitride layer. By the cross sectional optical micrographs of the substrate before and after nitriding, the marker is stay on the surface of nitride layer, therefore we can see that the nitride layer grows by nitrogen diffusion into the nitride layer. Less