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This paper presents experimental results regarding the efficiency of using acoustic panels made with fiber-reinforced alkali-activated slag foam concrete containing lightweight recycled aggregates produced by using Petrit-T (tunnel kiln slag). In the first stage, 72 acoustic panels with dimension 500 × 500 × 35 mm were cast and prepared. The mechanical properties of the panels were then assessed in terms of their compressive and flexural strengths. Moreover, the durability properties of acoustic panels were studied using harsh conditions (freeze/thaw and carbonation tests). The efficiency of the lightweight panels was also assessed in terms of thermal properties. In the second stage, 50 acoustic panels were used to cover the floor area in a reverberation room. The acoustic absorption in diffuse field conditions was measured, and the interrupted random noise source method was used to record the sound pressure decay rate over time. Moreover, the acoustic properties of the panels were separately assessed by impedance tubes and airflow resistivity measurements. The recorded results from these two sound absorption evaluations were compared. Additionally, a comparative study was presented on the results of impedance tube measurements to compare the influence of casting volumes (large and small scales) on the sound absorption of the acoustic panels. In the last stage, a comparative study was implemented to clarify the effects of harsh conditions on the sound absorption of the acoustic panels. The results showed that casting scale had great impacts on the mechanical and physical properties. Additionally, it was revealed that harsh conditions improved the sound properties of acoustic panels due to their effects on the porous structure of materials.

In this paper, we present results of a study about the possibilities of utilizing talc ore mining tailings as a refractory raw material aiming at magnesium aluminate MgAl2O4 spinel composition. The mine tailings are rich in magnesite but contain also other minerals such as talc, chlorite, dolomite, and iron sulphides. As alumina source for spinel synthesis, we studied also another secondary raw material, an aluminium hydroxide precipitate, a by-product generated from the pickling process of aluminium anodizing. The goal of this paper is to study and compare a pure Mg–Al–O system and the corresponding Mg–Al–O system with some impurities. The formed phase and microstructures were examined by XRD, FESEM, and EDS studies. The thermal behaviour was studied using thermogravimetric analysis.

In this paper, we present results of a study about the possibilities of utilizing talc ore mining tailings as a refractory raw material aiming at magnesium aluminate MgAl2O4 spinel composition. The mine tailings are rich in magnesite but contain also other minerals such as talc, chlorite, dolomite, and iron sulphides. As alumina source for spinel synthesis, we studied also another secondary raw material, an aluminium hydroxide precipitate, a by-product generated from the pickling process of aluminium anodizing. The goal of this paper is to study and compare a pure Mg-Al-O system and the corresponding Mg-Al-O system with some impurities. The formed phase and microstructures were examined by XRD, FESEM, and EDS studies. The thermal behaviour was studied using thermogravimetric analysis.

In this paper, we present results of a study about the possibilities of utilizing talc ore mining tailings as a refractory raw material aiming at magnesium aluminate Mg[Al.sub.2][O.sub.4] spinel composition. The mine tailings are rich in magnesite but contain also other minerals such as talc, chlorite, dolomite, and iron sulphides. As alumina source for spinel synthesis, we studied also another secondary raw material, an aluminium hydroxide precipitate, a by-product generated from the pickling process of aluminium anodizing. The goal of this paper is to study and compare a pure Mg-Al-O system and the corresponding Mg-Al-O system with some impurities. The formed phase and microstructures were examined by XRD, FESEM, and EDS studies. The thermal behaviour was studied using thermogravimetric analysis.

Cemented carbides are primarily used in metal cutting tools, metal forming tools (e.g. dies), construction and mining equipment where unique combination of mechanical, physical, and chemical properties are needed. The majority of cemented carbide material solution is based on tungsten carbide (WC) with cobalt (Co) binder metal. Development of novel titanium carbide (TiC) based hard metal is introduced. Properties of developed novel TiC based hard metal compositions are compared against traditional WC-Co grades. Performed tests show that mechanical properties (flexural strength, fracture toughness and hardness) of studied compositions are comparable to medium and coarse grain size WC-Co grades. The behavior of varied material compositions in crushing pin-on-disk test is also evaluated. Gained results shows that developed TiC hard metal grades are potential candidates to substitute traditional WC-Co in certain applications.

Nano sized tungsten carbide powder was synthesised using water soluble raw materials. Ammonium metatungstate and glycine were applied as tungsten and carbon sources. They were dissolved in water and spray-dried before thermal synthesis in argon atmosphere. The particle size was 50 nm in average and grain size was 12-13 nm in average. The synthesized nano size tungsten carbide powder and commercial submicron and micron tungsten carbide powders were mixed with cobalt powder with a ratio of 90:10 by weight. The powders were consolidated by pulsed electric current sintering under vacuum at 1100°C to relative density of approximately 99%. The effect of powder properties and phase structure on sintering mechanism was investigated. Mechanical and microstructure evaluation of the sintered compacts were carried out by dynamic indentation, electron microscopy and X-ray diffraction. The influence of grain growth of the carbides on mechanical properties was evaluated. The decomposition of fine carbides was also investigated.