R. Premkumar, R. Vignesh, R. Padmanaban, M. Govindaraju, R. Santhi
Abstract Aluminum alloy AA1100 has less wear resistance and mechanical properties than that of other aluminum alloys. This research work is on the fabrication of surface composites of AA1100 alloy by friction stir processing (FSP). The surface composites are fabricated by reinforcing hBN (hexagonal Boron Nitride) in AA1100 alloy to improve the mechanical and tribological properties. The influence of process parameters, rotational speed (rpm), and transverse speed (mm/min) on the microstructural evolution and properties of the fabricated surface composites is investigated.
{"title":"Investigation on the microstructure, microhardness, and tribological behavior of AA1100-hBN surface composite","authors":"R. Premkumar, R. Vignesh, R. Padmanaban, M. Govindaraju, R. Santhi","doi":"10.2478/kom-2021-0001","DOIUrl":"https://doi.org/10.2478/kom-2021-0001","url":null,"abstract":"Abstract Aluminum alloy AA1100 has less wear resistance and mechanical properties than that of other aluminum alloys. This research work is on the fabrication of surface composites of AA1100 alloy by friction stir processing (FSP). The surface composites are fabricated by reinforcing hBN (hexagonal Boron Nitride) in AA1100 alloy to improve the mechanical and tribological properties. The influence of process parameters, rotational speed (rpm), and transverse speed (mm/min) on the microstructural evolution and properties of the fabricated surface composites is investigated.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42519413","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}
Abstract Low pressure superheated H2-steam appears to be an interesting alternative to pressurized water environments, since it is capable of performing accelerated environmentally assisted cracking (EAC) experiments for nickel base and stainless steel alloys. Constant Extension Rate Tensile (CERT) tests were performed with displacement rates of 2×10-6 or 2×10-8 ms-1 at 350, 400, 440 and 480 °C on flat tapered specimens of Type 316L austenitic stainless steel. The tapered shape allows the determination of crack initiation over a range of stresses and strains simultaneously on one specimen and therefore the threshold stress value was obtained. The environment was 6 times more oxidizing than the dissociation pressure of NiO. The acquired mechanical properties are summarized and threshold stresses for EAC crack initiation are evaluated.
{"title":"Environmentally assisted cracking in the low pressure superheated hydrogen steam","authors":"J. Janouŝek","doi":"10.2478/kom-2021-0003","DOIUrl":"https://doi.org/10.2478/kom-2021-0003","url":null,"abstract":"Abstract Low pressure superheated H2-steam appears to be an interesting alternative to pressurized water environments, since it is capable of performing accelerated environmentally assisted cracking (EAC) experiments for nickel base and stainless steel alloys. Constant Extension Rate Tensile (CERT) tests were performed with displacement rates of 2×10-6 or 2×10-8 ms-1 at 350, 400, 440 and 480 °C on flat tapered specimens of Type 316L austenitic stainless steel. The tapered shape allows the determination of crack initiation over a range of stresses and strains simultaneously on one specimen and therefore the threshold stress value was obtained. The environment was 6 times more oxidizing than the dissociation pressure of NiO. The acquired mechanical properties are summarized and threshold stresses for EAC crack initiation are evaluated.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47890531","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}
Abstract In this study, two different mathematical models have been proposed for estimating the diffusivities of boron in the Fe2B layer on ASTM A36 steel in the range of 1173 to 1273 K with exposure times of 2 to 8 h. The boride incubation period required for the formation of such a layer was constant regardless of the boriding conditions. In both approaches, the boron diffusivity in the iron phase was considered in an unsaturated matrix. The first approach was derived from the mass balance equation at the (Fe2B/substrate) interface while the second approach employed the integral diffusion model. The calculated values of boron activation energies for ASTM A36 steel were found to be very comparable for the two approaches (161.65 and 160.96 and kJ mol-1). Afterwards, these values of activation energy were confronted with the results from the literature. Experimental validation of these two approaches has been done by comparing the experimental value of Fe2B layer thickness measured at 1123 K for 2.5 h with the simulated values. Finally, the predicted values of Fe2B layer thickness were in line with the experimental measurement.
{"title":"Simulation of boronizing kinetics of ASTM A36 steel with the alternative kinetic model and the integral method","authors":"Z. Abdellah, M. Keddam, P. Jurči","doi":"10.2478/kom-2021-0004","DOIUrl":"https://doi.org/10.2478/kom-2021-0004","url":null,"abstract":"Abstract In this study, two different mathematical models have been proposed for estimating the diffusivities of boron in the Fe2B layer on ASTM A36 steel in the range of 1173 to 1273 K with exposure times of 2 to 8 h. The boride incubation period required for the formation of such a layer was constant regardless of the boriding conditions. In both approaches, the boron diffusivity in the iron phase was considered in an unsaturated matrix. The first approach was derived from the mass balance equation at the (Fe2B/substrate) interface while the second approach employed the integral diffusion model. The calculated values of boron activation energies for ASTM A36 steel were found to be very comparable for the two approaches (161.65 and 160.96 and kJ mol-1). Afterwards, these values of activation energy were confronted with the results from the literature. Experimental validation of these two approaches has been done by comparing the experimental value of Fe2B layer thickness measured at 1123 K for 2.5 h with the simulated values. Finally, the predicted values of Fe2B layer thickness were in line with the experimental measurement.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69228508","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}
J. Brezinová, A. Guzanová, D. Draganovská, J. Březina, J. Viňáš
Abstract The paper focuses on the quality of coatings applied by cataphoretic deposition and cataphoretic deposition technology with a phosphate layer. The quality of the coatings was evaluated by determining the roughness of the coatings, the morphology of the coatings, spectral analyses were performed detecting the presence of individual elements in the coatings. There was analysed also defect – uncoated spot.
{"title":"The change in the morphology of the blasted surface after phosphating and cataphoretic coating","authors":"J. Brezinová, A. Guzanová, D. Draganovská, J. Březina, J. Viňáš","doi":"10.2478/kom-2020-0019","DOIUrl":"https://doi.org/10.2478/kom-2020-0019","url":null,"abstract":"Abstract The paper focuses on the quality of coatings applied by cataphoretic deposition and cataphoretic deposition technology with a phosphate layer. The quality of the coatings was evaluated by determining the roughness of the coatings, the morphology of the coatings, spectral analyses were performed detecting the presence of individual elements in the coatings. There was analysed also defect – uncoated spot.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44180991","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}
Abstract This work deals with behaviour of steel in liquid lead environment and possibilities of corrosion resistance improvement. Liquid metal cooled systems are under wide investigation and development and represent a good alternative. It is necessary to find materials, which would be affected by liquid lead minimally. Austenitic steel 316L without coating and coated with TiSiC was studied in flowing liquid lead. Conditions of the experiment simulated real environment of the system. Deposition of protective barrier reduced the metals dissolution and diffusion of liquid lead into the steel substrate, degradation of substrate due to high temperature and mechanical stress. Presence of Si in the layer increased the surface ability to form stabile oxide and contribute to steel´s protection.
{"title":"Influence of surface treatment on corrosion resistance of steel in liquid Pb","authors":"M. Pazderová, L. Rozumová, L. Košek, A. Hojná","doi":"10.2478/kom-2020-0017","DOIUrl":"https://doi.org/10.2478/kom-2020-0017","url":null,"abstract":"Abstract This work deals with behaviour of steel in liquid lead environment and possibilities of corrosion resistance improvement. Liquid metal cooled systems are under wide investigation and development and represent a good alternative. It is necessary to find materials, which would be affected by liquid lead minimally. Austenitic steel 316L without coating and coated with TiSiC was studied in flowing liquid lead. Conditions of the experiment simulated real environment of the system. Deposition of protective barrier reduced the metals dissolution and diffusion of liquid lead into the steel substrate, degradation of substrate due to high temperature and mechanical stress. Presence of Si in the layer increased the surface ability to form stabile oxide and contribute to steel´s protection.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45817013","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}
A. Resen, M. Hanoon, R. D. Salim, A. Al-amiery, L. M. Shaker, A. Kadhum
Abstract The corrosion inhibition efficiency of the novel pyridine namely, 4-(Benzoimidazole-2-yl)pyridine has been studied for mild steel in a 1 M hydrochloric acid environment by utilizing gravimetrical techniques. The synthesized inhibitor exhibits a significant inhibitive efficiency of 93.8% at 0.005 M. The adsorption isotherm of the investigated inhibitor on mild steel surface obeys the Langmuir isotherm. Surface morphology investigated by utilizing scanning electron microscopy (SEM) demonstrates a smooth metal surface with the addition of 4-(Benzoimidazole-2-yl)pyridine in a hydrochloric acid environment. Quantum chemical calculations using density functional theory (DFT) have been used to investigate the molecular structure and behavior of 4-(Benzoimidazole-2-yl) pyridine as a corrosion inhibitor. Different parameters have been calculated using DFT, such as energies of highest occupied molecular orbital and lowest occupied molecular orbital (EHOMO and ELUMO), energy gap (∆E), and dipole moment (μ). These parameters were important to elucidate the behavior of the investigated molecule as a corrosion inhibitor in acidic solution and also suggest the mechanism of inhibition.
{"title":"Gravimetrical, theoretical, and surface morphological investigations of corrosion inhibition effect of 4-(benzoimidazole-2-yl) pyridine on mild steel in hydrochloric acid","authors":"A. Resen, M. Hanoon, R. D. Salim, A. Al-amiery, L. M. Shaker, A. Kadhum","doi":"10.2478/kom-2020-0018","DOIUrl":"https://doi.org/10.2478/kom-2020-0018","url":null,"abstract":"Abstract The corrosion inhibition efficiency of the novel pyridine namely, 4-(Benzoimidazole-2-yl)pyridine has been studied for mild steel in a 1 M hydrochloric acid environment by utilizing gravimetrical techniques. The synthesized inhibitor exhibits a significant inhibitive efficiency of 93.8% at 0.005 M. The adsorption isotherm of the investigated inhibitor on mild steel surface obeys the Langmuir isotherm. Surface morphology investigated by utilizing scanning electron microscopy (SEM) demonstrates a smooth metal surface with the addition of 4-(Benzoimidazole-2-yl)pyridine in a hydrochloric acid environment. Quantum chemical calculations using density functional theory (DFT) have been used to investigate the molecular structure and behavior of 4-(Benzoimidazole-2-yl) pyridine as a corrosion inhibitor. Different parameters have been calculated using DFT, such as energies of highest occupied molecular orbital and lowest occupied molecular orbital (EHOMO and ELUMO), energy gap (∆E), and dipole moment (μ). These parameters were important to elucidate the behavior of the investigated molecule as a corrosion inhibitor in acidic solution and also suggest the mechanism of inhibition.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41243852","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}
Abstract The Brayton cycle with supercritical carbon dioxide is considered as an innovative technology with the potential to replace conventional steam cycles. The optimization of the supercritical CO2 cycle (sCO2) is necessary and important to achieve the required thermal cycle parameters. The above optimization focuses on the setting of the energy cycle as such, the design solution of the individual components and, the last but not least, on the selection of suitable construction materials. Due to the operating conditions, namely temperatures exceeding 550 °C and pressure up to 25 MPa, material research is one of the important areas of the research and development of sCO2 energy cycles. Construction materials for sCO2 power cycle equipment include HR6W, T92 and Haynes HR235 alloys. This work presents results of the corrosion test, in which samples of these materials were exposed to sCO2 at 550 °C and 25 MPa for 1000 hours. Corrosion after exposure was examined using a light optical microscope (LOM) and a scanning electron microscope (SEM). The significant differences in corrosion attack between the investigated materials and the formation of a protective oxide layer on the surface were observed.
{"title":"Evaluation of microstructure of the steels after exposure in supercritical CO2","authors":"L. Rozumová, T. Melichar, J. Berka, L. Velebil","doi":"10.2478/kom-2020-0016","DOIUrl":"https://doi.org/10.2478/kom-2020-0016","url":null,"abstract":"Abstract The Brayton cycle with supercritical carbon dioxide is considered as an innovative technology with the potential to replace conventional steam cycles. The optimization of the supercritical CO2 cycle (sCO2) is necessary and important to achieve the required thermal cycle parameters. The above optimization focuses on the setting of the energy cycle as such, the design solution of the individual components and, the last but not least, on the selection of suitable construction materials. Due to the operating conditions, namely temperatures exceeding 550 °C and pressure up to 25 MPa, material research is one of the important areas of the research and development of sCO2 energy cycles. Construction materials for sCO2 power cycle equipment include HR6W, T92 and Haynes HR235 alloys. This work presents results of the corrosion test, in which samples of these materials were exposed to sCO2 at 550 °C and 25 MPa for 1000 hours. Corrosion after exposure was examined using a light optical microscope (LOM) and a scanning electron microscope (SEM). The significant differences in corrosion attack between the investigated materials and the formation of a protective oxide layer on the surface were observed.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42284327","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}
Abstract The search deals with the possibilities of increasing the fire resistance of paper, cardboard or paperboard. The article includes the principles of fire retardancy as well as requirements for a suitable preparation and lists substances and mixtures which, according to the literature, are/were used in the manufacturing process or after-treatment of paper products. The article is also continuously supplemented by examples from the patent literature.
{"title":"Methods of increasing the fire resistance of paper products","authors":"M. Nováková, M. Durovic","doi":"10.2478/kom-2020-0015","DOIUrl":"https://doi.org/10.2478/kom-2020-0015","url":null,"abstract":"Abstract The search deals with the possibilities of increasing the fire resistance of paper, cardboard or paperboard. The article includes the principles of fire retardancy as well as requirements for a suitable preparation and lists substances and mixtures which, according to the literature, are/were used in the manufacturing process or after-treatment of paper products. The article is also continuously supplemented by examples from the patent literature.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46803560","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}
Abstract A typical green layer of patina starts to cover copper in atmosphere condition, which is aesthetically acceptable and also provides protective properties. This work investigates stability of the artificial patina layer based on sulphates prepared from a gaseous phase during two-year exposure in atmosphere condition. XRD and SEM were employed to verify the composition and morphology of artificial patina. Colour and patina coverage were compared before and after exposure also. According to results after 1 and 2 years of exposure, it is possible to see changing of hydroxyl sulphates to more stable brochantite and filling pores in the patina layer. There is almost no colour change, however lower patina coverage is slightly evident due to precipitation and abrasive effect.
{"title":"Long-term outdoor exposure of artificial copper patina based on brochantite","authors":"R. Bureš, P. Rak, J. Stoulil","doi":"10.2478/kom-2020-0013","DOIUrl":"https://doi.org/10.2478/kom-2020-0013","url":null,"abstract":"Abstract A typical green layer of patina starts to cover copper in atmosphere condition, which is aesthetically acceptable and also provides protective properties. This work investigates stability of the artificial patina layer based on sulphates prepared from a gaseous phase during two-year exposure in atmosphere condition. XRD and SEM were employed to verify the composition and morphology of artificial patina. Colour and patina coverage were compared before and after exposure also. According to results after 1 and 2 years of exposure, it is possible to see changing of hydroxyl sulphates to more stable brochantite and filling pores in the patina layer. There is almost no colour change, however lower patina coverage is slightly evident due to precipitation and abrasive effect.","PeriodicalId":17911,"journal":{"name":"Koroze a ochrana materialu","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46139197","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}
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