Fibre-epoxy composites at low temperatures

The thermal and mechanical properties of carbon, glass and Kevlar fibre reinforced epoxy composites are discussed, with particular reference to the behaviour of these materials at cryogenic temperatures. The effects of production techniques and various fibre arrangements are determined.     

Automatic determination of the foam end point in a simulated dishwashing test

The disappearance of foam when increments of soil are added is frequently used to assess the foam performance of surfactants in dishwashing. A small scale screening test has been published using a Terg-o-tometer to generate foam and disperse the soil. However, the end point is difficult to determine visually because of the violent agitation of the surface. A method has been developed, whereby the surface foam reflectance is automatically and continuously recorded from four beakers of surfactant solution simultaneously. Near the end point, the rate of foam disappearance is determined and the complete foam disappearance can be interpolated from the instrumental recorded curves. Comparisons are given for experienced operator and instrumentally determined end points which are shown to be in agreement.     

Qualification of the LF-eddy current technique for the inspection of stainless steel cladding and applications on the reactor pressure vessel

As part of the re-inspection of the reactor pressure vessel of the nuclear power plant, the low-frequency-eddy current technique was implemented during the 1995 outage. Since then, this inspection technique and the testing equipment have seen steady further development. Therefore, optimization of the entire testing system, including qualification based on the 1995 results, was conducted. The eddy current testing system was designed as a ten-channel test system with sensors having separate transmitter and receiver coils. The first qualification of the testing technique and sensors was performed using a single-channel system; a second qualification was then carried out using the new testing electronics. The sensor design allows for a simultaneous detection of surface and subsurface flaws. This assumes that testing is performed simultaneously using four frequencies. Data analysis and evaluation are performed using a digital multi-frequency regression analysis technique The detection limits determined using this technique led to the definition of the following recording limits for testing in which the required signal-to-noise ratio of 6 dB was reliably observed.

• Detection of surface connected longitudinal and transverse flaws:

• notch, 3 mm deep and 10 mm long, for weave bead cladding;

• notch, 2 mm deep and 20 mm long, for strip weld cladding.

• Detection of embedded planar longitudinal and transverse flaws:

• ligament of 7 mm for 8 mm clad thickness and 3 mm;

• ligament for 4 mm clad thickness, notch starting at the carbon steel base material with a length of 20 mm.

• Detection of embedded volumetric longitudinal and transverse flaws:

• 3 mm diameter side-drilled hole (SDH) for 8 mm clad thickness; ligament, 4 mm. For 4 mm clad thickness: diameter, 2 mm SDH; ligament, 2 mm. All SDHs are 55 mm deep.

In Praise of Basic Research as a Vehicle to Practical Applications: Palladium-Catalyzed Coupling to Form Carbon-Nitrogen Bonds

Two groups′ research initiated to address two very different questions on problems of basic chemical research led, after much effort on catalyst development and studies of reaction mechanism, to the discovery and development of the coupling of amines with aryl halides in a practical fashion.     

APPLICATIONS OF THE DRAZIN INVERSE TO THE HILL CRYPTOGRAPHIC SYSTEM. PART II.

The present Part II continues the discussion in Part I of the Drazin inverse as applied to the Hill system. A second type of Drazin inverse key-matrix (V-key) is treated in detail. The V-key is of a more complex nature than the W-key considered in Part I and allows for the use of a general involution. There are several worked out Examples and some Problems for the reader. The reader should have available Part I which includes a mod 26 multiplication table.     

Equal-channel angular extrusion of beryllium

The equal-channel angular extrusion (ECAE) technique has been applied to a powder metallurgy (P/M) source Be alloy. Extrusions have been successfully completed on Ni-canned billets of Be at approximately 425°C. No cracking was observed in the billets, and significant grain refinement was achieved. In this article, microstructural features and dislocation structures are discussed for a singlepass extrusion, including evidence of <c> and <c+a> dislocations. Significant crystallographic texture developed during ECAE, which is discussed in terms of this unique deformation processing technique and the underlying physical processes which sustain the deformation. S.R. AGNEW, formerly with the Oak Ridge National Laboratory, Oak Ridge, TN 37831-6115 This article is based on a presentation made in the symposium entitled “Defect Properties and Mechanical Behavior of HCP Metals and Alloys” at the TMS Annual Meeting, February 11–15, 2001, in New Orleans, Louisiana, under the auspices of the following ASM committees: Materials Science Critical Technology Sector, Structural Materials Division, Electronic, Magnetic & Photonic Materials Division, Chemistry & Physics of Materials Committee, Joint Nuclear Materials Committee, and Titanium Committee.