Experimental Observation of Silver and Gold Penetration into Dental Ceramic by Means of a Radiotracer Technique

1987 ◽  
Vol 66 (12) ◽  
pp. 1717-1720 ◽  
Author(s):  
F. Moya ◽  
J. Payan ◽  
J. Bernardini ◽  
E.G. Moya
Keyword(s):  
Solid State ◽  
Penetration Depth ◽  
Diffusion Rate ◽  
Diffusion Mechanism ◽  
Solid State Diffusion ◽  
Ceramic Surface ◽  
Experimental Conditions ◽  
Radiotracer Technique ◽  
State Diffusion ◽  
Gold Diffusion

A radiotracer technique was used to study silver and gold diffusion into dental porcelain under experimental conditions close to the real conditions in prosthetic laboratories for porcelain bakes. It was clearly shown that these non-oxidizable elements were able to diffuse into the ceramic as well as oxidizable ones. The penetration depth varied widely according to the element. The ratio DAg/DA u was about 103 around 850°C. In contrast to gold, the silver diffusion rate was high enough to allow silver, from the metallic alloy, to be present at the external ceramic surface after diffusion into the ceramic. Hence, the greening of dental porcelains baked on silver-rich alloys could be explained mainly by a solid-state diffusion mechanism.

Metallurgists’ Insights on Diffusion-Assisted Dissimilar-Joints of Light- and Heavy-Alloys

2017 ◽  
Vol 380 ◽  
pp. 12-28 ◽  
Author(s):  
Gopinath Thirunavukarasu ◽  
Sukumar Kundu ◽  
Subrata Chatterjee
Keyword(s):  
Solid State ◽  
Integrated Circuits ◽  
Inner Core ◽  
Diffusion Mechanism ◽  
Bonding Temperature ◽  
High Vacuum ◽  
Solid State Diffusion ◽  
Dissimilar Metals ◽  
Dissimilar Joints ◽  
State Diffusion

In metallurgy and materials engineering, a number of phase transformation in solids like precipitation, oxidation, creep, annealing, homogenization, etc. are brought about by the process of diffusion. Many industrial manufacturing processes utilize solid-state diffusion principle, to name a few: 1. Rotating or sliding parts of steel have a hard outside case for wear resistance and a tough inner core for fracture resistance by gas carburizing procedure; 2. Integrated circuits were produced by diffusing impurity into silicon wafers; and 3. Joints between similar and dissimilar metals, alloys, and non-metals, were made using diffusion bonding (DB) technique. Day by day, the science of solid-state diffusion phenomenon is spreading inevitably into new areas of engineering and technology. Diffusion-Assisted-Joints (DAJs) meet the requirements for most critical structures in terms of strength, toughness, tightness, and resistance to heat and corrosion. DAJs can be made out of 730 pairs of dissimilar metals. Hence, DB is considered as an engineering marvel among all the physical welding metallurgists. Herein, experiments were performed to exactly map the quantum influence of the bonding temperature variation on the dissimilar joints of a popular light alloy, Ti-6Al-4V (TiA), and a heavily used heavy alloy, stainless steel (SS), using diffusion mechanism in high-vacuum environment. Cu foil (~200μm) was used as an interlayer. Necessary characterization tools for metallurgical investigations were used to understand the extent of diffusion along the TiA/Cu and Cu/SS interfaces, room-temperature mechanical properties, fracture morphologies, and fracture path of the TiA/Cu/SS DAJs. This paper discussed rational reasons backing the results of the characterizations.

Revisiting Electrochemical Techniques to Characterize the Solid-State Diffusion Mechanism in Lithium-Ion Batteries

2018 ◽  
Vol 17 (6) ◽  
Author(s):  
I. O. Santos-Mendoza ◽  
J. Vázquez-Arenas ◽  
I. González ◽  
G. Ramos-Sánchez ◽  
C. O. Castillo-Araiza
Keyword(s):  
Diffusion Coefficient ◽  
Solid State ◽  
Ab Initio ◽  
Lithium Ion Batteries ◽  
Transport Mechanism ◽  
Diffusion Mechanism ◽  
Electrochemical Techniques ◽  
Lithium Ion ◽  
Solid State Diffusion ◽  
State Diffusion

AbstractLithium-ion batteries (LiBs) have gained a worldwide position as energy storage devices due to their high energy density, power density and cycle life. Nevertheless, these performance parameters are yet insufficient for current and future demands diversifying their range of applications, and competitiveness against other power sources. In line with the materials science, the optimization of LiBs, first, requires an in-depth characterization and understanding of their determining steps regarding transport phenomena and electrode kinetics occurring within these devices. Experimental and theoretical studies have identified the solid-state diffusion of Li+into the composite cathode material as one of the transport mechanisms limiting the performance of LiBs, in particular at high charge and discharge rates (C-rates). Nowadays, there is however ambivalence to characterize this mass transport mechanism using the diffusion coefficient calculated either by electrochemical techniques orab initioquantum chemistry methods.  This contribution revisits conventional electrochemical methodologies employed in literature to estimate mass transport diffusivity of LiBs, in particular using LiFePO4in the cathode, and their suitability and reliability are comprehensively discussed. These experimental and theoretical methods include Galvanostatic and Potentiostatic Intermittent Titration Technique (GITT and PITT), Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV) andab initioquantum chemistry methods. On the one hand, experimental methods seem not to isolate the diffusion mechanism in the solid phase; thus, obtaining an unreliable apparent diffusion coefficient (ranging from 10–10to 10–16 cm2 s−1), which only serves as a criterion to discard among a set of LiBs. On the other hand, atomistic approaches based onab initio, density functional theory (DFT), cannot yet capture the complexity of the local environments involved at this scale; in consequence, these approaches have predicted inadequate diffusion coefficients for LiFePO4(ranging from 10–6to 10–7 cm2 s−1) which strongly differ from experimental values. This contribution, at long last, remarks the factors influencing diffusion mechanisms and addresses the uncertainties to characterize this transport mechanism in the cathode, stressing the needs to establish methods to determine the diffusion coefficient accurately, coupling electrochemical techniques,ab initiomethods, and engineering approaches based on modeling.

Joining of Ti3SiC2 with Ti–6Al–4V Alloy

2002 ◽  
Vol 17 (1) ◽  
pp. 52-59 ◽  
Author(s):  
N.F. Gao ◽  
Y. Miyamoto
Keyword(s):  
Solid State ◽  
Rate Constant ◽  
Liquid State ◽  
Parabolic Rate Constant ◽  
Diffusion Path ◽  
Solid State Diffusion ◽  
Diffusion Controlled ◽  
State Diffusion ◽  
Rate Controlled ◽  
Higher Temperature

The joining of a Ti3SiC2 ceramic with a Ti–6Al–4V alloy was carried out at the temperature range of 1200–1400 °C for 15 min to 4 h in a vacuum. The total diffusion path of joining was determined to be Ti3SiC2/Ti5Si3Cx/Ti5Si3Cx + TiCx/TiCx/Ti. The reaction was rate controlled by the solid-state diffusion below 1350 °C and turned to the liquid-state diffusion controlled with a dramatic increase of parabolic rate constant Kp when the temperature exceeded 1350 °C. The TiCx tended to grow at the boundarywith the Ti–6Al–4V alloy at a higher temperature and longer holding time. TheTi3SiC2/Ti–6Al–4V joint is expected to be applied to implant materials.

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