AUTHOR=Greenwood James A. TITLE=Metal Transfer and Wear JOURNAL=Frontiers in Mechanical Engineering VOLUME=6 YEAR=2020 URL=https://www.frontiersin.org/journals/mechanical-engineering/articles/10.3389/fmech.2020.00062 DOI=10.3389/fmech.2020.00062 ISSN=2297-3079