Author: Jay Edgar LanePublisher:
ISBN:
Category :
Languages : en
Pages : 436
Book Description
Kinetics and Mechanisms of Primary and Steady-state Creep in Sintered Alpha Silicon Carbide
Author: Jay Edgar LaneKinetics and Mechanisms of Creep in Sintered Alpha Silicon Carbide and Silicon Carbide Whisker Reinforced Silicon Nitride and Mullite
Author: Robert David NixonKinetics and Mechanisms of Creep in Sintered Alpha Silicon Carbide and Niobium Carbide
Author: Robert F. DavisPublisher:
ISBN:
Category :
Languages : en
Pages : 60
Book Description
Constant stress compressive creep studies and complementary TEM research have been conducted on sintered alpha-SiC and on dense polycrystalline NbCO737 to determine the kinetics and the mechanisms of deformation as a function of temperature and stress. In the former material, the values of the stress exponents of 1.44-1.71 indicate that either viscous flow or grain boundary sliding is controlling creep. However, the values of the activation energies (approx. 400kJ/mol below 1920K and approx. 850 kJ/mol above 1920K) coupled with the TEM studies which show the presence of considerable dislocation glide activity and the formation of corrugated grain boundaries and the formation of porosity on the boundaries and voids at the triple points. Originator supplied keywords include: Hot Isostatic pressing; Climb; Stacking faults; Diffusion.
Kinetics and Mechanisms of High-Temperature Creep in Silicon Carbide. II. Chemically Vapor Deposited
Author: C. H Carter (Jr)Publisher:
ISBN:
Category :
Languages : en
Pages : 10
Book Description
Chemically vapor deposited (CVD) silicon carbide was subjected to constant compressive stresses (110 to 220 MN/sq m) at high temperatures (1848 to 2023 K) in order to determine the controlling steady-state creep mechanisms under these conditions. An extensive TEM study was also conducted to facilitate this determination. The strong preferred crystallographic orientation of this material causes the creep rate to be very dependent on specimen orientation. The stress exponent, n, in the equation epsilon alpha sigma was calculated to be 2.3 below 1923 K and 3.7 at 1923 K. The activation energy for steady-state creep was determined 175 to be + or - 5 kJ/mol throughout the temperature range employed. At temperatures between 1673 and 1873 K, the controlling creep mechanism for CVD SiC is dislocation glide, which is believed to be controlled by the Peierls stress, Although the activation energy does not change, the increase in the stress exponent for samples deformed at 1923 K suggests that the controlling creep mechanism becomes dislocation glide/climb controlled by climb. Additional keywords: reprints; microstructure; x ray scattering.
Scientific and Technical Aerospace Reports
Author: Plastic Deformation of Ceramics
Author: R.C. BradtPublisher: Springer Science & Business Media
ISBN: 1489914412
Category : Science
Languages : en
Pages : 661
Book Description
This proceedings volume, "Plastic Deformation of Ceramics," constitutes the papers of an international symposium held at Snowbird, Utah from August 7-12, 1994. It was attended by nearly 100 scientists and engineers from more than a dozen countries representing academia, national laboratories, and industry. Two previous conferences on this topic were held at The Pennsylvania State University in 1974 and 1983. Therefore, the last major international conference focusing on the deformation of ceramic materials was held more than a decade ago. Since the early 1980s, ceramic materials have progressed through an evolutionary period of development and advancement. They are now under consideration for applications in engineering structures. The contents of the previous conferences indicate that considerable effort was directed towards a basic understanding of deformation processes in covalently bonded or simple oxide ceramics. However, now, more than a decade later, the focus has completely shifted. In particular, the drive for more efficient heat engines has resulted in the development of silicon-based ceramics and composite ceramics. The discovery of high-temperature cupric oxide-based superconductors has created a plethora of interesting perovskite-Iike structured ceramics. Additionally, nanophase ceramics, ceramic thin films, and various forms of toughened ceramics have potential applications and, hence, their deformation has been investigated. Finally, new and exciting areas of research have attracted interest since 1983, including fatigue, nanoindentation techniques, and superplasticity.
Research in Progress
Author: Engineered Materials Abstracts
Author: American Doctoral Dissertations
Author: Publisher:
ISBN:
Category : Dissertation abstracts
Languages : en
Pages : 800
Book Description
Kinetics and Mechanisms of High-temperature Creep in Chemically Vapor Deposited and Reaction-bonded Silicon Carbide
Author: Calvin Haywood CarterPublisher:
ISBN:
Category : Creep testing machines
Languages : en
Pages : 410
Book Description