Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie最新文献_第3页

The influence of austenitization time and temperature on the austenite grain growth in high Ti-V HSLA steels 奥氏体化时间和温度对高Ti-V HSLA钢中奥氏体晶粒长大的影响

Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie Pub Date : 2022-01-24 DOI: 10.36303/satnt.2021cosaami.28

Srj Rezaei, CW Siyayisa, Z. Tang, J. Moema

{"title":"The influence of austenitization time and temperature on the austenite grain growth in high Ti-V HSLA steels","authors":"Srj Rezaei, CW Siyayisa, Z. Tang, J. Moema","doi":"10.36303/satnt.2021cosaami.28","DOIUrl":"https://doi.org/10.36303/satnt.2021cosaami.28","url":null,"abstract":"Generally, in high titanium-containing high strength low alloy (HSLA) steels, the challenge is to ensure that an adequate amount of Ti dissolves during soaking for precipitate strengthening during cooling or hot working. Therefore, this work focused on the effect of soaking time and temperature on the austenite grain growth kinetics of HSLA steels, of the three alloys containing 0.1 %Ti, and 0 to 0.12 %V. The samples were austenitized at 1150 and 1280 °C for 1, 2 and 3 hrs and quenched in a 10% NaCl brine. Thereafter, the samples were tempered at 490 °C for 72 hrs in order to reveal the prior austenite grain boundaries. The grain size was analysed by the linear intercept method. The precipitation behaviour was predicted by Thermo-Calc software and confirmed by SEM-EDS. At 1150 °C austenitizing temperature, all three steel grades exhibited the Ti (C, N) (Type 1), (Mn-Ti) (C, S) (Type 2), MnS (Type 3 (Ti4C2S2) (Type 4) and TiC (Type 5) precipitates. After escalating the temperature to 1280 °C, only the TiC dissolved. Type 4 and 5 precipitates were the finest and possibly responsible for the grain size refinement. Consequently, alloy 1 with the highest S content of 140 ppm exhibited the finest grain size at both temperatures.","PeriodicalId":22035,"journal":{"name":"Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78355883","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}

引用次数: 0

Study of one-step and two-step quench and partition heat treatments on a medium carbon high silicon alloy using dilatometry 用膨胀法研究中碳高硅合金的一步和两步淬火和分区热处理

Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie Pub Date : 2022-01-24 DOI: 10.36303/satnt.2021cosaami.20

V. Kurup, CW Siyayisa, R. Mostert, J. Moema

引用次数: 0

Use of first principles and Thermo-Calc to identify potential low elastic modulus titanium-based alloys for biomedical applications 使用第一性原理和热钙识别潜在的低弹性模量钛基合金用于生物医学应用

Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie Pub Date : 2022-01-24 DOI: 10.36303/satnt.2021cosaami.42

MN Madigoe, R. Modiba, L. Cornish

{"title":"Use of first principles and Thermo-Calc to identify potential low elastic modulus titanium-based alloys for biomedical applications","authors":"MN Madigoe, R. Modiba, L. Cornish","doi":"10.36303/satnt.2021cosaami.42","DOIUrl":"https://doi.org/10.36303/satnt.2021cosaami.42","url":null,"abstract":"High alloyed β-phase stabilised titanium alloys are known to have low elastic moduli comparable to that of the human bone (≈30 GPa). The β-phase in titanium alloys exhibits an elastic modulus of about 60-80 GPa, which is nearly half that of α-phase (100-120 GPa). In this work, an attempt to develop a β-phase titanium-based alloy through first-principles calculations and Thermo-Calc calculations for biomedical applications was conducted. First-principles calculations were performed using the CASTEP code on a simple 2-atom bcc unit cell to predict the theoretical elastic modulus and mechanical stability of the Ti-Nb-Ta-Zr (TNTZ) system at 0 K. Thermo-Calc was used to determine the phase proportion diagrams of the proposed alloys at 500℃. The alloy comprised Ti-Nbx-Ta25-Zr5 (x = 5, 10, 20, 30, 40) (at.%). The theoretical results suggested that increasing niobium content introduced both mechanical (cʹ > 0) stability of the alloys. Alloy Ti-Nb5-Ta25-Zr5 gave the lowest elastic modulus of 55.23 ± 24.45 GPa which is half the elastic modulus of pure titanium (α phase). The phase proportion diagrams showed that up to 58.6 mol.% of β phase was retained at 20 at.% Nb, although the Voigt-Reuss-Hill Young’s modulus calculated from first principles increased with increasing niobium content while the α/β phase transformation temperature decreased down to 551.3℃ at 40 at.% Nb.","PeriodicalId":22035,"journal":{"name":"Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie","volume":"83 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73445333","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}

引用次数: 0

Investigating the electronic and magnetic properties of Dy, Y and La by site substitution on Nd2Fe14B permanent magnet employing the first-principle approach 用第一性原理法研究了Nd2Fe14B永磁体上Dy、Y和La的电子和磁性能

Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie Pub Date : 2022-01-24 DOI: 10.36303/satnt.2021cosaami.41

LE Miya, Methias Sithole, R. Modiba

引用次数: 0

Use of attenuated total reflectance fourier transform infrared spectroscopy as a tool to determine effect of hot air-drying on yield (%) of chitin from crab integument 用衰减全反射傅里叶变换红外光谱法测定了热风干燥对蟹皮中甲壳素得率的影响

Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie Pub Date : 2022-01-24 DOI: 10.36303/satnt.2021cosaami.31

T. Khumalo, AV Rane, MT Pandurangan, K. Kanny

{"title":"Use of attenuated total reflectance fourier transform infrared spectroscopy as a tool to determine effect of hot air-drying on yield (%) of chitin from crab integument","authors":"T. Khumalo, AV Rane, MT Pandurangan, K. Kanny","doi":"10.36303/satnt.2021cosaami.31","DOIUrl":"https://doi.org/10.36303/satnt.2021cosaami.31","url":null,"abstract":"Washing, hot air drying, mechanical grinding, and chemical treatments are used to extract chitin from the integument of crustaceans (crabs). Variable drying times are documented in the literature, but none of the publications correlate drying time to the percent yield of chitin from crab integument, therefore this investigation. The effects of hot air-drying duration on the percent yield of chitin from Ocypode Ryderi (Pink Ghost Crab) (found along the east coast of South Africa) are investigated in this study. The impact of hot air drying on intermolecular changes inside the crab integument was investigated. Using an Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR Spectroscopy), the intermolecular interactions occurring within the crab integument with respect to hot air-drying period were observed. To cover a study gap, crab integument was dried at 0h, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h,10h,11h, and 12h and extracted chitin at 0h, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, and 12h. The highest chitin output was found after 12 hours of hot air drying.","PeriodicalId":22035,"journal":{"name":"Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87326062","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}

引用次数: 0

Development of ATO as an alternative catalyst support for PEM fuel cells ATO作为PEM燃料电池替代催化剂的研究进展

Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie Pub Date : 2022-01-24 DOI: 10.36303/satnt.2021cosaami.47

M. Mkhabela, T. Ngwenya

{"title":"Development of ATO as an alternative catalyst support for PEM fuel cells","authors":"M. Mkhabela, T. Ngwenya","doi":"10.36303/satnt.2021cosaami.47","DOIUrl":"https://doi.org/10.36303/satnt.2021cosaami.47","url":null,"abstract":"Proton exchange membrane (PEM) fuel cells demonstrated to be feasible energy converters that convert chemical energy of fuels to electrical energy. The technology has proven to be competitive with conventional energy converters such as batteries and internal combustion engines. However; several challenges influence the commercialization of this technology which includes high costs, durability, and stability, which are contributed by the PEM fuel cell catalysts. Currently, the carbon-supported platinum electro-catalyst is being used. Unfortunately, carbon supports are not stable enough for fuel cell durability due to carbon corrosion on the cathode. Therefore it is necessary to replace carbon support materials to improve the durability of PEM fuel cells. In this study, antimony doped tin oxide (ATO) metal oxides are synthesized as alternative platinum catalyst support via co-precipitation with different antimony doping levels of 5, 7, and 10 %. The preliminary results of the acid resistance test show that the support is relatively acid-resistant with minor loss of dopant in acidic conditions. Surface area measurements, XRD, TEM, ICP characterization will be performed on the ATO before and after the addition of 40 wt. % of Pt particles. The mass and specific activity measurements for oxygen reduction reaction (ORR) and durability via ex-situ thin-fil rotating disc electrode (RDE) of Pt/ATO catalyst and the traditionally used Pt/C catalyst will be compared.","PeriodicalId":22035,"journal":{"name":"Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie","volume":"2015 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87004495","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}

引用次数: 0

Adsorption-desorption of F2 diatomic molecule on Ti (100) surface at different coverages 不同覆盖率下F2双原子分子在Ti(100)表面的吸附-解吸

Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie Pub Date : 2022-01-24 DOI: 10.36303/satnt.2021cosaami.38

D. Tshwane, R. Modiba, G. Govender, P. Ngoepe, H. Chauke

{"title":"Adsorption-desorption of F2 diatomic molecule on Ti (100) surface at different coverages","authors":"D. Tshwane, R. Modiba, G. Govender, P. Ngoepe, H. Chauke","doi":"10.36303/satnt.2021cosaami.38","DOIUrl":"https://doi.org/10.36303/satnt.2021cosaami.38","url":null,"abstract":"Fluorine molecules and ions are used as an etchant for metal surface processing. The presence of fluorine significantly influences the electrochemical behaviour on a metal surface, which has major relevance for etching, corrosion, electro-catalysis and galvanic deposition processes. Although the fluorine ions play an important role in metal surface etching, the studies remain limited and unclear, especially at the atomistic scale. In this work, density functional theory is used to investigate the structural and electronic properties of F2 diatomic molecule adsorption on Ti (100) surface at different coverages. Results revealed a dissociative adsorption mechanism of F2 on the Ti (100) surface. Adsorption energy analysis of F2 on Ti (100) surface denotes an exothermic process. Moreover, increasing F2 coverage resulted in the formation of TiF4 and Ti2F6 molecules on the surface. In addition, the calculated heat of formation for TiF4 was found to be more favourable than Ti2F6 species. Calculated desorption energies for TiF4 and Ti2F6 is 11.73 eV/atom and 9.04 eV/atom, suggesting non-spontaneous.","PeriodicalId":22035,"journal":{"name":"Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86718623","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}

引用次数: 0

Bio-based polyurethane coating synthesized from modified castor oil - applicable in base coat of automobile paint 以改性蓖麻油为原料合成的生物基聚氨酯涂料，适用于汽车漆底漆

Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie Pub Date : 2022-01-24 DOI: 10.36303/satnt.2021cosaami.24

D. Mohanty, M. Kanny, S. Mohanty, S. Nayak

引用次数: 0

Effect of Nb glue atom in the cluster formula on the microstructure and mechanical properties of Ti-Mo alloy 团簇配方中Nb胶原子对Ti-Mo合金显微组织和力学性能的影响

Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie Pub Date : 2022-01-24 DOI: 10.36303/satnt.2021cosaami.44

L. Ranganya, N. Moshokoa, B. Obadele, E. Makhatha, R. Machaka

引用次数: 0

Reduction of copper oxide powder by an inductively coupled thermal plasma 电感耦合热等离子体还原氧化铜粉末

Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie Pub Date : 2022-01-24 DOI: 10.36303/satnt.2021cosaami.16

H. Bissett, M. Makhofane, S. Lötter

{"title":"Reduction of copper oxide powder by an inductively coupled thermal plasma","authors":"H. Bissett, M. Makhofane, S. Lötter","doi":"10.36303/satnt.2021cosaami.16","DOIUrl":"https://doi.org/10.36303/satnt.2021cosaami.16","url":null,"abstract":"Additive manufacturing (AM) methods can be utilised to manufacture complex, custom Ti6Al4V components for medical implants. Infection at the bone-implant interface is a key reason for implant rejection. Advanced titanium implants with biocompatibility and antibacterial properties can be manufactured by modifying the titanium alloy with copper, which in small concentrations (< 1 at % copper) is a proven, non-toxic antibacterial agent. Copper can be embedded into the titanium implant during the AM process creating antibacterial functionality. In order to produce sufficiently fine metallic copper powder, copper oxide can be reduced, either by chemical reduction or thermal treatment methods. These include thermal decomposition or reduction of the oxide in the presence of a reactive gas at elevated temperatures. Making use of thermal treatment methods such as thermal plasma reduction, the process conditions can be tuned to manipulate the morphology and average particle size of the powders. The purpose of this study was to investigate the thermal plasma reduction of copper oxide to copper metal making use of the Tek-15 radio-frequency inductively coupled thermal plasma system at Necsa.\u0000\u0000In the presence of hydrogen, the black copper (II) oxide powder was converted to a dark red powder, while a yellow / orange coloured powder was obtained without hydrogen being present. A change in composition was observed using SEM-EDS and was confirmed by XRD analysis.","PeriodicalId":22035,"journal":{"name":"Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78084825","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}

引用次数: 0