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 10 December 1 1993 March 1 1994 written by and published by . This book was released on 1994 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Alkali corrosion kinetics of mullite were studied in a constant partial pressure of sodium nitrate. Reaction layer thickness appears to be linearly related to reaction time; linear reaction rate constants are 9 [mu]m/h at 1000°C and 25 [mu]m/h at 1050°C. XRD after reaction revealed sodium aluminate and carnegieite, with a suggestion of a solid solution of the sodium aluminate and carnegieite phases. SEM reveals a large number of microcracks in the reaction layer.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1994 with total page 806 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiannual, with semiannual and annual indexes. References to all scientific and technical literature coming from DOE, its laboratories, energy centers, and contractors. Includes all works deriving from DOE, other related government-sponsored information, and foreign nonnuclear information. Arranged under 39 categories, e.g., Biomedical sciences, basic studies; Biomedical sciences, applied studies; Health and safety; and Fusion energy. Entry gives bibliographical information and abstract. Corporate, author, subject, report number indexes.
Download or read book High Temperature Alkali Corrosion of Ceramics in Coal Gas Eighth Quarterly Progress Report June 1 1993 September 1 1993 written by and published by . This book was released on 1993 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gaseous alkali corrosion kinetics of Si3N4 were investigated from 950 to 1100°C in an atmosphere containing 0.98 vol % sodium nitrate vapors. Linear reaction rates from 950 to 1100°C indicate that the alkali reaction Of Si3N4 is interface-controlled with an activation energy of 199 kJ/mol. Rate controlling step of overall reaction appears to be the oxidation of Si3N4 to SiO2. An alkali reaction mechanism, involving a complex dissolution-oxidation process, was proposed. The difference between oxidation of Si3N4 in air and reaction of Si3N4 in presence of alkali is dissolution process of SiO2 in sodium silicate liquid. Gaseous alkali corrosion kinetics of alumina were also investigated at 1100 and 1150°C. The reaction thickness is linearly related to the reaction time, suggesting an interface-controlled reaction mechanism. The reaction rate constants are 0.24 [mu]m/h and 0.45 [mu]m/h at 1100 and 1150°C. The alumina grains seemed to be preferentially attacked along certain crystallographic directions. Subsolidus phase relations in the Na2O-Al2O3-TiO2 system were also studied. Phase analysis indicates that the Na2O-Al2TiO5 section is not a true binary system. A revised phase diagram was constructed.
Download or read book High Temperature Alkali Corrosion of Ceramics in Coal Gas Quarterly Progress Report No 6 December 1 1992 February 28 1993 written by and published by . This book was released on 1992 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: The high temperature alkali corrosion kinetics of SiC have been systematically investigated from 950 to 1100°C at 0.63 vol % alkali vapor concentration. The corrosion rate in the presence of alkaliis approximately 104 to 105 times faster than the oxidation rate of SiC in air. The activation energy associated with the alkali corrosion is 406 kJ/mol, indicating a highly temperature-dependent reaction rate. The rate-controlling step of the overall reaction is likely to be the dissolution of silica in the sodium silicate liquid, based on the oxygen diffusivity data.
Download or read book Broadening the Uses of Research written by and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Temperature Alkali Corrosion of Ceramics in Coal Gas Quarterly Progress Report No 11 March 1 1994 June 1 1994 written by and published by . This book was released on 1994 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: High temperature alkali corrosion has been 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.
Download or read book High Temperature Alkali Corrosion of Ceramics in Coal Gas Quarterly Progress Report No 3 December 1 April 1 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 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 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 Government Reports Annual Index written by and published by . This book was released on 1994 with total page 1224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Temperature Alkali Corrosion of Ceramics in Coal Gas Quarterly Progress Report No 3 March 1 1992 May 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 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.
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1995 with total page 928 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fossil Energy Update written by and published by . This book was released on 1982 with total page 936 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book China written by World Bank and published by World Bank Publications. This book was released on 1993 with total page 1422 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Republic of Korea's industrial policy has directed that nation's economy through nearly three decades of spectacular growth. But the authors of this paper maintain that this policy is showing signs of being outmoded. The time has come, the authors argue, for the Korean government to stop managing the economy's structural development and to redefine the responsibilities of business and government. Under this proposed compact, the allocation of resources would shift from the government to the private industrial and financial sectors. The transformation of the government bureaucracy from an ad hoc policy role to one of a transparent and predictable regulator is a key to the success of this undertaking. These new directions would present the government with enormous challenges. Greater competitive discipline and regulatory oversight would be required. While dealing with the complexities of the transition, the government would have to maintain macroeconomic stability and the momentum of savings and investment. For comparison, the study examines the industrial economies of France, Germany, Japan, and the United States, which underwent similar shifts.
Download or read book Engineered Materials Abstracts written by and published by . This book was released on 1995 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt:
