Stainless steel surface alloying process with molybdenum or ruthenium by high-energy excimer laser: structural electrochemical and corrosion properties

摘要

Abstract: Chemical transformations on stainless steel surfaces (304 AISI) are obtained by melting with an excimer laser. The very high quenching rate allows to create a thin continuous metastable gradient in composition and structure by opposition to other melting techniques which promote multiphase layer. The mechanical properties of the bulk are maintained and the external layer is chemically modified for a better resistance to environmental aggressivity. Molybdenum is used for corrosion protection and ruthenium for cathodic and anodic properties. The composition is analyzed on cross-sections obtained by ultramicrotomy. A continuous gradient approximately 500 nm (nanometer) of Mo or Ru with decreasing grain size ($LS 0,3 micrometer compared to 10 - 20 micrometers for 304 AISI) is observed. Mo and Ru surface alloys show an important beneficial effect from cathodic and transpassive potential range.!7