Non-contact methods of measuring moisture concentration in external layers of building partitions II—Monitoring of the water vapour condensation on porous surfaces

This paper present the results of the investigation into a potential application of laser radiation for the detection of phase transition processes occurring on the surface layers of porous materials. An attempt was made to discuss in the approximation equations, the relationships between coefficients of the reflected light, the temperature and humidity of the surrounding environment. Laser light reflected from the porous surface carries information about the roughness of the structure. The presence of water microdrop on the surface of the porous material, as a result of condensation and thus a phase transition, leads to the phase displacement of individual rays, which is represented by different images. Therefore, a comprehensive analysis of the reflected light parameters allows a dynamic study of the phase transition phenomena without mechanical intervention.     

Creation of TiN paths on titanium alloy OT4-1 by the use of a laser beam

TiN paths have been created on the surface of the titanium alloy OT4-1 by the use of a laser beam. The results of investigations of structure, phase composition, microhardness and surface roughness of the created TiN paths are given in the paper. The paths created in the work are inhomogenous two-phase mixtures of TiN and -Ti, in which the TiN phase with strong (2 0 0) texture is predominant over the other phase and presents a dendritic structure. © 1998 Chapman & Hall     

A search for optimal acrylic carriers for immobilization of penicillin acylase

Acrylic carriers were obtained by aminolysis of nitrile or ester groups in copolymers or terpolymers synthesized from acrylonitrile, acrylic esters and divinylbenzene or ethylene dimethacrylate in the presence of a mixture of inert diluents. The influence of the supermolecular structure of these carriers, generated during the suspension polymerization by adding a mixture of inert diluents, on the carrier properties was observed. Acrylic carriers for immobilization of penicillin acylase should be obtained from either porous or ‘sol’-type copolymers which aquire after aminolysis the structure of expanded gel.     

The role of microstructure on pesting during oxidation of MoSi2 and Mo(Si,Al)2 at 773 K

The pesting behavior of MoSi₂ and Mo(Si,Al)₂ has been examined in air at 773 K to clarify the origin and mechanism of pesting phenomena and the effect of aluminum on pesting phenomena. The initial cracks play a much more important role than the grain boundaries and the initial oxide layer in pesting. Mo and Si oxidize to amorphous Mo-Si-O simultaneously with about a 200% volume expansion. Therefore, large stress appears at the cracktips and induce many new cracks. MoO₃ vaporizes from the Mo-Si-O layer on the external surface and crack surfaces causing the oxides in the initial cracks to become porous. Oxygen has a short-circuit path to enter the sample in the cracks. Therefore, the partial pressure of oxygen is sufficiently high to allow oxidation of Mo in the materials. The platelet-like MoO₃ grows on the external surface and also in the cracks. Finally, the sample distintegrates into powder. Pesting of Mo(Si,Al)₂ occurs in the same way, however, its rate is much lower than that of MoSi₂. The role of Al is to decrease the initial crack density of the samples from the melt. Other effects of Al might be to decrease the oxygen flux toward the oxide-intermetallic interface and to increase the plasticity of the amorphous oxide being formed in the cracks.     

Synthesis of Mammalian Gonadoliberin Analogs with the N-terminal glutamine or glutamine or glutamic acid

Synthesis of two mammalian gonadoliberin analogs, [Gln¹]GnRH and [Glu¹]GnRH, in solution by the peptide segment coupling of the [(2 + 4) + 4] type has been described.     

The effect of halloysite additive on operation of boilers firing agricultural biomass

The paper presents results of investigations on using halloysite as an additive in biomass-fired boilers. It has been shown that in the case of a few different agricultural biomasses the halloysite addition increased the ash sintering temperature to the values noted for coals. This is an effect of bonding sodium and potassium in the form of chlorides and other compounds. In practical terms the halloysite additive may reduce slagging and fouling of boiler heating surfaces as well as deteriorate the agglomeration processes in fluidized beds. Moreover, addition of halloysite reduces the amount of KCl and NaCl present in ash (and therefore in ash deposits) thus decreasing the rate of high temperature corrosion.     

Effect of Thermal Treatment on the Photocatalytic Activity in Visible Light of TiO<Subscript>2</Subscript>-W Flame Spray Synthesised Nanopowders

Effect of W doping as well as a thermal treatment on the structural and photocatalytic properties of TiO₂ produced by flame spray synthesis (FSS) were the subject of investigation. Structural properties were studied by means of X-ray diffraction (XRD), BET adsorption isotherm and transmission electron microscopy (TEM). The surface condition was investigated by X-ray photoelectron spectroscopy (XPS) and differential scanning calorimetry (DSC) and differential thermal and thermogravimetric analysis (DTA-TGA). The photocatalytic properties were studied by optical measurements and photodecomposition of methylene blue under visible irradiation. It was found that the photoactivity in the visible region was enhanced significantly by the W-doping as well as by additional thermal treatment of those nanopowders. The obtained TiO₂-W nanopowders exhibited higher performance under visible light than P25.     

Testing of thin-walled steel joints fabricated by spot welding and plug welding

Selected methods of joining which can be used for manufacturing and repairing of car bodies by means of welding are presented in this article. Three kinds of 1 mm-thick steel sheets were used in the tests: deep drawing steel (DC04) and two-phase steels of increased high strength (DP600 and DP800). The comparative connections were carried out by means of resistance spot welding and with plug joints made by means of the MAG method and through braze welding. Comparative assessment of the strength and geometrical parameters of the test joints was then conducted.     

The Effect of Implanted Al and/or Y on the Scale Formation on Low-Al Fe20Cr2Al Alloy

The very early stages of the oxidation of an Fe20Cr2Al alloy, unmodified and ion-implanted by aluminium, yttrium and a combination of both elements, Al and Y, were studied at 1100 °C in oxygen using two-stage-oxidation exposures with ¹⁸O₂ as a tracer and subsequent characterisation of the scales using SIMS analyses of distribution of oxygen isotopes and oxide-related negative ion clusters, SEM observations of the surface morphology and photoluminescence spectroscopy analysis of the phase composition. The scales formed in all cases, except for the Al-implanted alloy, exhibited layered structures, with the outer part comprising Fe- and Cr-rich oxide, and the inner part being Al₂O₃, which grew due to a mixed outward–inward mechanism . The alumina sub-layers contained the transient oxides and α-Al₂O₃. Implanted Al significantly affected the mechanism of the scale growth, providing that the scale consisted essentially of α-Al₂O₃, and grew via a mixed inward-outward mechanism typical for scales on alumina formers.