Tribology and wear resistance of the stainless steel. The sol-gel coating impact on the friction and damage

The sol-gel coating method is considered to be simple, easy to adopt, requires low processing temperature and leads to high degree of purity oxide coatings. Moreover, the fabrication of metal oxide thin films by sol-gel technic is cost effective, reproducible and applicable to large substrates without any shape restriction. This work focuses on optimizing conditions for depositing alumina coatings by sol-gel method on stainless steel substrates with a low annealing temperature, in order not to degrade the metal substrate. Moreover, to obtain coatings of several micron thick, the sol-gel was adapted by adding ceramic powder or by successive layers deposition which reduces the stresses occurring in the coatings during the heat treatment. The various as-obtained layers are characterized in terms of morphological features, microstructure, hardness and the tribological behavior and wear resistance. The results showed that the deposited alumina coating at low temperature crystallized in delta-Al2O3. Adding to that, the increase of the temperature favors the presence of alpha-Al2O3 structure. Moreover, the measurements demonstrate that the mechanical properties of sol-gel deposited alumina coatings in terms of hardness, wear resistance are improved in comparison with uncoated stainless steel or the classic nitrited steel. (C) 2016 Elsevier Ltd. All rights reserved.