Kaolin-group clay minerals can be modified to form nanotubular and mesoporous structures with interesting catalytic properties, but knowledge of the best methods for preparing these structures is still incomplete. The objective of this study was to investigate intercalation/deintercalation as a method for the delamination and rolling of kaolinite layers in relation to structural order. To prepare nanotubular material, kaolinites of different crystallinities and halloysite (all from Polish deposits) were chosen. The experimental procedure consisted of four stages: (1) preparation of a dimethyl sulfoxide precursor intercalate; (2) interlayer grafting with 1,3-butanediol; (3) hexylamine intercalation; and (4) deintercalation of amine-intercalated minerals using toluene as the solvent. Structural perturbations and changes in the morphology of the minerals were examined by X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, and transmission electron microscopy (TEM). The number of rolled kaolinite layers depended heavily on the efficiency of the intercalation steps. An increase in the structural disorder and extensive delamination of the minerals subjected to chemical treatment were recorded. Kaolinite particles which exhibited tubular morphology or showed rolling effects were observed using TEM. The nanotubes formed were ∼30 nm in diameter, with their length depending on the particle sizes of the minerals.

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THE NITROGEN CONTENT EFFECT ON CARBONITRIDE COAGULATION IN 40Cr8 STEEL WITH MICRO-ADDITIONS V AND V + Al WPŁYW ZAWARTOŚCI AZOTU NA KOAGULACJĘ WĘGLIKOAZOTKÓW W STALI 40Cr8 Z MIKRODODATKAMI V I V+AlThe work examines the effect of nitrogen and micro-additions V and V+Al on the austenite grain size and the coagulation of carbonitride precipitates in 40Cr8 steel. The analyzed materials underwent heat treatment consisting in holding the material at 1200• C for 1h, which was next exposed to furnace cooling down to 820• C and maintained at this temperature for 20hrs, and subsequently quenched in water. With the application of electron microscopy, the microstructure and the formed carbonitride precipitates were examined. The SigmaScanPro software was used to perform the quantitative metallographic analysis of the precipitates. The study demonstrated that increase in the content of nitrogen inhibits the coagulation rate of carbonitrides, whereas aluminium favours the tendency for coagulation and efficiently inhibits the austenite grain growth.Keywords: Coagulation; Carbonitrides; HSLA steels W pracy badano wpływ azotu i mikrododatków V, V+Al na wielkość ziarna austenitu oraz koagulację wydzieleń węgli-koazotku w stali 40Cr8. Próbki z badanych wytopów poddano obróbce cieplnej polegającej na wygrzewaniu przy temperaturze 1200• C przez czas 1h, następnym chłodzeniem z piecem do temperatury 820• C i wytrzymaniu przy tej temperaturze przez czas 20h oraz chłodzeniu w wodzie. Przy wykorzystaniu mikroskopii elektronowej badano mikrostrukturę oraz powstałe wydzielenia węglikoazotku. Za pomocą programu SigmaScan Pro przeprowadzono ilościową analizę metalograficzną wydzieleń. Badania wykazały, że wzrost zawartości azotu hamuje szybkość koagulacji węglikoazotku, podczas gdy aluminium sprzyja skłonności do koagulacji i skutecznie hamuje rozrost ziarn austenitu.