Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 21
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

Soybean [Glycine max (L.)], one of the most important crops in Argentina, is commonly infected by Colletotrichum truncatum, the causal agent of anthracnose. Tagetes filifolia essential oil (EO) is presented as a natural approach to minimize the dose of chemical fungicides applied to the crop. The fungus Trichoderma harzianum is used as a biocontrol agent because of its ability to produce secondary metabolites that destroy cell walls of phytopathogenic fungi. However, its performance can be affected when it is exposed to chemical fungicides. The objective of this work was to evaluate the antifungal activity of T. filifolia EO both individually and combined with chemical fungicides against C. truncatum, and its effect on T. harzianum. Fungi were isolated from soybean crops. The following pesticides were assessed: carbendazim (F1), difenoconazole (F2) and trifloxystrobin + cyproconazole (F3). The EO was obtained from native plants and its chemical composition was analyzed by gas chromatography–mass spectrometry (GC–MS). The minimum fungicide concentration (MFC) was determined for each compound. Fungicides were combined with the EO to look for combinations that allowed a reduction of pesticide doses. Among fungicides, F1 showed the strongest antifungal activity against C. truncatum (MFC = 0.25 μl ⋅ l–1) and T. harzianum (MFC = 1.5 μl ⋅ l–1). The sensitivity of both fungi to the EO was lower than to fungicides. The EO presented MFCs of 6,000 and 9,000 μl ⋅ l–1 against C. truncatum and T. harzianum. The EO and F1 affected the growth of T. harzianum at concentrations that controlled C. truncatum (31 and 10%). Eight combinations of fungicides and the EO allowed fungicide concentration reductions of up to 80%, although the growth of the biocontrol strain was also affected. The results demonstrated that T. filifolia EO can be used to control anthracnose and reduce doses of chemical fungicides applied to soybean crops. Its effect on T. harzianum should be considered in the design of integrated pest management strategies.

Go to article

Authors and Affiliations

Laura Carolina Gadban
Boris Xavier Camiletti
Ezequiel Darío Bigatton
Silvia Graciela Distéfano
Enrique Iván Lucini Lucini
Download PDF Download RIS Download Bibtex

Abstract

Wheat grain discoloration, a worldwide disease that lowers grain quality and decreases grain yield, does not have a single etiology. It has been proposed that it is a consequence of an abiotic mechanism, a response to environmental conditions or enzymatic activity. It has also been suggest that it is a biotic mechanism, a fungal infection principally by Alternaria spp. and Bipolaris sorokiniana. The present work was carried out to analyze the possible etiology of this disease in nine durum wheat genotypes from two localities of southern Buenos Aires province (Argentina) on two sowing dates. Incidence (percentage of grain discoloration) was recorded and mycobiota associated with this pathology was registered following ISTA rules. Peroxidase activity in an extract obtained from grains belonging to genotypes of the locality that showed the highest incidence was measured.

The incidence among genotypes, localities and sowing dates varied, although the genotypes with the higher and lower values of incidence were the same for all the variables tested. The fungus Alternaria spp. was isolated the most frequently followed by Fusarium spp., while Bipolaris sorokiniana was found the least frequently. Peroxidase activity showed that all the treatments had similar levels of enzymatic activity, but there was no clear differentiation between controls either between genotypes with the lowest or the highest incidence values. This suggests that peroxidase activity did not have a clear relationship with grain discoloration. In this research, it is presumed that fungal infection is the main cause of this disease.

Go to article

Authors and Affiliations

Maria Josefina Cipollone
Paulina Moya
Iván Martínez
Mario Saparrat
Marina Sisterna
Download PDF Download RIS Download Bibtex

Abstract

Septoria melissae Desm., the most important pathogen of lemon balm (Melissa officinalis) occurs each year on plantations. The fungus may cause serious yield losses in the absence of proper plant protection. Breeding resistant or tolerant cultivars could play an important role in plant protection of medicinal plants. However, only a few descriptions of tolerant varieties of lemon balm are available. The goal of this work was to evaluate the susceptibility of three accessions of M. officinalis against the pathogen of Septoria leaf spot under field conditions at Budapest-Soroksár (Hungary) in 2017–2018. Differences in susceptibility of the accessions were observed in both years. The accession of M. officinalis subsp. altissima proved to be the least susceptible to Septoria infection. The frequency of the infected leaves was only 5.1 and 28.1% in 2017 and 2018, respectively. However, the cultivar M. officinalis subsp. officinalis ‘Lorelei’ turned out to be the most susceptible to the pathogen with an average infection level of 26.1 and 66.6%, 1.3–6.1 times higher than that of the other accessions in each year, respectively. Development of disease tolerant M. officinalis cultivars may be an effective tool in the plant protection of lemon balm.

Go to article

Authors and Affiliations

Gergő Kovács
Géza Nagy
Éva Zámbori-Németh
Download PDF Download RIS Download Bibtex

Abstract

Onion yellow dwarf virus (OYDV), an aphid-borne potyvirus is one of the major viral pathogens of garlic causing significant yield losses worldwide. It is found almost everywhere in the world where Allium species is grown. The aim of this study was to test the presence of OYDV infection in garlic from Ethiopia. The presence of the virus was tested by Reverse transcription polymerase chain reaction (RT-PCR). The direct sequencing of the PCR product produced a sequence of 296 bp. Sequence analysis showed 89.27% sequence homology with an isolate from Australia (HQ258894) and 89.29% with an isolate from Spain (JX429964). A phylogenetic tree constructed with MEGA 7.0 revealed high levels of homology with various isolates of OYDV from all over the world and thus further confirmed the identity of the virus.

Go to article

Authors and Affiliations

Yohanis Kebede
Jyoti Singh
Shahana Majumder
ORCID: ORCID
Download PDF Download RIS Download Bibtex

Abstract

The present study thoroughly evaluated the effect of hydroxypropyl-β-cyclodextrin (HP-β-CD) on eluting of Aroclor1242 (one kind of PCBs (polychlorinated biphenyls)) from contaminated soil. The factors that might affect eluting efficiency including HP-β-CD concentration, contact time, eluting cycles, temperature, pH, salt content, humic acid, and ultrasonic were all tested to evaluate the PCBs eluting efficiency by HP-β-CD. Results indicated that Aroclor1242 can be eluted effectively from soil by HP-β-CD solution, 81% of Aroclor1242 was eluted from soil by 50 g/L of HP-β-CD solution after three cycles eluting, and the eluting efficiency was improved by increasing temperature and with ultrasonic. Furthermore, it was shown that the humic acid and extreme acidic/alkaline condition both decreased the eluting efficiency. In addition, column eluting experiment was conducted to simulate the practical HP-β-CD eluting of Aroclor1242 from contaminated soil, 18% of the PCBs was eluted from the soil column by 10 g/L of HP-β-CD. Overall, the results indicated the high extract power of HP-β-CD toward PCBs polluted soil and potential use of HP-β-CD for in situ remediation of PCBs contaminated soils.
Go to article

Authors and Affiliations

Xun Liu
1
Ning Ding
2
Hong Liu
1
Houwang Chen
1

  1. Suzhou University of Science and Technology, China
  2. Beijing Technology and Business University, China
Download PDF Download RIS Download Bibtex

Abstract

The presented work introduces a simple modification of coal fl y ash (FA) with 30% solution of H 20 2, used as a new efficient sorbent for the removal of organic dye crystal violet (CV) in the presence of Cu(II) ions in single- and bi-component systems Cu(II)-CV. FT-IR, TG, SEM-EDS, and XRD suggested that the mechanism of Cu(II) and CV sorption onto FA-H 2O 2 includes ion-exchange and surface adsorption process. Comparing the values of the reduced chi-square test (χ 2/DoF) and the determination coefficient R 2 obtained for CV of the considered isotherms, the fitting degree follows the sequence: Jovanović > Langmuir > Elovich > Freundlich > Redlich-Peterson (R-P) > Tóth > Halsey > BET. Sorption of Cu(II) ions in a single system by means of FA-H 2O 2 was well fi tted by the Langmuir and R-P model. The studies of equilibrium in a bi-component system by means of extended Langmuir (EL), extended Langmuir-Freundlich (ELF), and Jain-Snoeyink (JS) models were analysed. The estimation of parameters of sorption isotherms in a bi-component system Cu(II)-CV has shown that the best of fi t calculated values of experimental data for both sorbates have been the EL model and the JS model, but only in the case of a CV dye. The sorption kinetic of Cu(II) and CV onto FA-H 2O 2 was discussed by means of the PFO, PSO, and intra-particle diff usion models.
Go to article

Authors and Affiliations

Eleonora Sočo
1
Dariusz Pająk
1
Jan Kalembkiewicz
1

  1. Department of Inorganic and Analytical Chemistry, University of Technology, Rzeszów, Poland
Download PDF Download RIS Download Bibtex

Abstract

Sugar beet molasses vinasse is a high-strength distillery wastewater. It contains colored substances which significantly affect the degree of pollution and toxicity of vinasse. This study aimed to optimize the medium composition and the process condition of sugar beet molasses vinasse decolorization by Lactobacillus plantarum MiLAB393. The research was conducted in two stages: the shake-fl ask stage in the 250 cm 3 Erlenmeyer flasks and the batch experiments in the 5 dm 3 working volume stirred-tank bioreactor. During the study, the concentrations of glucose and yeast extract were optimized using experimental design of experiments (DOE). The influences of the initial value of pH and pH control, temperature, stirrer speed and glucose concentration on decolorization were tested. The highest color reduction of 24.1% was achieved for an experiment in which 24.93 g/dm 3 of glucose was added to the medium and stirrer speed was 200 rpm. This efficiency of 30% v/v sugar beet molasses vinasse decolorization was obtained at non-controlled pH 6.0 and at 35.8°C. It was found that pH control determines vinasse decolorization. When the pH was controlled, decolorization did not exceed 9%. The glucose and yeast extract concentration and the stirrer speed have a great influence on the process. Changes in these parameters may increase biomass growth while decreasing the decolorization.
Go to article

Authors and Affiliations

Marta Wilk
1
Małgorzata Krzywonos
1

  1. Wroclaw University of Economics
Download PDF Download RIS Download Bibtex

Abstract

This paper presents a new concept of disinfection traditionally applied in water treatment systems. The new definition of this process results from the change in its functionality, aims and methods, which guarantee high quality of water supply. The literature review and technical practice demonstrate a demand for disinfection to act as a functional element of the integrated water distribution system and an active intermediate link between the technology of water treatment and the water distribution network. The presented concept of a disinfection process enables evaluation of water treatment, increases its effectiveness in integrated water treatment systems. Such defined disinfection addresses water conservation and its biological stability within the water supply network. The presented here new concept of disinfection assigns its new role and function in the integrated water distribution system. The controlling and diagnostic function of the disinfection defined in the paper provides a transparent and comprehensive method, with considerable application in experimental design, as well as practical solutions for integrated water distribution systems.
Go to article

Authors and Affiliations

Zbysław Dymaczewski
1
Joanna Jeż-Walkowiak
1
Michał Michałkiewicz
1
Marek M. Sozański
1
Aleksandra Makała
1

  1. Poznan University of Technology, Institute of Environmental Engineering and Building Installations
Download PDF Download RIS Download Bibtex

Abstract

High concentrations of nitrogen dioxide in the air, particularly in heavily urbanized areas, have an adverse eff ect on many aspects of residents’ health. A method is proposed for modelling daily average, minimal and maximal atmospheric NO 2 concentrations in a conurbation, using two types of modelling: multiple linear regression (LR) an advanced data mining technique – Random Forest (RF). It was shown that Random Forest technique can be successfully applied to predict daily NO 2 concentration based on data from 2015–2017 years and gives better fit than linear models. The best results were obtained for predicting daily average NO 2 values with R 2 =0.69 and RMSE=7.47 μg/m . The cost of receiving an explicit, interpretable function is a much worse fit (R 2 from 0.32 to 0.57). Verification of models on independent material from the first half of 2018 showed the correctness of the models with the mean average percentage error equal to 16.5% for RF and 28% for LR modelling daily average concentration. The most important factors were wind conditions and traffic flow. In prediction of maximal daily concentration, air temperature and air humidity take on greater importance. Prevailing westerly and south-westerly winds in Wrocław effectively implement the idea of ventilating the city within the studied intersection. Summarizing: when modeling natural phenomena, a compromise should be sought between the accuracy of the model and its interpretability.
Go to article

Authors and Affiliations

Joanna Amelia Kamińska
1
Tomasz Turek
1

  1. Wrocław University of Environmental and Life Sciences
Download PDF Download RIS Download Bibtex

Abstract

Ligninolytic enzymes are employed for the production of second-generation biofuel to minimize fuel crisis. Additionally, they play a crucial role in global carbon cycle and a variety of applications in food, agriculture, paper and textile industries. On a large scale production of ligninolytic enzymes, microorganisms can be cultured on lignocellulosic wastes. In the present study, proximate analysis including acid detergent lignin (ADL), acid detergent cellulose (ADC), acid detergent fi ber (ADF) and acid insoluble ash (AIA) were performed for Platanus orientalis (chinar), Bauhinia variegata (orchid tree), Pinus roxburghii (chir pine), wheat straw and wheat husk. Platanus orientalis was selected as substrate because of higher lignin contents for the production of ligninolytic enzymes by Aspergillus flavus. Solid State Fermentation was used and Response Surface Methodology was employed for optimizing various parameters and enzymes production. Maximum production was achieved at temperature 32°C, fermentation period 120 hours, pH 4.5, inoculums size 3.5 mL, substrate mesh size 80 mm, substrate size 7 g. Maximum purifi cation of laccase, manganese peroxidase (MnP) and lignin peroxidase (LiP) was achieved with 50%, 60% and 40% ammonium sulfate respectively and it was enhanced by gel filtration chromatography. Characterization of enzymes shows that Laccase has 35°C optimum temperature, 4.5 pH, 0.289 mM Km and 227.27 μM/ml Vmax. Manganese peroxidase has 30°C optimum temperature, 5.5 pH, 0.538 mM Km and 203.08 μM/ml Vmax. Lignin peroxidase has 30°C optimum temperature, 3 pH, 2 mM Km and 2000 µM/ml Vmax. Protein concentrations found in crude extracts and partially purified enzymes are respectively: laccase 1.78 and 0.71 mg/ml, MnP 1.59 and 0.68 mg/ml. LiP, 1.70 and 0.69 mg/ml.
Go to article

Authors and Affiliations

Jehangir Khan
1 3
Muahammad Javaid Asad
1
Raja Tahir Mahmood
2
Feeroza Hamid Wattoo
1
Tayyaba Zainab
1
Sidrah Nazir
1
Muhammad Basir Shah
4
Dawood Ahmed
5

  1. University Institute of Biochemistry and Biotechnology, PMAS-Arid Agriculture University Rawalpindi, Pakistan
  2. Department of Biotechnology, Mirpur University of Science and Technology (MUST), Mirpur-10250 (AJK), Pakistan
  3. Department of Biosciences, University of WAH, WAH Pakistan
  4. Department of Plant Breeding & Genetics, Balochistan Agriculture College Quetta, Pakistan
  5. Department of Medical Laboratory Technology, Haripur University, Haripur, KPK, Pakistan
Download PDF Download RIS Download Bibtex

Abstract

As polycarbonate is frequently used in many products, its accumulation in landfi lls is absolutely harmful to the environment. The aims of this study were the screening and isolation of polycarbonate-degrading bacteria (PDB) and the assessment of their ability in the degradation of polycarbonate (PC) polymers. Nine-month buried-PC films were used for PDB isolation and identification. The biodegradation ability of the isolates was determined by growth curve, clear zone formation, lipase and amylase production, AFM and FTIR. Bacillus cereus and Bacillus megaterium were identifi ed and considered as PDB. The degradation ability of B. megaterium was significantly higher than that of B. cereus. Both were lipase and amylase positive. AFM and FTIR results showed the initiation of bacterial attachment. The PC biodegradation ability of isolates can be very efficient. Finding such efficient isolates (which was less studied before) will promise a decrease in plastic contamination in the future.
Go to article

Authors and Affiliations

Mojgan Arefian
1
Arezoo Tahmourespour
2
Mohammadali Zia
2

  1. Fars Science and Research Branch, Islamic Azad University, Fars, Iran
  2. Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran
Download PDF Download RIS Download Bibtex

Abstract

This study investigated the potential of three microalgae taxonomic groups of Chlorophyta, Cyanoprokaryota and Bacillariophyceae for biogas production. Biogas potential was assessed in mesophilic anaerobic digestion batch tests over a period of 20 days. The cumulative biogas yield (CBY) of Chlorophyta and Cyanoprocaryota was respectively 396.21 mL/g Volatile Solids (VS) and 382.45 mL/g VS. Bacillariophyceae digestion showed lower biogas production of 357.07 mL/g VS. The highest cumulative methane yield (CMY) of 241.25 mL CH 4/g VS was recorded for Cyanoprocaryota biomass, which was signifi cantly higher (p<0.05) than the other two types of microalgae. The highest methane content in biogas of 63.08% was observed with Cyanoprokaryota. Chemical composition of biomass as well as biogas productivity are infl uenced by algal taxonomy.
Go to article

Authors and Affiliations

Marta Kisielewska
1
Marcin Dębowski
1
Marcin Zieliński
1

  1. Uniwersytet Warmińsko-Mazurski w Olsztynie, Department of Environmental Engineering
Download PDF Download RIS Download Bibtex

Abstract

The paper presents new non-ionic deep eutectic solvent (DES) composed of natural and non-toxic components i.e. guaiacol, camphor and levulinic acid in 1:1:3 molar ratio as a promising absorbent for removal of selected volatile organic compounds (VOCs) including dichloromethane, toluene, hexamethyldisiloxane and propionaldehyde from model biogas. The affi nity of DES for VOCs was determined as vapour-liquid coeffi cients and the results were compared with several well-known DESs based on quaternary ammonium salt as well as n-hexadecane and water. For new DES, the absorption process was carried out under dynamic conditions. The results indicate that non-ionic DES has high affi nity and capacity for VOCs being comparable to n-hexadecane. In addition, absorbed VOCs could be easily desorbed from DES using activated carbon and absorbent could be re-use minimum fi ve times without significant loss of absorption capacity.
Go to article

Authors and Affiliations

Edyta Słupek
1
ORCID: ORCID
Patrycja Makoś
1
Jacek Gębicki
1
ORCID: ORCID

  1. Gdansk University of Technology, Faculty of Chemistry, Department of Process Engineering and Chemical Technology, Gdańsk, Poland
Download PDF Download RIS Download Bibtex

Abstract

The aim of the study was to evaluate the biochemical possibilities of converting waste lignocellulosic biomass to second generation bioethanol. Three substrates were used in the research: barley straw, rye straw and triticale straw. In the first stage of the research bacterial strains capable of converting waste biomass to produce sugars used to produce energy-useful ethanol were selected. Of the eight strains isolated the three with the highest potential were selected on the basis of activity index value. The raw materials were subjected to enzymatic hydrolysis using the simultaneous saccharifi cation and fermentation method (SSF process). Based on the conducted research, it was found that the examined waste biomass is suitable for the production of cellulosic bioethanol. As a result of distillation 10% and 15% (v/v) ethanol was obtained, depending on the strain and the type of raw material. It was demonstrated that the bacterial strain had a greater impact on the effectiveness of the process than the type of straw used.
Go to article

Authors and Affiliations

Małgorzata Hawrot-Paw
1
Adam Koniuszy
1
Grzegorz Zając
2
Joanna Szyszlak-Bargłowicz
2
Julia Jaklewicz
1

  1. West Pomeranian University of Technology, Department of Renewable Energy Engineering, Poland
  2. University Of Life Sciences in Lublin, Department of Power Engineering and Transportation, Poland
Download PDF Download RIS Download Bibtex

Abstract

In our article the ordinary kriging interpolation method was used for a spatial presentation of PM2.5 concentrations. The data used in the research was obtained from the unique PM2.5 measuring system, based on low-cost optical sensors for PM2.5 concentration measurements, working on Wroclaw University of Science and Technology campus area. The data from this system was used as an input for the interpolations that were made for three different days characterized by the highest measured values of PM2.5 – 20.01.2019, 17.02.2019 and 30.03.2019. For each of the selected days, variants with the maximum and minimum PM2.5 values recorded on a given measurement day were presented. In the analyses performed, the ordinary kriging technique and cross-validation, was used as the interpolation and the validation method, respectively. Parameters determining the quality of performed interpolation were Mean Error, Mean Standardized Error, Root Mean Square Error, and Average Standard Error. As the main indicator of quality of interpolation RMSE parameter was used. Analysis of that parameter shows that the higher variability of the data used for interpolation affects its quality. The Root Mean Square Error parameter reached 0.64, 0.94 and 1.71 for the lowest concentrations variants characterized by low spatial variability, and 6.53, 7.51, 11.28 for the highest one, which were characterized by high spatial variability. The obtained results of the research with the use of GIS tools shows that the ordinary kriging method allowed for the correct spatial presentation of the PM2.5 concentration variability in areas not covered by the measurement system.
Go to article

Authors and Affiliations

Izabela Sówka
1
ORCID: ORCID
Marek Badura
1
Marcin Pawnuk
1
ORCID: ORCID
Piotr Szymański
2
Piotr Batog
3

  1. Wroclaw University of Technology, Faculty of Environmental Engineering
  2. Wrocław University of Science and Technology, Faculty of Computer Science and Management
  3. INSYSPOM, Wrocław
Download PDF Download RIS Download Bibtex

Abstract

The study discusses an experimental method for treatment of high strength domestic sewage on biofilters filled with polyurethane (PUR) waste in the form of trims of upholstery foam. We determined effectiveness of two biological preparations containing effective microorganisms in elimination of organic and biogenic compounds, indicator bacteria and total suspended solids from the sewage pretreated in a septic tank. After four months of work under a hydraulic loading of 76.4 mm∙d -1 we found the filter with 60 cm foam layer to be the most efficient in the elimination of BOD 5, COD Cr, NH 4 +-N and coliform bacteria. An average reduction in these pollutants reached 79.4%, 67.8%, 58.0% and 88.0%, respectively. Vertical filters filled with trims of upholstery foam and supplied with effective microorganisms ensured favorable conditions for development of heterotrophic and nitrifying bacteria without any need for additional aeration.
Go to article

Authors and Affiliations

Krzysztof Chmielowski
1
ORCID: ORCID
Jan Pawełek
1
Ewa Dacewicz
1

  1. University of Agriculture in Kraków, Faculty of Environmental Engineering and Land Surveying
Download PDF Download RIS Download Bibtex

Abstract

The paper presents an analysis of a selected grade of high silicon cast iron intended for work in corrosive and abrasive conditions. The text describes its microstructure taking into account the process of crystallization, TDA analysis, EDS, XRD and the chemical composition analysis. In order to determine the phase composition, X-ray diffraction tests were carried out. The tests were executed on a Panalytical X'Pert PRO X-ray diffractometer with filtration of radiation from a lamp with copper anode and PIXcel 3D detector on the deflected beam axis. Completed tests allowed to describe the microstructure with detailed consideration of intermetallic phases present in the alloy. Results of the analysis of the examined alloy clearly show that we deal with intermetallic phases of Fe3Si, Fe5Si3 types, as well as silicon ferrite and crystals of silicon. In the examined alloy, we observed the phenomenon of segregation of carbon, which, as a result of this process, enriches the surface of silicon crystals, not creating a compound with it. Moreover, the paper demonstrates capability for crystallization of spheroidal graphite in the examined alloy despite lack of elements that contribute to balling in the charge materials.

Go to article

Authors and Affiliations

M. Stawarz
ORCID: ORCID
Download PDF Download RIS Download Bibtex

Abstract

Filtration is one of the most efficient methods of removing Al2O3 inclusions from liquid steel. The efficiency of this process depends on the physicochemical parameters of liquid metal, inclusion and properties of the applied filters. The particles attracted during filtration undergo agglomeration, collisions and chemical reactions on the filter surface, with the emphasis on the mechanism of particle collisions and the role of material from which the filter was made. The aluminum oxide inclusions collide with the filter surface and as the growing process continues, the particles also collide with the previously adsorbed inclusions. At the interface of particle and filter the mixing of the metal bath is most intense, being a result of a sudden change of flow direction and breaking up the stream of liquid metal which is in a direct contact with material. The efficiency of filtration is defined not only by the behavior of individual particles but of all population. The simulations revealed that only a small fraction of these particles adheres directly to the filter material; most of them stick to the former ones. Attention should be also paid to the fact that some of the inclusions which contacted the filter walls do not form a permanent connection and are then entrained by metal. Authors solved the problem of agglomeration and collisions of Al2O3 inclusions with the ceramic surface of the filter with the PSG method, mainly used for the analysis of agglomeration of inclusions during steel refining in the ladle.

Go to article

Authors and Affiliations

D. Kalisz
K. Kuglin
Download PDF Download RIS Download Bibtex

Abstract

The paper presents the preliminary results of research on determining the possibilities of using available on the market commercial gypsum kinds as a binder for foundry moulding and core sandmixes. Construction gypsum and plaster gypsum, finishing coat and jewelry casting gypsum were tested. Elemental composition of gypsum kinds were carried out using a scanning electron microscope (SEM) with EDS/EDX probe, their crystal structure and phase composition was determined by analyzing the results of X-ray diffraction measurements (XRD) and thermogravimetric studies (TG-DTA). Evaluation of the mechanical properties of selected materials was carried out at the tensile strength test of the dog-bone samples after initial hardening of gypsum mortar at 25 °C for 5 h and drying at 110 °C for 24 hours. The impact of the properties of the used commercial gypsum kinds on the possibility of their use as a valuable binders in the manufacture of the foundry sandmixes for moulds and cores was evaluated. Construction gypsum and finishing coat have the highest tensile strength. Plaster gypsum and finishing coat have the longest setting time. In all tested types of gypsum, the initial water loss during heating occurs at a temperature of about 200 °C. The lowest valuable properties as a binder for sand moulding mixtures has jewelry casting gypsum mass.

Go to article

Authors and Affiliations

P. Paduchowicz
M. Stachowicz
ORCID: ORCID
A. Baszczuk
M. Hasiak
K. Granat
Download PDF Download RIS Download Bibtex

Abstract

The removal of inclusions is a major challenge prior to the casting process, as they cause a discontinuity in the cast material, thereby lowering its mechanical properties and have a negative impact on the feeding capability and fluidity of the liquid alloys. In order to achieve adequate melt quality for casting, it is important to clean the melts from inclusions, for which there are numerous methods that can be used. In the course of the presented research, the inclusion removal efficiency of rotary degassing coupled with the addition of different fluxes was investigated. The effects of various cleaning fluxes on the inclusion content and the susceptibility to pore formation were compared by the investigation of K-mold samples and the evaluation of Density Index values at different stages of melt preparation. The chemical composition of the applied fluxes was characterized by X-ray powder diffraction, while the melting temperature of the fluxes was evaluated by derivatographic measurements. It was found that only the solute hydrogen content of the liquid metal could be significantly reduced during the melt treatments, however, better inclusion removal efficiency could be achieved with fluxes that have a low melting temperature.

Go to article

Authors and Affiliations

M. Máté
M. Tokár
G. Fegyverneki
G. Gyarmati
Download PDF Download RIS Download Bibtex

Abstract

The paper presents the results of research on microstructure and impact strength of AlSi13Cu2 matrix composite reinforced by Ni-coating carbon fibers (CF) with a volume fraction of 5%, 10% and 15%. The composite suspensions were prepared using by stirring method and subsequently squeeze casted under different pressures of 25, 50, 75 and 100 MPa. As part of the study, fiber distribution in aluminum matrix was evaluated and variation in impact strength of composite as a function of the carbon fibers volume fraction and pressure applied were determined. It has been found that the presence of Ni coating on carbon fibers clearly improves their wettability by liquid aluminum alloy and in combination with the stirring parameters applied, composite material with relatively homogeneous structure can be produced. Charpy's test showed that the impact strength of composite reaches the highest value by carrying out the squeeze casting process at 75 MPa. In the next stage of research, it was found that the impact strength of composites increases with the increase of carbon fibers volume fraction and for 15% of fibers is close to 8 J/cm2. Observations of fracture surfaces have revealed that crack growth in the composites propagates with a quasi-cleavage mechanism. During the creation of the fracture, all fibers arranged perpendicular to its surface were sheared. At the same time, the metal matrix around the fibers deformed plastically creating characteristic ductile breaks. The fracture surface formation through the fibers indicates a cohesive and strong connection of the reinforcement with the matrix. In addition to the phenomena mentioned, debonding the fiber-matrix interfaces and the formation of voids between components were observed on the fracture surface.

Go to article

Authors and Affiliations

A. Zyska
Z. Konopka
Małgorzata Łągiewka
ORCID: ORCID

This page uses 'cookies'. Learn more