Corrosion properties of Ca65-xMg17.5Zn17.5+x (x = 0, 2.5, 5) alloys

The aim of the paper is to study the effect of zinc addition on the corrosion behavior of Ca65–xMg17.5Zn17.5+x (x = 0, 2.5, 5 at.%) alloys in simulated physiological fluids at 37°C. The electrochemical measurements allowed to determine a corrosion potential, which showed a positive shift from –1.60 V for Ca65Mg17.5Zn17.5 alloy to –1.58 V for Ca60Mg17.5Zn22.5 alloy, adequately. The more significant decrease of hydrogen evolution was noticed for Ca60Mg17.5Zn22.5 alloy (22.4 ml/cm2) than for Ca62.5Mg17.5Zn20 and Ca65Mg17.5Zn17.5 samples (29.9 ml/cm2 and 46.4 ml/cm2), consequently. The corrosion products after immersion tests in Ringer’s solution during 1 h were identified by X-ray diffraction and X-ray photoelectron spectroscopy as calcium, magnesium oxides, carbonates, hydroxides and calcium hydrate

Production aspects of inhomogeneous hot deformation in as-cast CuNi25 alloy

389-398The attempts are being made to achieve the best economic effects and material properties by optimizing the hot working process. Production requires an accurate, specified conditions and knowledge about the influence of almost all parameters on the manufacturing process. The misapplication of materials or technological parameters lead to increase in costs and often to destruction of materials during their production or operating. The fundamental problems associated with the hot working processes of many metals and commercial alloys focus on two associated phenomena: intermediate temperature loss of ductility and hot brittleness. This paper is the result of examination of these two phenomena on industrial CuNi25 alloys, with different chemical compositions and structures. Deformation rate has also been taken into consideration. All tests have been conducted in air, within 0.3-0.7 TH, selected ones in argon atmosphere. Numerous techniques are used to characterize material properties and to identify the inhomogeneities occurring, for example high temperature tensile tests, infrared thermography, SEM, EDS, WDS and TEM. </span

Haloizyt jako adsorbent mineralny CO2 – badania kinetyki adsorpcji i pojemności sorpcyjne

Physical adsorption of carbon dioxide on various mineral adsorbents is becoming extremely interesting in the field of energy and environment where CCS technology is an option for CO2 emission reduction. In the article the halloysite from Dunino deposit was assessed in terms of its potential use as a CO2 adsorbent. Results of tests indicate that modified halloysite (i.e. calcinated or modified by acid treatment) has a relatively low adsorption capacity which should be easily increased by other surface modification methods. Sorption kinetic is rather fast and over 85-89% of CO2 adsorption is accounted by a rapid sorption step i.e. 7 to 16 seconds.Procesy adsorpcji fizycznej CO2 na różnego rodzaju adsorbentach mineralnych są istotne z punktu widzenia technologii wychwytywania i separacji tego gazu z dużych źródeł stacjonarnych (CCS). W artykule przedstawiono wyniki adsorpcji CO2 na haloizycie ze złoża Dunino, który może mieć potencjalne zastosowanie w technologiach adsorpcyjnych. Rezultaty badań wskazują, że adsorpcja CO2 na modyfikowanym haloizycie tj. kalcynowanym oraz kwasowanym jest relatywnie niska w porównaniu z innymi adsorbentami mineralnymi, jednakże odpowiednia metoda jego modyfikacji może zwiększyć znacznie jego chłonność sorpcyjną. Przeanalizowano również kinetykę sorpcji, gdzie oszacowano iż 85-89% CO2 adsorbuje się w czasie 7-16 sekund

Kinetics of methane fermentation of selected post-processed poultry beddings — possibilities of process intensification and limitations

The kinetics of methane fermentation of selected post-processed poultry beddings was analyzed. A modified nonlinear Gompertz model was applied for the calculations. The presented kinetic parameter may be useful for design or optimization calculations of agricultural-biogas installations integrated with industrial-scale poultry breeding

Microstructural and chemical analysis of selected poultry bedding materials — potential substrates in agricultural biogas production technologies

The research results concerning microstructure and chemical composition of selected post-processed poultry beddings derived from industrial-scale poultry breeding are presented. It was found, that the proper trend is providing the optimal conditions in respect to bred-animals comfort. The highest concentration of biogenic elements — especially nitrogen and potassium — was observed for the samples of poultry manure premixed with the straw. High quality of bedding biomass influences the inhibition of poultry-manure decomposition processes advantageously. In effect, biogas yield increases (due to C/N adjustment), in spite of the fact that increase in ammonium nitrogen concentration simultaneously inhibits the methane fermentation process

Methane fermentation of poultry manure — shortcomings and advantages of the technology: fermentation or co-fermentation?

Overcoming of technological barriers in methane fermentation of substrates including poultry manure derived from poultry-breeding industry is regarded as one of strategic trends in biogas-technology development. The essential limitations and possibilities of such substrates for biogas production is presented here. It should be emphasized, that biogas production based on poultry manure from industrial-scale farms is effective solution of important ecological problem with simultaneous production of green energy and efficient solution of odours emission from the poultry breeding farm. Methane co-fermentation of post-processed bedding premixed with poultry manure solves, at least partly, problem of correct C/N ratio in the substrate mixture

Effect of plastic deformation rate at room temperature on structure and mechanical properties of high-Mn austenitic Mn-Al-Si 25-3-3 type steel

Purpose: The aim of the paper is to determine influence of plastic deformation rate at room temperature on structure and mechanical properties of high-Mn austenitic Mn-Al-Si 25-3-3 type steel tested at room temperature. Design/methodology/approach: Mechanical properties of tested steel was determined using Zwick Z100 static testing machine for testing with the deformation speed equal 0.008 s-1, and RSO rotary hammer for testing with deformation speeds of 250, 500 and 1000s-1. The microstructure evolution samples tested in static and dynamic conditions was determined in metallographic investigations using light microscopy as well as X-ray diffraction. Findings: Based on X-ray phase analysis results, together with observation using metallographic microscope, it was concluded, that the investigated high-Mn X13MnAlSiNbTi25-3-3 steel demonstrates austenitic structure with numerous mechanical twins, what agrees with TWIP effect. It was demonstrated, that raise of plastic deformation rate produces higher tensile strength UTS and higher conventional yield point YS0.2. The UTS strength values for deformation rate 250, 500 and 1000 s-1 grew by: 35, 24 and 31%, appropriately, whereas in case of YS0.2 these were: 7, 74 and 130%, accordingly, in respect to the results for the investigated steel deformed under static conditions, where UTS and YS0.2 values are 1050 MPa and 700 MPa. Opposite tendency was observed for experimentally measured uniform and total relative elongation. Homogeneous austenitic structure was confirmed by X-ray diffractometer tests. Research limitations/implications: To fully describe influence of strain rates on structure and mechanical properties, further investigations specially with using transmission electron microscope are required. Practical implications: Knowledge about obtained microstructures and mechanical properties results of tested X13MnAlSiNbTi25-3-3 steel under static and dynamic conditions can be useful for the appropriate use of this type of engineering material in machines and equipment susceptible to static or dynamic loads. Originality/value: The influence of plastic deformation at room temperature under static and dynamic conditions of new-developed high-manganese austenitic X13MnAlSiNbTi25-3-3 steels were investigated

Purification of halloysite by magnetic separation

Rational use of mineral resources requires advanced separation methods in order to obtain high quality products. In this study chemical treatment with magnetic separation of halloysite from Dunino (Poland) is presented. Initial crushing, hydrochloric acid absorption treatment, sedimentation (settling) and polygradient magnetic separation in weak magnetic field were applied to separate aluminosilicates from iron and titanium oxides (impurities). The process allowed to obtain a product of approximately 98% purity of the aluminosilicate fraction (halloysite + kaolinite). The tailings from magnetic separation consisted of iron oxides, while the intermediate product consisted mainly of aluminosilicate and iron chlorides resulting from the HCl treatment. The obtained products can be used as a component of polymer nanocomposites, sorbents and in ceramics industry

Corrosion of Biocompatible Mg66+xZn30-xCa4 (x=0.2) Bulk Metallic Glasses

The aim of this paper was to investigate the corrosion resistance of Mg66Zn30Ca4 and Mg68Zn28Ca4 metallic glasses and evaluate the ability of this amorphous alloy use for medical applications as biodegradable medical implants. Taking into account the amount of Mg, Zn, Ca elements dissolved in multielectrolyte physiological fluid (MPF) from Mg66+xZn30-xCa4 (x=0.2) alloys the daily dose of evolved ions from alloys components was determined. Additional goal of the paper was determination of corrosion rate (Vcorr) and amount of hydrogen evolved from amorphous magnesium alloys in simulated environment of human body fluids during 24h immersion and during electrochemical tests. Corrosion studies were done in the multielectrolyte physiological fluid (MPF) at 37°C. The amount of hydrogen evolved [ml/cm2] and corrosion rate Vcorr [mm/year] of amorphous Mg66Zn30Ca4 and Mg68Zn28Ca4 alloys were compared. The work also presents characterization of Mg-based bulk metallic glasses structure in the form of 2 mm thickness plates. Samples structure was analyzed by means of X-ray diffraction. Fracture and surface morphology of magnesium alloy samples were identified using scanning electron microscopy