Showing papers by "Ghulam Ishaq Khan Institute of Engineering Sciences and Technology published in 1998"
TL;DR: In this paper, a new family of high-strength low-alloy steels with copper additions (HSLA-100) has been developed, which includes a reduction in the carbon content, which improves toughness and weldability.
Abstract: The structural steels used in critical construction applications have traditionally been heat-treated low-alloy steels. These normalized and/or quenched and tempered steels derive strength from their carbon contents. Carbon is a very efficient and cost-effective element for increasing strength in ferrite-pearlite or tempered martensitic structures, but it is associated with poor notch toughness. Furthermore, it is well known that both the overall weldability and weldment toughness are inversely related to the carbon equivalent values, especially at high carbon contents. The stringent control needed for the welding of these traditional steels is one of the major causes of high fabrication costs. In order to reduce fabrication cost while simultaneously improving the quality of structural steels, a new family of high-strength low-alloy steels with copper additions (HSLA-100) has been developed. The alloy design philosophy of the new steels includes a reduction in the carbon content, which improves toughness and weldability.
69 citations
TL;DR: In this article, a long length of Bi-2223 conductors doped with Ag, Nb and B were fabricated and the recrystallization of the glasses during various heat treatments was studied by differential thermal analysis (DTA), differential scanning calorimetry, X-ray diffraction and resistivity measurements.
Abstract: Long lengths of Bi-2223 conductors doped with Ag, Nb and B were fabricated. The recrystallization of the glasses during various heat treatments was studied by differential thermal analysis (DTA), differential scanning calorimetry, X-ray diffraction and resistivity measurements. Activation energies and frequency factors for crystallization were determined by non-isothermal DTA, employing different models. It was found that both the peritectic transition and the reaction rate were dependent on the ambient atmosphere. Kinetic studies under different atmospheres revealed that the thermal stability of Bi-2223 was greatly enhanced under an oxygen atmosphere. Jc measurements at 77 K showed an increase on silver addition. Furthermore it was found that the silver addition does not destroy the superconductivity. © 1998 Chapman & Hall
8 citations
TL;DR: In this article, a sintering cycle is proposed for which the film properties are least modified with a minimum level of porosity, where the microstructure of the Ag layer is no longer composed of a contiguous network of large silver agglomerates.
Abstract: Silver films were deposited over porcelain substrates by using flexible adhesive transfer layers. These films were produced in order to use porcelain utensils over household induction heating plates. Mixtures of different glass ceramic powders with silver powder are used to prepare the self-transfer patterns. These patterns are deposited over porcelain substrates and sintered using different heating cycles. One defect observed in such films is the presence of porosity either at the Ag/porcelain interface or inside the Ag film structure. While lower sintering temperatures produce less porosity, the microstructure of the Ag layer at lower temperatures is no longer composed of a contiguous network of large silver agglomerates. Consequently, the heating capability of the layer through electromagnetic induction is affected. Finally a sintering cycle is proposed for which the film properties are least modified with a minimum level of porosity.
1 citations