Influence of static magnetic fields on the protective ability of phosphate coatings on aluminium alloys

Abstract

Phosphate coatings on aluminium are used to improve the corrosion resistance of aluminium before the latter is painted. Phosphate coatings deposited in phosphate solution treated with a magnetic field prior to deposition can take on new properties. A magnetic field can either improve or deteriorate the properties of the phosphate coating formed, depending on the composition of aluminium.     

Fluorescence Array Scanner Employing a Flying Objective

DNA-based fluorescent microarrays (sometimes called “biochips”) are fast becoming the preferred tool for studying a variety of complex biochemical phenomena ranging from multiplex mutation detection, to gene mapping and expression monitoring, to high throughput screening for new drug candidates. Fluorescence is a low energy phenomenon. The need for rapid, high resolution, wide field imaging of fluorescent microarrays calls for a specialized microscope architecture. We now describe the design of a “Flying Objective” epi-fluorescence microscope that is ideally suited to this application, and compare the performance of this novel instrument with two other commercial epi-fluorescence microscopes designed to read DNA microarrays.     

Corrosion of Mild Steel in the Tidal Waters of the Afon Dyfi and a Comparison With the River Thames

Abstract

Exposure of bare mild steel specimens for two years to the tidal waters of the Afon Dyfi estuary has shown that overall corrosion rates (weight-loss) and rates of pitting decrease with time of exposure to the relatively unpolluted waters in a similar manner to the corresponding rates in the heavily polluted Thames. Comparison between results in the two rivers shows that the corrosion risks are greater in the Afon Dyfi than in the Thames. This is explained from consideration of the greater oxygen content and higher rate of movement in the Dyfi.     

The Effect of Humidity on the Adhesion Behavior of AC Anodised Aluminium

The effect of humidity on the surface forces of hot AC anodised AA6060 alloy was studied. The surface adhesion forces were measured in various humidity environments using an atomic force microscope (AFM). The environmental durability of the joints bonded at different humidity conditions was investigated using wedge test experiments. The results from AFM and durability tests indicate that there is a strong capillary effect at around 70–80% relative humidity. This effect was attributed to the change in the adsorption behavior of water on the anodised oxide surface forming bulk liquid and hence dissociating the bonds across the interface. At the lower humidity levels below 60% RH, no capillary effect was observed and the total adhesion forces followed the dry case values.     

31—COMPARISONS OF MICROPROJECTION AND AIR-FLOW DIAMETER MEASUREMENTS FOR SCOURED WOOL

A comparison is reported of fineness results obtained for 27 lots of scoured wool by the projection-microscope and air-flow methods. The sampling of the scoured wool was done by core-boring, and the cores were hand-carded before air-flow tests were made. The sub-samples for projection-microscope measurement were cut into snippets 1 mm long in order to obtain a length-biassed sample. The air-flow apparatus was calibrated with reference tops in five different forms. The results show that there exists a systematic difference between the air-flow and projection-microscope mean diameters of scoured wool when the air-flow instrument is calibrated with reference tops in the original state. A better agreement results by hand-carding the test samples of the reference tops, but the closest agreement is obtained by cutting, washing, and hand-carding these test samples so that their condition is similar to that of the core sample being tested. Provided that this kind of calibration were applied, the mean diameter of washed wool could be determined by air-flow testing of cored and hand-carded samples.