Download or read book Surface Stability and Small scale Testing of Zirconia written by Erik Camposilvan and published by . This book was released on 2009 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tetragonal polycrystalline zirconia stabilized with 3 mol% of yttria (3Y-TZP) is a biocompatible ceramic showing superior mechanical properties, which are partly the consequence of phase transformation: the tetragonal metastable phase can transform, with a net volume increase, to the stable monoclinic phase by a martensitic transformation. The transformation can be activated either mechanically by the application of high stresses, or chemically by the diffusion of water species, when the material is exposed to humid environment and moderate temperatures. In the first case, the local transformation at the crack tip under tension hinders their propagation, producing a phenomenon known as transformation toughening, which allows the design of damage-tolerant ceramics. On the other hand, the spontaneous and progressive surface transformation in presence of humidity represents an aging phenomenon known as low-temperature degradation (LTD), hydrothermal degradation or aging. Affecting a surface layer of only few micrometers, this phenomenon is accompanied by a substantial impairment of the surface integrity, representing a serious issue for the use of 3Y-TZP in load-bearing biomedical applications. It was shown in orthopedics that zirconia femoral heads used in arthroplasty may be vulnerable to LTD, leading in some cases to premature failures. Likewise, some recent publications devoted to dental zirconia have highlighted that it is susceptible to LTD if exact processing conditions are not followed. The first subject of the thesis is the study of reliable solutions to avoid hydrothermal degradation of 3Y-TZP. Two novel methods are proposed, which allow a strong enhancement of the aging resistance through limited changes in the processing. These methods are based on co-doping the material from the surface with CeO2 by two different approaches. One includes infiltration of CeO2 precursors in the pre-sintered porous material. During thermal decomposition and sintering, CeO2 is trapped into the pores and diffused into 3Y-TZP, obtaining a functionally-graded material with decreasing CeO2 content from the surface to the bulk. The co-doping profile has been optimized by studying the pre-sintering, infiltration and sintering parameters in order to avoid a drop in the mechanical properties generally found in CeO2-doped zirconia. The second approach is applied to the dense material, where surface roughness has been created for adhesion or osseointegration purposes. After pressure infiltration of CeO2 precursors into the surface defects and pores created during the roughening process, a few-micrometers thick co-doped layer is obtained with a diffusion treatment. This helps sealing the surface defects and avoids hydrothermal degradation, without affecting the color or the mechanical properties, being so directly applicable in the manufacturing of dental crowns, abutments and dentures. The second subject focuses on small-scale testing of zirconia near-surface regions. The existence of extrinsic size effects on the mechanical properties has been investigated, and the mechanical response of the degraded and non-degraded state has been compared in bending and compression. By testing micropillars and micro-cantilevers milled with focused ion beam (FIB), higher strength and strain at failure have been recorded with respect to the bulk state, as a result of transformation-induced plasticity and the absence of processing defects. No size effect has been found in terms of strength among small-scale samples, whereas the "yield" stress for phase transformation is lower for smaller samples. Hydrothermal degradation produces a microcrack network which controls the behavior and strongly impairs the mechanical properties of small-scale samples milled inside the degraded layer. In bending, a different response in terms of strength and stiffness has been measured depending on sample orientation, proving that that the induced damage is anisotropic.

Download or read book Comprehensive Biomaterials II written by Kevin Healy and published by Elsevier. This book was released on 2017-05-18 with total page 4865 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive Biomaterials II, Second Edition, Seven Volume Set brings together the myriad facets of biomaterials into one expertly-written series of edited volumes. Articles address the current status of nearly all biomaterials in the field, their strengths and weaknesses, their future prospects, appropriate analytical methods and testing, device applications and performance, emerging candidate materials as competitors and disruptive technologies, research and development, regulatory management, commercial aspects, and applications, including medical applications. Detailed coverage is given to both new and emerging areas and the latest research in more traditional areas of the field. Particular attention is given to those areas in which major recent developments have taken place. This new edition, with 75% new or updated articles, will provide biomedical scientists in industry, government, academia, and research organizations with an accurate perspective on the field in a manner that is both accessible and thorough. Reviews the current status of nearly all biomaterials in the field by analyzing their strengths and weaknesses, performance, and future prospects Covers all significant emerging technologies in areas such as 3D printing of tissues, organs and scaffolds, cell encapsulation; multimodal delivery, cancer/vaccine - biomaterial applications, neural interface understanding, materials used for in situ imaging, and infection prevention and treatment Effectively describes the many modern aspects of biomaterials from basic science, to clinical applications

Download or read book Mechanical Physical Properties of Zirconia based Ceramic Restorations written by Ishita Agarwal and published by . This book was released on 2013 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: OBJECTIVE: The most critical issues facing restorations are strength, hardness, chemical stability and discoloration. Therefore, the aim of the in-vitro study was to evaluate and compare various full contour monolithic zirconia (FCZ) based restorations with the established lithium disilicate (LS2) in terms of flexural strength, hardness, solubility in acidic environment, critical surface tension and color stability. METHOD: Five different ceramic materials were tested in this study. Four materials were FCZ namely BruxZir (Glidewell Lab.), Zirlux (Zahn Dental), Zenostar (Ivoclar Vivadent) and Lava (3M ESPE). The fifth material was lithium disilicate (LS2) (Ivoclar Vivadent) that served as a control. Five parameters namely Flexural Strength, Critical Surface Tension (Surface energy), Hardness, Chemical Solubility and Color stability were determined. The groups were as follows: Group A had ten specimens from each group (n=10) of size 20 X 4 X 1. 2 mm. Flexural strength followed by Critical Surface Tension (CST) were measured for this group. Load bearing capacities of the materials were evaluated by measuring flexural strength through Three- point Bending Test on the Universal Testing Machine as per the ISO 6872 (International Organization for Standardization). Consecutively, in order to see the effect of Radiofrequency Glow Discharge Treatment (RFGDT) on surface energy and wettability, the CST of two samples per group was determined before and after RFGDT using the Goniometer. Group B had ten specimens from each group (n=10) of size 12 X 6 X 4 mm. They were tested for hardness, chemical solubility and color stability as per American Dental Association (ADA) Spec. 69. In order to determine the hardness of the material, Vickers Hardness was measured by Tukon Microhardness tester under a 1kgf load over 15s. Thereafter the specimens were tested for their chemical solubility as per ISO 6872 by extracting the samples using 4% acetic acid in the soxhlet extractor. To determine the effect of acid on the materials, the hardness was re-measured. Besides that, to find the color stability of ceramic materials the baseline color (CIELAB) was measured using a surface colorimeter. Then the specimens were subjected to staining solution in a rotating apparatus for four days. Color was measured two times in a day after every 12 hrs. RESULTS: One way ANOVA results indicated a statistically significant difference in mean flexural strength among the groups. The follow up Tukey HSD suggests that LS2 has significantly lower flexural strength than all other groups. Among FCZ, Zirlux had lower strength than BruxZir. Furthermore, RFGDT increased the CST of the ceramic materials from 33mN/m to 39mN/m. Hardness results showed that LS2 has significantly lower hardness than FCZ.^Among FCZ, Zenostar had lower hardness than Lava. However, there was no significant difference in color stability and chemical solubility among groups. CONCLUSION: Our study indicates superior load bearing capacity and hardness of FCZ as compared to LS2. Surface activation of all material after RFGDT is valuable in terms of cementation and bonding of FCZ and or LS2 to tooth. However the chemical solubility and color stability results did not show any difference among the groups. Therefore, it can be concluded that FCZ are significantly better than LS2 in terms of the flexural strength and hardness. Hence, FCZ have all the properties required for a restorative material. Further clinical studies are required to validate this.

Download or read book Bioceramics 15 written by Besim Ben-Nissan and published by Trans Tech Publications Ltd. This book was released on 2003-05-15 with total page 1010 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume is indexed by Thomson Reuters CPCI-S (WoS). Since their inception Bioceramics meetings have provided a treasure house of information for both scientists and clinicians in the medical field. The clinical applications are numerous, in particular in the areas of orthopaedics, maxillofacial, plastic and ocular surgery, percutaneous devices, tissue engineering and sensors. This volume in addition to research papers contributed also presents selected overviews and discussions on recent bioceramics research and trends.

Download or read book Fracture Mechanics of Ceramics written by R.C. Bradt and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 591 pages. Available in PDF, EPUB and Kindle. Book excerpt: Second part of the proceedings of the Sixth International Symposium held in Karlsruhe, Germany, July 18-20, 1995.

Download or read book ASME Technical Papers written by and published by . This book was released on 1999 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Functionally Graded Materials in the 21st Century written by Kiyoshi Ichikawa and published by Springer Science & Business Media. This book was released on 2013-11-27 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: I am honored to chair this International Workshop on Functionally st Graded Materials in the 21 Century: A Workshop on Trends and Forecasts, and would like to first express my sincere gratitude to everyone participating. The Mechanical Engineering Laboratory and the Japan International Science and Technology Exchange Center (JISTEC) have co-organized this workshop with the sponsorship of the Science and Technology Agency of Japan and the cooperation of the Association of Mechanical Technology. This workshop is an international conference to focus on functionally graded materials and the aim is to provide an overview of the present global technical trends and the future development of functionally graded materials over the next 10 years. I am very happy to see many researchers meeting together here - including seven researchers invited from abroad. During the three-day oral sessions, 36 research reports will be presented, and I'm sure I'm not the only one who is very anxious to hear and participate in the upcoming interesting discussions. At present, the Mechanical Engineering Laboratory is conducting fundamental and ground-breaking research in such major areas as materials science and technology, bioengineering, information & system science, advanced machine technology, energy technology, manufacturing technology and robotics. In particular, we consider research on materials science and technology to have the highest priority for the 21st century. and since 1996 have participated in the US-Japan joint research project, Precompetitive Processing and Characterization of Functionally Graded Materials.

Download or read book Mechanical Properties of Ceramics written by John B. Wachtman and published by John Wiley & Sons. This book was released on 2009-08-13 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Comprehensive and Self-Contained Treatment of the Theory and Practical Applications of Ceramic Materials When failure occurs in ceramic materials, it is often catastrophic, instantaneous, and total. Now in its Second Edition, this important book arms readers with a thorough and accurate understanding of the causes of these failures and how to design ceramics for failure avoidance. It systematically covers: Stress and strain Types of mechanical behavior Strength of defect-free solids Linear elastic fracture mechanics Measurements of elasticity, strength, and fracture toughness Subcritical crack propagation Toughening mechanisms in ceramics Effects of microstructure on toughness and strength Cyclic fatigue of ceramics Thermal stress and thermal shock in ceramics Fractography Dislocation and plastic deformation in ceramics Creep and superplasticity of ceramics Creep rupture at high temperatures and safe life design Hardness and wear And more While maintaining the first edition's reputation for being an indispensable professional resource, this new edition has been updated with sketches, explanations, figures, tables, summaries, and problem sets to make it more student-friendly as a textbook in undergraduate and graduate courses on the mechanical properties of ceramics.

Download or read book Advances in Ceramics written by Costas Sikalidis and published by BoD – Books on Demand. This book was released on 2011-09-06 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt: The current book consists of twenty-four chapters divided into three sections. Section I includes fourteen chapters in electric and magnetic ceramics which deal with modern specific research on dielectrics and their applications, on nanodielectrics, on piezoceramics, on glass ceramics with para-, anti- or ferro-electric active phases, of varistors ceramics and magnetic ceramics. Section II includes seven chapters in bioceramics which include review information and research results/data on biocompatibility, on medical applications of alumina, zirconia, silicon nitride, ZrO2, bioglass, apatite-wollastonite glass ceramic and b-tri-calcium phosphate. Section III includes three chapters in applications of ceramics in environmental improvement and protection, in water cleaning, in metal bearing wastes stabilization and in utilization of wastes from ceramic industry in concrete and concrete products.

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1973 with total page 1554 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Comprehensive Energy Systems written by Ibrahim Dincer and published by Elsevier. This book was released on 2018-02-07 with total page 5543 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive Energy Systems, Seven Volume Set provides a unified source of information covering the entire spectrum of energy, one of the most significant issues humanity has to face. This comprehensive book describes traditional and novel energy systems, from single generation to multi-generation, also covering theory and applications. In addition, it also presents high-level coverage on energy policies, strategies, environmental impacts and sustainable development. No other published work covers such breadth of topics in similar depth. High-level sections include Energy Fundamentals, Energy Materials, Energy Production, Energy Conversion, and Energy Management. Offers the most comprehensive resource available on the topic of energy systems Presents an authoritative resource authored and edited by leading experts in the field Consolidates information currently scattered in publications from different research fields (engineering as well as physics, chemistry, environmental sciences and economics), thus ensuring a common standard and language

Download or read book Bamberger Carneval des Jahres 1885 written by and published by . This book was released on 1885 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1972-04 with total page 1068 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Proceedings of the 49th Industrial Waste Conference Purdue University May 1994 written by Ronald F. Wukasch and published by CRC Press. This book was released on 1994-12-29 with total page 884 pages. Available in PDF, EPUB and Kindle. Book excerpt: Known and used throughout the world, the Purdue Industrial Waste Conference Proceedings books are the most highly regarded in the waste treatment field. New research, case histories, and operating data cover every conceivable facet of today's big problems in environmental control, treatment, regulation, and compliance. This volume representing the proceedings from the 49th conference provides unparalled information and data for your current waste problems.

Download or read book Bioceramics written by and published by . This book was released on 2005 with total page 764 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Introduction to Surface Engineering written by P. A. Dearnley and published by Cambridge University Press. This book was released on 2017-01-16 with total page 798 pages. Available in PDF, EPUB and Kindle. Book excerpt: This highly illustrated reference work covers the three principal types of surface technologies that best protect engineering devices and products: diffusion technologies, deposition technologies, and other less commonly acknowledged surface engineering (SE) techniques. Various applications are noted throughout the text and additionally whole chapters are devoted to specific SE applications across the automotive, gas turbine engine (GTE), metal machining, and biomedical implant sectors. Along with the benefits of SE, this volume also critically examines SE's limitations. Materials degradation pathways - those which can and those which cannot be mitigated by SE - are rigorously explained. Written from a scientific, materials engineering perspective, this concise text is supported by high-quality images and photo-micrographs which show how surfaces can be engineered to overcome the limits of conventionally produced materials, even in complex or hostile operating environments. This book is a useful resource for undergraduate and postgraduate students as well as professional engineers.