Effect Of Treatment Atmosphere Research Articles

Effect of treatment atmosphere on the vanadium species of V/TiO2 catalysts for the selective catalytic reduction of NOx with NH3

The decrease of polymeric vanadyl species due to treatment under different atmospheres results in the reduction of NH3-SCR activity.

UV-Induced Modification of Fluorocarbon Polymer: Effect of Treatment Atmosphere and Aging on Dissolution in Organic Solvent

In back-end of line (BEOL), the use of fluorocarbon-containing plasmas such as CF4 and C4F8 for patterning of low-k dielectrics with k-value ~2.3-2.5 can result in the presence of a highly fluorinated layer, deposited on the sidewalls and bottom of the trenches [1,. This polymer layer must be removed prior to subsequent processing steps to achieve good adhesion and coverage of materials (metals) deposited in the etched features. However, it is known that this type of fluorocarbon polymer is chemically inert to many existing wet clean solutions, including aqueous solutions such as fluoride ion-containing or highly alkaline solutions, and solvent mixtures [2]. Exposure of the polymer to UV irradiation (λ 200 nm) with doses 3 J/cm2 significantly modifies the polymer film, which results in substantial removal ability in a subsequent wet clean process. Polymer film modification was shown to be efficient either by using a narrow band single wavelength source with λ = 254 nm [ or by a broad band UV source with λ~200-300 nm [.

Phase Relations and Transformations in Advanced Ceramic Materials

This article reviews the phase diagrams contributing to the understanding of compound formations, phase transformations, phase separation and microstructural development in advanced ceramic systems. Phase equilibrium relations in the Al 2 O 3 -AlN and AlN-B 2 O 3 systems are presented for the fabrication of translucent aluminum oxynitride spinel ceramics and in-situ hexagonal boron nitride composites. In oxide systems, especially in glass-forming systems, crystallized phases vary with not only composition and temperature but also time of heat-treatment. Considering this aspect, time-temperature-transformation (TTT) diagrams in the solidification processes of cordierite, high-T c superconducting oxide and fluorphlogopite melts and the phase transformations of ammonium aluminum carbonate hydroxide to α-alumina are introduced and specific phase transformations in these systems are also discussed. The effect of treatment atmosphere on microstructure in phase transformations is described in the surface-treatment of AlN ceramics and the sintering of transparent silica glass.

Microstructural analysis and crystallographic characterisation of plasma oxynitrided Ti–6Al–4V

Combined glow discharge oxidising and nitriding treatments allow the production on Ti–6Al–4V of modified surface layers with enhanced hardness properties compared with a traditional ion nitriding process. The treatment atmosphere has a marked influence on the properties of these hardened layers: as the oxygen concentration increases, thicker diffusion layers, characterised by greater hardness values and smoother gradients, are obtained. In the present paper the effects of treatment atmosphere and duration on the glow discharge oxynitriding of Ti–6Al–4V specimens are evaluated, by performing tests at 1173 K with oxygen concentration varied in the range 0–21 vol.-% and for treatment durations in the range 0·5–8 h. The modified layers produced consist of an outer compound layer and an inner diffusion layer. The compound layer consists of nitrides, oxides, and oxynitrides of titanium and, in some cases, of alloy element oxides too. With increasing oxygen concentration and/or time, the compound layer develops a stratified structure and its adhesion to the substrate becomes poor; this fact can be attributed to the high content of titanium oxide, TiO2 , in the layer. In the diffusion layer α-Ti crystals, rich in interstitial atoms, are present. The diffusion layers in the oxynitrided specimens are thicker and show higher hardness (up to 1300 HK) and smoother gradients than those produced by a traditional ion nitriding process under the same treatment conditions. Case depths of comparable thickness (around 45 μm) can be obtained by performing an 8 h nitriding treatment or a 2 h oxynitriding treatment with 6 vol.-%O2 . Moreover, α-Ti lattice parameters a, c were evaluated as a function of the experimental conditions; the values of these parameters can be correlated with changes in hardness values.