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Eiichi Sato - One of the best experts on this subject based on the ideXlab platform.

  • micrometeoroid impact damage on thin Ceramic Component for interplanetary probe
    Transactions of The Japan Society for Aeronautical and Space Sciences Space Technology Japan, 2009
    Co-Authors: Yasuko Motoyashiki, Daisuke Shindo, K Okudaira, Sunao Hasegawa, Eiichi Sato
    Abstract:

    A new Ceramic thruster for an interplanetary probe is currently under development. Monolithic silicon nitride (Si3N4) , which has good heat resistance and high fracture toughness among conventional structural Ceramics, is a promising material for a high performance thruster. However Ceramics are brittle compared to metallic materials. In order to evaluate reliability of the Ceramic thruster as a space-use Component, fracture behavior against micrometeoroid impacts was investigated. First the risk probability of the meteoroid impacts which may occur during a mission was estimated based on impact energy which may cause failure of the material. Second, damage of the silicon nitride Ceramics by a possible micrometeoroid impact was investigated experimentally. Hypervelocity impact tests were carried out on the silicon nitride Ceramic samples with a two-stage light-gas gun. Impacts at various velocities ranging from 1.0 km/s up to 4.5 km/s brought about three types of failure. However no shattering occurred by the hypervelocity impact with a possible energy. The experimental results together with the risk evaluation considering the flight mission conditions show that the Si3N4 Ceramic thruster for the interplanetary probe would have no serious problems caused by a meteoroid impact during the flight mission even with local damage.

  • Micrometeoroid impact on Ceramic thin Components for interplanetary probe
    International Journal of Impact Engineering, 2008
    Co-Authors: Yasuko Motoyashiki, K Okudaira, Sunao Hasegawa, Eiichi Sato
    Abstract:

    Abstract A new advanced Ceramic thruster made of monolithic silicon nitride (Si3N4) is under development for the next interplanetary probe of PLANET-C Venus exploration mission in Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA). In order for secure operation of a spacecraft with a Ceramic Component onboard a real mission, the reliability against micrometeoroid impacts on the Ceramic Component has to be investigated in addition to the quasi-static mechanical and thermal analyses and verifications. First, the risk probability of the micrometeoroid impacts was evaluated by using an interplanetary flux model, and the risk evaluation in terms of impact energy was proposed by combining the velocity distribution with the flux model. The probability of impacts on the Ceramic thruster during the mission was estimated with this model. Second, hypervelocity impact tests were performed with a two-stage light-gas gun. Three types of failure were observed: one was only a crater formed on the impact surface. Another type was crater formation on the front-face and spall fracture on the back-face and in the last type a perforation was formed in addition to cratering and spalling. The samples did not either shatter or breakdown for the impact energies tested in this study. The impact failure morphology observed in this study showed dependency on the plate thicknesses and the projectile kinetic energy. The energy-based risk evaluation together with the series of the hypervelocity impact tests indicated that the silicon nitride Ceramic thruster onboard the interplanetary probe would have only a local damage and survive during the mission term.

Nasa - One of the best experts on this subject based on the ideXlab platform.

  • Advanced Turbine Technology Applications Project (ATTAP)
    2013
    Co-Authors: Nasa
    Abstract:

    ATTAP activities during the past year were highlighted by an extensive materials assessment, execution of a reference powertrain design, test-bed engine design and development, Ceramic Component design, materials and Component characterization, Ceramic Component process development and fabrication, Component rig design and fabrication, test-bed engine fabrication, and hot gasifier rig and engine testing. Materials assessment activities entailed engine environment evaluation of domestically supplied radial gasifier turbine rotors that were available at the conclusion of the Advanced Gas Turbine (AGT) Technology Development Project as well as an extensive survey of both domestic and foreign Ceramic suppliers and Government laboratories performing Ceramic materials research applicable to advanced heat engines. A reference powertrain design was executed to reflect the selection of the AGT-5 as the Ceramic Component test-bed engine for the ATTAP. Test-bed engine development activity focused on upgrading the AGT-5 from a 1038 C (1900 F) metal engine to a durable 1371 C (2500 F) structural Ceramic Component test-bed engine. Ceramic Component design activities included the combustor, gasifier turbine static structure, and gasifier turbine rotor. The materials and Component characterization efforts have included the testing and evaluation of several candidate Ceramic materials and Components being developed for use in the ATTAP. Ceramic Component process development and fabrication activities were initiated for the gasifier turbine rotor, gasifier turbine vanes, gasifier turbine scroll, extruded regenerator disks, and thermal insulation. Component rig development activities included combustor, hot gasifier, and regenerator rigs. Test-bed engine fabrication activities consisted of the fabrication of an all-new AGT-5 durability test-bed engine and support of all engine test activities through instrumentation/build/repair. Hot gasifier rig and test-bed engine testing activities were performed.

  • Advanced Gas Turbine (AGT) technology report
    2013
    Co-Authors: Nasa
    Abstract:

    Engine testing, Ceramic Component fabrication and evaluation, Component performance rig testing, and producibility experiments at Pontiac comprised AGT 100 activities of this period, January to December 1984. Two experimental engines were available and allowed the evaluation of eight experimental assemblies. Operating time accumulated was 115 hr of burning and 156 hr total. Total cumulative engine operating time is now 225 hr. Build number 11 and 12 of engine S/N 1 totaled 28 burning hours and constituted a single assembly of the engine core--the compressor, both turbines, and the gearbox. Build number 11 of engine S/N 1 included a 1:07 hr continuous test at 100% gasifier speed (86,000 rpm). Build number 8 of engine S/N 2 was the first engine test with a Ceramic turbine rotor. A mechanical loss test of an engine assembly revealed the actual losses to be near the original design allowance. Component development activity included rig testing of the compressor, combustor, and regenerator. Compressor testing was initiated on a rig modified to control the transfer of heat between flow path, lubricating oil, and structure. Results show successful thermal decoupling of the rig and lubricating/cooling oil. Rig evaluation of a reduced-friction compressor was initiated. Combustor testing covered qualification of Ceramic parts for engine use, mapping of operating range limits, and evaluation of a relocated igniter plug. Several seal refinements were tested on the hot regenerator rig. An alternate regenerator disk, extruded MAS, was examined and found to be currently inadequate for the AGT 100 application. Also, a new technique for measuring leakage was explored on the regenerator rig. Ceramic Component activity has focused on the development of state-of-the-art material strength characteristics in full-scale hardware. Injection-molded sintered alpha-SiC rotors were produced at Carborundum in an extensive process and tool optimization study.

  • Advanced Gas Turbine (AGT) Technology Project
    2013
    Co-Authors: Nasa
    Abstract:

    Engine testing, Ceramic Component fabrication and evaluation, Component performance rig testing, and analytical studies comprised AGT 100 activities during the 1985 year. Ten experimental assemblies (builds) were evaluated using two engines. Accrued operating time was 120 hr of burning and 170 hr total, bringing cumulative total operating time to 395 hr, all devoid of major failures. Tests identified the generator seals as the primary working fluid leakage sources. Power transfer clutch operation was demonstrated. An alpha SiC gasifier rotor engine test resulted in blade tip failures. Recurring case vibration and shaft whip have limited gasifier shaft speeds to 84%. Ceramic Components successfully engine tested now include the SiC scroll assembly, Si3N3 turbine rotor, combustor assembly, regenerator disk bulkhead, turbine vanes, piston rings, and couplings. A compressor shroud design change to reduce heat recirculation back to the inlet was executed. Ceramic Components activity continues to focus on the development of state-of-the-art material strength characteristics in full-scale engine hardware. Fiber reinforced glass-Ceramic composite turbine (inner) backplates were fabricated by Corning Glass Works. The BMAS/III material performed well in engine testing. Backplates of MAS material have not been engine tested.

John A. Skinner - One of the best experts on this subject based on the ideXlab platform.

  • Fracture of a Ceramic Component in total hip replacement
    The Journal of bone and joint surgery. British volume, 2012
    Co-Authors: Paul Whittingham-jones, Bhupinder Mann, P. Coward, Alister Hart, John A. Skinner
    Abstract:

    Fracture of a Ceramic Component in total hip replacement is a rare but potentially catastrophic complication. The incidence is likely to increase as the use of Ceramics becomes more widespread. We describe such a case, which illustrates how inadequate initial management will lead to further morbidity and require additional surgery. We present the case as a warning that fracture of a Ceramic Component should be revised to another Ceramic-on-Ceramic articulation in order to minimise the risk of further catastrophic wear.

Kenneth T Stanton - One of the best experts on this subject based on the ideXlab platform.

  • regression analysis of temperature dependent mechanical and thermal properties of dielectric technical Ceramics
    Journal of Materials Science, 2013
    Co-Authors: Daithi De Faoite, David J Browne, Kenneth T Stanton
    Abstract:

    Regression analysis is performed on a data set of temperature-dependent material properties of several Ceramic materials. The materials considered are alumina, aluminium nitride, beryllia, fused quartz, sialon, and silicon nitride. The properties considered are density, Young’s, bulk, and shear moduli, Poisson’s ratio, tensile, flexural and compressive strength, thermal conductivity, specific heat capacity, and thermal expansion coefficient. The data set, previously reported by de Faoite et al. (J Mater Sci 47(10):4211, 2012), was compiled to facilitate the materials selection and design of a Ceramic Component for the Variable Specific-Impulse Magnetoplasma Rocket (VASIMR®). Temperature-dependent material property data are required for accurate thermo-structural modelling of such Ceramic Components which operate over a wide temperature range. The goal of this paper is to calculate a set of regression coefficients to reduce this data set to a tractable format for use in the materials selection and design of such Components. Regression analysis could not be performed for all material properties for all of these materials, due to a lack of data in the literature, and these gaps in the available data are highlighted.

Kotoji Ando - One of the best experts on this subject based on the ideXlab platform.

  • a new methodology to guarantee the structural integrity of al2o3 sic composite using crack healing and a proof test
    Fatigue & Fracture of Engineering Materials & Structures, 2007
    Co-Authors: Masato Ono, Koji Takahashi, Wataru Nakao, M Nakatani, Kotoji Ando
    Abstract:

    Structural Ceramics are brittle and sensitive to flaws. As a result, the structural integrity of a Ceramic Component may be seriously affected by inherent flaws. Self-crack-healing is an excellent answer to this problem. At the moment, however, there is no technique to heal embedded flaws. Therefore, a technique to guarantee the reliability of Ceramic Components is demanded, and thus a technique using crack healing followed by proof test was developed by K. Ando et al. to accomplish this. With this technique, testing the mechanical behaviour of the crack-healed zone is very important for ensuring the structural integrity of a Ceramic Component. In this study, first Al 2 O 3 /SiC composite with an excellent crack-healing ability was sintered. Second, a crack was introduced on the sample (3 mm x 4 mm x 36 mm), which reduced the bending strength by about 80%, and subsequently the crack was healed. Third, a proof test was carried out on the crack-healed sample. Last, using the crack-healed and proof-tested sample, a fracture test was carried out up to 1373 K. The measured minimum fracture stress (σ Fmin ) was compared with the theoretical minimum strength (σ G ) from room temperature (R.T.) to 1373 K. It was concluded that σ G showed good agreement with σ Fmin up to 1373 K and that the crack healing followed by proof test was an excellent technique to increase the survival probability by administering a proof test and to guarantee the reliability of Al 2 O 3 /SiC composite.

  • crack healing and mechanical behaviour of al2o3 sic composites at elevated temperature
    Fatigue & Fracture of Engineering Materials & Structures, 2004
    Co-Authors: Kotoji Ando, Byungsoo Kim, Mincheol Chu, Sinji Saito, Koji Takahashi
    Abstract:

    Alumina/silicon carbide (Al 2 O 3 /SiC) composite Ceramics with large self-crack-healing ability, high strength and high heat-resistance limit temperature for strength were developed and subjected to three-point bending. A semicircular surface crack 100 μm in diameter was made on each sample. Crack-healing behaviour was systematically studied, as functions of crack-healing temperature and healing time, and the fatigue strengths of the crack-healed sample at room temperature and 1373 K were investigated. Four main conclusions were drawn from the present study. (1) Al 2 O 3 /SiC composite Ceramics have the ability to heal after cracking from 1273to 1673 K in air. (2) The heat-resistance limit temperature for strength of the crack-healed sample is ≅ 1573 K, and ≅68% of the samples fractured from outside the crack-healed zone in the testing-temperature range 873-1573 K. (3) The crack-healed sample exhibited very high fatigue limit at room temperature and also 1373 K. (4) The large self-crack-healing ability is a desirable technique for the high structural integrity of Ceramic Component.

  • Crack‐healing and mechanical behaviour of Al2O3/SiC composites at elevated temperature
    Fatigue Fracture of Engineering Materials and Structures, 2004
    Co-Authors: Kotoji Ando, Byungsoo Kim, Mincheol Chu, Sinji Saito, Koji Takahashi
    Abstract:

    Alumina/silicon carbide (Al 2 O 3 /SiC) composite Ceramics with large self-crack-healing ability, high strength and high heat-resistance limit temperature for strength were developed and subjected to three-point bending. A semicircular surface crack 100 μm in diameter was made on each sample. Crack-healing behaviour was systematically studied, as functions of crack-healing temperature and healing time, and the fatigue strengths of the crack-healed sample at room temperature and 1373 K were investigated. Four main conclusions were drawn from the present study. (1) Al 2 O 3 /SiC composite Ceramics have the ability to heal after cracking from 1273to 1673 K in air. (2) The heat-resistance limit temperature for strength of the crack-healed sample is ≅ 1573 K, and ≅68% of the samples fractured from outside the crack-healed zone in the testing-temperature range 873-1573 K. (3) The crack-healed sample exhibited very high fatigue limit at room temperature and also 1373 K. (4) The large self-crack-healing ability is a desirable technique for the high structural integrity of Ceramic Component.

  • crack healing proof test a new methodology to guarantee the structural integrity of a Ceramics Component
    Journal of The European Ceramic Society, 2002
    Co-Authors: Kotoji Ando, M Nakatani, Y Shirai, Yasuyoshi Kobayashi, Shigemi Sato
    Abstract:

    Abstract Structural Ceramics are brittle and sensitive to flaws. As a result, the structural integrity of a Ceramic Component may be seriously affected. To overcome this problem, there are three ways: (a) inspect carefully and repair the unacceptable flaws, (b) toughen the Ceramics by fiber reinforcing, (c) heal the flaws and recover strength. At the moment, there is no technique to heal embedded flaws. Therefore, a new technique to guarantee the reliability of Ceramics Components is demanded and so we proposed new technique: (crack-healing+proof test). For this technique, the mechanical behaviour of the crack-healed zone is very important for the structural integrity. Bending strength and fatigue strength test results of the crack-healed zone at high temperature are described. Using a process zone size failure criterion, an equation for the temperature-dependence of proof stress ( σ P T ) is derived. The accuracy of the equation has been verified for monotonic loading tests up to 1300°C.