Cho In-Shik, Lee Chang-Soon, Amanov Auezhan, Pyoun Young-Shik, Park In-Gyu
Department of Hybrid Engineering, Sun Moon University, Asan 336-708, Korea.
J Nanosci Nanotechnol. 2011 Jan;11(1):742-6. doi: 10.1166/jnn.2011.3219.
The fact that one of fundamental characteristics of fretting is the very small sliding amplitude dictates the unique feature of wear mechanism. Ultrasonic Nanocrystalline Surface Modification (UNSM) technology was applied in order to investigate its effect on the high-frequency fretting wear behavior of AISI304 steel. Its influence on the fretting wear is also reported in this paper with these treated and untreated samples. UNSM delivers force onto the workpiece surface 20,000 times per second with 1,000 to 4,000 contact counts per square millimeter. UNSM creates homogenous nanocrystalline structures as well on the surface. UNSM process is expected to eliminate or significantly retard the formation of fretting wear. Nanocrystalline structure generation after UNSM has been reported to produce its unique structure and to offer a variety of beneficial properties compared to conventionally treated materials. A deformed layer of 220 microm exhibits high dislocation density, where top layer transformed to a nanostructure of the grain size in 23 nm and mechanical twins were observed. Deformation-induced martensite was observed to form at the intersections of mechanical twins, whose volume fraction has increased up to 38.4% and wear loss rate at 800,000 cycles has decreased by 40%. In this paper, experimental results are discussed to elucidate potential mechanism of high-frequency fretting wear.
微动磨损的一个基本特征是滑动幅度非常小，这决定了磨损机制的独特性。为了研究超声纳米晶表面改性（UNSM）技术对AISI304钢高频微动磨损行为的影响，采用了该技术。本文还报道了该技术对这些经过处理和未处理样品的微动磨损的影响。UNSM每秒向工件表面施加20000次力，每平方毫米有1000至4000次接触次数。UNSM还能在表面形成均匀的纳米晶结构。预计UNSM工艺可消除或显著延缓微动磨损的形成。据报道，UNSM处理后产生的纳米晶结构具有独特的结构，与传统处理材料相比具有多种有益特性。观察到一个220微米的变形层具有高位错密度，其中顶层转变为晶粒尺寸为23纳米的纳米结构，并观察到机械孪晶。在机械孪晶的交叉处观察到变形诱发马氏体，其体积分数增加到38.4%，在800000次循环时的磨损率降低了40%。本文讨论了实验结果，以阐明高频微动磨损的潜在机制。
