A.A. Shcherbakov, R.A. Vasin, A. Balagurov, Vladimir V. Khovaylo, I.S. Golovin
We report on experimental investigations of a Ni2.36Mn0.64Ga Heusler alloy, which transforms to tetragonal martensite at cooling below Ms ≈ 271°С. The evolution of lattice constants was tracked by in situ neutron diffraction measurements. It was found that the martensite tetragonality c/a gradually decreases during heating from room temperature to austenite transition start temperature As ≈ 272°С. The phenomenon of martensite stabilization was investigated by differential scanning calorimetry utilizing three different protocols of the martensite aging. It was found that the martensite aging at a constant temperature T = 255°С merely shifts the reverse transformation to higher temperatures, while the reverse transformation temperature interval (Af – As) remains the same (≈ 30°C) independently of aging time. On the other hand, a multistep aging at different temperatures starting from T = 255°С not only shifts the reverse transformation temperature, but makes the transformation temperature interval narrower down to As – Af ≈ 10°C.
我们报告了对 Ni2.36Mn0.64Ga Heusler 合金的实验研究，这种合金在冷却到 Ms ≈ 271°С 以下时会转变为四方马氏体。通过现场中子衍射测量跟踪了晶格常数的演变。结果发现，在从室温加热到奥氏体转变起始温度 As ≈ 272°С的过程中，马氏体的四方性 c/a 逐渐减小。利用三种不同的马氏体时效方案，通过差示扫描量热法研究了马氏体的稳定现象。结果发现，在恒温 T = 255°С 下进行马氏体时效只是将反向转变转移到更高的温度，而反向转变温度区间（Af - As）保持不变（≈ 30°C），与时效时间无关。另一方面，从 T = 255°С 开始在不同温度下进行多级老化，不仅会使反向转化温度发生变化，还会使转化温度区间缩小到 As - Af ≈ 10°C。
{"title":"Phase Transformations and Martensite Stabilization in Ni2.36Mn0.64Ga High-Temperature Shape Memory Alloy","authors":"A.A. Shcherbakov, R.A. Vasin, A. Balagurov, Vladimir V. Khovaylo, I.S. Golovin","doi":"10.4028/p-oqvVm1","DOIUrl":"https://doi.org/10.4028/p-oqvVm1","url":null,"abstract":"We report on experimental investigations of a Ni2.36Mn0.64Ga Heusler alloy, which transforms to tetragonal martensite at cooling below Ms ≈ 271°С. The evolution of lattice constants was tracked by in situ neutron diffraction measurements. It was found that the martensite tetragonality c/a gradually decreases during heating from room temperature to austenite transition start temperature As ≈ 272°С. The phenomenon of martensite stabilization was investigated by differential scanning calorimetry utilizing three different protocols of the martensite aging. It was found that the martensite aging at a constant temperature T = 255°С merely shifts the reverse transformation to higher temperatures, while the reverse transformation temperature interval (Af – As) remains the same (≈ 30°C) independently of aging time. On the other hand, a multistep aging at different temperatures starting from T = 255°С not only shifts the reverse transformation temperature, but makes the transformation temperature interval narrower down to As – Af ≈ 10°C.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"39 12","pages":"117 - 126"},"PeriodicalIF":0.0,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139007011","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 research paper investigates the effect of the addition of carbon nanotubes (0.5 and 1.0% by weight) on crystallisation procedure in isotactic polypropylene. The study found that the crystallisation temperature increased with increasing nanotube content, while the crystallisation of polymers did not substantially change. The critical cooling speed, at which PP does not crystalize, increases with the increase in carbon nanotube content. Using the critical cooling speed and nanotube content, a nucleation effectiveness parameter was developed, that is not dependent on the crystallisation temperature or the CNT load. The study also found that carbon nanotubes only speed up the development of α-phase in isothermal crystallisation experiments. The control fibers had a shrinkage of 27% to 160°C, while the shrinkage of the composite fibers was less than 5%. The melting temperature of PP and its nanocomposites was approximately 150 to 152°C. However, the values for the degree of crystallinity of the nanocomposites rose along with the CNT content.
{"title":"The Impact of Carbon Nanotube on the Thermal Properties of Polypropylene","authors":"M. Sabet, H. Soleimani","doi":"10.4028/p-uUQ9pX","DOIUrl":"https://doi.org/10.4028/p-uUQ9pX","url":null,"abstract":"This research paper investigates the effect of the addition of carbon nanotubes (0.5 and 1.0% by weight) on crystallisation procedure in isotactic polypropylene. The study found that the crystallisation temperature increased with increasing nanotube content, while the crystallisation of polymers did not substantially change. The critical cooling speed, at which PP does not crystalize, increases with the increase in carbon nanotube content. Using the critical cooling speed and nanotube content, a nucleation effectiveness parameter was developed, that is not dependent on the crystallisation temperature or the CNT load. The study also found that carbon nanotubes only speed up the development of α-phase in isothermal crystallisation experiments. The control fibers had a shrinkage of 27% to 160°C, while the shrinkage of the composite fibers was less than 5%. The melting temperature of PP and its nanocomposites was approximately 150 to 152°C. However, the values for the degree of crystallinity of the nanocomposites rose along with the CNT content.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"1 1","pages":"191 - 208"},"PeriodicalIF":0.0,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139009108","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}
In laser cutting processes, the removal of material is achieved without the application of external force, distinguishing it from traditional machining methods. An additional advantage of laser cutting is the ability to achieve desired surface quality in a single step, eliminating the need for additional finishing processes to smoothen and clean the cutting surface. To ensure the quality of the resulting cuts, a comprehensive understanding of the thermal behavior of the cut parts, influenced by the movement of the laser beam, is essential. The article focuses on the numerical simulation of the laser cutting process of the AISI 304 steel sheets with a thickness of 2 mm to investigate the impact of laser cutting parameters on transient thermal fields and the quality of the resulting cuts. A simulation model was developed and verified through temperature measurements during an experimental laser cutting process using the Bystronic Bysprint 3015 CO2 Laser Cutting Machine. Numerical simulations in ANSYS software were used to design a working diagram showing the relationship between laser power and cutting kerf width for three different cutting speeds: 2000 mm.min-1, 4000 mm.min-1, and 5000 mm.min-1.
{"title":"A Simulation Model for the Analysis of Laser Cutting of Stainless Steel Sheets","authors":"E. Babalová, M. Behúlová","doi":"10.4028/p-Ez4KIq","DOIUrl":"https://doi.org/10.4028/p-Ez4KIq","url":null,"abstract":"In laser cutting processes, the removal of material is achieved without the application of external force, distinguishing it from traditional machining methods. An additional advantage of laser cutting is the ability to achieve desired surface quality in a single step, eliminating the need for additional finishing processes to smoothen and clean the cutting surface. To ensure the quality of the resulting cuts, a comprehensive understanding of the thermal behavior of the cut parts, influenced by the movement of the laser beam, is essential. The article focuses on the numerical simulation of the laser cutting process of the AISI 304 steel sheets with a thickness of 2 mm to investigate the impact of laser cutting parameters on transient thermal fields and the quality of the resulting cuts. A simulation model was developed and verified through temperature measurements during an experimental laser cutting process using the Bystronic Bysprint 3015 CO2 Laser Cutting Machine. Numerical simulations in ANSYS software were used to design a working diagram showing the relationship between laser power and cutting kerf width for three different cutting speeds: 2000 mm.min-1, 4000 mm.min-1, and 5000 mm.min-1.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"6 9","pages":"71 - 80"},"PeriodicalIF":0.0,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139009691","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}
Hojjatollah Soleimani, Surajudden Sikiru, Hassan Soleimani, Leila Khodapanah, M. Sabet
The oil and gas sector faces challenges in optimizing oil recovery from reservoirs due to trapped oil due to interfacial tension and surface forces. Characterizing anisotropic dielectric properties is crucial. The petroleum business is quickly changing, and a massive advancement in the application of nanotechnology in this field is envisaged. Because magnetic nanoparticles (MNP) are solid, tiny, and adsorb at the oil-water interface, they might be helpful. The interaction of MNP with electromagnetic waves appears to be capable of altering interfacial tension, which will boost oil recovery. The interaction of an oscillating B-field of electromagnetic waves with magnetic domains causes energy dissipation due to a shift in magnetic anisotropy from the easy axis of magnetization. The use of anisotropy energy in mobilizing oil in a porous media has recently been investigated. BaTiO3 nanoparticles (NPs) were synthesized for this purpose, and their influence on oil mobility under electromagnetic waves (EM) was studied. The anisotropy energy was computed and determined to be 7.34kJ/mol. Under EM, the easy axis magnetization of BaTiO3 nanoparticles oscillates and changes direction continually, facilitating oil mobilization in the porous media. The EM findings for reducing interfacial tension (IFT) between oil and water ranged from 4.5mN/m to 0.89mN/m. Under EM, it was discovered that BaTiO3 nanoparticles might lower IFT by roughly 60%. The IFT must be small enough to allow oil flow during mobilization. The simulation findings demonstrate that the adsorption energy of n-hexane on the surface of hematite has a 47.9% lower energy value than water. With a 115.4% percentage difference, the stress autocorrelation function of n-hexane with hematite is greater than that of water.
{"title":"Impact of Anisotropy and Electromagnetic Modified Effect on Fluid Mobility in Reservoir Sandstone","authors":"Hojjatollah Soleimani, Surajudden Sikiru, Hassan Soleimani, Leila Khodapanah, M. Sabet","doi":"10.4028/p-WMZWk3","DOIUrl":"https://doi.org/10.4028/p-WMZWk3","url":null,"abstract":"The oil and gas sector faces challenges in optimizing oil recovery from reservoirs due to trapped oil due to interfacial tension and surface forces. Characterizing anisotropic dielectric properties is crucial. The petroleum business is quickly changing, and a massive advancement in the application of nanotechnology in this field is envisaged. Because magnetic nanoparticles (MNP) are solid, tiny, and adsorb at the oil-water interface, they might be helpful. The interaction of MNP with electromagnetic waves appears to be capable of altering interfacial tension, which will boost oil recovery. The interaction of an oscillating B-field of electromagnetic waves with magnetic domains causes energy dissipation due to a shift in magnetic anisotropy from the easy axis of magnetization. The use of anisotropy energy in mobilizing oil in a porous media has recently been investigated. BaTiO3 nanoparticles (NPs) were synthesized for this purpose, and their influence on oil mobility under electromagnetic waves (EM) was studied. The anisotropy energy was computed and determined to be 7.34kJ/mol. Under EM, the easy axis magnetization of BaTiO3 nanoparticles oscillates and changes direction continually, facilitating oil mobilization in the porous media. The EM findings for reducing interfacial tension (IFT) between oil and water ranged from 4.5mN/m to 0.89mN/m. Under EM, it was discovered that BaTiO3 nanoparticles might lower IFT by roughly 60%. The IFT must be small enough to allow oil flow during mobilization. The simulation findings demonstrate that the adsorption energy of n-hexane on the surface of hematite has a 47.9% lower energy value than water. With a 115.4% percentage difference, the stress autocorrelation function of n-hexane with hematite is greater than that of water.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"5 1","pages":"179 - 188"},"PeriodicalIF":0.0,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139009325","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}
E. R. di Schio, Abderrahim Mokhefi, A. N. Impiombato, C. Biserni
In the present work, a numerical investigation of the unsteady mixed convection and entropy generation of a nanofluid in an annular cylindrical space is presented using the Buongiorno’s two-phase flow model. It deals with a concentric tube heat exchanger where the inner cylinder rotates with a constant frequency and is maintained at hot temperature, while the outer cylinder is cold. The aim of the present investigation is to highlight the effects of some parameters on the hydrodynamic, thermal and mass behavior of the considered nanofluid as well as on the system irreversibility, namely: the inertia (1 ⩽ Re ⩽ 20), the buoyancy (0 ⩽ Ri ⩽ 5), the mass diffusion (0.1 ⩽ Le ⩽ 10) and the vertical positions of the inner cylinder (-0.4 ⩽ H ⩽ 0.4). Moreover, at specific parameters, an optimal position in terms of heat transfer has been determined. The flow of the nanofluid is two-dimensional and governed by the equations of continuity, momentum, energy as well as volume fraction conservation. After performing a finite element method mesh test and validation with the literature, the Nusselt number and the entropy generation are discussed. The results show that the heat transfer rate and entropy generation increase with increasing values of Richardson and Reynolds number, especially when positioning the inner cylinder in the lower part. On the other hand, the nanoparticles migration under the thermophoretic diffusion decrease with the increase of the Lewis number, which consequent decrease of the heat transfer rate.
本研究采用 Buongiorno 两相流模型，对环形圆柱空间中纳米流体的非稳定混合对流和熵生成进行了数值研究。它涉及一个同心管热交换器，其中内筒以恒定的频率旋转并保持高温，而外筒为冷态。本研究旨在强调一些参数对所考虑的纳米流体的流体力学、热学和质量行为以及系统不可逆性的影响，即：惯性（1 ⩽ Re ⩽20）、浮力（0 ⩽ Ri ⩽5）、质量扩散（0.1 ⩽ Le ⩽ 10）和内圆柱体的垂直位置（-0.4 ⩽ H ⩽0.4）。此外，还确定了特定参数下的最佳传热位置。纳米流体的流动是二维的，受连续性、动量、能量和体积分数守恒方程的控制。在进行有限元法网格测试并与文献进行验证后，讨论了努塞尔特数和熵的产生。结果表明，随着理查德森数和雷诺数值的增加，传热速率和熵生成量也随之增加，尤其是当内圆柱体位于下部时。另一方面，随着路易斯数的增加，纳米粒子在热泳扩散下的迁移量减少，传热速率随之降低。
{"title":"Numerical Analysis of the Unsteady Mixed Convection of a Nanofluid in a Concentric Tube Heat Exchanger","authors":"E. R. di Schio, Abderrahim Mokhefi, A. N. Impiombato, C. Biserni","doi":"10.4028/p-1eZhC5","DOIUrl":"https://doi.org/10.4028/p-1eZhC5","url":null,"abstract":"In the present work, a numerical investigation of the unsteady mixed convection and entropy generation of a nanofluid in an annular cylindrical space is presented using the Buongiorno’s two-phase flow model. It deals with a concentric tube heat exchanger where the inner cylinder rotates with a constant frequency and is maintained at hot temperature, while the outer cylinder is cold. The aim of the present investigation is to highlight the effects of some parameters on the hydrodynamic, thermal and mass behavior of the considered nanofluid as well as on the system irreversibility, namely: the inertia (1 ⩽ Re ⩽ 20), the buoyancy (0 ⩽ Ri ⩽ 5), the mass diffusion (0.1 ⩽ Le ⩽ 10) and the vertical positions of the inner cylinder (-0.4 ⩽ H ⩽ 0.4). Moreover, at specific parameters, an optimal position in terms of heat transfer has been determined. The flow of the nanofluid is two-dimensional and governed by the equations of continuity, momentum, energy as well as volume fraction conservation. After performing a finite element method mesh test and validation with the literature, the Nusselt number and the entropy generation are discussed. The results show that the heat transfer rate and entropy generation increase with increasing values of Richardson and Reynolds number, especially when positioning the inner cylinder in the lower part. On the other hand, the nanoparticles migration under the thermophoretic diffusion decrease with the increase of the Lewis number, which consequent decrease of the heat transfer rate.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"8 2","pages":"13 - 32"},"PeriodicalIF":0.0,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139010189","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}
One of the most important challenges of modern materials engineering is to improve the efficiency and durability of materials, which directly translates into reducing the consumption of raw materials. In many applications, these goals are achieved by strengthening and functionalizing the surface, especially in the case of nanocoatings. The material for the study is the Ta/TaN multilayer systems obtained with the ALD technique (Atomic Layer Deposition, R200 by Picosun). For their structure characterisation electron microscopy (HR STEM, electron diffraction, EDS, EELS) was used. Geometrical parameters (thickness of the constituent Ta and TaN layers, ratio of thicknesses of metallic and ceramic layers) were determined, and their chemical and phase compositions were verified. The obtained results will be used to model mechanical properties and interpret the results of experimental nanoindentation measurements.
{"title":"Structure of Ta/TaN Nanolayered Systems Investigated by Transmission Electron Microscopy","authors":"B. Sobel, K. Lukaszkowicz, M. Pawlyta","doi":"10.4028/p-rX2K0B","DOIUrl":"https://doi.org/10.4028/p-rX2K0B","url":null,"abstract":"One of the most important challenges of modern materials engineering is to improve the efficiency and durability of materials, which directly translates into reducing the consumption of raw materials. In many applications, these goals are achieved by strengthening and functionalizing the surface, especially in the case of nanocoatings. The material for the study is the Ta/TaN multilayer systems obtained with the ALD technique (Atomic Layer Deposition, R200 by Picosun). For their structure characterisation electron microscopy (HR STEM, electron diffraction, EDS, EELS) was used. Geometrical parameters (thickness of the constituent Ta and TaN layers, ratio of thicknesses of metallic and ceramic layers) were determined, and their chemical and phase compositions were verified. The obtained results will be used to model mechanical properties and interpret the results of experimental nanoindentation measurements.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"32 12","pages":"219 - 226"},"PeriodicalIF":0.0,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139007297","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}
Jie Song, Qing Lian Li, Jun Sun, Xin Lin Liu, Lan Wei Chen
LOX/LCH4 rocket engine has been recognized as the ideal power choice for future space vehicles due to the merits of low cost, non-toxic and pollution-free, convenient maintenance, suitable for reuse and high specific impulse. In the process of wide range variable thrust of LOX/LCH4 rocket engine, the coolant methane is in a subcritical state due to the low combustor pressure under low operation conditions. The instability of two-phase flow is easy to occur in regenerative cooling channel (RCC), and it is urgent to investigate the heat transfer performance of methane with phase change in RCC. Experiments have been conducted to investigate the flow boiling characteristics of liquid methane in the single mini channels with the diameters of 1.0, 1.5 and 2.0 mm. Effects of the mass flux (266.75~1781.26 kg/m2·s), inlet pressure (0.56~4.24 MPa), heat flux (53.25~800.07 kW/m2) and channel diameter (1.0~2.0 mm) on the flow boiling heat transfer coefficients are tested. Results show that there are two regions with different heat transfer mechanism, one is the nucleate boiling dominated region for low mass quality and the other is the convection evaporation dominated region for high mass quality. A new correlation expressed by Bo, We, Kp, X, Co, Ftg is proposed, which yields good fitting for 355 experimental data with a mean absolute error (MAE) of 10.9%. Present experimental results can provide reference for the thermal protection prediction and optimal design of RCC in LOX/LCH4 rocket engine.
{"title":"Experimental Investigation on Boiling Heat Transfer Characteristics of Liquid Methane in Mini Channel","authors":"Jie Song, Qing Lian Li, Jun Sun, Xin Lin Liu, Lan Wei Chen","doi":"10.4028/p-eNC5GS","DOIUrl":"https://doi.org/10.4028/p-eNC5GS","url":null,"abstract":"LOX/LCH4 rocket engine has been recognized as the ideal power choice for future space vehicles due to the merits of low cost, non-toxic and pollution-free, convenient maintenance, suitable for reuse and high specific impulse. In the process of wide range variable thrust of LOX/LCH4 rocket engine, the coolant methane is in a subcritical state due to the low combustor pressure under low operation conditions. The instability of two-phase flow is easy to occur in regenerative cooling channel (RCC), and it is urgent to investigate the heat transfer performance of methane with phase change in RCC. Experiments have been conducted to investigate the flow boiling characteristics of liquid methane in the single mini channels with the diameters of 1.0, 1.5 and 2.0 mm. Effects of the mass flux (266.75~1781.26 kg/m2·s), inlet pressure (0.56~4.24 MPa), heat flux (53.25~800.07 kW/m2) and channel diameter (1.0~2.0 mm) on the flow boiling heat transfer coefficients are tested. Results show that there are two regions with different heat transfer mechanism, one is the nucleate boiling dominated region for low mass quality and the other is the convection evaporation dominated region for high mass quality. A new correlation expressed by Bo, We, Kp, X, Co, Ftg is proposed, which yields good fitting for 355 experimental data with a mean absolute error (MAE) of 10.9%. Present experimental results can provide reference for the thermal protection prediction and optimal design of RCC in LOX/LCH4 rocket engine.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"29 S2","pages":"239 - 246"},"PeriodicalIF":0.0,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139009975","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}
Andrey N. Dmitriev, E. Vyaznikova, G. Vitkina, R. Alektorov
The initial and final softening (melting) temperatures of redesigned iron ore agglomerates with basicities from 1.2 to 3.0, obtained under laboratory conditions, were investigated. The chemical and phase compositions of the laboratory agglomerates, their microstructures and local chemical compositions, the temperatures at the beginning and end of softening (melting), and the temperature interval of softening were studied. Dependencies of the influence of the basicity of iron ore agglomerates on their softening temperature interval, depending on the proportion of phase components, were obtained. It is shown that as the basicity and proportion of silicoferrite SFCA phases increase, the temperatures at the beginning and end of the softening increase and reach a maximum of 1200 and 1312 °С, respectively (at the basicity of the agglomerate of 1.8), after which the temperatures decrease. Simultaneously, the softening interval increased from 73 to 112 °C.
{"title":"Study of Softening Temperature Range of Agglomerate Depending on its Structure and Phase Composition","authors":"Andrey N. Dmitriev, E. Vyaznikova, G. Vitkina, R. Alektorov","doi":"10.4028/p-36AEtf","DOIUrl":"https://doi.org/10.4028/p-36AEtf","url":null,"abstract":"The initial and final softening (melting) temperatures of redesigned iron ore agglomerates with basicities from 1.2 to 3.0, obtained under laboratory conditions, were investigated. The chemical and phase compositions of the laboratory agglomerates, their microstructures and local chemical compositions, the temperatures at the beginning and end of softening (melting), and the temperature interval of softening were studied. Dependencies of the influence of the basicity of iron ore agglomerates on their softening temperature interval, depending on the proportion of phase components, were obtained. It is shown that as the basicity and proportion of silicoferrite SFCA phases increase, the temperatures at the beginning and end of the softening increase and reach a maximum of 1200 and 1312 °С, respectively (at the basicity of the agglomerate of 1.8), after which the temperatures decrease. Simultaneously, the softening interval increased from 73 to 112 °C.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"24 9","pages":"144 - 151"},"PeriodicalIF":0.0,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139007507","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}
M. D. Manfrinato, Luciana Sgarbi Rossino, A. Kliauga, O. Florêncio
Austenitic stainless steels are widely used due to their resistance to corrosion and to the possibility of using them at temperatures above 600 °C. Plasma nitriding and nitrocarburizing consist of a thermochemical process that introduces nitrogen and nitrogen/carbon, in atomic form, allowing the formation of second phases of these elements with the substrate. These thermochemical treatments of plasma nitriding and nitrocarburizing were performed on austenitic stainless steel AISI 312 at temperatures of 400 °C and 500 °C, obtaining thicknesses of around 12 μm and 24 μm, respectively. Mechanical properties of indentation were obtained using a Hit 300 nanoindenter (Anton Paar), in a load-unload cycle and with a depth of up to 10% of the layer, with Berkovich indenter. The elastic moduli obtained for the nitrided layers were 281 ± 21 GPa (400 °C) and 163 ± 32 GPa (500 °C) and for the nitrocarburized were 214 ± 12 GPa (400 °C) and 169 ± 25 GPa (500 °C). The indentation nanohardness obtained for the nitrided layers were 14.1 ± 1.0 GPa (400 °C) and 3.5 ± 1.2 GPa (500 °C) and for the nitrocarburized layers were 10.8 ± 0.8 GPa (400 °C) and 4.3 ± 1.2 GPa (500 °C). Therefore, these results indicate slightly higher values for the two mechanical properties indentation (elastic modulus and nanohardness) at 400 °C than at 500 °C caused by nitriding compared to nitrocarburizing treatment; however, when considering the percentages of standard deviations, the treatments at 500 °C present much higher values for these properties, as compared to the treatments at 400 °C, a behavior associated with the presence of chromium and iron nitrides.
{"title":"Mechanical Properties of Indentation in Plasma Nitrided and Nitrocarburized Austenitic Stainless Steel AISI 321","authors":"M. D. Manfrinato, Luciana Sgarbi Rossino, A. Kliauga, O. Florêncio","doi":"10.4028/p-45tuLi","DOIUrl":"https://doi.org/10.4028/p-45tuLi","url":null,"abstract":"Austenitic stainless steels are widely used due to their resistance to corrosion and to the possibility of using them at temperatures above 600 °C. Plasma nitriding and nitrocarburizing consist of a thermochemical process that introduces nitrogen and nitrogen/carbon, in atomic form, allowing the formation of second phases of these elements with the substrate. These thermochemical treatments of plasma nitriding and nitrocarburizing were performed on austenitic stainless steel AISI 312 at temperatures of 400 °C and 500 °C, obtaining thicknesses of around 12 μm and 24 μm, respectively. Mechanical properties of indentation were obtained using a Hit 300 nanoindenter (Anton Paar), in a load-unload cycle and with a depth of up to 10% of the layer, with Berkovich indenter. The elastic moduli obtained for the nitrided layers were 281 ± 21 GPa (400 °C) and 163 ± 32 GPa (500 °C) and for the nitrocarburized were 214 ± 12 GPa (400 °C) and 169 ± 25 GPa (500 °C). The indentation nanohardness obtained for the nitrided layers were 14.1 ± 1.0 GPa (400 °C) and 3.5 ± 1.2 GPa (500 °C) and for the nitrocarburized layers were 10.8 ± 0.8 GPa (400 °C) and 4.3 ± 1.2 GPa (500 °C). Therefore, these results indicate slightly higher values for the two mechanical properties indentation (elastic modulus and nanohardness) at 400 °C than at 500 °C caused by nitriding compared to nitrocarburizing treatment; however, when considering the percentages of standard deviations, the treatments at 500 °C present much higher values for these properties, as compared to the treatments at 400 °C, a behavior associated with the presence of chromium and iron nitrides.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"35 12","pages":"162 - 170"},"PeriodicalIF":0.0,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139007568","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. Chaus, M. Sahul, M. Behúlová, Martin Kusý, M. V. Sitkevich
The present investigation has been carried out to study the microstructure evolution and microhardness of the multi-component B–C–N diffusion coatings developed on wrought AISI M2 high-speed steel substrate at 560 and 650 °C for 1 and 4 h for both temperatures. The microstructure of the coatings was studied using scanning electron microscopy, energy dispersion spectroscopy and X-ray diffraction analysis. Vickers microhardness measurements were also performed. The investigations showed that varying conditions of the thermochemical treatment resulted in a variety of coatings which exhibited varying microstructure, phase composition and microhardness.
{"title":"Development of Multi-Component B-C-N Diffusion Coating on Wrought AISI M2 High-Speed Steel Substrate","authors":"A. Chaus, M. Sahul, M. Behúlová, Martin Kusý, M. V. Sitkevich","doi":"10.4028/p-t7uTZ0","DOIUrl":"https://doi.org/10.4028/p-t7uTZ0","url":null,"abstract":"The present investigation has been carried out to study the microstructure evolution and microhardness of the multi-component B–C–N diffusion coatings developed on wrought AISI M2 high-speed steel substrate at 560 and 650 °C for 1 and 4 h for both temperatures. The microstructure of the coatings was studied using scanning electron microscopy, energy dispersion spectroscopy and X-ray diffraction analysis. Vickers microhardness measurements were also performed. The investigations showed that varying conditions of the thermochemical treatment resulted in a variety of coatings which exhibited varying microstructure, phase composition and microhardness.","PeriodicalId":11306,"journal":{"name":"Defect and Diffusion Forum","volume":"57 2","pages":"107 - 116"},"PeriodicalIF":0.0,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139008370","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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