Kinetic studies of boride layers focus on trying to accurately predict their thicknesses according to some variables using different approaches. In this paper, an approach that is reliant on a multilinear regression is investigated. In doing so, with an engineering perspective, temperature and time are used as the sole variables in predicting a boride layer thickness u. The approach uses experimental data from a boriding process performed on iron substrates of the XC38 steel. A comparison between the proposed linear model and a nonlinear one is seen afterward to scrutinize the results. That nonlinear approach is known as the diffusion model and is based on Fick’s second law, where it uses more variables than the linear approach to estimate its predictions. Ultimately, the comparison elucidated that the use of a linear regression-based model can be an accurate engineering tool to identify boride layer thicknesses, but without interpolating the results outside the scope of the studied interval.
硼化物层的动力学研究主要是根据一些变量，采用不同的方法来准确预测硼化物层的厚度。本文研究了一种依赖于多元线性回归的方法。在此过程中，从工程角度出发，将温度和时间作为预测硼化物层厚度 u 的唯一变量。该方法使用了在 XC38 钢的铁基板上进行硼化处理的实验数据。随后，对所提出的线性模型和非线性模型进行了比较，以仔细研究结果。这种非线性方法被称为扩散模型，它以菲克第二定律为基础，使用比线性方法更多的变量来估计其预测结果。最终，比较结果表明，使用基于线性回归的模型可以作为一种精确的工程工具来确定硼化物层厚度，但不需要在研究区间范围之外对结果进行内插。
{"title":"Confrontation of linear versus nonlinear approach in Fe2B boridelayer thickness predictions","authors":"Y. El Guerri, B. Mebarek, Mourad Keddam","doi":"10.62638/zasmat1016","DOIUrl":"https://doi.org/10.62638/zasmat1016","url":null,"abstract":"Kinetic studies of boride layers focus on trying to accurately predict their thicknesses according to some variables using different approaches. In this paper, an approach that is reliant on a multilinear regression is investigated. In doing so, with an engineering perspective, temperature and time are used as the sole variables in predicting a boride layer thickness u. The approach uses experimental data from a boriding process performed on iron substrates of the XC38 steel. A comparison between the proposed linear model and a nonlinear one is seen afterward to scrutinize the results. That nonlinear approach is known as the diffusion model and is based on Fick’s second law, where it uses more variables than the linear approach to estimate its predictions. Ultimately, the comparison elucidated that the use of a linear regression-based model can be an accurate engineering tool to identify boride layer thicknesses, but without interpolating the results outside the scope of the studied interval.","PeriodicalId":23842,"journal":{"name":"Zastita materijala","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140239638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Epoxy resins are well-known because of their desirable thermal and mechanical characteristics in a variety of fields, including the automotive, construction, and aerospace sectors. However, the inherent brittle nature of highly cross-linked epoxy resins generally leads to weakness in resisting the formation of cracks and their movement. The brittleness of the epoxy resins is one of the major obstacles inhibiting its use at a wider scale. Therefore, many researchers focused on reinforcement of epoxy resins by different types of nanostructures including carbon nanotubes (CNTs), organic/inorganic nanofillers to provide higher strength, without diminishing other essential thermo-physical characteristics of the nanocomposites. Most of the review articles focused on the CNT-reinforced epoxy composites and very limited review articles are available that focus on the oxide nanofiller reinforced epoxy composites. In this review article, epoxy nanocomposites reinforced with alumina (Al2O3), titania (TiO2), silica (SiO2), and zirconia (ZrO2) nanoparticles have been investigated. The influence of the oxide nanoparticles in modifying the physical and thermal properties of the epoxy nanocomposites has been presented, compared, and critically analysed to optimize the performance of epoxy nanocomposites.
{"title":"A review on improved physical and thermal properties of oxide nanoparticles reinforced epoxy composites","authors":"A. Upadhyay, M. Goyat","doi":"10.62638/zasmat1038","DOIUrl":"https://doi.org/10.62638/zasmat1038","url":null,"abstract":"Epoxy resins are well-known because of their desirable thermal and mechanical characteristics in a variety of fields, including the automotive, construction, and aerospace sectors. However, the inherent brittle nature of highly cross-linked epoxy resins generally leads to weakness in resisting the formation of cracks and their movement. The brittleness of the epoxy resins is one of the major obstacles inhibiting its use at a wider scale. Therefore, many researchers focused on reinforcement of epoxy resins by different types of nanostructures including carbon nanotubes (CNTs), organic/inorganic nanofillers to provide higher strength, without diminishing other essential thermo-physical characteristics of the nanocomposites. Most of the review articles focused on the CNT-reinforced epoxy composites and very limited review articles are available that focus on the oxide nanofiller reinforced epoxy composites. In this review article, epoxy nanocomposites reinforced with alumina (Al2O3), titania (TiO2), silica (SiO2), and zirconia (ZrO2) nanoparticles have been investigated. The influence of the oxide nanoparticles in modifying the physical and thermal properties of the epoxy nanocomposites has been presented, compared, and critically analysed to optimize the performance of epoxy nanocomposites.","PeriodicalId":23842,"journal":{"name":"Zastita materijala","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140241168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper concerns the overview of previous studies on the corrosion and inhibition of carbon steel that is allowed to degrade in a corrosive medium by the extract of the eucalyptus plant, with an emphasis on the extract's adsorption behaviour. Many researchers have largely employed eucalyptus plant bark, oil, and leaf extracts to prevent the corrosion of mild steel in acidic environments under various temperature settings. According to the results, when the bark extract of the eucalyptus plant was added to HCl (5%) at a concentration of 900 ppm, the inhibitor's maximum efficiency was 98.2 %. The leaf extract, on the other hand, had the maximum inhibitory efficacy of 93.09 % at 600 mg/L extract concentration in the H2SO4 (0.5 M) medium. The extracts' potency was shown to diminish with increasing temperature. The mechanism for eucalyptus extract's protection of carbon steel from corrosion in diverse corrosive situations was largely associated with the adsorption of the extract's inhibitive components on the steel's surface to reduce the interaction between the metal and the corrosive surroundings. The majority of the reported inhibitive behaviour of the eucalyptus extract was consistent with the Langmuir adsorption isotherm model.
{"title":"Corrosion inhibition of carbon steel by eucalyptus leaves in acidic media: An overview","authors":"A. Ndukwe","doi":"10.62638/zasmat1034","DOIUrl":"https://doi.org/10.62638/zasmat1034","url":null,"abstract":"This paper concerns the overview of previous studies on the corrosion and inhibition of carbon steel that is allowed to degrade in a corrosive medium by the extract of the eucalyptus plant, with an emphasis on the extract's adsorption behaviour. Many researchers have largely employed eucalyptus plant bark, oil, and leaf extracts to prevent the corrosion of mild steel in acidic environments under various temperature settings. According to the results, when the bark extract of the eucalyptus plant was added to HCl (5%) at a concentration of 900 ppm, the inhibitor's maximum efficiency was 98.2 %. The leaf extract, on the other hand, had the maximum inhibitory efficacy of 93.09 % at 600 mg/L extract concentration in the H2SO4 (0.5 M) medium. The extracts' potency was shown to diminish with increasing temperature. The mechanism for eucalyptus extract's protection of carbon steel from corrosion in diverse corrosive situations was largely associated with the adsorption of the extract's inhibitive components on the steel's surface to reduce the interaction between the metal and the corrosive surroundings. The majority of the reported inhibitive behaviour of the eucalyptus extract was consistent with the Langmuir adsorption isotherm model.","PeriodicalId":23842,"journal":{"name":"Zastita materijala","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140238973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Since activated carbon is a highly porous material with a sizable internal surface area, it is simple to adsorb a wide range of substances when used in energy storage devices, sewage treatment, water purification, catalyst, food processing and other applications. This work focuses on the viability of using mixed fruit peels as a precursor for the carbonization process with physical activation to produce activated carbon. The Phase confirmation was examined using X-ray diffraction (XRD). Fourier transform infrared spectrometer (FTIR) concludes the functional groups present in mixed fruit peels activated carbon. Field emission scanning electron microscopy (FESEM) was used to analyze the morphological makeup and textural traits of the activated carbon that was produced. Energy Dispersive X-Ray Analysis (EDX) shows the elemental composition of nano powdered carbon. Raman spectroscopy confirms the presence of graphene that appears at 1580cm-1. Electrochemical Impedance Spectroscopy (EIS) and Nyquist plot in order to evaluate the conductivity performance over the frequency range of 1mHz to 10 kHz, measurements were used. Carbon yield analysis were conducted and analyzed. Wettability of the mixed fruit peels were examined using contact angle. The Mixed Fruit peels activated carbon were subjected to low temperature plasma to increase its surface properties, The outcomes were evaluated, and the charge transfer resistance and the polarization resistance for air plasma treatment is 1.43 and 0.2 ohms. Hydrophilic nature is occurred when treated with air plasma. According to these findings, air plasma treatment of mixed fruit peel activated carbon improves its surface characteristics, making it suitable for electrode in energy storage applications.
由于活性炭是一种高多孔材料，具有相当大的内表面积，因此在用于储能设备、污水处理、水净化、催化剂、食品加工和其他应用时，可以简单地吸附多种物质。这项研究的重点是利用混合果皮作为前驱体，通过物理活化的碳化工艺生产活性炭的可行性。使用 X 射线衍射（XRD）对相位确认进行了检验。傅立叶变换红外光谱仪（FTIR）确定了混合果皮活性炭中存在的官能团。场发射扫描电子显微镜（FESEM）用于分析生产出的活性炭的形态构成和纹理特征。能量色散 X 射线分析（EDX）显示了纳米碳粉的元素组成。拉曼光谱证实了石墨烯的存在，它出现在 1580cm-1 处。为了评估 1mHz 至 10 kHz 频率范围内的导电性能，使用了电化学阻抗光谱（EIS）和奈奎斯特图进行测量。使用接触角检测了混合果皮的润湿性。对混合果皮活性炭进行了低温等离子处理，以增加其表面特性，并对结果进行了评估。经空气等离子体处理的材料具有亲水性。 根据这些研究结果，空气等离子体处理混合果皮活性炭可改善其表面特性，使其适用于储能应用中的电极。
{"title":"Reinforce the surface properties of domestic garbage activated carbon by low temperature plasma accustomed in energy storage applications","authors":"Vijayalakshmi K.A, Sowmiya K C","doi":"10.62638/zasmat1000","DOIUrl":"https://doi.org/10.62638/zasmat1000","url":null,"abstract":"Since activated carbon is a highly porous material with a sizable internal surface area, it is simple to adsorb a wide range of substances when used in energy storage devices, sewage treatment, water purification, catalyst, food processing and other applications. This work focuses on the viability of using mixed fruit peels as a precursor for the carbonization process with physical activation to produce activated carbon. The Phase confirmation was examined using X-ray diffraction (XRD). Fourier transform infrared spectrometer (FTIR) concludes the functional groups present in mixed fruit peels activated carbon. Field emission scanning electron microscopy (FESEM) was used to analyze the morphological makeup and textural traits of the activated carbon that was produced. Energy Dispersive X-Ray Analysis (EDX) shows the elemental composition of nano powdered carbon. Raman spectroscopy confirms the presence of graphene that appears at 1580cm-1. Electrochemical Impedance Spectroscopy (EIS) and Nyquist plot in order to evaluate the conductivity performance over the frequency range of 1mHz to 10 kHz, measurements were used.\u0000Carbon yield analysis were conducted and analyzed. Wettability of the mixed fruit peels were examined using contact angle. The Mixed Fruit peels activated carbon were subjected to low temperature plasma to increase its surface properties, The outcomes were evaluated, and the charge transfer resistance and the polarization resistance for air plasma treatment is 1.43 and 0.2 ohms. Hydrophilic nature is occurred when treated with air plasma. According to these findings, air plasma treatment of mixed fruit peel activated carbon improves its surface characteristics, making it suitable for electrode in energy storage applications.","PeriodicalId":23842,"journal":{"name":"Zastita materijala","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140241412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lev Chernyak, N. Dorogan, L. Melnyk, P. Varshavets, Victoria Pakhomova
The possibility to produce white Eco-cement with the use of a dry method under low-temperature firing of a raw material mixture based on the CaO - SiO2 - AL2O3 - MgO system is shown. Computer calculations were performed and an analysis of the dependence of the characteristics of cement clinker on the quantitative ratio of raw components was carried out. A new composition of the raw material mixture with a decrease of 19 wt. % amount of the carbonate component and, accordingly, CO2 emissions during combustion was determined. The peculiarities of phase transformations in the material during firing with a maximum temperature of 1100 °S when microtalcum was introduced into the initial mixture with the formation of pericloze, ockermanite and merwinite as a factor in the structure and properties of cement clinker were noted.
{"title":"Analysis of white cement production during low-temperature firing","authors":"Lev Chernyak, N. Dorogan, L. Melnyk, P. Varshavets, Victoria Pakhomova","doi":"10.5937/zasmat2303256c","DOIUrl":"https://doi.org/10.5937/zasmat2303256c","url":null,"abstract":"The possibility to produce white Eco-cement with the use of a dry method under low-temperature firing of a raw material mixture based on the CaO - SiO2 - AL2O3 - MgO system is shown. Computer calculations were performed and an analysis of the dependence of the characteristics of cement clinker on the quantitative ratio of raw components was carried out. A new composition of the raw material mixture with a decrease of 19 wt. % amount of the carbonate component and, accordingly, CO2 emissions during combustion was determined. The peculiarities of phase transformations in the material during firing with a maximum temperature of 1100 °S when microtalcum was introduced into the initial mixture with the formation of pericloze, ockermanite and merwinite as a factor in the structure and properties of cement clinker were noted.","PeriodicalId":23842,"journal":{"name":"Zastita materijala","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85874139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An effective corrosion inhibitor for steel is Hexamine (HMTA). There have been few studies on its corrosion-inhibiting characteristics, particularly in NaCl solution. The electrochemical characteristics of HMTA performance in NaCl 3.5 wt% solution were examined during this study. Additionally, the properties of the HMTA film on the steel surface was investigated. When tested in NaCl solution, electrochemical results revealed that HMTA is a very efficient corrosion inhibitor for mild steel, with an efficacy of 92% at a concentration of 0.08 M. HMTA exhibited mixed type activity in terms of inhibition, according to the findings. Due to the physical adsorption of HMTA compound, as shown by the XRD results, an organic layer was formed as a strategy for HMTA inhibition. Adsorption of chloride ions as a corrosive factor is reduced by the HMTA films, according to EDS and thermodynamic studies.
{"title":"Investigation of the corrosion inhibition properties of hexamine (HMTA) for mild steel in NaCl solution","authors":"Fathabadi Ebrahim, M. Ghorbani","doi":"10.5937/zasmat2302134f","DOIUrl":"https://doi.org/10.5937/zasmat2302134f","url":null,"abstract":"An effective corrosion inhibitor for steel is Hexamine (HMTA). There have been few studies on its corrosion-inhibiting characteristics, particularly in NaCl solution. The electrochemical characteristics of HMTA performance in NaCl 3.5 wt% solution were examined during this study. Additionally, the properties of the HMTA film on the steel surface was investigated. When tested in NaCl solution, electrochemical results revealed that HMTA is a very efficient corrosion inhibitor for mild steel, with an efficacy of 92% at a concentration of 0.08 M. HMTA exhibited mixed type activity in terms of inhibition, according to the findings. Due to the physical adsorption of HMTA compound, as shown by the XRD results, an organic layer was formed as a strategy for HMTA inhibition. Adsorption of chloride ions as a corrosive factor is reduced by the HMTA films, according to EDS and thermodynamic studies.","PeriodicalId":23842,"journal":{"name":"Zastita materijala","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84197692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zirconium dioxide ZrO2 is used as a basic material for thermal barriers and as a biomaterial for manufacturing parts for hip implants in orthopedic surgery and in dentistry for making crowns. Use of ZrO2 ceramics as an insulating material and biomaterial is due to its good chemical and dimensional stability, mechanical strength, toughness and elastic modulus. The aim of this study was to analyze the characteristics of zirconium oxide coating of stabilized cerium and yttrium oxide deposited by atmospheric plasma spraying (APS) process on the bond coating of nickel chromium cobalt yttrium oxide. Coatings were deposited on cold substrates and on substrates preheated to 180°C. Composite powder nickel chromium/aluminum/cobalt/yttrium oxide was used for the production of bond layers and for the ceramic layers zirconium oxide stabilized with cerium and yttrium oxide powder. Testing the quality of coatings was done by measuring microhardness of layers using the HV method and for bond tensile strength of the coating system tensile testing was applied. Metallographic evaluation of the share of pores in the bond and ceramic layers was performed with image analysis - processing of images from a light microscope. Powder particle morphology and EDS analysis were performed on the SEM. The obtained results confirm that the preheating temperature of the substrate has a significant impact on structural mechanical properties of the tested coatings system.
{"title":"Characterization of zirconium oxidecoating stabilized with cerium and yttrium oxide deposited on the bonding coating nickel chromium aluminum cobalt yttrium oxide","authors":"M. Mrdak, Č. Lačnjevac, D. Bajić","doi":"10.5937/zasmat2301005m","DOIUrl":"https://doi.org/10.5937/zasmat2301005m","url":null,"abstract":"Zirconium dioxide ZrO2 is used as a basic material for thermal barriers and as a biomaterial for manufacturing parts for hip implants in orthopedic surgery and in dentistry for making crowns. Use of ZrO2 ceramics as an insulating material and biomaterial is due to its good chemical and dimensional stability, mechanical strength, toughness and elastic modulus. The aim of this study was to analyze the characteristics of zirconium oxide coating of stabilized cerium and yttrium oxide deposited by atmospheric plasma spraying (APS) process on the bond coating of nickel chromium cobalt yttrium oxide. Coatings were deposited on cold substrates and on substrates preheated to 180°C. Composite powder nickel chromium/aluminum/cobalt/yttrium oxide was used for the production of bond layers and for the ceramic layers zirconium oxide stabilized with cerium and yttrium oxide powder. Testing the quality of coatings was done by measuring microhardness of layers using the HV method and for bond tensile strength of the coating system tensile testing was applied. Metallographic evaluation of the share of pores in the bond and ceramic layers was performed with image analysis - processing of images from a light microscope. Powder particle morphology and EDS analysis were performed on the SEM. The obtained results confirm that the preheating temperature of the substrate has a significant impact on structural mechanical properties of the tested coatings system.","PeriodicalId":23842,"journal":{"name":"Zastita materijala","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76534246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Nyrkova, P. Lisovyi, Larysa Gonchasrenko, S. Osadchuk, Yulia Kharchenko, Anatoly Klymenko, V. Kostin
Study of stress-corrosion cracking of welded joints made of X70 steel at cathodic polarization in near neutral solution NS4 was carried out. It was established that the tendency of base metal of X70 steel to stress-corrosion cracking, estimated by KS coefficient, increases from 1.07 to 1.13 whereas polarization potential changing from the corrosion potential to maximum protective potential -1.05 V. Such regularity correlates with increasing of hydrogen penetration through X70 steel, which at maximum protective potential -1.05 V is equal to 0.000518 mol/m3 . Susceptibility of welded joint is lower than the base metal, KS coefficient change not much near the value 1.0. With increasing of polarization potential from -0,75V to -1.05V fracture surface of X70 steel characterized by decreasing in the size of holes and the appearance of flat areas, through that the rupture occurred. A similar nature of the rupture was observed for the welded joint, but visually larger proportion of flat areas can be noted. It was established that the rupture of the welded joint occurs on the base metal, which allows to propose stress-corrosion cracking susceptibility factor KS to be legitimately used for estimation to stress-corrosion cracking of welded joint, provided the weld is performed in a high-quality manner. Stress-corrosion cracking results of welded joint of X70 steel correlate satisfactorily with the experience of stress-corrosion cracking on main gas pipelines, where stress-corrosion cracks form and develop along the base metal of gas pipelines.
{"title":"Investigation of stress-corrosion cracking of welded joint of H70 steel under cathodic polarization in near neutral environment","authors":"L. Nyrkova, P. Lisovyi, Larysa Gonchasrenko, S. Osadchuk, Yulia Kharchenko, Anatoly Klymenko, V. Kostin","doi":"10.5937/zasmat2301096n","DOIUrl":"https://doi.org/10.5937/zasmat2301096n","url":null,"abstract":"Study of stress-corrosion cracking of welded joints made of X70 steel at cathodic polarization in near neutral solution NS4 was carried out. It was established that the tendency of base metal of X70 steel to stress-corrosion cracking, estimated by KS coefficient, increases from 1.07 to 1.13 whereas polarization potential changing from the corrosion potential to maximum protective potential -1.05 V. Such regularity correlates with increasing of hydrogen penetration through X70 steel, which at maximum protective potential -1.05 V is equal to 0.000518 mol/m3 . Susceptibility of welded joint is lower than the base metal, KS coefficient change not much near the value 1.0. With increasing of polarization potential from -0,75V to -1.05V fracture surface of X70 steel characterized by decreasing in the size of holes and the appearance of flat areas, through that the rupture occurred. A similar nature of the rupture was observed for the welded joint, but visually larger proportion of flat areas can be noted. It was established that the rupture of the welded joint occurs on the base metal, which allows to propose stress-corrosion cracking susceptibility factor KS to be legitimately used for estimation to stress-corrosion cracking of welded joint, provided the weld is performed in a high-quality manner. Stress-corrosion cracking results of welded joint of X70 steel correlate satisfactorily with the experience of stress-corrosion cracking on main gas pipelines, where stress-corrosion cracks form and develop along the base metal of gas pipelines.","PeriodicalId":23842,"journal":{"name":"Zastita materijala","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89692970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Saša Papuga, Aleksandra Kolundžija, Milica Đurđević
Bioenergy, or energy derived from biomass, today is recognized as an important component in many energy scenarios, being an integral part of various global, regional, and national policies and strategies. This has led to intensified research into more efficient biofuel production. This paper explains the advantages, disadvantages, and problems related to the production of biofuels from different types of raw materials. Several examples of commercialized and demonstration plants for the production of biofuels in different parts of the world are listed. It is to be expected that, with greater use of modern biofuel production solutions, the contribution of these sources of (bio)energy will be the main part of future energy consumption from renewable sources.
{"title":"Biofuels as a challenge of sustainable development","authors":"Saša Papuga, Aleksandra Kolundžija, Milica Đurđević","doi":"10.5937/zasmat2303291p","DOIUrl":"https://doi.org/10.5937/zasmat2303291p","url":null,"abstract":"Bioenergy, or energy derived from biomass, today is recognized as an important component in many energy scenarios, being an integral part of various global, regional, and national policies and strategies. This has led to intensified research into more efficient biofuel production. This paper explains the advantages, disadvantages, and problems related to the production of biofuels from different types of raw materials. Several examples of commercialized and demonstration plants for the production of biofuels in different parts of the world are listed. It is to be expected that, with greater use of modern biofuel production solutions, the contribution of these sources of (bio)energy will be the main part of future energy consumption from renewable sources.","PeriodicalId":23842,"journal":{"name":"Zastita materijala","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81538718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Esmeralda Halo, Jonida Tahiraj, B. Murtaj, Sonila Kane, E. Marku, A. Nuro
In this study, levels of polycyclic aromatic hydrocarbons (PAH), aliphatic hydrocarbons (n-alkanes) and volatile hydrocarbons were determined in water samples of the port of Vlora which is the second largest port in Albania. It is located in Vlora Bay, near Vlora city. Presence of these pollutants in port area is mainly because of ships transport, commercial/passengers processing and the water currents in-side/out-side the port area. Hydrocarbons (PAHs, n-alkanes and BTEX) are generated mainly by the transport (automobiles, ships, trains, etc), extracting/processing of oil industry, coal mine and other industries. Forest burning and their natural background make them very often in environment. Water samples were taken in May 2022 in different stations of the Vlora's port (inside and outside its area). Aromatic and aliphatic hydrocarbons were extracted simultaneously using two steps liquid-liquid extraction (LLE) technique. Firstly, dichloromethane (MeCl2) and after that n-hexane were used as extraction solvents. After extraction, the organic phase was dried with sodium sulfate anhydrous, for water removing. "Clean-up" procedure was realized in an alumina column. After the concentration to 2 ml, the samples were injected in Varian 450 GC equipped with FID detectors. BTEX were analyzed using head space solid phase micro-extraction technique (HS/SPME) by using polydimethylsiloxane fiber (PDMS) followed by GC/FID technique. PAH, n-alkanes and BTEX were found almost in all water samples of Vlora's port. Their presence could be because of anthropogenic factors (elevated activity and ship transport) in the port area. The levels of hydrocarbons in water samples of Vlora's port were higher / comparable than reported levels for them in other stations of the Adriatic Sea, Albania part.
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