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High-temperature Applications (high-temperature + application)
Selected AbstractsMicrostructure and Mechanical Properties of New AlCoxCrFeMo0.5Ni High-Entropy AlloysADVANCED ENGINEERING MATERIALS, Issue 1-2 2010Chin-You Hsu Effects of Co content on microstructures and hot hardness of a new high-entropy alloy system, AlCoxCrFeMo0.5Ni (x,=,0.5 to 2.0) were investigated. As cobalt content increases, the microstructure changes from dendrite to polygrain type and the constituent phases change from BCC,+,, at x,=,0.5 to BCC,+,FCC,+,, at x,=,2.0. The alloy hardness varies from Hv 788 at x,=,0.5 to Hv 596 at x,=,2.0. This can be explained with the relative amount of hard , phase, medium hard BCC phase and soft FCC phase. All the AlCoxCrFeMo0.5Ni alloys possess higher hardness level than that of Ni-based superalloys In 718/In 718 H from room temperature to 1273,K. They obey the Westbrook equation presenting the normal heating behavior. Both alloys of x,=,0.5 and 1.0 exhibit a transition temperature higher than that of Co-based alloy T-800 by about 200,K. They also have a high hot hardness of Hv 347 at 1273,K, which is higher than those of In 718 and In718 H by Hv 220. The strengthening mechanism for their superiority is proposed. The AlCoxCrFeMo0.5Ni alloy system has great potential in high-temperature applications. [source] Thermal Stability of W- xRe/TiC/SiC Systems,=,0, 5 and 25 at % Re) at High Temperature,ADVANCED ENGINEERING MATERIALS, Issue 5 2009Jerome Roger To ensure the integrity and sustainability of high-temperature applications, the development of protective materials is actually one of the major challenge in materials science. In our study, we examined the effect of a TiC film interlayered between W- xRe (x,=,0, 5 or 25 at % Re) and SiC. The protection given by TiC layer was considered in the 1573,1873,K temperature range and for TiC thicknesses up to about 100,,m. [source] Processing and Properties of TiB2 with MoSi2 Sinter-additive: A First ReportJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2006T. S. R. Ch. The densification of non-oxide ceramics like titanium boride (TiB2) has always been a major challenge. The use of metallic binders to obtain a high density in liquid phase-sintered borides is investigated and reported. However, a non-metallic sintering additive needs to be used to obtain dense borides for high-temperature applications. This contribution, for the first time, reports the sintering, microstructure, and properties of TiB2 materials densified using a MoSi2 sinter-additive. The densification experiments were carried out using a hot-pressing and pressureless sintering route. The binderless densification of monolithic TiB2 to 98% theoretical density with 2,5 ,m grain size was achieved by hot pressing at 1800°C for 1 h in vacuum. The addition of 10,20 wt% MoSi2 enables us to achieve 97%,99%,th in the composites at 1700°C under similar hot-pressing conditions. The densification mechanism is dominated by liquid-phase sintering in the presence of TiSi2. In the pressureless sintering route, a maximum of 90%,th is achieved after sintering at 1900°C for 2 h in an (Ar+H2) atmosphere. The hot-pressed TiB2,10 wt% MoSi2 composites exhibit high Vickers hardness (,26,27 GPa) and modest indentation toughness (,4,5 MPa·m1/2). [source] Diffusion Bonding of Silicon Nitride Using a Superplastic ,-SiAlON InterlayerJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2001Rong-Jun Xie A superplastic ,-SiAlON was used as an interlayer to diffusionally bond a hot-pressed silicon nitride to itself. The bonding was conducted in a graphite furnace under a constant uniaxial load of 5 MPa at temperatures varying from 1500° to 1650°C for 2 h, followed by annealing at temperatures in the range of 1600° to 1750oC for 2 h. The bonds were evaluated using the four-point-bend method at both room temperature and high temperatures. The results indicate that strong, void-free joints can be produced with the superplastic ,-SiAlON interlayer, with bond strengths ranging from 438 to 682 MPa, and that the Si3N4 joints are heat resistant, being able to retain their strength up to 1000°C (635 MPa), and therefore have potential for high-temperature applications. [source] Analytical, Risk Assessment, and Remedial Implications Due to the Co-Presence of Polychlorinated Biphenyls and Terphenyls at Inactive Hazardous Waste SitesREMEDIATION, Issue 1 2000James J. Pagano Investigations conducted at three inactive hazardous waste sites in New York State have confirmed the co-presence of polychlorinated hiphenyls (PCBs) and polychlorinated terphenyls (PCTs) in soils, sediments, and biota. The PCTs at all three sites were positively identified as Aroclor 5432, with the most probable source being the hydraulic fluid Pydraul 312A utilized for high-temperature applications. The identification of the lower-chlorinated PCT formulations in environmental samples is problematical, since PCT Aroclors 5432 and 5442 are not chromatographically distinct from the higher-chlorinated (PCB) Aroclors 1254, 1260, 1262, and 1268 using conventional gas chromatography,electron capture detection. Results from this study indicate that U.S. Environmental Protection Agency (USEPA) approved PCB methods routinely utilized by most commercial laboratories based on Florisil adsorption column chromatography cleanup are inadequate to produce valid chromatographic separation and quantitative results with soils, sediment, and biota samples containing both PCBs and PCTs. The presence of co-eluting PCBs and PCTs precludes accurate quantitation due to significant differences in PCB/PCT electron capture detector response factors, and the potential for misidentification of PCT Aroclors as higher chlorinated PCB Aroclors. A method based on alumina column adsorption chromatography was used, allowing for the accurate identification and quantitation of PCB and PCT Aroclors. The results of this study suggest that the utilization of alumina adsorption column separation may have applicability and regulatory significance to other industrially contaminated sites which historically used Pydraul 312A. Inferences. [source] | ||||||||||