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A superconducting material with a composition Y1−xBa2Cu3O7−3/2x − x/2 Bi2O3 (x = 0·1 and 0·2) was synthesised. The influence of Bi2O3 additions on sintering was studied. Preliminary investigations of the Bi‐Sr‐Ca‐Cu‐O system were also made. Thick film pastes, prepared from Y1−xBixBa2Cu3O7 compositions, from the compound YBa2Cu3O7 with 10 w/o addition of Bi2CuO4 and from two compositions in the Bi‐Sr‐Ca‐Cu‐0 system, were fired on Al2O3 and ZrO2 substrates. All thick film materials based on YBa2Cu3O7 compound were superconducting at temperatures above 77 K when fired on ZrO2 substrates, while only a material with the starting composition Y0·8Ba2Cu3O6.7 − 0·1 Bi2O3 reached zero resistivity above 77 K on Al2O3 substrates. Tc (onset) of samples based on the YBa2Cu3O7 compound was around 95 K, and of samples from the Bi‐Sr‐Ca‐Cu‐O system between 95 and 100 K.

Nickel aluminide coatings on mild steel have been prepared by pack cementation process. The high temperature oxidation behaviour of the coatings have been studied at 750°, 800° and 850° in flowing air. The influence of different rare earth oxide addition on the oxidation rates of nickel aluminide coating on mild steel has also been investigated. The kinetic of the oxidation of nickel aluminide coating on mild steel, with or without addition of RE2O3 proceeds by a diffusion controlled mechanism as revealed by the parabolic nature of weight gain Vs time plots. At higher temperatures the oxidation rates of the nickel aluminide coatings are lowered down markedly irrespective of rare earth oxide concentration. The oxidation rates are significantly affected by the morphology of the oxide scales, in cases where the structure of oxide scales is not seriously disrupted due to decarburization, the oxidation rates are significantly reduced.

A superconducting material with the composition YBa1.8Pb0.2Cu3O7 was synthesised. The influence of PbO addition on the sintering and formation of the superconducting compound YBa2Cu3O7 was investigated. A thick film paste, prepared from prereacted material and an organic vehicle, was fired on Al2O3 and ZrO2 substrates. The resistivity of samples on ZrO2 substrates decreased to zero around 90 K, while samples on Al2O3 substrates did not reach zero resistivity until 77 K, which is probably due to the differences in thermal expansion coefficient between Al2O3 and the superconducting material. Interactions between Pt alloy based thick film conductors and superconducting material were studied.

The similarity of its temperature expansion coefficient to that of silicon, as well as its high thermal conductivity, makes AlN a material suited for application in microelectronics. A comparison of the various AlN manufacturers shows above all differences in the choice of sintering aids and the type of sintering process. A comparison of a standard paste system (Du Pont) with a new special development (Shoei) demonstrates the need for adapting the pastes to AlN ceramics. Thin film technology is possible at a standard similar to that of Al2O3.

The aim of the present paper was the study of mechanical and microstructural behaviour of 6061/Al2O3/20p metal matrix composite sheets joined by Friction Stir Welding. The material was welded into the form of sheets of 7 mm thickness after T6 treatment and was tested in tension and fatigue at room temperature. The mechanical behaviour of the material was found to depend strongly on the particles fracture across the weld. The tensile properties in longitudinal direction resulted higher respect to the transversal ones. The fatigue endurance (S‐N) curve of the welds was obtained by using a resonant electro‐mechanical testing machine under constant loading control up to 250 Hz sine wave loading. The cyclic fatigue tests were conducted in the axial total stress‐amplitude control mode with min max R = σ / σ The microstructure resulting from the FSW process was studied by employing optical and scanning electron microscopy.

Knowledge of critical materials and process parameters necessary to fabricate quality copper thick film multilayer and hybrid circuits is being amassed and distributed throughout the industry via technical reports and presentations. Generally the information being provided in a single report deals with specific segments of the industry or only one or two specific nitrogen fireable materials. In order for hybrid manufacturers to commit themselves to the technology they need to know that sufficient flexibility exists to permit design of complex circuits and accommodate circuit design changes without imposing changes in basic process guidelines and controls. The OEM's concern, which is valid, has been that the investment required for capital equipment and establishing new processes must be fully supported by and provide reasonable return from the technology being initiated. This paper introduces new information on wire bonding in copper thick film circuits and some improvements in nitrogen fireable resistor characteristics and processing. Materials are available to produce a broad range of circuits without varying basic process parameters, and adding wirebonding as an interconnect capability further expands the circuit complexity and density achievable with copper thick films.

The purpose of this paper is to investigate the oxidation behavior of Ti‐48Al‐8Cr‐2Ag (at.%) at 900°C and 1000°C for various different times.

Laboratory tests were performed to determine growth process of the oxide scale at 900°C and 1000°C for various different times with SEM/EDX, XRD and TEM.

Merely Al2O3 occurred on the Laves phase at the initial stage at 900°C, while a mixture of Al2O3+TiO2 formed at the initial stage at 1000°C. Oxidation rate of the alloy at 900°C after long‐term oxidation was higher than that at 1000°C because a dense Al2O3 scale formed on the surface at 1000°C.

The paper shows that the oxidation behavior of TiAl alloy at initial stage is the basis of the revealing mechanism of oxidation. It is necessary to further investigate the oxidation of Ti‐Al‐Cr‐Ag alloy in more detail to clearly understand its oxidation process and growth process of the oxide scale.

This contribution aims to introduce an effective low cost polymer-nanocomposite for possible application to achieve a super protection for highly damaged ancient Egyptian wall paintings.

SiO2 and Al2O3 nanoparticles were synthesized by the sol-gel method. Then, the polymer-nanocomposite was prepared by simple mixing and dispersing the nanoparticles into the tetraethoxysilane polymer solution, with the aid of an ultrasonic dismembrator. The application of the polymer-nanocomposite and other polymeric nanodispersions, on laboratory models, was performed by the brushing technique. Next, the materials stability was evaluated by means of digital optical microscope, colorimetry, FE-scanning electron microscope, measuring the static contact angle and water absorption rates.

The results were promising in creating a superhydrophobicity and the static contact angle (?S) measured for the polymer-nanocomposite reached 135o. An average of three measurements of the water absorption rate after polymer-nanocomposite treatment was 0.66 g/m2 s, compared to 2.60 g/m2 s for the control model (untreated). Further, an average of color difference (?E*) for the treated surface was 2.78, and after the accelerated thermal aging was 3.6. Observing the surface morphology, the polymer-nanocomposite enhanced the roughness of the treated surface and showed a high resistance to laboratory salt weathering.

Preparation of a polymer-nanocomposite by adding SiO2 and Al2O3 NPs to tetraethoxysilane polymer has been proposed. As a promising conservation material, the produced polymer-nanocomposite helped to form an efficient protective film.

This paper attains to develop an economic polymer-nanocomposite to maintain a high protection to damaged ancient Egyptian wall paintings and similar objects.

Accurate measurements of the temperature distributions in hot section components are indispensable for the prognostic and health management of gas turbines. Thin film thermocouple (TFTC) sensors, directly fabricated on the surface of a component, add negligible mass and create little or no disturbance to airflow, and therefore, can provide accurate measurements of fast temperature fluctuations of gas turbines. The purpose of this paper is to evaluate TFTC sensors fabricated by combining pulsed laser deposition (PLD) and micromachining techniques (LM).

The “dry” PLD/LM fabrication approach allows for excellent control of the chemical composition and physical characteristics of the constituent layers and their interfaces, thus achieving good adhesion of the layers to the substrate.

The results of thermal cyclic durability testing of the fabricated TFTC sensors demonstrated that the proposed PLD-based approach can be used to fabricate sensors that are fully functional at temperatures up to 750°C. Analyses of the sensor performance during durability testing revealed: the existence of a threshold temperature below which accurate temperature measurements were achieved; an abrupt drop in the sensor output occurring when the sensor temperature exceeded the threshold value, with a fast recovery of the sensor output once the temperature was reduced below the threshold level; and sensor “training” capable of increasing the threshold value of the TFTC through its exposure to above-the-threshold temperatures.

The work is the first time to demonstrate that simple PLD and LM processes can be used to fabricate TFTC that are fully functional at temperatures up to 750°C.

This paper reports the preliminary investigations on the effect of Bi2O3, Al2O3 and MgF2 thick film overlays on a symmetrical branch line microstrip directional coupler with a 3 db power split at 9.0 GHz. The changes in isolation and coupling with overlay thickness varying from 200 µm to 3000 µm were studied. It was observed that, for an overlay thickness of 200 µm to 600 µm, there was a 900 MHz bandwidth broadening with 3 db power split irrespective of the overlay material. The isolation also increased. Above 700 µm thickness an oscillatory behaviour was observed in the coupled ports with a decrease in coupling after about 10.5 GHz. The isolation characteristic of the 3 db directional coupler showed dependence on thickness as well as permittivity. It is felt that, with a suitable choice of dielectric material of appropriate thickness, an improved broadband coupling and high isolation may be realised by a simple overlay technique.