Ghulam Ishaq Khan Institute of Engineering Sciences and Technology

About: Ghulam Ishaq Khan Institute of Engineering Sciences and Technology is a education organization based out in Topi, Pakistan. It is known for research contribution in the topics: Quantum efficiency & Diode. The organization has 618 authors who have published 940 publications receiving 10674 citations.

Investigation on Failure in Thermal Barrier Coatings on Gas Turbine First-Stage Rotor Blade

Abstract: Failure in turbine blades can affect the safety and performance of the gas turbine engine. Results of coating decohesion, erosion and cracking at the first-stage high-pressure (HPT) blade working in gas turbine engine are being reported in this paper. This investigation was carried out for the possibility of various failure mechanisms in the thermal barrier coating exposed to high operating temperature. The blade was made of nickel-based superalloy, having directionally solidified grain structure coated with thermal barrier coatings of yttria-stabilized zirconia with EB-PVD process and platinum-modified aluminum (Pt–Al) bond coat with electro-deposition. The starting point of analysis was apparent coating decohesion close to the leading edge on the suction side of blade. The coating decohesion was found to be widening of interdiffusion zone toward the bond coat at higher operating temperature which could change the composition and induce thermal stresses in the bond coat. The erosion, cracking and decohesion of the coating on the pressure side was also observed during failure investigation. The erosion of the coating was coupled by two factors: one by increase in temperature as demonstrated by change in microstructure of the substrate and second by increase in coating inclination toward the trailing side. As a result of high operating temperature, swelling and thickening of TGO was observed due to outward diffusion of aluminum from the bond coat to form alumina (non-protective oxide) which causes internal stresses that leads to top coat decohesion and cracking. The possibility of hot corrosion was also investigated, and it was found that top coat decohesion did not involve this failure mechanism. Visual inspection, optical microscopy, scanning electron microscopy and energy-dispersive spectroscopy have been used as characterization tools.

A low-cost printed humidity sensor on cellulose substrate by EHD printing

Abstract: The use of printing technologies is rapidly increasing in area of electronic devices. Electrohydrodynamic (EHD) jet printing has been a target of research because of its aptness to produce high-resolution patterns for wide range functional materials onto flexible substrates. In this paper, a stable humidity sensor was printed utilizing PEDOT: PSS as sensing layer. Meander-type electrodes using silver nanoparticles ink were fabricated using continuous EHD inkjet printing on flexible paper (cellulose) substrate. The sensing material PEDOT: PSS was dissolved in ethylene glycol and then deposited on silver electrodes. The fabricated sensor exhibited decent response toward change in capacitance above 50% relative humidity. The response and recovery time of the printed sensor for increasing and decreasing humidity levels were approximately 0.58 s and 0.7 s, respectively. This low-cost sensor has potential applications in agriculture, food monitoring, medical and industrial environment as a disposable sensor for humidity detection. Fig. (A): Schematic illustration of EHD printing system, (B): (1) 200 × Optical microscopy images of PEDOT: PSS (a) 50% layer (b) 30% layer (c) 20% layer and (2) AFM images of PEDOT: PSS (a) 50% layer (b) 30% layer (c) 20% layer, (C): Humidity sensor (a) Schematics (b) Printed Ag Electrodes and (c) PEDOT: PSS deposited, and (D): (a) Measured capacitance and (b) Response and Recovery time of 50% PEDOT:PSS sensor and (E): PEDOT:PSS ink preparation.

A proposed optimized solution for wireless power transfer using magnetic resonance coupling

Abstract: In this modern system, power is part of our lives. These days power is being transmitted through wires and it has some limitations like in medical area or in robotics because it's difficult to be connected with wires all the time. Rechargeable batteries are also not feasible solution because they needed to be charged regularly and also carry some weight and space. In medical area pacemakers and defibrillators need to be installed inside human skin and required to replace their batteries after specific interval of time. But using wireless power transfer we can charger their batteries without cutting skin. Wireless power transfer (WPT) is under development technology these days. Researchers have developed many techniques to transfer power without wires but recently MIT researcher's demonstration got attention when they transmitted 60W over a distance of two meters using WPT magnetic resonance technique but the efficiency and range remained serious problem. This paper will describe optimized model of maximum wireless power transfer and also way to increase the range between transmitting and receiving coil.