Development of Innovative Nanoparticle-based Protective Coatings for the Production of High-Strength Steel Compounds by Press- hardening

摘要

The use of high-strength steels (HSS) in the automotive industry has been increased in the past decade due to the high demand to reduce CO_2 emissions and fuel consumption. In order to increase the safety of passengers more HSS parts are installed in the automotive today. The main challenge in this process is the formation of an oxide layer which affects the processing for further applications. The aim of this work is to produce purely inorganic protective coatings on steel surfaces by the sol-gel method and investigate their ability to enhance the oxidation resistance during the press-hardening process. Several binary and ternary systems containing alkali oxides were produced. Among them, ternary systems containing Si/AI/Li and Si/AI/K oxides showed the best protective properties. The forming of the different phases was determined by XRD measurements It was shown that mixed oxide layers containing lithium show a crystalline structure at higher temperatures whereas a sol containing potassium has an amorphous nature. Several other methods such as SEM, DTA and IR spectroscopy were used to characterize the film.