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 | REVIEW OF AGEING BEHAVIOUR OF YTTRIA-TETRAGONAL ZIRCONIA POLYCRYSTALS (Y-TZP): PART 2, AGEING MECHANISM | |
ABSTRACT:
This second ageing paper is focused mainly on the various mechanisms used to explain the low temperature degradation phenomenon in Y-TZP ceramics. An understanding of the ageing phenomenon in Y-TZP ceramics has been established and discussed. In general, although the theories are contradictory in nature, it has been universally accepted that the cause of degradation was due to the tetragonal to monoclinic phase transformation. Water has been identified as the key player in triggering the phase transformation.
AUTHOR:
Ramesh Singh |
| Year:
1999 |
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| INVESTIGATION OF TURBULENCE STRUCTURES IN LIQUID/LIQUID TWO-PHASE FLOW: PART 1: LIQUID MEAN VELOCITY AND TURBULENCE MEASUREMENT | |
ABSTRACT:
The liquid phase turbulent structure of kerosene/water, bubbly upflow in a circular pipe has been experimentally investigated. Liquid phase velocities and turbulent stress were simultaneously measured, using single normal boundary layer hot-film anemometer probes. A highly accurate digital process, based on combination of amplitude and threshold methods, was developed to identify the phases. Methods are described and discussed for the evaluation of longitudinal mean velocity, normal stress, autocorrelation and energy spectrum. Finally typical results for a vertical up-flow of bubbly kerosene/ water mixtures are presented.
AUTHOR:
Jusni Ali and Yahya Sukirman |
| Year:
1999 |
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| INTERFACIAL REACTION BETWEEN SiC AND ALUMINIUM DUE TO EXTRUSION AND HEAT TREATMENT PROCESS | |
ABSTRACT:
Chemical interaction between aluminium (Al) and silicon carbide (SiC) produces aluminium carbide (Al4C3) which presents potential problems in the production and application of AI/SiC Metal Matrix Composite (MMC). The (Al4C3) formed can reduce material properties such as strength in the MMC. This research work investigates the interface reaction in Al 7075/SiC MMC made through hot extrusion process. Mixed Al 7075/SiC MMC powders were pressed at 300°C and extruded at 500°C, with a reduction ratio of 20:1. The extruded MMC was then heat-treated in air at various temperatures from 560°C, 600°C, 640°C, 700°C to 800°C in order to observe the interface reaction of the MMC materials. The heat-treated MMCs were then analyzed under the optical microscope, X-ray Diffraction (XRD) Spectroscope and Scanning Electron Microscope (SEM) with Energy Dispersive X-ray (EDAX) attachment to observe the interface reaction within the MMCs. This investigation confirms there was interface reaction between SiC and aluminium.
AUTHOR:
Junaidah Jai, Fauzi Ismail, Samsiah Sulaiman, Patthi Hussain and Azmi Idris |
| Year:
1999 |
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| ESTERS IN WATER/OIL MICROEMULSION STABILISED BY ANIONIC SURFACTANT AND A MEDIUM CHAIN ALCOHOL | |
ABSTRACT:
Four esters were applied in the W/0 microemulsion phase of water/ sodium dodecyl sulphate (SDS): hexan-1-ol (35:65)/hydrocarbon (n-decane and p-xylene) to study their solubility behaviour in such system. The esters used were ethyl-n-butyrate, ethyl benzoate, methyl oleate and methyl linolenate. The solubility of the esters was observed to be dependent of the ratio of the SDS: hexan-1-ol and hydrocarbon. A higher solubility of the esters was observed in a larger ratio with ethyl-n-butyrate showing the highest solubility. The solubility was, however, inversely proportional to the water content of the microemulsion. The type of hydrocarbon was observed to have little or no appreciable effect on the solubility of the esters.
AUTHOR:
Hamdan, Suhaimi, Laili Che Rose, Faujan Ahmad, Dzulkefly Kuang and Ambar Yarmo |
| Year:
1999 |
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| DEVELOPMENT OF SUPERCONDUCTOR APPLICATIONS IN THE POWER SYSTEM INDUSTRY | |
ABSTRACT:
The discovery of high temperature superconductors has revived interests for the development of superconductive devices for power system applications. Substantial progress has been made towards the consequent acceptance of superconductive power components into the power system with further improvements to material fabrication and refrigeration system aimed at justifying its application and economic feasibility. Commercialisation of these devices is dependent on their ability to compete cost effectively in the marketplace with prevailing technology. In addition, the operational advantages and hoped for improvements in the reliability of superconductors are also key factors for potential widespread superconductor applications in the future utility market. The most significant development in countries (U.S.A., Japan, Germany) with the largest superconductor R&D programmes are highlighted with relevance to the device discussed. A discussion of the significance of these development programmes to the Malaysian power and energy sector is also presented at the end of this article.
AUTHOR:
M. Moghavvemi, S.S. Yang and A.M.R. Mustafizur |
| Year:
1999 |
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| BUOYANCY EFFECT OF PURGE GAS IN THE DETERMINATION OF CARBON BLACK CONTENT IN POLYETHYLENE | |
ABSTRACT:
Oxygen and air have been interchangeably used as the purge gas in the determination of carbon black content in polyethylene. This study shows that accuracy of the carbon black filler content is significantly affected by the choice of oxygen as the purge gas used to oxidise the carbon filler. It is believed that the difference in the density of the oxygen give rise to the buoyancy effect. Air, having closer density to the initial nitrogen purge gas in the analysis, is the better choice for purge gas for accuracy of analysis and reproducibility of results.
AUTHOR:
M.Y. Ahmad Fuad, Z. Ismail, S. Rahmad and H. Hanim |
| Year:
1999 |
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