Search results

The purpose of this paper is to study the sensitivity and selectivity properties of polyaniline/tantalum pentoxide (PANI/Ta₂O₅) composite to liquid petroleum gas (LPG).

Polyaniline/tantalum pentaoxide (PANI/Ta₂O₅) composites were synthesized by in situ chemical polymerization method using ammonium persulphate as an oxidizing agent. This is the novel polymerization process for the direct synthesis of emeraldine salt phase of the polymer. The composites were characterized by FTIR, XRD and SEM. Temperature dependence conductivity of the composites shows thermally activated behaviour. Sensitivity and selectivity of the composites are studied.

The PANI/ Ta₂O₅ composites of 20 wt% and 30 wt% are showing maximum change in resistance against time when compared to pure PANI and other polyaniline composites when exposed to LPG. The 20 wt % composites show maximum sensitivity of 83% to LPG. The selectivity studies reveals that LPG could be sensed better when compared to oxyacetylene and other test gases.

Selectivity studies have been carried out and the sensor proved to be better than metal oxides sensors.

The sensing material is of low cost.

To the best of the authors' knowledge, studies on Ta₂O₅‐based gas sensor have not been reported previously.

Oxalate coating process. The Pyrene Co. Ltd. announce the availability of their new oxalate coating process, Bonderite SS4, for assisting the cold drawing of stainless steel and heat‐resisting alloys.

THE previous articles in this series, concerning the titanium, magnesium and aluminium alloys, followed a very similar form, in that in each case consideration of the aircraft engineering applications was preceded by a metallurgical appreciation of the alloy systems under review. In the case of steels, a comprehensive article on similar lines would be nothing less than a monograph, and if steels are to be discussed within the space of a single article, then a quite different approach must be adopted. This review will not, then, examine steels generally in any great metallurgical detail, but will rather consider their special merits in aircraft engineering, particularly in the context of supersonic aircraft.

The purpose of this study is to solve the oil drill pipe joints and casing excessive wear problems and to improve the drill pipe joint-casing wear resistance and anti-friction properties.

On the surface of the drill pipe joints using oxyacetylene flame bead weld (BW) wear-resistant welding wire ARNCO-100XT^TM prepares welding layer, high-velocity oxygen fuel (HVOF) Cr₃C₂75-NiCr25 prepares coating and subsonic flame spray and remelt (SFSR) Ni60 prepares coating, then comparing and analyzing the friction and wear of the three types of wear-resistant layers and the casing under the condition of 1.8 g/cm³ mud drilling fluid lubrication. The wear resistance and anti-friction performance of the drill pipe joints were evaluated based on the wear situation, finally revealing its friction and wear mechanisms.

Three types of wear-resistant layers can improve the surface wear resistance of drill pipe joints, the wear-resistant layer and the substrate are well combined and the welding layers and coating are both dense and uniform. The wear resistance of the HVOF-Cr₃C₂75-NiCr25 coating is 10.9 times that of the BW-ARNCO-100XT^TM weld layer, and the wear resistance of the SFSR-Ni60 weld layer is 2.45 times that of the BW-ARNCO-100XT^TM weld layer. The anti-friction properties of SFSR-Ni60 welding layer is the best, followed by HVOF-Cr₃C₂75-NiCr25 coating, and the anti-friction properties of BW-ARNCO-100XT^TM welding layer is the worst among the three.

The research results of this paper have great practical value in the process and material of improving the wear resistance and anti-friction performance of the drill pipe joint casing.

The Corrosion Exhibition, organised by CORROSION TECHNOLOGY at the Royal Horticultural Society's Old Hall, Westminster, on October 15, 16 and 17 can truthfully be said to have been an outstanding success. Many exhibitors sought out the Exhibition organisers to congratulate them on this success. Practically without exception every exhibitor spoken to by our staff expressed the view that the attendance—which was in the region of 10,000 for the total three days—the interest, and the number of genuine enquiries was far greater that they had ever expected. Several exhibitors said that during the Exhibition they heard details of corrosion problems that previously they did not know exsited. In this review are details of the main exhibits of those firms not included in the preview of the Exhibition given last month.

A multi-physics process model is developed to analyze reactive melt infiltration (RMI) fabrication of ceramic-matrix composite (CMC) materials and components. The paper aims to discuss this issue.

Within this model, the following key physical phenomena governing this process are accounted for: capillary and gravity-driven unsaturated flow of the molten silicon into the SiC/SiC CMC preform; chemical reactions between the silicon melt and carbon (either the one produced by the polymer-binder pyrolysis or the one residing within the dried matrix slurry); thermal-energy transfer and source/sink phenomena accompanying reactive-flow infiltration; volumetric changes accompanying chemical reactions of the molten silicon with the SiC preform and cooling of the as-fabricated CMC component to room temperature; development of residual stresses within, and thermal distortions of, the as-fabricated CMC component; and grain-microstructure development within the SiC matrix during RMI.

The model is validated, at the material level, by comparing its predictions with the experimental and modeling results available in the open literature. The model is subsequently applied to simulate RMI fabrication of a prototypical gas-turbine engine hot-section component, i.e. a shroud. The latter portion of the work revealed the utility of the present computational approach to model fabrication of complex-geometry CMC components via the RMI process.

To the authors’ knowledge, the present work constitutes the first reported attempt to apply a multi-physics RMI process model to a gas-turbine CMC component.

One of the oldest metals known to man is copper and its use in the chemical industry dates back many centuries, as is attested by the traditional spirit and essence stills and brewing vats. Modern developments in copper and its alloys are reviewed in this article which discusses the importance of this group of metals to the present‐day plant designer.

Discusses some aspects of welding of FERRALIUM alloy SD40 and considers differences from the penultimate alloy refinement FERRALIUM alloy 255–3SF. Gives details relating to the metallurgy of FERRALIUM SD 40, noting that it has approximately equal amounts of ferrite and austenite. Reports on methods of achieving the optimum composition after hot working. Also notes methods of accomplishing welding of FERRALIUM alloy and parameters that must be adhered to.

Tantalum has a resistance to aqueous corrosion that may be compared closely with that of glass. The principal use of the metal is in the construction of chemical plant where its excellent corrosion‐resistant properties have assured a place for it in special applications, particularly where corrosion resistance needs to be combined with a high degree of heat transfer. This sphere of application is expanding rapidly.