Nano-Voids Formation And Hydrogen Configuration In Low Frictional Cr-Mo Layers Electrodeposited With Organic Sulfonic Acid Catalyst

Chromium molybdenum (Cr-Mo) layers electrodeposited with organic sulphonic acid as catalyst have lower friction coefficient. The purpose of this report is to understand the low friction mechanism focusing on both nano structures and hydrogen configuration in electrodeposited layer. The Cr-Mo plated layers were characterized by XRD, TEM, PALS and ERDA. The TEM observations revealed that nano voids were dispersed in crystal grains of chromium and the size of nano voids was in the same order with that predicted by PALS. The study on interaction between void and hydrogen by first principles showed that voids containing hydrogen shorten positron lifetime. These results suggest that hydrogen does not exist in nano voids. However existence of hydrogen was confirmed in electrodeposited layer by analysis of ERDA. This should probably show the state of hydrogen atoms trapped by vacancies existing stably in electrodeposited layer. During electrodeposition, two hydrogen atoms trapped by mono vacancy diffuse in crystal grain and gather together to form clusters on (110) plane in Cr-Mo layers, which have the ability to weaken interaction force between (110) planes. As a result, sliding along (110) planes was considered to take place easily, lowering the friction coefficient of Cr-Mo layers.