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Article
Publication date: 26 June 2009

Da‐jing Fang, Xu‐hui Mao, Ye‐ming Zhang, Zhi‐liang Chen, Min Liu and Fu‐xing Gan

The purpose of this paper is to study the compound effect between silane and cerium salts in the passivation process of chemical conversion treatment of zinc.

Abstract

Purpose

The purpose of this paper is to study the compound effect between silane and cerium salts in the passivation process of chemical conversion treatment of zinc.

Design/methodology/approach

Chemical conversion treatment using 3‐Glycidoxypropyltrimethoxysilane on zinc is investigated as an alternative treatment to chromate conversion. The surface chemistry of the silane‐treated samples is investigated with mass change measurements, polarization curves, electrochemical impedance spectroscopy (EIS) and the salt spray tests (SST). The surface morphology of samples was studied using a scanning electron microscope.

Findings

The polarization curves, EIS and SST data are in agreement. On the surface of zinc, the silane formed a compound with the cerium, thus enhancing the adhesion and corrosion resistance of the polymer film.

Originality/value

There have been few reports on the compound effects of silanes and cerium salts in the passivation process. The mechanism of this compound effect may be due to the ability of Ce3 + ions to gain access to the interface through tiny cracks or micropores in the cross‐linking structure of GPS polymer films on zinc, and the subsequent oxidation of Ce3 + to Ce4 + by H2O2 may result in a barrier effect between the electrolyte and the metallic substrate.

Details

Anti-Corrosion Methods and Materials, vol. 56 no. 4
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 26 April 2013

S.N. Mathad, R.N. Jadhav and Vijaya Puri

The purpose of this paper was to determine the complex permittivity of bismuth strontium manganites (Bi1−xSrxMnO3) in the 8‐12 GHz range by using perturbation of Ag thick…

Abstract

Purpose

The purpose of this paper was to determine the complex permittivity of bismuth strontium manganites (Bi1−xSrxMnO3) in the 8‐12 GHz range by using perturbation of Ag thick film microstrip ring resonator (MSRR) due to superstrate of both bulk and thick film.

Design/methodology/approach

The BSM ceramics were synthesized by simple low cost solid state reaction method and their fritless thick films were fabricated by screen printing technique on alumina substrate. A comparison has been made between the X band response of Ag thick film microstrip ring resonator due to perturbation of bulk and thick film Bi1−xSrxMnO3 ceramic.

Findings

The bulk and thick film superstrate decreases the resonance frequency of MSRR. In this technique even minor change in the properties of superstrate material changes the MSRR response. Variation of strontium content also influences microwave conductivity and penetration depth of bulk and thick films.

Originality/value

The microwave complex permittivity decreases with increase in Sr content in bismuth manganite and it is higher for bulk as compared to its thick films. The superstrate on Ag thick film microstrip ring resonator is an efficient tool capable of detecting the composition dependent changes in microwave properties of ceramic bulk and thick films.

Details

Microelectronics International, vol. 30 no. 2
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 11 May 2010

R.K. Nahar and Vikram Singh

High‐dielectric thin films are considered as future dielectric for Si based advanced integrated circuit technology and also for the development of organic thin film

Abstract

Purpose

High‐dielectric thin films are considered as future dielectric for Si based advanced integrated circuit technology and also for the development of organic thin film transistors and micro sensors. The conventional dielectric SiO2 is grown by thermal oxidation of silicon whereas the HfO2 films are grown by both physical and chemical methods. Depending on film deposition technique, the film and interface characteristics are affected. The purpose of this paper is to investigate the effect of thermal annealing in oxygen and nitrogen ambient on the electrical properties of HfO2‐based metal oxide semiconductor (MOS) capacitor and evaluate thermal stability of the characteristics.

Design/methodology/approach

HfO2 films are deposited by rf sputtering and Al‐HfO2‐Si MOS capacitor fabricated. The electrical I‐V and C‐V characteristics are measured and the effect of temperature in the range of 25‐200°C is evaluated for films annealed in oxygen and nitrogen.

Findings

It is found that thermal annealing in nitrogen reduces oxide trap density and improves the temperature stability compared to the film annealed in oxygen for MOS devices. From the conductance characteristics Dit oxide trap density in the film is estimated to be 2.1×1011/cm2 for nitrogen and 3.23×1011/cm2 for oxygen, which indicates the role of nitrogen in reducing oxide traps. The thermal activation energy of electron traps is found to be about 0.19 eV for nitrogen and 0.58 eV for oxygen annealed films in the temperature range of 25‐150°C.

Originality/value

The paper examines and compares the role and effect of thermal annealing in nitrogen ambient and oxygen ambient on the electrical properties of sputtered HfO2 thin film for improved MOS device reliability.

Details

Microelectronics International, vol. 27 no. 2
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 18 January 2013

P.B. Kashid, D.C. Kulkarni, V.G. Surve and Vijaya Puri

The purpose of this paper is to study thickness dependent variation in microwave properties of the MgxMn(0.9−x)Al0.1Zn0.8Fe1.2O4 (x=0.8, 0.9) thick films and enhancement of

Abstract

Purpose

The purpose of this paper is to study thickness dependent variation in microwave properties of the MgxMn(0.9−x)Al0.1Zn0.8Fe1.2O4 (x=0.8, 0.9) thick films and enhancement of power efficiency of Ag thick film EMC patch antenna.

Design/methodology/approach

X‐band microwave properties of the MgxMn(0.9−x)Al0.1Zn0.8Fe1.2O4 (x=0.8, 0.9) thick films were measured by superstrate technique using Ag thick film EMC patch antenna as the resonant element. The complex permittivity and permeability of these thick films were also measured by this technique. The microwave response of the EMC patch, complex permeability and permittivity of Mg0.8Mn0.1Al0.1Zn0.8Fe1.2O4 and Mg0.9Al0.1Zn0.8Fe1.2O4 thick films and their thickness dependency were investigated.

Findings

The XRD patterns reveal the cubic spinel crystal system was obtained for both compositions. The crystallite size obtained was 134.68 nm for Mg0.8Mn0.1Al0.1Zn0.8Fe1.2O4 and 155.99 nm for Mg0.9Al0.1Zn0.8Fe1.2O4 The superstrate technique has been used successfully to evaluate the complex permittivity and permeability of the ferrite thick films in the X band. The EMC patch also show thickness and composition dependent frequency agility and enhancement of power efficiency.

Originality/value

The complex permeability of MgxMn(0.9−x)Al0.1Zn0.8Fe1.2O4 (x=0.8, 0.9) thick films measured by superstrate technique is reported in this paper. The superstrate of MgxMn(0.9−x)Al0.1Zn0.8Fe1.2O4 (x=0.8, 0.9) thick films makes the Ag thick film EMC patch antenna frequency agile and power amplification is obtained.

Details

Microelectronics International, vol. 30 no. 1
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 8 May 2009

Björn Carlberg, Teng Wang, Johan Liu and Dongkai Shangguan

The purpose of this paper is to present a novel nanostructured polymer‐metal composite film providing continuous all‐metal thermally conductive pathways, intended to meet…

Abstract

Purpose

The purpose of this paper is to present a novel nanostructured polymer‐metal composite film providing continuous all‐metal thermally conductive pathways, intended to meet future performance requirements on thermal interface materials (TIMs) in microelectronics packaging applications.

Design/methodology/approach

Porous polymer structures with a thickness of approximately 100 μm were manufactured using electrospinning technology. Pressure‐assisted infiltration of low‐melting temperature alloy into the porous polymeric carrier resulted in the final composite film. Thermal performance was evaluated using an accurate and improved implementation of the ASTM D5470 standard in combination with an Instron 5548 MicroTester. Finally, a brief comparative study using three current stateof‐the‐art commercial TIMs were carried out for reference purposes.

Findings

Composite films with continuous all‐metal thermally conductive pathways from surface to surface were successfully fabricated. Thermal resistances down to 8.5 K mm2 W−1 at 70 μm bond‐line thickness were observed, corresponding to an effective thermal conductivity of 8 W m−1 K−1, at moderate assembly pressures (200‐800 kPa), more than twice the effective thermal conductivity of the commercial reference materials evaluated.

Originality/value

A unique high‐performance nanostructured polymer‐metal composite film for TIM applications with the potential to meet the microelectronics industry's future demands on thermal performance and cost efficiency is presented.

Details

Microelectronics International, vol. 26 no. 2
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 1 June 2006

A. Immarigeon and I. Hassan

The present study aims to conduct a numerical investigation of a novel film cooling scheme combining in‐hole impingement cooling and flow turbulators with traditional…

Abstract

Purpose

The present study aims to conduct a numerical investigation of a novel film cooling scheme combining in‐hole impingement cooling and flow turbulators with traditional downstream film cooling, and was originally proposed by Pratt & Whitney Canada for high temperature gas turbine applications.

Design/methodology/approach

Steady‐state simulations were performed and the flow was considered incompressible and turbulent. The CFD package FLUENT 6.1 was used to solve the Navier‐Stokes equations numerically, and the preprocessor, Gambit, was used to generate the required grid.

Findings

It was determined that the proposed scheme geometry can prevent coolant lift‐off much better than standard round holes, since the cooling jet remains attached to the surface at much higher blowing rates, indicating a superior performance for the proposed scheme.

Research limitations/implications

The present study was concerned only with the downstream effectiveness aspect of performance. The performance related to the heat transfer coefficient is a prospective topic for future studies.

Practical implications

Advanced and innovative cooling techniques are essential in order to improve the efficiency and power output of gas turbines. This scheme combines in‐hole impingement cooling and flow turbulators with traditional downstream film cooling for improved cooling capabilities.

Originality/value

This new advanced cooling scheme both combines the advantages of traditional film cooling with those of impingement cooling, and provides greater airfoil protection than traditional film cooling. This study is of value for those interested in gas turbine cooling.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 16 no. 4
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 December 2004

Jaw‐Ren Lin, Rong‐Fang Lu, Won‐Hsion Liao and Chia‐Chuan Kuo

A theoretical study of the combined effects of non‐Newtonian couple stresses and fluid inertia forces on the squeeze‐film behaviors for parallel circular plates is…

Abstract

A theoretical study of the combined effects of non‐Newtonian couple stresses and fluid inertia forces on the squeeze‐film behaviors for parallel circular plates is presented in this paper. Based upon the micro‐continuum theory, the Stokes constitutive equations are used to account for the couple stress effects resulting from the lubricant blended with various additives. The convective inertia forces included in the momentum equation are approximated by the mean value averaged across the fluid film thickness. Numerical solutions for the squeezing film characteristics are presented for various values of couple stress parameter and Reynolds number. Comparing with the classical Newtonian non‐inertia flow, the combined effects of couple stresses and convective inertia forces result in a larger load‐carrying capacity and therefore, increase the response time of the squeezing film plates.

Details

Industrial Lubrication and Tribology, vol. 56 no. 6
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 31 July 2007

U.B. Lonkar and Vijaya Puri

This paper aims to study tuning effects on thick film microstripline due to ferrite thick film overlay.

Abstract

Purpose

This paper aims to study tuning effects on thick film microstripline due to ferrite thick film overlay.

Design/methodology/approach

The possibility of obtaining tuning characteristics in the Ku band microwave region in the absence of external magnetic field by a simple process of using NixZn1−xFe2O4 thick film and bulk as in‐touch overlay over Ag thick film microstripline was investigated. The microstripline is basically a non‐resonant component with high‐transmission at a large microwave frequency band. The ferrite was synthesized by precursor method and the thick films were deposited by screen printing.

Findings

It was found that tuning characteristics were observed and composition, thickness and precursor dependent changes occurred. The changes with composition are more prominent in the 14.5‐16.5 GHz range. Also, the ferrite thick film overlay produces a deep notch at 15.7 GHz. It is observed that the pellet overlay also makes the microstripline very dispersive with a high‐insertion loss in the 16‐17 GHz range. The presence of permeability‐related effects interfering with the normal propagation of the microstrip circuits might be causing the changes in the circuits.

Originality/value

Owing to the NixZn1−xFe2O4 overlay the simple microstripline can be tuned to have narrow band filter type of characteristics. Thick film NixZn1−xFe2O4 overlay gives the added advantage of planer configuration along with cost‐effectiveness in the absence of magnetic field.

Details

Microelectronics International, vol. 24 no. 3
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 4 January 2013

Shun'an Cao, Jiayuan Hu, Jianli Xie, Qinqin Liang and Li Yin

The purpose of this paper is to set out a study of the film‐forming characteristics of octadecylamine (ODA), estimate the feasibility of shutdown protection using ODA at…

Abstract

Purpose

The purpose of this paper is to set out a study of the film‐forming characteristics of octadecylamine (ODA), estimate the feasibility of shutdown protection using ODA at high temperatures, and determine the optimum process condition of shutdown protection for units under full load if ODA has a good film‐forming effect at high temperatures.

Design/methodology/approach

An autoclave was used to simulate the water‐vapor environments at 350‐560°C in the water‐steam system of power plants. The decomposition test of ODA was investigated and the ODA film‐forming characteristics were studied for furnace tube materials used in gas‐fired power plants.

Findings

Results showed that ODA had a decomposition equilibrium and the decomposition products did not contain harmful organic substances such as low molecular organic acids. ODA would form a satisfactory protective film in the range of 350‐560°C with the best film at 480°C. The protection effect of the film formed by ODA at 560°C was much stronger than was that of its oxide film, which showed the feasibility of shutdown protection using ODA for gas‐fired power plants operating under full load. The optimal conditions of shutdown protection under full load were as follows: the temperature was 560°C, the concentration of ODA was 80 mg/L, the pH was 9.5 and the exposure time was 2 h. From the experimental results of X‐ray photoelectron spectroscopy, it was known that the surface film on the specimens was composed of a compound of ferroferric oxide and ODA, and the film‐forming mechanism was chemical adsorption between N in the ODA and Fe.

Originality/value

It was found that ODA has a good film‐forming effect at high temperatures and it is practicable to implement shutdown protection for base‐load units. The research results can provide theoretical guidelines for shutdown protection of gas‐fired power plants.

Details

Anti-Corrosion Methods and Materials, vol. 60 no. 1
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 24 April 2007

J. Kulawik, D. Szwagierczak, B. Gröger and A. Skwarek

The aim of the present work was the characterization of a group of compounds with the perovskite‐type structure in respect of their applicability as thermistor materials.

Abstract

Purpose

The aim of the present work was the characterization of a group of compounds with the perovskite‐type structure in respect of their applicability as thermistor materials.

Design/methodology/approach

Four compositions: La0.7Sr0.3Zr0.5Co0.22+Co0.33+O3, La0.8Sr0.2Ti0.5Co0.32+Co0.23+O3, La0.4Sr0.6Ti0.3Fe0.7O3 and CaTi0.8Co0.2O3 were synthesized by solid‐state reaction. Ceramic thermistor materials were sintered in the temperature range 1,300‐1,400°C. The synthesized powders were used for fabrication of thick film pastes and thermistors fired at 1,100‐1,250°C. Resistance‐temperature characteristics of the ceramic samples were studied in the range −55 to 800°C for the ceramic samples and 20‐600°C for thick films. Endurance tests at 300°C for 500 h were performed.

Findings

The developed NTC materials exhibited high temperature coefficients of resistivity, dense microstructure and good stability. The most advantageous characteristics have been shown by La0.7Sr0.3Zr0.5Co0.22+Co0.33+O3 and La0.8Sr0.2Ti0.5Co0.32+Co0.23+O3 thermistors. The highest Temperature coefficient of resistances for the ceramics were found in the temperature range from −55 to 180°C (−10.7 to −2.9 per cent/°C) and for the thick films in the temperature range 40‐300°C (−5.6 to −1.5 per cent/°C).

Research limitations/implications

This work has been focused on preliminary choice of compositions appropriate for practical thermistor thick film applications. Elucidation of conduction mechanism of the investigated materials needs further complex studies of conductivity, nonstoichiometry, thermoelectric power, etc. as a function of temperature and oxygen partial pressure.

Originality/value

In this work, an attempt has been made to extend the typical range of NTC compositions and to fulfil the demand for improved stability of bulk and thick film thermistors at elevated temperatures.

Details

Microelectronics International, vol. 24 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

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