Effect of Accelerated Aging on the Translucency of Monolithic Zirconia at Minimal Thickness

Lubricants and leather dressings are the most common treatments of dry and water logged historical leathers. Color change has a great importance during the time and treatment process, due to visual and aesthetic values of historic leather relics. Polyethylene glycol (PEG) and silicone oil (SiO) are frequently used leather dressings in the conservation procedures. Therefore, color stability of treated leathers with PEG and SiO were investigated before and after heat accelerated aging. Moreover, application of ascorbic acid was evaluated as an antioxidant additive for PEG (PEG+AA).Color change after treatment and aging were studied by colorimetry technique in the CIE *L*a*b system. Results indicated to severe color alteration in PEG treated and aged leathers with or without ascorbic acid. Whereas, SiO treated samples showed better stability and minimum color shift after aging. Silicone oil was characterized as the best dressing for historical leathers with compared to PEG and PEG+AA, due to its high stability and aesthetical properties.

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Lifetime Prediction of Tires with Regard to Oxidative Aging5

Tire Science and Technology ◽

10.2346/1.2839371 ◽

2008 ◽

Vol 36 (1) ◽

pp. 63-79 ◽

Cited By ~ 4

Author(s):

L. Nasdala ◽

Y. Wei ◽

H. Rothert ◽

M. Kaliske

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Temperature Distribution ◽

Superposition Principle ◽

Accelerated Aging ◽

Material Model ◽

Aging Behavior ◽

Element Analysis ◽

Material Parameters ◽

Reaction Processes

Abstract It is a challenging task in the design of automobile tires to predict lifetime and performance on the basis of numerical simulations. Several factors have to be taken into account to correctly estimate the aging behavior. This paper focuses on oxygen reaction processes which, apart from mechanical and thermal aspects, effect the tire durability. The material parameters needed to describe the temperature-dependent oxygen diffusion and reaction processes are derived by means of the time–temperature–superposition principle from modulus profiling tests. These experiments are designed to examine the diffusion-limited oxidation (DLO) effect which occurs when accelerated aging tests are performed. For the cord-reinforced rubber composites, homogenization techniques are adopted to obtain effective material parameters (diffusivities and reaction constants). The selection and arrangement of rubber components influence the temperature distribution and the oxygen penetration depth which impact tire durability. The goal of this paper is to establish a finite element analysis based criterion to predict lifetime with respect to oxidative aging. The finite element analysis is carried out in three stages. First the heat generation rate distribution is calculated using a viscoelastic material model. Then the temperature distribution can be determined. In the third step we evaluate the oxygen distribution or rather the oxygen consumption rate, which is a measure for the tire lifetime. Thus, the aging behavior of different kinds of tires can be compared. Numerical examples show how diffusivities, reaction coefficients, and temperature influence the durability of different tire parts. It is found that due to the DLO effect, some interior parts may age slower even if the temperature is increased.

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EFFECT OF FINISH LINE DESIGN AND THERMO-MECHANICAL AGING ON THE FRACTURE RESISTANCE OF TWO TYPES OF MONOLITHIC ZIRCONIA CROWNS

Egyptian Dental Journal ◽

10.21608/edj.2017.76461 ◽

2017 ◽

Vol 63 (4) ◽

pp. 3947-3953

Author(s):

Khaled Haggag ◽

Mohammed Hosny ◽

Muhammad Abbas ◽

Hussein Ramadan

Keyword(s):

Fracture Resistance ◽

Finish Line ◽

Zirconia Crowns ◽

Monolithic Zirconia ◽

Line Design ◽

Mechanical Aging

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ACCELERATED AGING AND CHARACTERIZATION OF A PLASTICIZED POLY(ESTER URETHANE) BINDER

10.2172/1074589 ◽

2007 ◽

Cited By ~ 1

Author(s):

DEBRA A. WROBLESKI ◽

DAVID A. LANGLOIS ◽

E. BRUCE ORLER ◽

ANDREA LABOURIAU ◽

MARIANA M. URIBE ◽

...

Keyword(s):

Accelerated Aging

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Factors Affecting the Wear Behavior of Monolithic Zirconia and the Antagonists: Literature Review

Current Dentistry ◽

10.2174/2542579x02666200206111259 ◽

2020 ◽

Vol 2 (1) ◽

pp. 4-11

Author(s):

Marcia Borba ◽

Paula Benetti ◽

Giordana P. Furini ◽

Kátia R. Weber ◽

Tábata M. da Silva

Keyword(s):

Literature Review ◽

Glass Ceramic ◽

Wear Behavior ◽

Glass Ceramics ◽

Surface Treatments ◽

Human Tooth ◽

Initial Surface ◽

Monolithic Zirconia ◽

Feldspathic Porcelain

Background: The use of zirconia-based ceramics to produce monolithic restorations has increased due to improvements in the optical properties of the materials. Traditionally, zirconiabased ceramics were veneered with porcelain or glass-ceramic and were not directly exposed to the oral environment. Therefore, there are several doubts regarding the wear of the monolithic zirconia restoration and their antagonists. Additionally, different surface treatments are recommended to promote a smooth surface, including glaze and several polishing protocols. To support the correct clinical application, it is important to understand the advantages and limitations of each surface treatment. Objective: The aim of this short literature review is to investigate the factors that may affect the wear of monolithic zirconia restorations in service and their antagonists. Methods: Pubmed/Medline database was accessed to review the literature from a 10-year period using the keywords: zirconia, monolithic, prosthesis, wear. Both clinical and in vitro studies were included in the review. Results: Studies investigated the effect of several surface treatments, including grinding with diamond- burs, polishing and glazing, on the surface roughness, phase transformation and wear capacity of monolithic zirconia. The wear behavior of monolithic zirconia was frequently compared to the wear behavior of other ceramics, such as feldspathic porcelain, lithium disilicate-based glassceramic and leucite-reinforced glass-ceramic. Human tooth, ceramics and resin composites were used as antagonist in the investigations. Only short-term clinical studies are available (up to 2 years). Conclusion: Literature findings suggest that zirconia monolithic restorations are wear resistant and unlikely to cause excessive wear to the antagonist, especially when compared to feldspathic porcelain and glass-ceramics. Monolithic zirconia should be polished rather than glazed. Yet, none of the polishing systems studied was able to completely restore the initial surface conditions of zirconia after being adjusted with burs. More clinical evidence of the antagonist tooth wear potential of monolithic zirconia is needed.

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