主题:   Tuning tribological and mechanical properties of surfaces by gradient and graded fabrication主讲人:   Shivaprakash Ramakrishna地点:   松江校区逸夫科技创新楼 307 室时间:   2018-01-22 13:00:00组织单位:   化学化工与生物工程学院

报告人简介：

Dr. Ramakrishna is a senior scientist at the Laboratory for Surface Science and Technology in the Department of Materials, ETH Zurich. He has received his Bachelor’s and Master’s degrees from Kuvempu University, Karnataka, India. He completed his PhD in 2013 in the Department of Materials, ETH Zurich. During his PhD, he carried out research on adhesion and tribology on nanoscale rough surfaces. He worked as a postdoctoral researcher at the Laboratory for Surface Science and Technology from 2013 until June 2015, where he investigated the frictional and mechanical properties of stratified layers of polymer brush-gel structures using the colloidal-probe AFM technique.

报告内容简介：

The consequences of nanoscale adhesion and friction can differ from what is observed at the macroscale. This is due to an increase in the surface-to-volume ratio, which can lead to undesirable effects, such as static friction of mechanical parts within microdevices—for example in microelectromechanical/nanoelectromechanical systems (MEMS/NEMS) and micro/nano robotic devices. As the size of mechanical components continues to decrease, the accurate determination of adhesion, friction and mechanical properties at the nanoscale is becoming crucial for the designing of materials, and to ultimately determine their performance. Also, the precise tuning of roughness, chemical composition and stiffness on surfaces becomes a potential tool for tailoring adhesive and frictional properties.  

In this talk, he will describe the methods used to fabricate surfaces with variable roughness and chemistry, in a gradient and a graded fashion, by depositing nanoparticles (NPs) and functionalizing the surface by grafted polymer films. Adhesion, friction and mechanical properties are characterized by colloidal-probe atomic force microscopy (CP-AFM). The continuum contact-mechanics models applied to estimate the real area of contact are discussed, and finally a direct correlation between roughness, chemistry, adhesion and friction at the nanometer scale is provided.

报告语言：英语