Download or read book High Temperature Alkali Corrosion of Dense SiC and Si3Nsub 4 Coated with CMZP and Mg doped Alsub 2TiOsub 5 in Coal Gas Quarterly Technical Progress Report 1 July 30 September 1995 written by and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Temperature Alkali Corrosion of Dense SiC and Si3Nsub 4 Coated with CMZP and Mg doped Alsub 2TiOsub 5 in Coal Gas Quarterly Technical Progress Report April 1 June 30 1995 written by and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Temperature Alkali Corrosion of Dense SiC and Si3Nsub 4 Coated with CMZP and Mg doped Alsub 2TiOsub 5 in Coal Gas written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Temperature Alkali Corrosion of Dense SiC and Si3N4 Coated with CMZP and Mg doped Al2TiO5 in Coal Gas Quarterly Progress Report No 4 April 1 1995 June 30 1995 written by and published by . This book was released on 1995 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: High temperature alkali corrosion has been known to cause premature failure of ceramic components used in advanced high temperature coal combustion systems such as coal gasification and clean-up, coal fired gas turbines, and high efficiency heat engines. Non-oxide ceramics, such as SiC and Si3N4, are applied in HITAF systems for their well-known and desirable high temperature thermal and mechanical properties. However, these materials are prone to rapid corrosion under some types of high temperature coal combustion conditions. The objective of this research is to apply CMZP and Mg-stabilized Al2TiO5 as coatings to SiC and Si3N4 to improve the corrosion resistance under coal combustion atmospheres as well as to improve high temperature mechanical properties. The research will not only develop and characterize CMZP and Mg-Al2TiO5 coatings but will also strive to expand the existing knowledge of the mechanism of coal combustion corrosion of SiC and Si3N4 in the temperature range of 1000-1400°C.
Download or read book High Temperature Alkali Corrosion of Dense SiC and Si3N4 Coated with CMZP and Mg doped Al2TiO5 in Coal Gas Quarterly Report July 1 1995 September 30 1995 written by and published by . This book was released on 1995 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: SiC samples coated with CMZP and Mg-Al2TiO5, respectively, were tested in a 100-hour slagging combustion test at the Energy and Environmental Research Center at the University of North Dakota. Results of measurements and analysis indicate that CMZP and Mg-Al2TiO5 coatings improved the high temperature alkali corrosion resistance under coal combustion atmospheres. It is clearly shown that it is important to obtain a homogeneous and crack-free coating and good adhesion of the coating to the surface of the substrate for the best corrosion resistance. Some measures to improve the coating procedure are presented.
Download or read book High Temperature Alkali Corrosion of Dense SiC and Si3N4 Coated with CMZP and Mg Doped Al2TiO5 in Coal Gas written by and published by . This book was released on 1996 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The second phase, coating of Si3N4 by oxides, was started during this reporting period. Si3N4 samples were coated by CMZP and Mg-coated Al2TiO5 by a double-dip procedure.
Download or read book High Temperature Alkali Corrosion of Dense SiC and Si3N4 Coated with CMZP and Mg DOPED Al2TiO5 in Coal Gas Quarterly Progress Report No 6 October 1 1995 December 31 1995 written by and published by . This book was released on 1995 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: High temperature alkali corrosion has been known to cause premature failure of ceramic components used in advanced high temperature coal combustion systems such as coal gasification and clean-up, coal fired gas turbines, and high efficiency heat engines. Non-oxide ceramics, such as SiC and Si3N4, are applied in HITAF systems for their well-known and desirable high temperature thermal and mechanical properties. However, these materials are prone to rapid corrosion under some types of high temperature coal combustion conditions. The objective of this research is to apply CMZP and Mg- Al2TiO5 as coatings to SiC to improve corrosion resistance under coal combustion atmospheres as well as to improve high temperature mechanical properties. The research will not only develop and characterize CMZP and Mg-Al2TiO5 coatings but will also strive to expand the existing knowledge of the mechanism of coal combustion corrosion of SiC in the temperature range of 1000- 4000°C.
Download or read book High Temperature Alkali Corrosion of Dense SiC and Si3N4 Coated with CMZP and Mg doped Al2TiO5 in Coal Gas Quarterly Progress Report No 7 January 1 1996 March 31 1996 written by and published by . This book was released on 1996 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Objective is to apply CMZP and Mg-Al2TiO5 as coatings to SiC to improve corrosion resistance under coal combustion atmospheres as well as to improve high temperature mechanical properties. The research will also study the mechanism of coal combustion corrosion of SiC at 1000-1400 C. 16 figs, 8 tabs.
Download or read book High Temperature Alkali Corrosion of Dense SiC and Si 3 N 4 Coated with CMZP and Mg Doped Al 2 TiO 5 in Coal Gas written by and published by . This book was released on 1997 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hot pressed Si3N4 has been extensively studied in the past years mainly because it is a potential candidate for high temperature structural applications. If its behavior in alkaline environments has been widely investigated and is now well understood, only a few authors have conducted research on thin film to enhance Si3N4 lifetime in harsh environments. Thus, it is the first objective of this work to develop thin film of CMZP and Mg doped Al2TiO5 using the sol-gel process and the dip coating technique. In the previous report relatively good coverage of the substrate surface was achieved with low concentration solutions and double coatings. However, the aggregation of the sol-gel at the bottom of some samples suggested that more viscous sol-gels, i.e. higher concentrations, could alleviate this phenomenon. This report will therefore present the results obtained with more concentrated solutions and also those obtained with two other CMZP solutions utilizing different precursors.
Download or read book High Temperature Alkali Corrosion of Dense SiC and Si3N4 Coated with CMZP and Mg doped Al2TiO5 in Coal Gas Quarterly Progress Report No 10 October 1 1996 December 31 1996 written by and published by . This book was released on 1997 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: In high temperature engineering applications, commercially available silicon nitride non-oxide ceramics have retained special attention because of their superior thermal, mechanical, and chemical properties. These properties mainly include a high fracture strength and toughness, a low coefficient of thermal expansion relative to other ceramics, good thermal shock resistance, and good chemical stability. With silicon carbide, silicon nitride was the second material selected for heat exchangers in the High Temperature Advanced Furnace being developed under the DOE Combustion 2000 program. Their potential use in heat exchangers is, however, limited in time since both materials corrode severely in high temperature coal combustion atmospheres containing alkali compounds. Thus, this research will first focus on enhancing the performance of Si3N4 ceramics by coating them with alkali corrosion resistant materials such as CMZP and Mg-doped Al2TiO5 oxide ceramics.
Download or read book High Temperature Alkali Corrosion of Dense SiC and Si3N4 Coated with CMZP and Mg doped Al2TiO5 in Coal Gas written by and published by . This book was released on 1996 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The second phase, coating of Si3N4 by oxides, was started during this reporting period. Si3N4 samples were coated by CMZP and Mg-doped Al2TiO5 by a double-dip procedure.
Download or read book High Temperature Alkali Corrosion of Dense SN4 Coated with CMZP and Mg Doped A21TiO5 in Coal Gas written by and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Si3N4 heat exchangers used in industrial systems are usually operating in harsh environments. Not only is this structural material experiencing high temperatures, but it is also subjected to corrosive gases and condensed phases. Past studies have demonstrated that condensed phases severely attack Si3N4 and as a consequence, dramatically reduce its lifetime in industrial operating systems. 1,2 Previous research conducted at Virginia Tech on low thermal expansion coefficient oxide ceramics,3,4,5 (Ca1-X, MgX)Zr4(PO4)6 (CMZP), and Mg-doped Al2TiO5, for structural application have shown that these two materials exhibited better resistance to alkaline corrosion than Si3N4. Thus, they were envisioned as good candidates for a protective coating on Si3N4 heat exchangers. As a result, the goal of the present work is to develop CMZP and Mg-doped Al2TiO5 protective thin films using the sol-gel process and the dip coating technique and to test their effectiveness in an alkali-containing atmosphere.
Download or read book High Temperature Akali Corrosion of Dense SiC and Si 3 N 4 Coated with CMZP and Mg Doped Al 2 TiO 5 in Coal Gas written by and published by . This book was released on 1997 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: Si3N4 ceramics possess properties that are attractive for high temperature heat exchanger applications. These properties include high strength, good thermal conductivity and excellent resistance to thermal shock and oxidation. However when subjected to alkaline containing environments, Si3N4 is prone to corrode and eventually loses its properties. Because it was found that oxide ceramics corrode substantially less, they can be used as a coating to protect Si3N4. Therefore the first objective of this work is to develop thin film of CMZP and Mg-doped Al2TiO5 since both of them are good candidate coating materials of primary interest for the protection of Si3N4 against alkaline corrosion.
Download or read book High Temperature Alkali Corrosion of Ceramics in Coal Gas Quarterly Progress Report No 5 September 1 1992 December 1 1992 written by and published by . This book was released on 1992 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Calcia-stabilized cubic zirconia was mixed with soda, then fired at 840-1100 C. SiC was also reacted with alkali-containing atmosphere at 1000 C.
Download or read book High Temperature Alkali Corrosion of Ceramics in Coal Gas Quarterly Progress Report No 4 June 1 1992 August 31 1992 written by and published by . This book was released on 1992 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: High temperature alkali corrosion has been known to cause premature failure of ceramic components used in advanced high temperature coal combustion systems such as coal gasification and clean-up, coal fired gas turbines, and high efficiency heat engines. The objective of this research is to systematically evaluate the alkali corrosion resistance of the most commonly used structural ceramics including silicon carbide, silicon nitride, cordierite, mullite, alumina, aluminum titanate, zirconia, and fireclay glass. The study consists of identification of the alkali reaction products (phase equilibria) and the kinetics of the alkali reactions as a function of temperature and time.
Download or read book High Temperature Alkali Corrosion of Ceramics in Coal Gas Quarterly Progress Report No 7 March 1 1993 June 1 1993 written by and published by . This book was released on 1993 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Corrosion kinetics of SiC were investigated from 950 to 1100C at 0.63 vol% alkali vapor concentration. Corrosion rate in alkali is 104 to 105 times faster than oxidation rate of SiC in air. Activation energy of the alkali corrosion is 406 kj/mol, indicating a high sensitivity to temperature changes. Overall reaction appears to be controlled by the oxidation of SiC. The alkali corrosion kinetics of Si3N4 from 950 to 1050°C were also examined in the same atmosphere (0.63 vol% alkali vapors). Reaction thickness of Si3N4 appears to vary linearly with reaction time from 950 to 1050C, suggesting that the alkali corrosion process is controlled by the oxidation of Si3N4. At 1050°C, the alkali-enhanced oxidation of Si3N4 is approximately 107 times faster than the oxidation of Si3N4 in dry oxygen. Compared to SiC corroded in the same alkali atmosphere, Si3N4 seems to be less alkali-resistant than SiC. Phase relations of the Na2O-Al2TiO5 vertical section from 5--40 wt% Na2O and 840-1100C were studied. Phase analysis indicates that this section is not a true binary system. A tentative phase diagram for the Na2O-Al2O3-TiO2 system was constructed.
Download or read book High Temperature Alkali Corrosion of Ceramics in Coal Gas Quarterly Progress Report No 1 September 1 1991 November 31 1991 written by and published by . This book was released on 1991 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: High temperature alkali corrosion has been known to cause premature failure of ceramic components used in advanced high temperature coal combustion systems such as coal gasification and clean-up, coal fired gas turbines, and high efficiency heat engines. The objective of this program is to systematically evaluate the alkali corrosion resistance of the most commonly used structural ceramics including silicon carbide, silicon nitride, cordierite, mullite, alumina, aluminum titanate, zirconia, and fireclay glass. The study consists of identification of the alkali reaction products (phase equilibria) and the kinetics of the alkali reactions as a function of temperature and time.
