Pub Date : 2002-07-01DOI: 10.2320/MATERTRANS.43.1451
M. Mizuno, H. Araki, Y. Shirai
Positron states for the bulk and vacancy in intermetallic compounds CoAl and CoTi crystallizing in the B2 structure have been calculated using the DV-Xa electronic structure calculation and compared with experimental results. The calculated positron lifetimes in CoAl can explain the compositional dependence of the positron lifetimes in CoAl. The calculated positron lifetime at the Ti vacancy in CoTi is longer than that at the Co vacancy. The charge transfer from Ti to Co leads to the difference of the localization of the positron wave function at the vacancy. At the Co vacancy site surrounded by the positively charged Ti atoms, the positron wave function does not localize as well as at the Ti vacancy site, which decrease the positron lifetime. The calculated results suggest that the positron lifetimes in intermetallic compounds can not be directly correlated to those of the pure component and the charge transfer between the constituent atoms affects the localization of the positron wave function.
{"title":"Theoretical calculation of positron lifetimes in CoAl and CoTi : Special issue on grain boundaries, interfaces, defects and localized quantum structures in ceramics","authors":"M. Mizuno, H. Araki, Y. Shirai","doi":"10.2320/MATERTRANS.43.1451","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.1451","url":null,"abstract":"Positron states for the bulk and vacancy in intermetallic compounds CoAl and CoTi crystallizing in the B2 structure have been calculated using the DV-Xa electronic structure calculation and compared with experimental results. The calculated positron lifetimes in CoAl can explain the compositional dependence of the positron lifetimes in CoAl. The calculated positron lifetime at the Ti vacancy in CoTi is longer than that at the Co vacancy. The charge transfer from Ti to Co leads to the difference of the localization of the positron wave function at the vacancy. At the Co vacancy site surrounded by the positively charged Ti atoms, the positron wave function does not localize as well as at the Ti vacancy site, which decrease the positron lifetime. The calculated results suggest that the positron lifetimes in intermetallic compounds can not be directly correlated to those of the pure component and the charge transfer between the constituent atoms affects the localization of the positron wave function.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"81 1","pages":"1451-1455"},"PeriodicalIF":0.0,"publicationDate":"2002-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88161787","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}
Pub Date : 2002-05-01DOI: 10.2320/MATERTRANS.43.780
S. Ishida, S. Asano
Titanium nickel (TiNi) and the pseudo binary containing a small amount of iron has the R phase as an intermediate phase. To examine theoretically the stability of the R phase, the electronic structures of TiNi and TiN1 8/9 Fe 1/9 were calculated for four structures of B2, P3, P31m and P31m. The total energies predict that the P3 structure is most stable among the four structures and in the P3 structure the added iron atoms prefer the 1c site. It is also revealed that the approach between a nickel (or iron) atom at the 1c site and a titanium atom at the 1c site in the P3 structure plays an important role in stabilizing the P3 structure. These features are clearly reflected on the band energies and the local density-of-states of the constituent atoms.
钛镍(TiNi)和含少量铁的伪二元以R相为中间相。为了从理论上检验R相的稳定性，我们计算了B2、P3、P31m和P31m四种结构的TiNi和TiN1 /9 Fe /9的电子结构。总能量预测P3结构在四种结构中最稳定，在P3结构中加入的铁原子倾向于1c位。结果还表明，P3结构中1c位点的镍(或铁)原子与1c位点的钛原子之间的接近对P3结构的稳定起着重要作用。这些特征清楚地反映在带能和组成原子的局域态密度上。
{"title":"R-phase and electronic structures of TiNi and TiNi8/9Fe1/9 : Special issue on smart materials-fundamentals and applications","authors":"S. Ishida, S. Asano","doi":"10.2320/MATERTRANS.43.780","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.780","url":null,"abstract":"Titanium nickel (TiNi) and the pseudo binary containing a small amount of iron has the R phase as an intermediate phase. To examine theoretically the stability of the R phase, the electronic structures of TiNi and TiN1 8/9 Fe 1/9 were calculated for four structures of B2, P3, P31m and P31m. The total energies predict that the P3 structure is most stable among the four structures and in the P3 structure the added iron atoms prefer the 1c site. It is also revealed that the approach between a nickel (or iron) atom at the 1c site and a titanium atom at the 1c site in the P3 structure plays an important role in stabilizing the P3 structure. These features are clearly reflected on the band energies and the local density-of-states of the constituent atoms.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"12 1","pages":"780-784"},"PeriodicalIF":0.0,"publicationDate":"2002-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85547982","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}
Pub Date : 2002-05-01DOI: 10.2320/MATERTRANS.43.1100
Itoko Saita, Liquan Li, Katsushi Saito, T. Akiyama
Pure Mg 2 NiH 4 was first prepared by Hydriding Combustion Synthesis (HCS), under which pressure and temperature were sensitively controlled. The purpose of this paper was to study Pressure-Composition-Temperature (PCT) properties of the HCSed product, in which hydrogen storage capacity, hydriding reaction rate, and PCT curves were mainly examined, in comparison to the commercially available product, i.e., Ingot Metallurgy product. The results showed that the HCSed Mg 2 NiH 4 has 3.6 mass%, same as theoretical value, in hydrogen storage capacity in the first cycle just after synthesized without activation treatment, and very large reactibn rate; only five minutes for full charge. Plateau pressure of the HCSed Mg 2 NiH 4 in PCT curves also became relatively lower than the conventional one. One of the most interesting results is the high activity of our product: it stored hydrogen even at room temperature. These results appealed a possibility of new productive process of hydrogen storage alloy from the viewpoint of product property.
{"title":"Pressure-composition-temperature properties of hydriding combustion-synthesized Mg2NiH4 : Special issue on hydrogen absorbing materials","authors":"Itoko Saita, Liquan Li, Katsushi Saito, T. Akiyama","doi":"10.2320/MATERTRANS.43.1100","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.1100","url":null,"abstract":"Pure Mg 2 NiH 4 was first prepared by Hydriding Combustion Synthesis (HCS), under which pressure and temperature were sensitively controlled. The purpose of this paper was to study Pressure-Composition-Temperature (PCT) properties of the HCSed product, in which hydrogen storage capacity, hydriding reaction rate, and PCT curves were mainly examined, in comparison to the commercially available product, i.e., Ingot Metallurgy product. The results showed that the HCSed Mg 2 NiH 4 has 3.6 mass%, same as theoretical value, in hydrogen storage capacity in the first cycle just after synthesized without activation treatment, and very large reactibn rate; only five minutes for full charge. Plateau pressure of the HCSed Mg 2 NiH 4 in PCT curves also became relatively lower than the conventional one. One of the most interesting results is the high activity of our product: it stored hydrogen even at room temperature. These results appealed a possibility of new productive process of hydrogen storage alloy from the viewpoint of product property.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"67 1","pages":"1100-1104"},"PeriodicalIF":0.0,"publicationDate":"2002-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82604492","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}
Pub Date : 2002-05-01DOI: 10.2320/MATERTRANS.43.1133
N. Ismail, M. Uhlemann, A. Gebert, J. Eckert, L. Schultz
Amorphous Zr-Cu-Al-Ni alloys are of interest for hydrogenation studies because they consist of a combination of early and late transition metals. Potentiodynamic polarisation tests were conducted to investigate the cathodic hydrogen reduction reactions on the surface of melt-spun Zr 55 Cu 30 Al 10 Ni 5 and Zr 65 Cu 17.5 Al 7.5 Ni 10 ribbons. In the Tafel region, the electrodic desorption reaction is the rate-determining step which competes with the hydrogen absorption reaction. In the next polarisation region, the hydrogen reduction takes place under mass transfer-control. The ribbons are galvanostatically charged with hydrogen to different hydrogen-to-metal ratios in 0.1 mol/l NaOH solution. The rate of hydrogen absorption of the Zr 55 Cu 30 Al 10 Ni 5 alloy is higher than that of the Zr 65 Cu 17.5 Al 7.5 Ni 10 alloy, although the hydrogen discharge rate on the surface of the Zr 65 Cu 17.5 Al 7.5 Ni 10 alloy is higher. Upon charging the samples at room temperature to H/M = 1.3 using a low charging rate (-1 mA/cm 2 ), the X-ray diffraction pattern show the main peaks of a Zr-hydride and Cu and/or a Cu rich phase(s) besides the amorphous phase. The potentiostatic double-pulse technique (PDP) was applied to estimate the fraction of reversibly absorbed hydrogen in the amorphous alloy samples by charging at different cathodic potentials. Subsequently, the residual hydrogen concentration (irreversibly absorbed hydrogen) was determined by hot extraction. The Zr 55 Cu 30 Al 10 Ni 5 alloy was found to absorb a higher fraction of reversible hydrogen than the Zr 65 Cu 17.5 Al 7.5 Ni 10 alloy.
非晶Zr-Cu-Al-Ni合金是氢化研究的热点，因为它们由早期和晚期过渡金属组成。采用动电位极化实验研究了熔融纺丝Zr 55 Cu 30 Al 10 Ni 5和Zr 65 Cu 17.5 Al 7.5 Ni 10带表面的阴极氢还原反应。在塔菲尔区，电解吸反应是与氢吸收反应竞争的速率决定步骤。在下一个极化区，氢还原发生在传质控制下。在0.1 mol/l的NaOH溶液中，以不同的氢金属比对带进行恒电流充电。Zr 55 Cu 30 Al 10 Ni 5合金的吸氢率高于Zr 65 Cu 17.5 Al 7.5 Ni 10合金，但Zr 65 Cu 17.5 Al 7.5 Ni 10合金表面的氢放电率更高。在室温下以低充电速率(-1 mA/ cm2)将样品充电至H/M = 1.3时，x射线衍射图显示出除非晶相外的主要峰为zr -氢化物和Cu和/或富Cu相。采用恒电位双脉冲技术(PDP)测定了在不同阴极电位下充电的非晶合金样品中可逆吸收氢的比例。随后，用热萃取法测定残余氢浓度(不可逆吸收氢)。Zr 55 Cu 30 Al 10 Ni 5合金比Zr 65 Cu 17.5 Al 7.5 Ni 10合金吸收了更高比例的可逆氢。
{"title":"The electrochemical hydrogen sorption behaviour of Zr-Cu-Al-Ni metallic glasses : Special issue on hydrogen absorbing materials","authors":"N. Ismail, M. Uhlemann, A. Gebert, J. Eckert, L. Schultz","doi":"10.2320/MATERTRANS.43.1133","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.1133","url":null,"abstract":"Amorphous Zr-Cu-Al-Ni alloys are of interest for hydrogenation studies because they consist of a combination of early and late transition metals. Potentiodynamic polarisation tests were conducted to investigate the cathodic hydrogen reduction reactions on the surface of melt-spun Zr 55 Cu 30 Al 10 Ni 5 and Zr 65 Cu 17.5 Al 7.5 Ni 10 ribbons. In the Tafel region, the electrodic desorption reaction is the rate-determining step which competes with the hydrogen absorption reaction. In the next polarisation region, the hydrogen reduction takes place under mass transfer-control. The ribbons are galvanostatically charged with hydrogen to different hydrogen-to-metal ratios in 0.1 mol/l NaOH solution. The rate of hydrogen absorption of the Zr 55 Cu 30 Al 10 Ni 5 alloy is higher than that of the Zr 65 Cu 17.5 Al 7.5 Ni 10 alloy, although the hydrogen discharge rate on the surface of the Zr 65 Cu 17.5 Al 7.5 Ni 10 alloy is higher. Upon charging the samples at room temperature to H/M = 1.3 using a low charging rate (-1 mA/cm 2 ), the X-ray diffraction pattern show the main peaks of a Zr-hydride and Cu and/or a Cu rich phase(s) besides the amorphous phase. The potentiostatic double-pulse technique (PDP) was applied to estimate the fraction of reversibly absorbed hydrogen in the amorphous alloy samples by charging at different cathodic potentials. Subsequently, the residual hydrogen concentration (irreversibly absorbed hydrogen) was determined by hot extraction. The Zr 55 Cu 30 Al 10 Ni 5 alloy was found to absorb a higher fraction of reversible hydrogen than the Zr 65 Cu 17.5 Al 7.5 Ni 10 alloy.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"71 1","pages":"1133-1137"},"PeriodicalIF":0.0,"publicationDate":"2002-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91051291","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}
Pub Date : 2002-05-01DOI: 10.2320/MATERTRANS.43.1089
M. Dilixiati, Kazuyuki Kanda, K. Ishikawa, K. Aoki
The pressure dependence of structural changes of C 15 Laves phase TbFe 2 heated in a hydrogen atmosphere was investigated using a pressure differential scanning calorimeter (PDSC), a powder X-ray diffractometer (XRD), a differential scanning calorimeter (DSC) and a hydrogen analyzer. Hydrogen absorption in the crystalline state, hydrogen-induced amorphization (HIA), precipitation of TbH 2 and decomposition of the remaining amorphous alloy into α-Fe and TbH 2 occurred exothermally with increasing temperature above 0.5 MPa H 2 , independent of the heating rate. HIA and precipitation of TbH 2 occurred simultaneously in 0.2 MPa H 2 (0.33 K/s) and in 0.1 MPa H 2 (0.17 K/s). On the contrary, hydrogen absorbed crystalline c-TbFe 2 H 3.5 decomposed directly into α-Fe and TbH 2 in 0.1 MPa H 2 (0.33 K/s). That is, no amorphous phase was formed at the lower hydrogen pressure and at a high heating rate. The reason why HIA occurs above, the critical hydrogen pressure and below the critical heating rate was discussed on the basis of the hydrogen content absorbed in the crystalline state or TbFe 2 .
采用压差扫描量热仪(PDSC)、粉末x射线衍射仪(XRD)、差示扫描量热仪(DSC)和氢分析仪研究了c15 Laves相TbFe 2在氢气气氛中加热时结构变化的压力依赖性。在0.5 MPa H以上，随着温度的升高，晶态吸氢、氢致非晶化(HIA)、tbh2的析出和剩余非晶态合金分解为α-Fe和tbh2的过程均发生放热，与升温速率无关。在0.2 MPa H 2 (0.33 K/s)和0.1 MPa H 2 (0.17 K/s)条件下，HIA和tbh2降水同时发生。而在0.1 MPa H 2 (0.33 K/s)下，吸附氢的c- tbfe2h 3.5晶体直接分解为α-Fe和tbh2。即在较低的氢压力和较高的加热速率下，未形成非晶态相。根据结晶态或tfe2中吸收的氢含量，讨论了在临界氢压力以上和临界加热速率以下发生HIA的原因。
{"title":"Pressure dependence of hydrogen-induced amorphization in C15 Laves phase TbFe2 : Special issue on hydrogen absorbing materials","authors":"M. Dilixiati, Kazuyuki Kanda, K. Ishikawa, K. Aoki","doi":"10.2320/MATERTRANS.43.1089","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.1089","url":null,"abstract":"The pressure dependence of structural changes of C 15 Laves phase TbFe 2 heated in a hydrogen atmosphere was investigated using a pressure differential scanning calorimeter (PDSC), a powder X-ray diffractometer (XRD), a differential scanning calorimeter (DSC) and a hydrogen analyzer. Hydrogen absorption in the crystalline state, hydrogen-induced amorphization (HIA), precipitation of TbH 2 and decomposition of the remaining amorphous alloy into α-Fe and TbH 2 occurred exothermally with increasing temperature above 0.5 MPa H 2 , independent of the heating rate. HIA and precipitation of TbH 2 occurred simultaneously in 0.2 MPa H 2 (0.33 K/s) and in 0.1 MPa H 2 (0.17 K/s). On the contrary, hydrogen absorbed crystalline c-TbFe 2 H 3.5 decomposed directly into α-Fe and TbH 2 in 0.1 MPa H 2 (0.33 K/s). That is, no amorphous phase was formed at the lower hydrogen pressure and at a high heating rate. The reason why HIA occurs above, the critical hydrogen pressure and below the critical heating rate was discussed on the basis of the hydrogen content absorbed in the crystalline state or TbFe 2 .","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"1 1 1","pages":"1089-1094"},"PeriodicalIF":0.0,"publicationDate":"2002-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89568827","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}
Pub Date : 2002-05-01DOI: 10.2320/MATERTRANS.43.1074
Y. Hirabayashi
Regenerated cellulose and chitosan membranes were studied for the pervaporation separation of an aqueous solution of urine component (ammonia, uric acid or creatinine). The permeation rate of water increased with increase of the temperature of feed solution induced into the upstream side of membrane module. Uric acid, creatine and creatinine were not found in the permeate through the all membranes investigated. Selective permeation of water and ammonia depends on membrane. The removal of ammonia through the chitosan membrane was from 57% to 59%. Adsorption of ammonia from the downstream vapor by silica gels was carried out. And desorption of ammonia from the adsorbents by heating under the reduced pressure to regenerate the capacity of adsorption was also confirmed. In the case of new pervaporation system, the combination of pervaporation and adsorption/desorption process, ammonia was almost completely removed, and finally.the pure condensed water was obtained in the cold trap.
{"title":"Pervaporation membrane system for the removal of ammonia from water : Special issue on smart materials-fundamentals and applications","authors":"Y. Hirabayashi","doi":"10.2320/MATERTRANS.43.1074","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.1074","url":null,"abstract":"Regenerated cellulose and chitosan membranes were studied for the pervaporation separation of an aqueous solution of urine component (ammonia, uric acid or creatinine). The permeation rate of water increased with increase of the temperature of feed solution induced into the upstream side of membrane module. Uric acid, creatine and creatinine were not found in the permeate through the all membranes investigated. Selective permeation of water and ammonia depends on membrane. The removal of ammonia through the chitosan membrane was from 57% to 59%. Adsorption of ammonia from the downstream vapor by silica gels was carried out. And desorption of ammonia from the adsorbents by heating under the reduced pressure to regenerate the capacity of adsorption was also confirmed. In the case of new pervaporation system, the combination of pervaporation and adsorption/desorption process, ammonia was almost completely removed, and finally.the pure condensed water was obtained in the cold trap.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"41 1","pages":"1074-1077"},"PeriodicalIF":0.0,"publicationDate":"2002-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74368859","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}
Pub Date : 2002-05-01DOI: 10.2320/MATERTRANS.43.939
S. Ikeno, T. Kawabata, Hiroaki Hayashi, K. Matsuda, Seiichi Rengakuji, Toshiaki Suzuki, Y. Hatano, Katsuyoshi Tanaka
TiO 2 films were formed on aluminum plates by a dip-coating in an advanced sol-gel precursor solution, and the effect of sintering conditions on the photocatalytic properties of the oxide were investigated by UV adsorption. The samples prepared in this way exhibit photocatalytic activity in a range of suitable sintering conditions compatible with the region of crystallization of anatase characterized by X-ray diffraction. The surface morphology and adhesion between the TiO 2 nano-film and aluminum plate were confirmed by energy filtering transmission electron microscopy, and the surface morphology was found to affect the photocatalitic activity. The TiO 2 film was 30nm thick and was confirmed to be finely crystallines with a mean diameter of 12 nm.
{"title":"Fabrication of photocatalytic TiO2 films on pure aluminum plates : Special issue on smart materials-fundamentals and applications","authors":"S. Ikeno, T. Kawabata, Hiroaki Hayashi, K. Matsuda, Seiichi Rengakuji, Toshiaki Suzuki, Y. Hatano, Katsuyoshi Tanaka","doi":"10.2320/MATERTRANS.43.939","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.939","url":null,"abstract":"TiO 2 films were formed on aluminum plates by a dip-coating in an advanced sol-gel precursor solution, and the effect of sintering conditions on the photocatalytic properties of the oxide were investigated by UV adsorption. The samples prepared in this way exhibit photocatalytic activity in a range of suitable sintering conditions compatible with the region of crystallization of anatase characterized by X-ray diffraction. The surface morphology and adhesion between the TiO 2 nano-film and aluminum plate were confirmed by energy filtering transmission electron microscopy, and the surface morphology was found to affect the photocatalitic activity. The TiO 2 film was 30nm thick and was confirmed to be finely crystallines with a mean diameter of 12 nm.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"57-58 1","pages":"939-945"},"PeriodicalIF":0.0,"publicationDate":"2002-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73329184","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}
Pub Date : 2002-05-01DOI: 10.2320/MATERTRANS.43.1015
T. Raparelli, P. B. Zobel, F. Durante
In this paper the design and the manufacture of a 3-dof (degrees of freedom) robot driven by shape memory alloys (SMA) is presented. This robot has a parallel structure including a fixed plate and a moving plate. The plates are linked together by 3 SMA wires and a mechanical spring is located in the central part. Possible applications are the control devices to orient a mirror, a sample under a microscope or to orient the head of a micro snake like robot. The paper explains the kinematic model, the mechanical design and the control system of the robot. The feedback signals of the closed loop control system are the displacements of the SMA joints located on the moving plate, measured by three conductive potentiometers. The control system is P.C. based. The SMA actuators are driven by Nitinol wires of a diameter of 0.15 mm. The robot takes up a cylinder with a diameter of 100 mm and a height of 180 mm. A prototype of the robot has been manufactured and some experimental tests were carried out. These tests are carried out both using a simple test bed made by a SMA wire and a pulley, and using the prototype itself. The step response of a single SMA wire and the trajectory control to describe a circle in the prototype are also shown as validation tests of the robot. The results of the experimental validation show the feasibility of this design, but particular attention has to be paid to the machining and to the assembly.
{"title":"Design of a parallel robot actuated by shape memory alloy wires : Special issue on smart materials-fundamentals and applications","authors":"T. Raparelli, P. B. Zobel, F. Durante","doi":"10.2320/MATERTRANS.43.1015","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.1015","url":null,"abstract":"In this paper the design and the manufacture of a 3-dof (degrees of freedom) robot driven by shape memory alloys (SMA) is presented. This robot has a parallel structure including a fixed plate and a moving plate. The plates are linked together by 3 SMA wires and a mechanical spring is located in the central part. Possible applications are the control devices to orient a mirror, a sample under a microscope or to orient the head of a micro snake like robot. The paper explains the kinematic model, the mechanical design and the control system of the robot. The feedback signals of the closed loop control system are the displacements of the SMA joints located on the moving plate, measured by three conductive potentiometers. The control system is P.C. based. The SMA actuators are driven by Nitinol wires of a diameter of 0.15 mm. The robot takes up a cylinder with a diameter of 100 mm and a height of 180 mm. A prototype of the robot has been manufactured and some experimental tests were carried out. These tests are carried out both using a simple test bed made by a SMA wire and a pulley, and using the prototype itself. The step response of a single SMA wire and the trajectory control to describe a circle in the prototype are also shown as validation tests of the robot. The results of the experimental validation show the feasibility of this design, but particular attention has to be paid to the machining and to the assembly.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"56 1","pages":"1015-1022"},"PeriodicalIF":0.0,"publicationDate":"2002-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88890372","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}
Pub Date : 2002-03-01DOI: 10.2320/MATERTRANS.43.292
K. Shibata, Soek-Jong Seo, Masashi Kaga, H. Uchino, Akio Sasanuma, K. Asakura, C. Nagasaki
The most serious problem in the recycling of steel is the occurrence of surface hot shortness during hot deformation due to the mixing of Cu from scrap into steels. Tin accelerates the effect of Cu. The surface hot shortness is caused by liquid embrittlement, that is, formation of the liquid Cu-enriched phase through preferential oxidation of Fe atoms at the steel/scale interface during heating for hot deformation and penetration of this Cu-enriched phase into the grain boundaries. Decrease in the amount of the liquid Cu-enriched phase penetrating into grain boundaries can suppress the surface hot shortness. The amount of the liquid Cu-enriched phase penetrating into the grain boundaries can be reduced by the suppression of oxidation, occlusion of the Cu-enriched phase into the scale, back-diffusion of Cu into the steel matrix and suppression of penetration of the liquid Cu-enriched phase. Therefore, the effects of various elements and conditions of heating and deformation on the surface hot shortness, oxidation, amount of the Cu-enriched phase at the interface and the penetration were examined by tensile tests at high temperatures, thermogravimetry and optical microscopy. The conclusion can be summarized as follows. Silicon, Mn, S (+Mn) and B reduce the susceptibility to the surface hot shortness through decreasing the amount of Cu-enriched phase at the steel/scale interface. The effect of Si is significant. Carbon reduces the oxidation rate in LNG combustion gas. Phosphorus, Si, B and C reduce the susceptibility to the surface hot shortness through restraining the penetration of the Cu-enriched phase into grain boundaries. Heating at higher temperatures reduces the susceptibility mainly through a reduction in the amount of the Cu-enriched phase at the steel/scale interface, although the loss of steels by oxidation increases. A large grain size accelerates the surface hot shortness. A small amount of H 2 O in air significantly accelerates the surface hot shortness. Effects of H 2 O in heating atmosphere depend on the steel composition and more detailed research on this is desired. Very slow deformation does not cause liquid embrittlement through dynamical re-crystallization, while at a fast deformation rate the embrittlement is suppressed by an increase in the critical stress for the liquid embrittlement. Multiple methods using physical metallurgy suggested by the present research for suppressing the surface hot shortness should be applied together with other methods through separation, smelting and design of fabrication in order to promote the recycling of steels.
{"title":"Suppression of surface hot shortness due to Cu in recycled steels : Environmental benign manufacturing and material processing toward dematerialization","authors":"K. Shibata, Soek-Jong Seo, Masashi Kaga, H. Uchino, Akio Sasanuma, K. Asakura, C. Nagasaki","doi":"10.2320/MATERTRANS.43.292","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.292","url":null,"abstract":"The most serious problem in the recycling of steel is the occurrence of surface hot shortness during hot deformation due to the mixing of Cu from scrap into steels. Tin accelerates the effect of Cu. The surface hot shortness is caused by liquid embrittlement, that is, formation of the liquid Cu-enriched phase through preferential oxidation of Fe atoms at the steel/scale interface during heating for hot deformation and penetration of this Cu-enriched phase into the grain boundaries. Decrease in the amount of the liquid Cu-enriched phase penetrating into grain boundaries can suppress the surface hot shortness. The amount of the liquid Cu-enriched phase penetrating into the grain boundaries can be reduced by the suppression of oxidation, occlusion of the Cu-enriched phase into the scale, back-diffusion of Cu into the steel matrix and suppression of penetration of the liquid Cu-enriched phase. Therefore, the effects of various elements and conditions of heating and deformation on the surface hot shortness, oxidation, amount of the Cu-enriched phase at the interface and the penetration were examined by tensile tests at high temperatures, thermogravimetry and optical microscopy. The conclusion can be summarized as follows. Silicon, Mn, S (+Mn) and B reduce the susceptibility to the surface hot shortness through decreasing the amount of Cu-enriched phase at the steel/scale interface. The effect of Si is significant. Carbon reduces the oxidation rate in LNG combustion gas. Phosphorus, Si, B and C reduce the susceptibility to the surface hot shortness through restraining the penetration of the Cu-enriched phase into grain boundaries. Heating at higher temperatures reduces the susceptibility mainly through a reduction in the amount of the Cu-enriched phase at the steel/scale interface, although the loss of steels by oxidation increases. A large grain size accelerates the surface hot shortness. A small amount of H 2 O in air significantly accelerates the surface hot shortness. Effects of H 2 O in heating atmosphere depend on the steel composition and more detailed research on this is desired. Very slow deformation does not cause liquid embrittlement through dynamical re-crystallization, while at a fast deformation rate the embrittlement is suppressed by an increase in the critical stress for the liquid embrittlement. Multiple methods using physical metallurgy suggested by the present research for suppressing the surface hot shortness should be applied together with other methods through separation, smelting and design of fabrication in order to promote the recycling of steels.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"11 1","pages":"292-300"},"PeriodicalIF":0.0,"publicationDate":"2002-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83279637","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}
Pub Date : 2002-03-01DOI: 10.2320/MATERTRANS.43.326
Y. Kubota, Shigekuni Nakada, Y. Sugi
As a candidate for the alternate of conventional, insoluble thermosetting resins that are matrix components of fiber reinforced plastics (FRP), soluble and heat-resistant aramids (wholly aromatic polyamides) were synthesized. To obtain rigid biphenyl-containing aramid, one-step procedure from dihalobiphenyl and aromatic diamine by palladium-catalyzed carbonylation-polycondensation was successfully applied. Reaction parameters, such as base, solvent, palladium-phosphine catalyst and CO pressure in the reaction of 2,7-dibromo-9,10-dihydrophenanthrene (1) and 4,4'-diaminodipheyl ether (2a), were very important for successful synthesis. They affected the molecular weight of resulting aramid significantly. Under optimum conditions, poly[amino-1,4-phenyleneoxy-1,4-phenyleneaminocarbonyl(9,10-dihydro-2,7-phenanthrenediyl)carbonyl] (3a) Was obtained in 99% yield with high molecular weight (polystyrene equivalent M W = 128100). The procedure was applied to some other diamines. The aramid 3a was heat-resistant and soluble in polar organic solvent. On the basis of thermal analysis, 10% weight loss temperature (T 10 ) of the aramid was 461°C. The tensile strength and tensile modulus were 48 MPa and 1.6 GPa, respectively; these properties are roughly in the same level as those of conventional unsaturated polyester resin. Judging from the data, aramid 3a is applicable for matrix of FRP. Some other aramids exhibited similar properties.
作为传统的不溶性热固性树脂的替代品，纤维增强塑料(FRP)的基体成分，合成了可溶性和耐热的芳纶(全芳香族聚酰胺)。采用钯催化羰基缩聚一步法，成功制备了刚性含联苯芳烃。在2,7-二溴-9,10-二氢菲(1)和4,4′-二氨基二苯醚(2a)的反应中，碱、溶剂、钯-膦催化剂和CO压力等参数对成功合成至关重要。它们显著地影响了合成芳纶的分子量。在最佳条件下，可制得聚[氨基-1,4-苯乙烯氧基-1,4-苯乙烯氨基羰基(9,10-二氢-2,7-苯乙烯二基)羰基](3a)，收率99%，分子量高(聚苯乙烯当量M W = 128100)。该方法也适用于其他一些二胺。芳纶3a耐热，可溶于极性有机溶剂。热分析表明，芳纶10%失重温度(t10)为461℃。拉伸强度和拉伸模量分别为48 MPa和1.6 GPa;这些性能与常规不饱和聚酯树脂大致处于同一水平。从数据来看，芳纶3a适用于FRP的基体。其他一些芳烃也表现出类似的性质。
{"title":"New heat-resistant and soluble aramids synthesized by palladium-catalyzed carbonylation-polycondensation : Environmental benign manufacturing and material processing toward dematerialization","authors":"Y. Kubota, Shigekuni Nakada, Y. Sugi","doi":"10.2320/MATERTRANS.43.326","DOIUrl":"https://doi.org/10.2320/MATERTRANS.43.326","url":null,"abstract":"As a candidate for the alternate of conventional, insoluble thermosetting resins that are matrix components of fiber reinforced plastics (FRP), soluble and heat-resistant aramids (wholly aromatic polyamides) were synthesized. To obtain rigid biphenyl-containing aramid, one-step procedure from dihalobiphenyl and aromatic diamine by palladium-catalyzed carbonylation-polycondensation was successfully applied. Reaction parameters, such as base, solvent, palladium-phosphine catalyst and CO pressure in the reaction of 2,7-dibromo-9,10-dihydrophenanthrene (1) and 4,4'-diaminodipheyl ether (2a), were very important for successful synthesis. They affected the molecular weight of resulting aramid significantly. Under optimum conditions, poly[amino-1,4-phenyleneoxy-1,4-phenyleneaminocarbonyl(9,10-dihydro-2,7-phenanthrenediyl)carbonyl] (3a) Was obtained in 99% yield with high molecular weight (polystyrene equivalent M W = 128100). The procedure was applied to some other diamines. The aramid 3a was heat-resistant and soluble in polar organic solvent. On the basis of thermal analysis, 10% weight loss temperature (T 10 ) of the aramid was 461°C. The tensile strength and tensile modulus were 48 MPa and 1.6 GPa, respectively; these properties are roughly in the same level as those of conventional unsaturated polyester resin. Judging from the data, aramid 3a is applicable for matrix of FRP. Some other aramids exhibited similar properties.","PeriodicalId":18264,"journal":{"name":"Materials Transactions Jim","volume":"130 1","pages":"326-331"},"PeriodicalIF":0.0,"publicationDate":"2002-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76407127","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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