Pub Date : 2022-01-24DOI: 10.36303/satnt.2021cosaami.28
Srj Rezaei, CW Siyayisa, Z. Tang, J. Moema
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.
{"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}
Pub Date : 2022-01-24DOI: 10.36303/satnt.2021cosaami.20
V. Kurup, CW Siyayisa, R. Mostert, J. Moema
This study evaluated the microstructural evolution in a medium carbon high silicon steel during one-step, and two-step quench and partition (Q&P) processes using dilatometry experiments. The two-step Q&P process was carried out using different quench temperatures ranging from 180 to 260 °C. In the one-step process, Q&P heat treatment samples were held isothermally for ten minutes after quenching at specified temperatures ranging between 200 and 4°50 C. The two-step Q&P process yielded a higher fraction of retained austenite than a one-step Q&P process. During the isothermal hold step, the volume expansion due to carbon partitioning and austenite decomposition behavior was interpreted by experimentally determined strain values. For the one-step Q&P process, the austenite decomposition kinetics above and below the Ms temperature differed, as evidenced by the JMAK parameters. The TTT diagram generated for the one-step Q & P process showed a “swing back” at a temperature of around 355 °C.
{"title":"Study of one-step and two-step quench and partition heat treatments on a medium carbon high silicon alloy using dilatometry","authors":"V. Kurup, CW Siyayisa, R. Mostert, J. Moema","doi":"10.36303/satnt.2021cosaami.20","DOIUrl":"https://doi.org/10.36303/satnt.2021cosaami.20","url":null,"abstract":"This study evaluated the microstructural evolution in a medium carbon high silicon steel during one-step, and two-step quench and partition (Q&P) processes using dilatometry experiments. The two-step Q&P process was carried out using different quench temperatures ranging from 180 to 260 °C. In the one-step process, Q&P heat treatment samples were held isothermally for ten minutes after quenching at specified temperatures ranging between 200 and 4°50 C. The two-step Q&P process yielded a higher fraction of retained austenite than a one-step Q&P process. During the isothermal hold step, the volume expansion due to carbon partitioning and austenite decomposition behavior was interpreted by experimentally determined strain values. For the one-step Q&P process, the austenite decomposition kinetics above and below the Ms temperature differed, as evidenced by the JMAK parameters. The TTT diagram generated for the one-step Q & P process showed a “swing back” at a temperature of around 355 °C.","PeriodicalId":22035,"journal":{"name":"Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie","volume":"72 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77303394","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 : 2022-01-24DOI: 10.36303/satnt.2021cosaami.42
MN Madigoe, R. Modiba, L. Cornish
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.
{"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}
Pub Date : 2022-01-24DOI: 10.36303/satnt.2021cosaami.41
LE Miya, Methias Sithole, R. Modiba
The development of new Nd-Fe-B permanent magnets continues to be a pressing matter for the transition to a green economy. Permanent magnets have become significant in applications of highly efficient energy conversion machines and devices. First-principles calculations have been performed by using the density function theory (DFT) within the generalized gradient approximation (GGA) to study the Nd2Fe14B magnets. The effects of Dy/La/Y on the electronic and magnetic properties of Nd2Fe14B permanent magnet with the site substitution mechanism were studied. The spin and the orbital magnetic moments of the Nd, Dy, Y, and La ion were found to be opposite to each other, which is in agreement with Hund’s rule. Moreover, the total orbital magnetic moment was found to be larger than that of the total spin magnetic moment. Y prefers the 4f site, while La on the other hand prefers the 4g site. The total magnetic moment of the Nd2Fe14B was in close agreement with the previous reported experimental value.
{"title":"Investigating the electronic and magnetic properties of Dy, Y and La by site substitution on Nd2Fe14B permanent magnet employing the first-principle approach","authors":"LE Miya, Methias Sithole, R. Modiba","doi":"10.36303/satnt.2021cosaami.41","DOIUrl":"https://doi.org/10.36303/satnt.2021cosaami.41","url":null,"abstract":"The development of new Nd-Fe-B permanent magnets continues to be a pressing matter for the transition to a green economy. Permanent magnets have become significant in applications of highly efficient energy conversion machines and devices. First-principles calculations have been performed by using the density function theory (DFT) within the generalized gradient approximation (GGA) to study the Nd2Fe14B magnets. The effects of Dy/La/Y on the electronic and magnetic properties of Nd2Fe14B permanent magnet with the site substitution mechanism were studied. The spin and the orbital magnetic moments of the Nd, Dy, Y, and La ion were found to be opposite to each other, which is in agreement with Hund’s rule. Moreover, the total orbital magnetic moment was found to be larger than that of the total spin magnetic moment. Y prefers the 4f site, while La on the other hand prefers the 4g site. The total magnetic moment of the Nd2Fe14B was in close agreement with the previous reported experimental value.","PeriodicalId":22035,"journal":{"name":"Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie","volume":"71 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78742882","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 : 2022-01-24DOI: 10.36303/satnt.2021cosaami.31
T. Khumalo, AV Rane, MT Pandurangan, K. Kanny
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.
{"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}
Pub Date : 2022-01-24DOI: 10.36303/satnt.2021cosaami.47
M. Mkhabela, T. Ngwenya
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.
{"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}
Pub Date : 2022-01-24DOI: 10.36303/satnt.2021cosaami.38
D. Tshwane, R. Modiba, G. Govender, P. Ngoepe, H. Chauke
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.
{"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}
Pub Date : 2022-01-24DOI: 10.36303/satnt.2021cosaami.24
D. Mohanty, M. Kanny, S. Mohanty, S. Nayak
The current study reports the epoxidation of castor oil (CO) by using hydrogen peroxide as catalyst and formic acid as oxidizing agent. Subsequently bio based polyurethane based base coat was synthesized by using epoxidised castor oil (ECO) as polyol, Isophorone diisocyanate (IPDI) as curing agent and dibutylin dilaurate (DBTDL) as catalyst. The paint formulation with OH:NCO ratio 1:1.2 was optimized. An independent study was carried out employing the mechanical test like cross-cut tape test was carried out to evaluate th paint properties. Morphological and structural studies like FTIR, SEM, HNMR were carried out with the paint formulation. Thermal property studies like TGA, DSC were carried out with the paint. Gloss, weather resistance of the paint was evaluated.
{"title":"Bio-based polyurethane coating synthesized from modified castor oil - applicable in base coat of automobile paint","authors":"D. Mohanty, M. Kanny, S. Mohanty, S. Nayak","doi":"10.36303/satnt.2021cosaami.24","DOIUrl":"https://doi.org/10.36303/satnt.2021cosaami.24","url":null,"abstract":"The current study reports the epoxidation of castor oil (CO) by using hydrogen peroxide as catalyst and formic acid as oxidizing agent. Subsequently bio based polyurethane based base coat was synthesized by using epoxidised castor oil (ECO) as polyol, Isophorone diisocyanate (IPDI) as curing agent and dibutylin dilaurate (DBTDL) as catalyst. The paint formulation with OH:NCO ratio 1:1.2 was optimized. An independent study was carried out employing the mechanical test like cross-cut tape test was carried out to evaluate th paint properties. Morphological and structural studies like FTIR, SEM, HNMR were carried out with the paint formulation. Thermal property studies like TGA, DSC were carried out with the paint. Gloss, weather resistance of the paint was evaluated.","PeriodicalId":22035,"journal":{"name":"Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72579308","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 : 2022-01-24DOI: 10.36303/satnt.2021cosaami.44
L. Ranganya, N. Moshokoa, B. Obadele, E. Makhatha, R. Machaka
The effect of Nb in the glue site of the cluster-plus-glue atom model formula on the microstructure and mechanical properties of Ti-Mo alloy was investigated. Phase and microstructural analysis were performed by X-ray diffraction and electron backscatter diffraction. Tensile properties were also examined. A small amount of secondary martensitic α” and ωath nano particles were precipitated in the β matrix of both alloys, due to to the inhomogeneous distribution of Mo and/ or Nb caused by segregation, which formed local regions with high- and low-stability of the β phase. The elastic modulus was significantly reduced to 56.9 ± 3.08 GPa, while the elastic admissible strain was substantially improved. The increased β stability and suppression of the ωath phase led to no significant change in both the yield and ultimate tensile strengths, and the brittle fracture behavior. The alloy can be a potential alternative of the conventional orthopedic implant materials in orthopedic applications.
{"title":"Effect of Nb glue atom in the cluster formula on the microstructure and mechanical properties of Ti-Mo alloy","authors":"L. Ranganya, N. Moshokoa, B. Obadele, E. Makhatha, R. Machaka","doi":"10.36303/satnt.2021cosaami.44","DOIUrl":"https://doi.org/10.36303/satnt.2021cosaami.44","url":null,"abstract":"The effect of Nb in the glue site of the cluster-plus-glue atom model formula on the microstructure and mechanical properties of Ti-Mo alloy was investigated. Phase and microstructural analysis were performed by X-ray diffraction and electron backscatter diffraction. Tensile properties were also examined. A small amount of secondary martensitic α” and ωath nano particles were precipitated in the β matrix of both alloys, due to to the inhomogeneous distribution of Mo and/ or Nb caused by segregation, which formed local regions with high- and low-stability of the β phase. The elastic modulus was significantly reduced to 56.9 ± 3.08 GPa, while the elastic admissible strain was substantially improved. The increased β stability and suppression of the ωath phase led to no significant change in both the yield and ultimate tensile strengths, and the brittle fracture behavior. The alloy can be a potential alternative of the conventional orthopedic implant materials in orthopedic applications.","PeriodicalId":22035,"journal":{"name":"Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80721413","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 : 2022-01-24DOI: 10.36303/satnt.2021cosaami.16
H. Bissett, M. Makhofane, S. Lötter
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. In 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.
增材制造(AM)方法可用于制造用于医疗植入物的复杂定制Ti6Al4V组件。骨-种植体界面感染是引起种植体排斥反应的重要原因。先进的钛植入物具有生物相容性和抗菌性能，可以通过用铜修饰钛合金来制造，铜在低浓度(< 1 at %铜)是一种经过验证的无毒抗菌剂。在增材制造过程中，铜可以嵌入到钛植入物中，从而产生抗菌功能。为了生产足够细的金属铜粉，氧化铜可以通过化学还原或热处理方法进行还原。这些包括热分解或氧化物在高温反应气体存在下的还原。利用热等离子体还原等热处理方法，可以调整工艺条件来控制粉末的形貌和平均粒度。本研究的目的是利用Necsa的Tek-15射频电感耦合热等离子体系统，研究铜氧化物的热等离子体还原为铜金属。在有氢存在的情况下，黑色氧化铜(II)粉末转化为暗红色粉末，而在没有氢存在的情况下，得到黄色/橙色粉末。通过SEM-EDS和XRD分析证实了其成分的变化。
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