B. Tomiczek

Structure and properties of aluminium–magnesium casting alloys after heat treatment

Since the forming of the microstructure depends on the specific of the casting method, which directly affects further mechanical and physical properties of the material, it is important to understand how to control the microstructure of the cast to understand changes that taking place during the crystallisation process. For estimating the metallurgical quality of the liquid metal before casting, the thermal-derivative analysis (TDA) is utilised. The TDA has been used for a long time, in both ferrous and non-ferrous industries casting. The Universal Metallurgical Simulator and Analyser (UMSA) platform is a rapid, sensitive and economical method of determining a full range of solidification features. The work focuses on the thermal analysis and heat treatment of aluminium alloys. The liquidus and solidus temperatures and dendrite coherency point (DCP) are then characterised. The research shows that the UMSA platform allows precise determination and calculation of thermal parameters. The influence of the heat treatment on structure and properties of aluminium castings has been determined as well. Heat treatment was carried out to increase the mechanical properties of aluminium alloys. Based on the findings above, the influence of microstructure on properties of the alloys is discussed.

Employment of the artificial neural networks for prediction of magnetic properties of the metallic amorphous alloys

The aim of this work is to employ the artificial neural networks for modelling the magnetic properties of the amorphous alloys with the iron and cobalt matrix. The artificial neural networks implemented in StatSoft Statistica Neural Network PL 4.0F were used to determine the relationship between the chemical compositions of amorphous alloys, heat treatment parameters and magnetic properties. The attempt to use the artificial neural networks for predicting the effect of the chemical composition and heat treatment parameters on the magnetic flux density BS succeeded, as the level of the obtained results was acceptable, as the level of the obtained results was acceptable. For different magnetic properties of soft magnetic materials, further calculations are planned. The results of calculation makes it possible to design new advantageous combinations of concentrations of the particular elements to develop grades of the soft magnetic alloys. This paper employs the artificial neural networks for modelling chemical composition and heat treatment parameters of amorphous soft magnetic alloys to obtain the best magnetic properties. [Received 15 August 2007; Accepted 20 October 2007]

Role of Halloysite Nanoparticles and Milling Time on the Synthesis of AA 6061 Aluminium Matrix Composites

The aim of this work is to determine the effect of a reinforcing phase and manufacturing conditions on the structure and properties of newly developed nanostructural powders of composite materials with the aluminium alloy matrix reinforced with natural halloysite nanotubes. Composite materials were manufactured employing as a matrix the air atomized powders of AA 6061 aluminium alloy and as a reinforcement the halloysite nanotubes. Composite powders of aluminium alloy matrix reinforced with 5, 10 and 15 wt.% of halloysite nanotubes were fabricated by high-energy mechanical alloying using a planetary mill. Elaborated composite powders were characterized for their apparent density, microhardness, particle size distribution and microstructure. A structure of newly developed nanostructured composite materials reinforced with halloysite nanotubes prove that a mechanical alloying process allow to improve the arrangement of reinforcing particles in the matrix material. A homogenous structure with uniformly arranged reinforcing particles can be achieved by employing reinforcement with halloysite nanotubes if short time of mechanical alloying is maintained thus eliminating an issue of their agglomeration.

TEM and XRD Study of Nanostructured Composite Materials Reinforced with the Halloysite Particles

In the present work selected results of TEM and XRD investigations of the new AA-6061 matrix composite materials reinforced with halloysite nanoparticles manufactured by mechanical alloying and hot extrusion are present. Halloysite nanotubes, being a clayey mineral of volcanic origin which is characterized by high porosity, large specific surface, high ion exchange and easy chemical and mechanical treatment, can be used as alternative reinforcement of metal matrix composite materials. The composite materials obtained as a result of mechanical alloying and hot extrusion are characterized with the structure of evenly distributed, disperse mineral phase particles in fine-grain matrix of AA-6061 alloy, facilitate the obtainment of higher values of strength properties, compared to the initial alloy. Thanks to HRTEM analysis, the occurrence of grains sized ca. 20÷30nm in the composite materials reinforced with halloysite nanotubes with 15% mass share has been confirmed. The crystallite size and lattice strain of the obtained composites were calculated from X-ray line broadening, applying different profiles of diffraction lines. The achieved values of crystallite size for composites powders after 6 hours of milling were in the range 65-150nm, depending on the calculation method.

Application of thermal analysis in the selection of polymer components used as a binder for metal injection moulding of Co–Cr–Mo alloy powder

To produce the polymer-powder slurry for injection moulding the thermoplastic polymers such as polypropylene, high-density polyethylene and ethylene-vinyl acetate were used. Depending on skeletal polymers, in every feedstock paraffin wax (PW) was used in the amount of 50% of binder. Application of PW gives the possibility using solvent debinding or thermal debinding at a lower temperature. Then the open porosity into the injected samples reduces the time of thermal debinding of binder residue. Application of one type of skeletal polymer requires using a long isothermal step. The use of a blend of skeletal polymers enables subsequent thermal degradation which consecutively removes skeletal polymers during the heating to the sintering temperature, to minimise the time of isothermal stops. The rheological properties of blends used as a binder and next feedstocks were investigated during mixing in the twin-screw extruder and capillary rheometer. This results gives the information about the possibility to produce feedstocks and then to their injection moulding. Thermal behaviour of samples was determined by differential scanning calorimetry and thermogravimetric analysis to obtain the information about the temperature of mixing the polymers and to propose the thermal debinding cycle.

Modified halloysite nanoclay as a vehicle for sustained drug delivery

This paper presents the effect of modified halloysite nanotubes on the sustained drug release mechanisms of sodium salicylate. Acid treatment and composite polymer-halloysite modification techniques were adopted in this study. After each modification, sodium salicylate drug was loaded, and in vitro release properties were evaluated and compared with the raw unmodified halloysite nanotubes. The results obtained from SEM, TEM and FTIR analyses indicate that both acid treatment and composite formation have no effect on the tubular structure and morphology of halloysite. However, modification of the halloysite nanotubes did influence the drug release rate. In the acid treatment modification, there was an improved loading of sodium salicylate drug which resulted in the sustain release of large amount of the sodium salicylate. In the polymer/halloysite composite formation, a consistent layer of polymer was formed around the halloysite during the composite formation and thus delayed release providing sustained release of sodium salicylate drug over a longer period of time as compared to the acid treated and unmodified halloysite. The results from the invitro release were best fitted with the Higuchi and the Koresymer-Peppas models.

Fabrication, Composition, Properties and Application of the AlMg1SiCu Aluminium Alloy Matrix Composite Materials Reinforced with Halloysite or Carbon Nanotubes

In this chapter, the characterisation of the halloysite nanotubes (HNTs) and multiwalled carbon nanotubes (MWCNTs) as the reinforcement in the composite materials was described. The original and author technology of production of the aluminium AlMg1SiCu matrix composite materials reinforced with halloysite or carbon nanotubes using powder metallurgy techniques, including mechanical alloying and hot extrusion and the range of own research in the case to determine microstructure, as well as mechanical properties of those materials was present. It was investigated that the addition of carbon and halloysite nanotubes causes a significant improvement in mechanical properties of the obtained nanocomposites. The investigation results show that the technology used in manufacturing nanocomposite materials can find the practical application in the production of new light metal matrix nanocomposites.

Synthesis of Pt nanowires with the participation of physical vapour deposition

Abstract The following paper presents the possibility of formation of Pt nanowires, achieved by a three-step method consisting of conformal deposition of a carbon nanotube and conformal coverage with platinum by physical vapour deposition, followed by removal of the carbonaceous template. The characterization of this new nanostructure was carried out through scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD).