February 5, 1996 Location: Anaheim Marriott Hotel
Session Chairperson: TBA
CALIBRATION METHOD OF THE INDENTER TIP SHARPNESS FOR MICROINDENTATION TESTS: Youngman Kim, R&D Center, Korea Gas Corp. Ansan, Korea; Min-Tae Kim, KIA Motors, Seoul, Korea
A calibration method of the indenter tip sharpness is suggested for microindentation tests. Microindentation tests were carried out on quartz glass plates and <111> silicon wafers using a microhardness tester with continuous depth recording. The worn-out height of the indenter tip was obtained from the load-depth data based on a derived linear relation between the load and the square of the penetration depth. The as-obtained values of load and penetration depth were calibrated in terms of 'worn-out' height considering near-surface effects of specimens. The elastic modulus values of quartz glass obtained from the calibrated data showed a good agreement with those from references.
MATERIALS, EVOLUTION OF THE CHOICE CONSIDERATIONS: Tawfik Benabdallah, Mohammed B. Benabdallah, University of Science and Technology of ORAN-ALGERIA
Up to the last few years, choosing any material was obeying considerations strongly related to the conditions of use. The coming years and the next century will definitely add new requirements that should be taken into account in order to fulfill conditions of satisfaction. The meaning of that is, neither the environment effect nor the energy consumption of the process are to be neglected. The aim of this contribution is showing that, the nature of the chosen material is no more firstly considered, as the Quality/price ratio is strongly related now to energy, recycling, and environment. All these considerations will make engineers facing new priorities for decision. A personal point of view will be given closed to Algerians engineers considerations as a sample of a third world country.
CONDUCTING POLYMERS: Ajay Pratap Singh, Rahul Asthana, Department of Metallurgical Engineering, Malviya Regional Engineering College, Jaipur India
Conducting polymers are emerging as new class of electronic material. These polymers have a highly anisotropic quasi-one-dimensional structure, which makes them fundamentally different from conventional inorganic semiconductors. The conducting polymers area has experienced phenomenal growth over past few years with the discovery that the polyacetylene (CH)x,could be doped with electron acceptors and electron donors to conductivity levels (1000-Omega-1cm-1) approaching those of some metals. This paper attempts to review the novel concepts associated with this new class of electronic material by describing some important properties of polyacetylene (CH)x-a well studied sample.
TOUGHENING OF CERAMICS: Rajeev Agrawal, Rajendra Kumar Goya, Department of Metallurgical Engineering, Malaviya Regional Engineering College, Jaipur, India
Advanced Ceramics have drawn much attention for engineering parts. They are finding increasing applications in electrical, electronics, defence, thermal, structural, chemical, biological, nuclear plant etc. They possess high hot strength, high compressive strength, good wear and corrosion resistance, low density, but they are brittle. In this paper recent development in toughening of ceramics have been critically summarized and reviewed. Paper deals with special case of alumina toughening. Addition of about 10 to 20 % by weight of partially stabilized zirconia (PSZ) raises the toughness and transverse rupture strength of alumina by transformation toughening. In which metastable zirconia is transformed to stable monoclinic zirconia with an increase of about 3 to 5% volume and induction of shear strain (about 7%) during the crack propagation or during machining the matrix. This enables increase in toughness and transverse rupture strength of the alumina.
LIFETIME ASSESSMENT OF INSULATION FOAMS USING THIN FILM BENDING: Sung-Sik Shin, Youngman Kim, R&D Center, Korea Gas Corp., Ansan-City, Kyunggi-do, Korea
The PU(polyurethane) foams for LNG (Liquified Natural Gas) pipe insulation are applied using RIM (Reactive Injection Molding) and covering processes. For the RIM process the adhesion force at the interface between PU foams and substrate is associated with the various properties of foams and substrate. The cracks forrned at the interface by the CTE(coefficient of thermal expansion) difference have influence on the properties and lifetime of the insulation foams since two different materials with different CTE's are bonded. In this study thermal stress variations were measured as a function of temperature to assess the lifetime of the insulation foams. The foams were applied on thin SUS304 substrates under controlled atmosphere to measure the bending caused by the CTE difference between the two materials. The amount of bending was converted to the thermal stress, in turn, the stress was used to predict the lifetime of the insulation foams.
3:40 pm BREAK
A GENETICS BASED ALGORITHM FOR INTERPRETING DOPPLER PAS DATA FOR SAMPLES WITH MULTIPLE DEFECT TYPES: Nicholas Barbosa III, James P. Schaffer, Dept. Chemical Engineering, Brian K. Aldershof, Mathematics Department, Lafayette College, Easton, PA 18042
This paper describes a new method ofor modeling Doppler broadened positron annihelation spectroscopy (DBPAS) data. The model assumes each spectrum is composed of a Gaussian and a series of parabolas associated with various defect types. The method utilizes a curve fitting procedure based on maximum liklihood estimation. A combination of expectation-maximization and genetic algorithms is used to obtain optimal values for each of the fitting parameters. The result is an ability to both identify defect types and track their relative concentrartions of DBPAS.
PROCESSING-STRUCTURE-PROPERTY RELATIONSHIPS IN MAGNETICALLY TREATED NICKLE: Marna B. Schmidt, Nicholas Barbosa III, James P. Schaffer, Dept. of Chemical Engineering, Layfayette College, Easton, PA 18042
Positron anihilation specroscopy (both Doppler and lifetime), transmission electron microscopy, and tensile tests have been using to investigate the effects of pulsed magnetic fields on the defect structure in heavily cold-worked nickle samples. The key results can be summarized as follows: i) the extent of the magnetically induced recovery is significant, ii) the pulsed magnetic field interacts preferential with dislocations while having little effect on the point defect concentration.
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