Fretting fatigue wear behavior of Y-TZP dental ceramics processed by non-conventional microwave sintering

This is the peer reviewed version of the following article: PRESENDA-BARRERA, ALVARO, Salvador Moya, Mª Dolores, Vleugels, Jozef , Moreno, Rodrigo, Borrell Tomás, María Amparo. (2017). Fretting fatigue wear behavior of Y-TZP dental ceramics processed by non-conventional microwave sintering.Journal of the American Ceramic Society, 100, 5, 1842-1852. DOI: 10.1111/jace.14769, which has been published in final form at http://doi.org/10.1111/jace.14769. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving[EN] The fretting wear behavior of self-mated Y-TZP dental materials obtained by non-conventional microwave and conventional sintering has been investigated. Two 3Y-TZP materials, a widely utilized commercial dental ceramic (LAVA) and a lab-prepared 3Y-TZP powder based equivalent have been assessed. Relative density and mechanical properties as well as the grain size variations upon sintering have been evaluated. After exposure to selected gross slip regime fretting wear conditions, the wear tracks have been characterized allowing the measurement of the coefficient of friction, track profiles, and pit features. The results indicate thaT microwave sintering results in a similar fretting wear behavior as observed for conventional sintered 3YTZP, since the measured volumetric wear loss is of a comparable order of magnitude. Regarding the influence of the grain size, the analysis revealed that a large grain size (>300 nm) results in an increased wear volume and that a higher resistance to fretting wear is constrained to a midrange particle size. Since the fracture toughness of all investigated ceramic grades was comparable, the influence of the fracture toughness could not be assessed. Abrasive grooving, delamination and microcracking have been identified as major wear mechanisms inside the wear tracks for both conventional and microwave sintered 3Y-TZP. In general, microwave sintering can provide 3Y-TZP dental materials with a comparable fretting wear resistance as that observed for conventional sintering using lower dwell sintering temperatures and a shorter processing time.Spanish Ministry of Economy and Competitiveness MINECO, Grant/Award Number: MAT2015-67586-C3-R; Generalitat Valenciana, Grant/Award Number: GRI-SOLIA/2013/035, GV/2014/009; MINECO, Grant/Award Number: IJCI-2014-19839.Presenda-Barrera, A.; Salvador Moya, MD.; Vleugels, J.; Moreno, R.; Borrell Tomás, MA. (2017). Fretting fatigue wear behavior of Y-TZP dental ceramics processed by non-conventional microwave sintering. Journal of the American Ceramic Society. 100(5):1842-1852. https://doi.org/10.1111/jace.14769S18421852100

DEVELOPPEMENT D'UN FOUR MICRO-ONDES MONOMODE ET FRITTAGE DE POUDRES CERAMIQUE ET METALLIQUE

A single-mode microwave cavity was developed to study the sintering of ceramic and metallic powders. In this TE10p cavity, the electromagnetic pattern is controlled and the materials can be heated up under either predominant electric or magnetic field. Samples can be microwave-sintered directly or with a cylindrical SiC susceptor. The temperature was measured by an infrared camera. A new microwave heating procedure was proposed to control a thermal cycle. Comparatives studies between microwave and conventional sintering processes were achieved on ceramic and metallic powders. Microwave sintering of yttria-doped zirconia at 25°C/min heating rate led to a shift of the densification curve, an enhancement of the kinetics of densification during the initial and intermediate stages and a restricted grain growth. A submicronic nickel powder can be only sintered by plasma-induced heating under predominant electric field.Un four micro-ondes à cavité monomode a été développé afin d'étudier le frittage de poudres céramiques et métalliques. Dans cette cavité TE10p, la distribution du champ électromagnétique est maîtrisée et les matériaux peuvent être chauffés en champ soit électrique soit magnétique prépondérant. Le chauffage micro-onde peut être direct ou hybride (avec suscepteur). La température est mesurée par une caméra infrarouge. Un pilotage en température original a été mis au point. Des études comparatives entre les frittages micro-ondes et conventionnel ont porté sur une poudre céramique et une poudre métallique. Pour la zircone yttriée avec une vitesse de chauffage de 25°C/min, le chauffage micro-ondes décale d'une centaine de degrés les courbes de densification, accélère les cinétiques pendant les premiers stades et permet de limiter la croissance granulaire. Pour une poudre de nickel submicronique un frittage n'a été observé qu'en champ électrique dominant et en présence d'un plasma

DEVELOPPEMENT D'UN FOUR MICRO-ONDES MONOMODE ET FRITTAGE DE POUDRES CERAMIQUE ET METALLIQUE

A single-mode microwave cavity was developed to study the sintering of ceramic and metallic powders. In this TE10p cavity, the electromagnetic pattern is controlled and the materials can be heated up under either predominant electric or magnetic field. Samples can be microwave-sintered directly or with a cylindrical SiC susceptor. The temperature was measured by an infrared camera. A new microwave heating procedure was proposed to control a thermal cycle. Comparatives studies between microwave and conventional sintering processes were achieved on ceramic and metallic powders. Microwave sintering of yttria-doped zirconia at 25°C/min heating rate led to a shift of the densification curve, an enhancement of the kinetics of densification during the initial and intermediate stages and a restricted grain growth. A submicronic nickel powder can be only sintered by plasma-induced heating under predominant electric field.Un four micro-ondes à cavité monomode a été développé afin d'étudier le frittage de poudres céramiques et métalliques. Dans cette cavité TE10p, la distribution du champ électromagnétique est maîtrisée et les matériaux peuvent être chauffés en champ soit électrique soit magnétique prépondérant. Le chauffage micro-onde peut être direct ou hybride (avec suscepteur). La température est mesurée par une caméra infrarouge. Un pilotage en température original a été mis au point. Des études comparatives entre les frittages micro-ondes et conventionnel ont porté sur une poudre céramique et une poudre métallique. Pour la zircone yttriée avec une vitesse de chauffage de 25°C/min, le chauffage micro-ondes décale d'une centaine de degrés les courbes de densification, accélère les cinétiques pendant les premiers stades et permet de limiter la croissance granulaire. Pour une poudre de nickel submicronique un frittage n'a été observé qu'en champ électrique dominant et en présence d'un plasma

Densification and microstructure evolution of Y-Tetragonal Zirconia Polycrystal powder during direct and hybrid microwave sintering in a single-mode cavity

International audienceThe densification and microstructure changes of 2 mol% yttria-stabilized zirconia nanopowder have been investigated during direct and hybrid microwave sintering. Microwave heating tests were achieved in a resonant single-mode cavity at 2.45 GHz and a cylindrical SiC susceptor was used for hybrid sintering experiments. Constant heating rate runs (25 degrees C/min) were controlled by adjusting the position of a sliding piston at constant forward microwave power. The temperature on the upper surface of the specimen was measured with an infrared camera. The final densities and the microstructures observed by SEM were compared to those of conventionally sintered materials. Homogeneous microstructures have been obtained by hybrid heating whereas direct microwave heating led to rather heterogeneous microstructures due to thermal gradients. Nevertheless, microwave-sintered materials always exhibited higher final densities for a given sintering temperature. This significant enhancement of the densification process was particularly observed in the intermediate sintering stage (1200-1350 degrees C range). Besides, grain growth was found to be mainly influenced by the sintering temperature rather than by the heating mode

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A 2D Multiphase Model of Drop Behavior during Electroslag Remelting

Electroslag remelting is a process extensively used to produce metallic ingots with high quality standards. During the remelting operation, liquid metal droplets fall from the electrode through the liquid slag before entering the liquid pool of the secondary ingot. To better understand the process and help to optimize the operating condition choice, a 2D axisymmetric multiphase model of the slag domain has been developed using a two fluid Eulerian approach. During their fall, droplets hydrodynamic interactions are calculated thanks to an appropriate drag law. Influence of droplets on the electromagnetic field and on the slag hydrodynamics is discussed, as well as their heat exchange with the slag. Even with a small volume fraction, the droplets influence is noticeable. The present investigation shows that small droplets have a large influence on the slag hydrodynamics, due to a great momentum exchange. However heat transfer is more influenced by large drops, which are found to be relatively far from the thermal equilibrium with the slag phase

Inherent heating instability of direct microwave sintering process: Sample analysis for porous 3Y-ZrO2

International audienceDirect microwave heating of 3Y-ZrO 2 is studied at frequency of 2.45 GHz. Different conditions of input power, sample position and size are tested. For the first time, the experimentally known instability of microwave sintering is explained coupling the effective medium approximation and finite-element method. We show how the material dielectric permittivity imaginary part which increases with temperature and relative density encourages high hot spot phenomena. It is shown that the sample location has a great impact on th