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Full-Text Articles in Engineering Science and Materials
Combustion Synthesis Of Molybdenum Silicides And Borosilicides For Ultrahigh-Temperature Structural Applications, Mohammad Shafiul Alam
Combustion Synthesis Of Molybdenum Silicides And Borosilicides For Ultrahigh-Temperature Structural Applications, Mohammad Shafiul Alam
Open Access Theses & Dissertations
Molybdenum silicides and borosilicides are promising structural materials for gas-turbine power plants. A major challenge, however, is to simultaneously achieve high oxidation resistance and acceptable mechanical properties at high temperatures. For example, molybdenum disilicide (MoSi2) has excellent oxidation resistance and poor mechanical properties, while Mo-rich silicides such as Mo5Si3 (called T1) have much better mechanical properties but poor oxidation resistance. One approach is based on the fabrication of MoSi2−T1 composites that combine high oxidation resistance of MoSi2 and good mechanical properties of T1. Another approach involves the …
Development And Characterization Of The Oxidation Behavior Of Various High Temperature Niobium Based Alloys, Benedict Isabel Portillo
Development And Characterization Of The Oxidation Behavior Of Various High Temperature Niobium Based Alloys, Benedict Isabel Portillo
Open Access Theses & Dissertations
The oxidation response of various niobium based refractory alloys from the Nb-Mo-Si-B-X alloy system has been examined at temperatures between 700 and 1400°C in air. The development of these alloys was part of an ongoing effort to develop and discover a new materials system capable of replacing nickel based super alloys. Additions of titanium were found to provide limited oxidation resistance. A discontinuous layer of TiO2 was observed to from at temperatures above 1100°C. Alloys containing titanium additions were observed to suffer from pest oxidation at low and intermediate temperatures due to the development of Nb2O5. Poor oxidation resistance at …
Processing Of Zrb2-Zrc-Zrxsiy Ceramic By Reactive Metal Penetration, Nischel B. Maheswaraiah
Processing Of Zrb2-Zrc-Zrxsiy Ceramic By Reactive Metal Penetration, Nischel B. Maheswaraiah
Open Access Theses & Dissertations
The processing of ZrB2-ZrC-ZrxSiy composite by reactive metal penetration was investigated as a successor to the ZrB2-SiC composites for hypersonic vehicles application, which cannot be used for extended time at temperatures greater than 1600C due to formation of SiO and CO gases. Zirconium (Zr), zirconium disilicide (ZrSi2), and boron carbide (B4C) were reacted in graphite crucibles for 60, 120, 180, and 240 minutes. Microscopy and x-ray diffraction (XRD) deduced the formation of a heterogeneous microstructure of ZrB2-ZrC-ZrxSiy precipitates surrounded by a solidified Zr-Si melt. Unreacted boron carbide was observed in samples held at 1860C for 60 minutes and 120 minutes, …