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Number of results: 7
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Abstract

The Legnica deposit is one of the most prospective in the context of future lignite mining. Its extraction will be inseparable from the removal of the rocks of the overburden, the volume of which is very large. Due to the raw material properties, some of the rocks can be classified as accompanying minerals. The raw material identification of overburden sediments in the Legnica lignite deposit is insufficient. So far, they haven’t been the subject of detailed and comprehensive research to prove their usefulness. The article was a summary of the knowledge on this subject. The following should be included in the accompanying minerals: Quaternary sands and gravels, tertiary sands and clays (Poznan clays). They are present in two colour variants in the Legnica deposit - and fiery. The mineral composition of greenish-blue clays allows them to be included in illite-kaolinite- smectite varieties, in turn fiery clays as kaolinite-illite-smectite varieties. The tertiary clays are a very useful raw material for the production of building materials. In addition, they are potential mineral sorbents due to the nature of the association of clay minerals (occurrence of montmorillonite). They also show suitability for building waterproofing barriers. Quaternary gravels and sands, developed in the overburden Legnica deposit are differentiated raw materials. Some of them are raw materials for the construction industry. The glacial tills can be used as a component of ceramic mixtures. Tertiary sands can be used as a proppant material. The information on the raw material properties of these sediments will be one of the essential criteria for their treatment as accompanying minerals. Minerals accompanying those developed in the Legnica deposit should be exploited and deposited selectively. The creation of anthropogenic deposits accumulating these minerals will provide the possibility of their use for decades after the termination of operation.
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Abstract

High-tin bronzes are used for church bells and concert bells (carillons). Therefore, beside their decorative value, they should also offer other functional properties, including their permanence and good quality of sound. The latter is highly influenced by the structure of bell material, i.e. mostly by the presence of internal porosity which interferes with vibration of the bell waist and rim, and therefore should be eliminated. The presented investigations concerning the influence of tin content ranging from 20 to 24 wt% on mechanical properties of high-tin bronzes allowed to prove the increase in hardness of these alloys with simultaneous decrease in the tensile and the impact strengths (Rm and KV, respectively) for the increased tin content. Fractures of examined specimens, their porosity and microstructures were also assessed to explain the observed regularities. A reason of the change in the values of mechanical properties was revealed to be the change in the shape of α-phase crystals from dendritic to acicular one, and generation of grain structure related to the increased Sn content in the alloy.
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Abstract

In this paper the influence of high power airborne ultrasound on drying biological material (Lobo apple) properties is considered. Apple samples were dried convectively at 75 ◦C and air flow of 2 m/s with and without ultrasound assist at 200W. During experiments, sun-drenched and not sun-drenched part of fruits were considered separately to show, how the maturity of the product influences dry material properties. Dried apple crisps in a size of small bars were subjected to compression tests during which acoustic emission (AE) was used. Analysis of AE and strength test results shows that correlations between received acoustic signals and sensory attributes (crispness, brittleness) of dried apples can be found. It was noted that ultrasound improved fruit brittleness in comparison with pure convective processes, where fruit maturity determines a kind of destruction and behaviour of dried apple crisps.
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Abstract

In earlier works were described trends in the production of tools for die casting (hot work). Almost the entire set of issues dealt with may seem insignificant when incompletely assembled acceptance of the material and the associated risks of processing a material with an inappropriate structure, leading to a very early defect of the die. Therefore, further work will focus particularly on identifying the causes of thermal cracks and preventing a suitable choice of acceptance criteria conditions and heat treatment.
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Abstract

The aim of this publication is to present practical application of the R. Kolman’s quality rating method used in the evaluation of aluminium alloys. The results of studies of the mechanical and physical properties of the three selected test materials are discussed. To find the best material, the quality level of each of the tested materials was assessed using quality ratings proposed by R. Kolman. The results of the conducted analysis have proved that the best material was an AKII MM alloy, i.e. a casting AK11 aluminium alloy from the 4XXX series.
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Abstract

The paper described properties of electro-spark deposited coatings under influence of the laser treatment process. The properties were assessed by analyzing the coating microstructure, X-ray radiation, microhardness, bonding strength, corrosion resistance, porosity and wear tests. The tests were conducted for Mo and Cu coatings (the anode) which were electro-spark deposited over the C45 steel substrate (the cathode) and melted with a laser beam. The coatings were deposited by means of an ELFA-541. The laser processing was performed with an Nd:YAG laser. The coatings after laser processing are still distinguished by very good performance properties, which make them suitable for use in sliding friction pairs.
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Abstract

The article presents the results of investigation of ultra-strength nanostructured bainitic steel Fe-0.6%C-1.9%Mn-1.8%Si-1.3%Cr-0.7%Mo (in wt. %) subjected to shear and uniaxial compression under high strain rate loading. Steel of microstructure consisted of carbide-free bainite and carbon enriched retained austenite presents a perfect balance of mechanical properties especially strength to toughness ratio. Two retained austenite morphologies exist which controlled ductility of the steel: film between bainite laths and separated blocks. It is well established that the strain induced transformation of carbon enriched retained austenite to martensite takes place during deformation. Shear localisation has been found to be an important and often dominant deformation and fracture mode in high-strength steels at high strain rate. Deformation tests were carried out using Gleeble simulator and Split Hopkinson Pressure Bar. Shear and compression strength were determined and toughness and crack resistance were assessed. Susceptibility of nanostructured bainitic steel to the formation of adiabatic shear bands (ASBs) and conditions of the bands formation were analysed. The results suggest that the main mechanism of hardening and failure at the dynamic shearing is local retained austenite transformation to high-carbon martensite which preceded ASBs formation. In the area of strain localization retained austenite transformed to fresh martensite and then steel capability to deformation and strengthening decreases.
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