Papers by Keyword: Ceramic Coating

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Authors: Hai He Luo, Qi Zhou Cai
Abstract: A ZrO2-Y2O3-containing composite ceramic coating was firstly in situ prepared on AZ91D magnesium alloy by plasma electrolytic oxidation (PEO) technique in an alkaline silicate-containing electrolyte. The morphology, chemical composition and corrosion resistance of the PEO coating were investigated by environmental scanning electron microscopy (ESEM), X-ray diffractometer (XRD), energy dispersive X-ray (EDX) spectrometer, dropping corrosion and electrochemical corrosion test. The results showed that the ceramic coating consisted of two distinct structural layers: an outer loose layer and an inner dense layer; it was composed of t-ZrO2, Y2O3, SiO2 and some magnesium compounds, such as MgO, MgF2 and Mg2SiO4. In addition, the ceramic coating also showed excellent dropping and electrochemical corrosion resistance, which was mainly attributed to its special phase composition and microstructure.
Authors: Hui Zhao, Zhen Liu, Zhong Han
Abstract: Characteristics of ceramic coatings on AM50 magnesium alloy by micro-arc oxidation in silicate and phosphate electrolytes have been investigated in this study. This study reveals that the thickness of the ceramic coatings increases with the treated time in both electrolytes, the growth rate of ceramic layer in phosphate is faster than that in silicate electrolyte. The surface roughness of the ceramic coating formed in phosphate electrolyte is higher than that formed in silicate electrolyte. The coatings formed in silicate, containing a thicker inner barrier layer and a thinner outer porous layer, consist of MgO, Mg2SiO4 and MgSiO3 phases. For the coatings formed in phosphate, the outer porous layer is thicker than the inner layer, it consist mainly of MgO and MgAlO4 phases.
Authors: Jair Silveira, Luiz Renato de A.P. Pontes, Josinaldo P. Leite, Jorge H. Echude-Silva
Abstract: This article presents a method to optimize the formulation of ceramic masses for coatings using the statistical design of experiments. The project of simplex mixtures in pseudocomponents considered six control factors (wt. %): talc, quartz, limestone, phyllite, dolomite and clay and three response variables: linear retraction, bending resistance and water absorption. The proposed method was implemented in the stages: (1) identification of the problem, (2) planning and execution of the experiments and (3) optimization and discussion of the results. The optimization method is defined through the simulation, imposing the restrictions that each response demands.
Authors: A.V. Karlov, O.I. Nalesnick, E.A. Eremkina, M.I. Mockshina
Authors: Sóstenes Rodrigues Do Rego, Kelly Cristiane Gomes, Antonio Farias Leal, Normando Perazzo Barbosa, Sandro Marden Torres, Silvio Romero de Barros
Abstract: The detachment of ceramic tiles from buildings is a problem that still persists in several modern constructions. Although there are several specific techniques for the prevention of tiles from detaching this issue still requires in-depth research in order to be fully solved. These detachments happen commonly in facades that are submitted to the incidence of solar rays on the surfaces. In this work, the adhesion of porcelanate-adhesive-substrate was investigated through direct detachment tests according to Brazilian standards. Two types of adhesives were used: a commercial adhesive, classified by Brazilian standard as being of high adhesion (ACIII-E) and a geopolymer, developed through alkaline activation of metakaolin with sodium silicate. The bonded systems were submitted to two temperature exposure regimes. In general, geopolymeric adhesives had better adhesion than the systems bonded with ACIII-E adhesive mortar, especially with temperature increase.
Authors: Pankaj N. Shrirao, Parvezalam I. Shaikh, Farazuddin Zafaruddin, A.N. Pawar
Abstract: Tests were performed on a single cylinder, four stroke, direct injection, diesel engine whose piston crown, cylinder head and valves were coated with a 0.5 mm thickness of 3Al2O3 .2SiO2 (mullite) (Al2O3= 60%, SiO2= 40%) over a 150 µm thickness of NiCrAlY bond coat. The working conditions for the conventional engine (without coating) and LHR (mullite coated) engine were kept exactly same to ensure a comparison between the two configurations of the engine. This paper is intended to emphasis on emission characteristics of diesel engine with and without mullite coating under identical conditions. Tests were carried out at same operational constraints i.e. air-fuel ratio and engine speed conditions for both conventional engine (without coating) and LHR (mullite coated) engines. The results showed that, there was as much as29.41% and 24.35% decreasing on CO and HC emissions respectively for LHR (mullite coated) engine compared to conventional engine (without coating) at full load. The average decrease in smoke density in the LHR engine compared with the conventional engine was 13.82 % for full engine load. However, there was as much as 20% increasing on NOx emission for LHR engine compared to conventional engine at full load. Also the results revealed that, there was as much as 22% increasing on exhaust gas temperature for LHR engine compared to conventional engine at full engine load.
Authors: Wen Ge Li, He Ping Zhou, Yan Ling Zhao, Yin Li
Authors: Alan de Oliveira Feitosa, José Elson Soares Filho, Leonardo Leandro dos Santos, Romualdo Rodrigues Menezes, Ricardo Peixoto Suassuna Dutra
Abstract: Color is a very important characteristic in ceramic products. In ceramic coatings, the basis of ceramic is normally classified as red or white basis. Another relevant factor for color variation is the processing to which the material is submitted. In this sense, this work aims to analyze and quantify the color of ceramic pieces used as coatings, which were developed from a formulation of masses, using raw materials such as clay, feldspar, kaolin and quartz. Each raw material was analyzed separately and then a standard formulation was made, involving all of them, and these ones were submitted to different processing temperatures. All the samples were quantified regarding the color, by using the tridimensional colorimetric space by CIELAB method. Results point out that each raw material has an own value regarding color and the temperature has contributed directly to the color variation of the ceramic pieces.
Authors: Lei Zhang, Bi Bo Shao, Yong Wu, Peng Ling Yang, Meng Meng Tao, Yan Yan
Abstract: With the consistent improvement of the laser power and energy, further enhancement of the laser resistant ability of the target board is becoming a more and more crucial task in high energy laser diagnostics and irradiation effect studies. Applications of ceramic materials in high energy laser damage were studied. An aluminum panel was coated with ZrO2 ceramic for high power laser proof. Reflectivity and diffuse reflection characteristics of the coating were investigated at different wavelengths. Numerical simulation was conducted to analyze the thermal response of the coating under high power laser radiation. And, related experiments were carried out with high power fiber lasers. Irradiation experiments indicate that the ceramic layer helps to delay the heat conduction and reduce the peak temperature of the target board.
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