Microstructure and indentation mechanical properties of YSZ nanostructured coatings obtained by suspension plasma spraying

[EN] A commercial nanosuspension of yttria-stabilised zirconia (YSZ) was successfully deposited on austenitic stainless steel substrate by suspension plasma spraying technique (SPS). A SG-100 torch with internal radial injection was used for the spraying. The pneumatic system transported the feed suspension from the containers to the plasma torch. In order to study the effect of the spraying parameters, a factorial model was used to design the experiments, changing both spraying translation speed and suspension flow rate. The coating microstructure was characterised by FEG-SEM. All coatings displayed a two-zone microstructure formed by nanometre-sized particles surrounded by fully molten areas. Moreover, crystalline phases were determined by XRD and Raman spectroscopy. Mechanical properties were also determined using nanoindentation technique. Nanoindentation tests showed a bimodal distribution of the mechanical properties (hardness and Young's modulus) which is related to the two zones (molten and partially molten) present in the coatings. (C) 2012 Elsevier B.V. All rights reserved.This work has been supported by the Spanish Ministry of Science and Innovation (project MAT2009-14144-C03) and the Research Promotion Plan of the Universitat Jaume I, action 2.1 (ref. E-2011-05) and action 3.1 (ref. PREDOC/2009/10). The authors are grateful to Leszek Łatka for his help in plasma spray experiments.Carpio, P.; Rayón Encinas, E.; Pawlowski, L.; Cattini, A.; Benavente Martínez, R.; Bannier, E.; Salvador Moya, MD.... (2013). Microstructure and indentation mechanical properties of YSZ nanostructured coatings obtained by suspension plasma spraying. Surface and Coatings Technology. 220:237-243. https://doi.org/10.1016/j.surfcoat.2012.09.047S23724322

Modeling of elastic modulus and hardness determination by indentation of porous yttria stabilized zirconia coatings

International audienc

Characterization of microstructure and thermal properties of YCSZ coatings obtained by suspension plasma spraying

International audienc

Artificial neural network model of hardness, porosity and cavitation erosion wear of APS deposited Al2O3 -13 wt% TiO2 coatings

The aim of the article is to build-up a simplified model of the effect of atmospheric plasma spraying process parameters on the deposits’ functional properties. The artificial neural networks were employed to elaborate on the model and the Matlab software was used. The model is crucial to study the relationship between process parameters, such as stand-off distance and torch velocity, and the properties of Al2O3-13 wt% TiO2 ceramic coatings. During this study, the coatings morphology, as well as its properties such as Vickers microhardness, porosity, and cavitation erosion resistance were taken into consideration. The cavitation erosion tests were conducted according to the ASTM G32 standard. Moreover, the cavitation erosion wear mechanism was presented. The proposed neural model is essential for establishing the optimisation procedure for the selection of the spray process parameters to obtain the Al2O3-13 wt% TiO2 ceramic coatings with specified functional propertie

Bilayer Suspension Plasma-Sprayed Thermal Barrier Coatings with Enhanced Thermal Cyclic Lifetime : Experiments and Modeling

Suspension plasma spraying (SPS) has been shown as a promising process to produce porous columnar strain tolerant coatings for thermal barrier coatings (TBCs) in gas turbine engines. However, the highly porous structure is vulnerable to crack propagation, especially near the topcoat-bondcoat interface where high stresses are generated due to thermal cycling. A topcoat layer with high toughness near the topcoat-bondcoat interface could be beneficial to enhance thermal cyclic lifetime of SPS TBCs. In this work, a bilayer coating system consisting of first a dense layer near the topcoat-bondcoat interface followed by a porous columnar layer was fabricated by SPS using Yttria-stabilised zirconia suspension. The objective of this work was to investigate if the bilayer topcoat architecture could enhance the thermal cyclic lifetime of SPS TBCs through experiments and to understand the effect of the column gaps/vertical cracks and the dense layer on the generated stresses in the TBC during thermal cyclic loading through finite element modeling. The experimental results show that the bilayer TBC had significantly higher lifetime than the single-layer TBC. The modeling results show that the dense layer and vertical cracks are beneficial as they reduce the thermally induced stresses which thus increase the lifetime