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Abstract

The use of environmentally friendly inorganic binders and new technologies for cores production is widely discussed topic in recent years. This paper contains information about new hot curing process for core making with alumina-silicate based inorganic binders – geopolymers. Main differences between hot cured geopolymers and hot cured alkali silicate based inorganic binders are discussed. The main objective of this research paper was to investigate basic technological properties of geopolymer binder system such as strength, compaction, storage ability and knock-out properties. For this purpose, three mixtures with different powder additives were prepared and tested in laboratory conditions using specific methods. Strength properties evaluation showed sufficient levels as well as knock-out properties measurement, even with additives B and C originally designed for the use with alkali silicate based two component binder systems. Additives B and C were considered compatible with geopolymer binders after casting production trial results. Storage ability of geopolymers seems to be more sensitive than of alkali silicate based binders in the same tested conditions. Mixtures with geopolymer binder showed 20% more decrease of strength compared to alkali silicate binders after 24 hours in conditions of 25 °C and 65 %RH.
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Abstract

The article presents the analysis of properties of the high-strength AlZnMgCu (abbr AlZn) aluminium alloy and estimates possibilities of its application for responsible structures with reduced weight as an alternative to iron alloy castings. The aim of the conducted studies was to develop and select the best heat treatment regime for a 7xx casting alloy based on high-strength materials for plastic working from the 7xxx series. For analysis, wrought AlZnMgCu alloy (7075) was selected. Its potential of the estimated as-cast mechanical properties indicates a broad spectrum of possible applications for automotive parts and in the armaments industry. The resulting tensile and fatigue properties support the thesis adopted, while the design works further confirm these assumptions.
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Abstract

The study has identified selected mechanical properties of fresh and stored fruit of large cranberry. The analyses focused on the changes in the values of peel and flesh puncture strength in the selected cranberry varieties depending on water content and storage duration. Measurements were also performed to examine deformations and energy needed to cut through the fruit peel and flesh. The value of breaking stress was calculated. The findings show a decrease in the relevant parameters during storage of fruit obtained from the examined varieties of large cranberry. Mean water contents in the fruit of the relevant varieties were in the range of 86.4-89.1%. There was a notable decrease in the mean value of peel and flesh puncture strength in the fruit of the relevant varieties of large cranberry. The mean value of peel and flesh puncture strength in the fresh fruit of cranberry was 6.1 N, and after 40 days in storage the value decreased by 2.3 N.
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Abstract

Ductile iron casts with a higher silicone content were produced. The austempering process of high silicone ductile iron involving different austempering times was studied and the results presented. The results of metallographical observations and tensile strength tests were offered. The obtained results point to the fact that the silicone content which is considered as acceptable in the literature may in fact be exceeded. The issue is viewed as requiring further research.
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Abstract

The results presented in this paper are a continuation of the previously published studies. The results of hest treatment of ductile iron with content 3,66%Si and 3,80% Si were produced. The experimental castings were subjected to austempering process for time 30, 60 and 90 minutes at temperature 300o C. The mechanical properties of heat treated specimens were studied using tensile testing and hardness measurement, while microstructures were evaluated with conventional metallographic observations. It was again stated that austempering of high silicone ferritic matrix ductile iron allowed producing ADI-type cast iron with mechanical properties comparable with standard ADI.
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Abstract

The paper presents results of measuring attenuation coefficient of the Al-20 wt.% Zn alloy (AlZn20) inoculated with different grain refiners. During experiments the melted alloys were doped with Al-Ti3-C0.15 refining master alloy. Basing on measurements performed by Krautkramer USLT2000 device with 1MHz ultrasound wave frequency it was stated that grain refinement reduces the attenuation coefficient by about 20-25%. However, the examined alloys can be still classified as the high-damping ones of attenuation greater than 150 dB/m.
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