Papers by Keyword: Enamel

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Authors: Jiang Wu, Jin Hong Zhang, Wei Feng Xu, Yu Ran Cai, Yuan Huang Ouyang, Chen Wang, Yi Peng Jiang, Guan Jie Tong
Abstract: Along with the rapid development of electric power industry in China, the pollutant discharge limits are getting more strict, and WFGD (wet flue gas desulfurization) technology and its equipment have been greatly developed and extensively applied, in which the gas-gas heater (GGH) is adopted at lots of the power stations. The corrosion is a very important issue in GGH, and it is experimentally studied in this paper. Through experiment of polarization curves and the control variable method, a comparative analysis of the corrosion resistance between the commonly used materials of the GGH is made. The results have shown that the corrosion resistance with the heat transfer surface in GGH will decrease with the temperature increasing, but the enamel steel’s corrosion resistance and stability is strikingly better than that of others, and the increasing volume of corrosion resistance by plating enamel is remarkable.
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Authors: Ai Wen Zhang, Si Hai Jiao, Zheng Yi Jiang, Quan She Sun, Dong Bin Wei
Abstract: The as-rolled and enamel fired microstructure and mechanical properties of two low carbon steels with different compositions were analysed in the paper. The results show that the grains do not coarsen in lab firing process, and could be refined after industrial enamel firing process. The strength can keep stable in the firing process and the impact energy could be enhanced greatly under the industrial enamel firing process. The surface decarburized layer was occurred as a result of chemical reaction among the carbon in steel and water, oxides in the enamel frit.
144
Authors: M. Al-Jawad, L.M. Simmons, Axel Steuwer, S.H. Kilcoyne, R.C. Shore, R. Cywinski, David J. Wood
Abstract: We have used synchrotron x-ray diffraction to study the crystal orientation in human dental enamel as a function of position within intact tooth sections. Keeping tooth sections intact has allowed us to construct 2D and 3D spatial distribution maps of the magnitude and orientation of texture in dental enamel. We have found that the enamel crystallites are most highly aligned at the expected occlusal points for a maxillary first premolar, and that the texture direction varies spatially in a three dimensional curling arrangement. Our results provide a model for texture in enamel which can aid researchers in developing dental composite materials for fillings and crowns with optimal characteristics for longevity, and will guide clinicians to the best method for drilling into enamel, in order to minimize weakening of remaining tooth structure, during dental restoration procedures.
877
Authors: Alireza Sadr, Toru Nikaido, Tomohiro Takagaki, Ilnaz Hariri, Amir Nazari, Junji Tagami
Abstract: Using various electron microscopy techniques, we have demonstrated that resistance of enamel and dentin to acid attack could be increased in an acid-base resistant zone which was formed following the application of some acidic monomers, especially phosphoric-acid ester methacrylates incorporated into a few self-etching dental adhesives. We proposed that the diffusion of such acidic monomers beyond the classic hybrid layer (interfacial zone) and their ion-exchange interactions with the available hydroxyapatite could result in formation of stable organic-inorganic complexes, and that the structures should be termed “super tooth”, as they would in concept withstand major causes of dental caries and tissue degradation. We also reported that the fluoride-release from these biomaterials could contribute to reinforcement of the underlying tissue. On mechanical testing methodology, we demonstrated that time-dependent nanomechanical response of dental structures in nanoindentation could provide useful information that may not be derived under large-scale fracture experiments such as the common bonding tests. In the present paper, we present some of our recent findings on the ultra-morphological and nanomechanical characteristics of super enamel and super dentin created by self-etching adhesives, compared with sound tissue and the tissue bonded by conventional adhesives following phosphoric-acid treatment or etch-and-rinse adhesives.
131
Authors: Q.P. Gao, Yong Lie Chao, X.Ch. Jian, F. Guo, Y.K. Meng, H. Wang, Jun Cui, Wei Qun Zhang, Y.F. Tian
Abstract: This in vitro study compared the wear behavior between the enamel/dentine, two types of dental veneering ceramics for all-ceramic restorations (Vita-alpha,Vintage -AL ). A variety of factors including hardness, fracture toughness, flexural strength, frictional coefficients, wear scar width, element concentrations were considered. The wear scars of the samples were characterized by dynamic atomic force microscopy (DFM). The element concentrations of the surface before/after the wear test were determined with energy dispersion spectrometry (EDS). In this study Enamel/dentine, Vita-alpha and Vintage-AL have showed good wear resistance. The results also showed that there were statistical significance in samples. The friction coefficient varied from time in each kind of materials. The analytical differences between materials were observed in wear width and properties of materials (p<0.05). The wear ability among four materials ranked from highest to lowest as follows, Vintage-AL, Vita-alpha, enamel and dentine. DFM results demonstrated the wear patterns of natural tooth detected as abrasive and denaturation of dental texture. Wear patterns of tested veneering ceramics consisted mainly of abrasive wear, adhesion and fatigue wear and the different pattern plays different roles in Vita-alpha and Vintage-AL. The EDS results showed the element concentration of Fe was obviously found on the samples. Resistance ability against wear of veneering ceramics is better than that of natural human teeth. And the ability may have some correlation with the ceramics mechanical properties.
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