Abstract: Composite sheets were made of cyclic butylene terephthalate as matrix and carbon fibers as reinforcing material.Hot press method was used at different temperatures for composite processing. The mechanical properties of these materials and the effect of processing temperature were tested. The samples were kept in a climate chamber, and the effect of air humidity was examined through the change of the mechanical properties. Pictures were taken by a scanning electron microscope of the broken surfaces of the specimens. The results give conclusions about the outdoor application of these composites.
Abstract: The cold rolling effect on the hydrogen permeability (TH value) and on the microstructure have been studied on samples prepared from Al-killed low carbon steel sheets after several cold rolling levels. The TH values of the hot rolled strips were very short, but due to the cold rolling increase exponentially. The fragmentation of large cementite phase has a significant influence on the evolution of texture during the cold rolling process.
The cold deformation effects on the TH value were studied on four annealed enamelling grade steel sheets also. Depending on the carbides sizes and carbides position in ferrite grains after annealing the TH values increase or decrease after low deformation degrees, due to the steel texture modification and dislocation character.
Dislocations act as major tripping site for hydrogen, if deformation degree is higher than 30%.
Abstract: Along the metallurgical length at continuous casting, the temperature within the strand ranges from above melt temperature (>1500) to about 900 oC. In this range, mechanical properties drastically drop at above the zero deformation temperature (ZDT) and the zero strength temperature (ZST), therefore crack susceptibility increases. These temperatures depend on (local) chemical and microstructural properties. We investigated the change in ZDT and ZST for ST52-3 steel grade by taking samples from the as-cast strand from positions of the columnar grains and from the centreline segregated zone. We found more than 100 oC drop in ZDT due to segregations in the centreline compared to the columnar zone within the strand.
Abstract: During the fine comminution of clay minerals and layered silicate materials with relative large volume of specific surface area appreciable changes in chemical and minerological compositions can be observed. In this paper is described the mechanochemical investigation of conventional clay minerals from „Lenti” region (Hungary), having natural BET specific surface larger than 35-40 square metres per grams. The laboratory experiments made by author had shown an intensive reduction of specific surface volume at the beginning of grinding, further relatively slow growth and reduction of BET and Langmuir surfaces were observed. The content of mineral Muscovite–2M1 – (K, NH4Na)Al2(SiAl)4O10(OH)2 – has decreased and the contents of Quartz – SiO2 – and Illite-1M (NR) – KO.7Al2(SiAl)4O10(OH)2 – have increased considerable depending on grinding time. Increasing the milling time the amount of Albite – NaAlO.91Si3O8 – and other mineral components were also not stable, but their content have varied not so strong as Muscovite–2M1 or Quartz and Illite–1M. The examined clay minerals had a certain proportion of amorphous particles as well, but in this contribution only the changes in proportions of crystalline particles are described.
Abstract: In the present work the weldability of self-reinforced composite was investigated. As reinforcement a fabric, woven from highly stretched split PP yarns, whereas as matrix materials of two kinds of random polypropylene copolymer (with ethylene) were used. The composite sheets were produced by film-stacking method and compression molded with different thickness (1 mm,
2 mm) with different contents at different processing temperatures keeping the holding time and pressure constant. The SRPPC sheets were welded by ultrasonic welding machine with different welding parameters. The welds were qualified by mechanical and microscopic tests. The results showed that the thermoplastic reinforcement has not got melted; therefore the reinforcement was kept the strength-increasing effect.
Abstract: Solid solutions formed within the Al2O3-TiO2-Fe2O3 (Fe2xAl2(1-x)TiO5) system upon heat treatment were investigated by adjusting the substituting Fe3+ content in the range of x=0.0 to 1.0.
X-ray diffraction phase analyses and lattice parameter determinations confirmed that substitution of Fe3+ ions within the aluminium titanate lattice was complete.
For this complete solid solution, however, the trends observed for changes in d-spacing values indicated that there were certain discrete compositions to identify with Fe3+ substitution. Within these, Fe0.4Al1.6TiO5 and Fe1.6Al0.4TiO5 crystalline phases were investigated in detail and their
X-ray diffraction cards were constructed.
Self-healing effect occurring in repeated heating-cooling cycles in Fe3+ doped AT ceramics were proved; it was demonstrated that Fe3+ doped AT ceramics do not decompose even if exposed to repeated thermal shock.
Abstract: Vegetal materials are generated in high amounts and are applied as additives in clay bricks since ancient times. They have a certain heat contribution to the firing process. As revealed by X-ray Powder Diffraction, main component of vegetal waste materials is cellulose. Thermal and Evolved Gas Analysis revealed the combustion process in its details. Mixtures of clay and vegetal additives prepare for test bodies were analyzed by Thermal Analysis. The thermal effects were quantified by Differential Thermal Analysis and correlated with Thermogravimetry and Derivative Thermogravimetry.