General Electric

About: General Electric is a company organization based out in Boston, Massachusetts, United States. It is known for research contribution in the topics: Turbine & Signal. The organization has 76365 authors who have published 110557 publications receiving 1885108 citations. The organization is also known as: General Electric Company & GE.

Infrared Absorption in Some II-VI Compounds Doped with Cr

Abstract: The optical absorption spectra of substitutional ${\mathrm{Cr}}^{2+}$ ($3{d}^{4}$) in single crystals of ZnS (cubic and mixed cubic-and-hexagonal), ZnSe, ZnTe, CdS, and CdTe have been measured for Cr concentrations of ${10}^{18}$-${10}^{20}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ and at 2, 15, and 300\ifmmode^\circ\else\textdegree\fi{}K in the wave-number range $5\ensuremath{\le}\overline{\ensuremath{ u}}\ensuremath{\le}30000$ ${\mathrm{cm}}^{\ensuremath{-}1}$. The room-temperature spectrum in the range $500\ensuremath{\le}\overline{\ensuremath{ u}}\ensuremath{\le}30000$ ${\mathrm{cm}}^{\ensuremath{-}1}$ is dominated by a broad absorption band at 5500 ${\mathrm{cm}}^{\ensuremath{-}1}$ arising from the $^{5}T_{2}\ensuremath{\rightarrow}^{5}E$ transition. These two levels originate from the crystal-field splitting of the $^{5}D$ free-ion ground state. At helium temperatures distinct lines appear on the low-energy side of the $^{5}T_{2}\ensuremath{\rightarrow}^{5}E_{2}$ absorption band in all samples except for CdTe. These lines are associated with zero-phonon transitions and phonon-assisted transitions. As the temperature is increased, the relative intensities of some of the lines change due to the thermal population of low-lying levels belonging to the orbital ${T}_{2}$ state. In the case of ZnSe these levels have been studied in the far infrared in the range $5\ensuremath{\le}\overline{\ensuremath{ u}}\ensuremath{\le}200$ ${\mathrm{cm}}^{\ensuremath{-}1}$, both with and without a magnetic field. An interpretation of the results is made based on crystal-field theory with a strong, static, Jahn-Teller distortion of $E$ symmetry in the $^{5}T_{2}$ orbital ground state. There is little or no Jahn-Teller effect in the $^{5}E$ orbital excited state. The optical transitions exhibit a strong coupling to $E$-mode phonons of average energy \ensuremath{\sim}70 ${\mathrm{cm}}^{\ensuremath{-}1}$.

Composite compact of interleaved polycrystalline particles and cemented carbide masses

Abstract: One or more masses of bonded particles of diamond, cubic boron nitride (CBN), and wurtzite boron nitride (WBN) are sandwiched between or encapsulated by two masses of cemented carbide bonded to the particle masses. In the preferred embodiment, the particle masses are comprised of (1) at least 70% by volume of said particles, and (2) a metallic phase comprised of the cementing agent of the carbide mass. The composite compacts find utility in drill bit, mining tool and wear part applications. A method for making such a composite compact comprises (1) placing within a reaction cell masses of abrasive particles and at least two carbide masses interleaved with the abrasive particle masses, (2) the masses are placed in the cell in such a manner to allow for the accommodation of pressure and (3) simultaneously subjecting the cell and the contents thereof to temperature and pressure conditions at which the particles are stable. A method for abrading or cutting a workpiece with a composite compact comprises providing (1) a tubular carbide mass and a bonded mass of abrasive particles disposed in and bonded to the carbide mass in a central cavity thereof and (2) moving either the compact or workpiece relative to the other to provide the cutting or abrading action.

Anisotropic Thermal Conductivity of Pyrolytic Graphite

Abstract: The thermal conductivity $K$ of a bulk sample of pyrolytic graphite has been measured from 3 to 300\ifmmode^\circ\else\textdegree\fi{}K both perpendicular and parallel to the $c$ axis. Over the whole temperature range below 100\ifmmode^\circ\else\textdegree\fi{}K the thermal conductivity in both directions appears to be limited by the crystallite size. The measured value of ${K}_{\ensuremath{\perp}}$ is 0.72 W/cm deg at 300\ifmmode^\circ\else\textdegree\fi{}K, and ${K}_{\ensuremath{\perp}}$ decreases monotonically to 1.4\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$ W/cm deg at 3\ifmmode^\circ\else\textdegree\fi{}K. The measured anisotropy $\frac{{K}_{\ensuremath{\perp}}}{{K}_{\mathrm{II}}}$ decreases monotonically from 47 at 300\ifmmode^\circ\else\textdegree\fi{}K to 2.5 at 3\ifmmode^\circ\else\textdegree\fi{}K. A theoretical calculation of the anisotropy from the elastic constants yields a value of 2.27 for $T\ensuremath{\le}1\ifmmode^\circ\else\textdegree\fi{}$K. A suggestion is offered to explain the rapid rise in the anisotropy with increasing temperature. Previous measurements of $\frac{{K}_{\ensuremath{\perp}}}{{K}_{\mathrm{II}}}$ in natural and commercial graphite samples are much smaller.

Quantitative Prediction of Environmentally Assisted Cracking

Abstract: It has long been recognized that the stress corrosion cracking (SCC) and corrosion fatigue cracking susceptibility of various alloy and environment systems is dependent upon complex interactions between stress, material, and environmental parameters. This complexity can lead to scatter in cracking responses that, in turn, leads to difficulty in predicting the life of engineering structures. F.P. Ford was the 1995 recipient of the W.R. Whitney Award sponsored by NACE International. The present work is taken from his award lecture at CORROSION/95 held in March 1995 in Orlando, Florida. His lecture focused on how these interactions may be predicted quantitatively for ductile alloys in aqueous environments with knowledge of the cracking mechanism. This capability may lead to life prediction of critical structures in, for instance, boiling-water nuclear reactors (BWR).

The insulated gate rectifier (IGR): A new power switching device

Abstract: A new power semiconductor device called the Insulated Gate Rectifier (IGR) is described in this paper. This device has the advantages of operating at high current densities while requiring low gate drive power. The devices exhibit relatively slow switching speeds due to bipolar operation. The results of two dimensional computer modelling of the device structure are compared with measurements taken on devices fabricated with 600 volt forward and reverse blocking capability.