http://localhost:80/xmlui/handle/123456789/17211 2026-04-05T21:22:14Z 2026-04-05T21:22:14Z S. Z. Hussain S. K. Durrani S. K. Durrani M A. Hussain N. Hussain M. Ahmad http://localhost:80/xmlui/handle/123456789/18654 2023-03-13T08:16:46Z 2010-06-06T00:00:00Z

Title: Phase and Thermal Analysis of Magnesium Aluminum Silicate Glass Ceramic Authors: S. Z. Hussain; S. K. Durrani; S. K. Durrani; M A. Hussain; N. Hussain; M. Ahmad Abstract: Magnesium aluminum silicate (MAS) glass ceramic systems are of technological importance due to their application for high voltage and in ultra high vacuum. These materials not only possess peculiar feature of machinability but also have superior electrical insulation, ultra-high vacuum compatibility, high thermal stability, low thermal conductivity and good mechanical strength. MAS glass-ceramic material was prepared by sintering route. A three-stage heating schedule consisting of calcination, nucleation and crystallization has been evolved with MgF2 as a nucleating agent. The effect of stoichiometric composition and sintering temperature on density of compacted materials and development of phases were studied by X-ray diffraction (XRD). XRD revealed the formation of magnesium silicate, fluorophlogopite, nobergite, and siliminite at different processing temperatures. Thermal stability of MAS was measured by thermogravimetry (TG), differential thermal analysis (DTA). TG/DTA studies revealed that powder existed as MgO-Al2O3-SiO2-H2O in solid state and then transformed to MgO-Al2O3-SiO2 via some meta-stable intermediates after 300oC and thermally stable above 900oC with mass loss of 9.14%. Some surface porosity (3-4%) was detected by scanning electron microscope.

2010-06-06T00:00:00Z A. Maqsood K Iqbal http://localhost:80/xmlui/handle/123456789/18653 2023-03-13T08:16:37Z 2010-06-04T00:00:00Z

Title: Materials Characterization by Non-Destructive Methods Authors: A. Maqsood; K Iqbal Abstract: The correlation of physical and chemical properties with structural characteristic is important in Materials Science. There are two methods destructive method first and non-destructive second. The destructive method requires dissolution into a fluid phase but non-destructive method does not require it. The non-destructive characterization methods of solid materials can be described in different categories depending upon the type of information required. For elemental analysis, the techniques XRF and EDXRF are used. Structural properties are known by XRD and XPS. To get the information of morphology and topography, SEM and AFM are the recommended techniques. Qualitative and quantitative characterization techniques for solids are discussed with limitations.

2010-06-04T00:00:00Z Muhammad Daniel Pirzada Mian M. Nawaz http://localhost:80/xmlui/handle/123456789/18652 2023-03-13T08:16:19Z 2010-06-03T00:00:00Z

Title: Surface Modification of Powders Authors: Muhammad Daniel Pirzada; Mian M. Nawaz Abstract: Materials in powder form find vast applications that range from structural applications to food items. Many situations demand different or even contradicting set of bulk characteristics and surface characteristics of powders employed in certain applications. The solution of this problem is an appropriate surface engineering process to tailor the properties of the powders according to the particular set of required characteristics. Various processes developed for this purpose include physical as well as wet chemical methods. Chemical Vapor deposition (CVD) has many advantages over other competing processes like rigorous mixing, excellent heat and mass transfer, homogeneous temperatures and consequently uniform coating. Fluidized Bed Chemical Vapor Deposition (CVD-FBR) process, a variant of CVD is a novel method for coating of powders and whiskers. This paper reviews some of the important processes used for this purpose. The salient features of the major processes used for surface modification have been discussed with a reference to their areas of application. The limitations of the processes have also been highlighted.

2010-06-03T00:00:00Z S. Ali F. Gonella P. Mazzoldi http://localhost:80/xmlui/handle/123456789/18650 2023-03-13T08:15:30Z 2010-01-02T00:00:00Z

Title: Transport mechanism of multivalent ions of transition metals into silicate glasses by solid-state field-assisted ion exchange Authors: S. Ali; F. Gonella; P. Mazzoldi Abstract: Field-Assisted Solid-State Ion-Exchange (FASSIE) technique for doping silicate glasses with transition metals and rare-earths has been attracting much attention for its potential applications in light waveguides, luminescent materials and for the possibility to realize systems in which formation of metal nano-cluster is controlled by suitable postexchange techniques1-6. In the presented experiments, metallic films of Au and Co are deposited onto the soda-lime (SL) and borosilicate (BK7) substrates by the radiofrequency (rf) sputtering technique. Metal ions substitute the glass alkali by means of field-assisted diffusion realized at different values of temperature and electric field. Preliminary results are also presented for the direct diffusion of Er owing to the applied field. The nanocomposites are characterized by secondary ion mass spectrometry (SIMS), Rutherford backscattering spectrometry (RBS), optical absorption and transmission electron microscopy (TEM), indicating that the migration not only depends on the experimental parameters but also on the local structure and the chemical phenomena occurring at the metal/glass interface. The alkali composition in both glasses dramatically changes the diffusion profiles, resulting in a homogenous and uniform in-depth diffusion in BK7 glass than SL.

2010-01-02T00:00:00Z