Sarah. H. Abead, Khaldoon N. Abbas, Mahasin F. Hadi Al-kadhemy
Polyvinyl alcohol (PVA)/Carboxymethyl cellulose (CMC) blend films with equal amounts (0.25 g) of both polymers were prepared via a simple and low-cost comparative casting method. Then, the PVA/CMC blend films were exposed to UV-irradiation for varied time intervals (1, 12, 26, 32, 40, and 48 h). The UV-irradiations effect on the physical properties of as-prepared films including the structure, morphology, composite and optical properties (transmittance, absorbance, and band-gap (Eg)) was examined. FESEM images display that UV-irradiation has a strong effect on the shape of PVA/CMC blend films. The XRD patterns show various crystalline qualities in the microstructure of as-synthesis samples. The FTIR spectra demonstrate that UV-irradiation time and CMC film had a positive impact on the blend polymer structure since covalent connections were formed between CMC and PVA. Furthermore, the analysis results of optical inspections show the absorbance of the PVA/CMC films was improved with an increment of irradiation times from (1 to 40 h). An important tunning of Eg values of blend films was realized. It shows a slightly increased from (4.64 eV to 4.84 eV) with increasing irradiation time from (1 to 40 h). The Eg value (3.21 eV), however, displayed an inverted behaviour due to an increased irradiation time of 48 h, this reduction can be ascribed to the creation of defects inside the blend band gap. Finally, the physical properties modification of PVA/CMC blend films using UV-Irradiation makes it an amazing contender in the optoelectronic area.
{"title":"The structural and optical properties of PVA/CMC copolymer cured by UV-irradiation at different times","authors":"Sarah. H. Abead, Khaldoon N. Abbas, Mahasin F. Hadi Al-kadhemy","doi":"10.1680/jemmr.22.00150","DOIUrl":"https://doi.org/10.1680/jemmr.22.00150","url":null,"abstract":"Polyvinyl alcohol (PVA)/Carboxymethyl cellulose (CMC) blend films with equal amounts (0.25 g) of both polymers were prepared via a simple and low-cost comparative casting method. Then, the PVA/CMC blend films were exposed to UV-irradiation for varied time intervals (1, 12, 26, 32, 40, and 48 h). The UV-irradiations effect on the physical properties of as-prepared films including the structure, morphology, composite and optical properties (transmittance, absorbance, and band-gap (Eg)) was examined. FESEM images display that UV-irradiation has a strong effect on the shape of PVA/CMC blend films. The XRD patterns show various crystalline qualities in the microstructure of as-synthesis samples. The FTIR spectra demonstrate that UV-irradiation time and CMC film had a positive impact on the blend polymer structure since covalent connections were formed between CMC and PVA. Furthermore, the analysis results of optical inspections show the absorbance of the PVA/CMC films was improved with an increment of irradiation times from (1 to 40 h). An important tunning of Eg values of blend films was realized. It shows a slightly increased from (4.64 eV to 4.84 eV) with increasing irradiation time from (1 to 40 h). The Eg value (3.21 eV), however, displayed an inverted behaviour due to an increased irradiation time of 48 h, this reduction can be ascribed to the creation of defects inside the blend band gap. Finally, the physical properties modification of PVA/CMC blend films using UV-Irradiation makes it an amazing contender in the optoelectronic area.","PeriodicalId":11537,"journal":{"name":"Emerging Materials Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138609214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Present experimental study aims to scrutinize the effect of different process parameters on material removal rate (MRR) and surface roughness (SR) of titanium grade 12 alloy during wire electro discharge machining (WEDM) using response surface methodology (RSM). Four parameters (pulse on time, pulse off time, wire feed, and gap voltage) and three levels of each selected variables are considered to conduct the experimental work. Depending on experimental results, mathematical model is generated for both MRR and SR. Analysis of variance (ANOVA) study is performed to find significant process parameters. ANOVA results yield that developed models for both MRR and SR are significant and pulse-on time is found to be the most significant parameter. Additionally, help of desirability approach is also taken to scrutinize single-objective and multi-objective criterion of response variables. Desirability function for all the cases are found to be 1. Maximum material removal rate is observed as 12.4845 mm3/sec while minimum value of surface roughness is found as 1.4911 μm. For multi-objective optimization, maximum value of MRR and minimum value of surface roughness are obtained as 12.0942 mm3/min and 1.7167 μm respectively. Finally, surface morphology of machined surfaces is examined using SEM micrographs.
{"title":"Parametric study of WEDM on titanium grade 12 using response surface methodology and desirability approach","authors":"Debal Pramanik, B. Panja, Sudip Banerjee","doi":"10.1680/jemmr.22.00192","DOIUrl":"https://doi.org/10.1680/jemmr.22.00192","url":null,"abstract":"Present experimental study aims to scrutinize the effect of different process parameters on material removal rate (MRR) and surface roughness (SR) of titanium grade 12 alloy during wire electro discharge machining (WEDM) using response surface methodology (RSM). Four parameters (pulse on time, pulse off time, wire feed, and gap voltage) and three levels of each selected variables are considered to conduct the experimental work. Depending on experimental results, mathematical model is generated for both MRR and SR. Analysis of variance (ANOVA) study is performed to find significant process parameters. ANOVA results yield that developed models for both MRR and SR are significant and pulse-on time is found to be the most significant parameter. Additionally, help of desirability approach is also taken to scrutinize single-objective and multi-objective criterion of response variables. Desirability function for all the cases are found to be 1. Maximum material removal rate is observed as 12.4845 mm3/sec while minimum value of surface roughness is found as 1.4911 μm. For multi-objective optimization, maximum value of MRR and minimum value of surface roughness are obtained as 12.0942 mm3/min and 1.7167 μm respectively. Finally, surface morphology of machined surfaces is examined using SEM micrographs.","PeriodicalId":11537,"journal":{"name":"Emerging Materials Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138615883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jing Xia, Yuan Gao, Shuxiang Li, Dakui Zhang, Keliang Pang
Mesophase pitch based graphite foams have attracted an increasing attention because of their broad applications in thermal management, catalysis and so on. However, the common approach of high pressure method to fabricate graphite foams is complex and risky. Herein, the research reports a simple and relatively safe technique for preparation of mesophase pitch based graphite foams, which is conducted under atmospheric pressure.Through foaming of mesophase pitch in the presence of epoxy resin at 700°C under atmospheric pressure and graphitization at 3000°C, the graphite foam is fabricated.The obtained graphite foam is highly graphitic and has an open pore structure, the interlayer spacing of the (002) plane of which is about 0.3366 nm. Its density is 0.52 g/cm3 with a porosity of 73.5%. The properties of graphite foams can be tailored by pitch particle sizes and foaming temperatures. With the increase of pitch particle sizes from <25 to 75-150 μm or foaming temperatures from 400 to 850°C, the pore sizes vary from 10-25 μm to 35-90 μm, and their bulk densities change from 0.50 to 1.11 g/cm3. Also, a foaming mechanism is proposed that the residue of epoxy resin can form a framework during heating, in which the pitch softens and decomposes forming the foam. This study suggests a relatively simple and safe method for production of graphite foams from the mesophase pitch.
{"title":"Preparation of mesophase pitch based graphite foams at atmospheric pressure","authors":"Jing Xia, Yuan Gao, Shuxiang Li, Dakui Zhang, Keliang Pang","doi":"10.1680/jemmr.23.00037","DOIUrl":"https://doi.org/10.1680/jemmr.23.00037","url":null,"abstract":"Mesophase pitch based graphite foams have attracted an increasing attention because of their broad applications in thermal management, catalysis and so on. However, the common approach of high pressure method to fabricate graphite foams is complex and risky. Herein, the research reports a simple and relatively safe technique for preparation of mesophase pitch based graphite foams, which is conducted under atmospheric pressure.Through foaming of mesophase pitch in the presence of epoxy resin at 700°C under atmospheric pressure and graphitization at 3000°C, the graphite foam is fabricated.The obtained graphite foam is highly graphitic and has an open pore structure, the interlayer spacing of the (002) plane of which is about 0.3366 nm. Its density is 0.52 g/cm3 with a porosity of 73.5%. The properties of graphite foams can be tailored by pitch particle sizes and foaming temperatures. With the increase of pitch particle sizes from <25 to 75-150 μm or foaming temperatures from 400 to 850°C, the pore sizes vary from 10-25 μm to 35-90 μm, and their bulk densities change from 0.50 to 1.11 g/cm3. Also, a foaming mechanism is proposed that the residue of epoxy resin can form a framework during heating, in which the pitch softens and decomposes forming the foam. This study suggests a relatively simple and safe method for production of graphite foams from the mesophase pitch.","PeriodicalId":11537,"journal":{"name":"Emerging Materials Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139021263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mine Kırkbınar, Erhan İbrahimoğlu, S. Yetgin, Fatih Çalışkan
PMMA, a thermoplastic polymer, is widely used in biomedical applications like bone cement. However, it is known to have low wear resistance. To enhance its tribological behavior, a reinforcement phase is necessary. For this purpose, in this study, homemade hydroxyapatite (HAp) was utilized to enhance the mechanical properties and wear resistance of PMMA, while also increasing its biocompatibility. The HAp was reinforced into the PMMA matrix to enable its use under load. Using the thermal extraction method, natural raw materials were used to successfully synthesize homemade HAp powder. The powder's elemental composition was determined using an X-ray fluorescence spectrometer (XRF). The d0.5 of HAp powders in particle size analysis was 7.464 µm. Hot isostatic pressing was used to create PMMA-HAp biocomposites with various HAp rates (5%, 10%, and 15% wt.) in the PMMA (HIP). The wear morphology was characterized by scanning electron microscopy (SEM). The SEM images showed a severe abrasive wear mechanism, but a relatively stable wear surface was observed that indicated slight abrasion during the wear tests with the increase of HAp ratio. The wear tests were carried out with a ball-on-disc system under dry environment conditions at sliding speed between 0.5-1.0 m/s and loads of 10-20-30 N. The highest wear rate was obtained in 15% HAp reinforced PMMA with a sliding speed of 1.0 m/s and value of 4.72x10-4 mm3/Nm under 20 N load. The HIPed densities of the samples increased from 1.15 to 1.31 g/cm3 with increasing the amount of HAp. Similarly, the Vickers test results showed that the hardness values increased from 14.76 Hv to 22.03 Hv.
{"title":"Investigation on tribological behaviour of poly (methyl methacrylate) biocomposite containing hydroxyapatite","authors":"Mine Kırkbınar, Erhan İbrahimoğlu, S. Yetgin, Fatih Çalışkan","doi":"10.1680/jemmr.23.00039","DOIUrl":"https://doi.org/10.1680/jemmr.23.00039","url":null,"abstract":"PMMA, a thermoplastic polymer, is widely used in biomedical applications like bone cement. However, it is known to have low wear resistance. To enhance its tribological behavior, a reinforcement phase is necessary. For this purpose, in this study, homemade hydroxyapatite (HAp) was utilized to enhance the mechanical properties and wear resistance of PMMA, while also increasing its biocompatibility. The HAp was reinforced into the PMMA matrix to enable its use under load. Using the thermal extraction method, natural raw materials were used to successfully synthesize homemade HAp powder. The powder's elemental composition was determined using an X-ray fluorescence spectrometer (XRF). The d0.5 of HAp powders in particle size analysis was 7.464 µm. Hot isostatic pressing was used to create PMMA-HAp biocomposites with various HAp rates (5%, 10%, and 15% wt.) in the PMMA (HIP). The wear morphology was characterized by scanning electron microscopy (SEM). The SEM images showed a severe abrasive wear mechanism, but a relatively stable wear surface was observed that indicated slight abrasion during the wear tests with the increase of HAp ratio. The wear tests were carried out with a ball-on-disc system under dry environment conditions at sliding speed between 0.5-1.0 m/s and loads of 10-20-30 N. The highest wear rate was obtained in 15% HAp reinforced PMMA with a sliding speed of 1.0 m/s and value of 4.72x10-4 mm3/Nm under 20 N load. The HIPed densities of the samples increased from 1.15 to 1.31 g/cm3 with increasing the amount of HAp. Similarly, the Vickers test results showed that the hardness values increased from 14.76 Hv to 22.03 Hv.","PeriodicalId":11537,"journal":{"name":"Emerging Materials Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138620760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mineral additives are preferred to improve the physical, mechanical and durability properties of cement-based composites and to reduce the use of cement in order to prevent environmental pollution and high production costs. Within the scope of this study, a new pozzolanic material, Ground Profillite Powder (GPP), was evaluated by comparing it with Granular Ground Blast Furnace Slag (GGBFS), and it was used as a substitution with cement at rates of 5%, 10% and 15% by weight. The effects of these two mineral additives on the mechanical and physical properties of mortars and their resistance to Sulfuric Acid (SA) were investigated. In the production of the mortar samples, CEM I 42.5/R type Portland Cement (OPC) was used as the binder, and 0-4 mm crushed sand was used as the aggregate. Mineral additive and non-additive mortars produced in the laboratory environment in dimensions of 40x40x160 mm; spreading values, bending and compressive strengths, water absorption and porosity values and weight and strength loss values under the effect of SA were examined comparatively. It was determined that the mortar samples produced using GPP showed higher resistance to SA attacks than the pure and GGBFS added mortars, reducing weight losses up to 21% and compressive strength losses up to 30%.
为了改善水泥基复合材料的物理、机械和耐久性，减少水泥的使用，防止环境污染和生产成本高，矿物添加剂是首选。在本研究范围内，通过将一种新型火山灰材料——磨碎型铝粉(GPP)与颗粒状磨碎高炉渣(GGBFS)进行比较，对其进行了评价，并以5%、10%和15%的重量比例替代水泥。研究了这两种矿物添加剂对砂浆力学、物理性能及抗硫酸性能的影响。在砂浆样品的制作中，采用CEM I 42.5/R型波特兰水泥(OPC)作为粘结剂，0-4 mm碎砂作为骨料。实验室环境下生产的尺寸为40x40x160 mm的矿物添加剂和非添加剂砂浆;对SA作用下的拉伸值、弯曲强度和抗压强度、吸水率和孔隙率以及重量和强度损失值进行了比较研究。经测定，使用GPP生产的砂浆样品比纯和添加GGBFS的砂浆具有更高的抗SA攻击能力，可减少高达21%的重量损失和高达30%的抗压强度损失。
{"title":"An experimental study on the sulfuric acid resistance of mineral additive mortars","authors":"Cebrail Kaplan, Behçet Dündar, Emriye Çınar Resuloğulları","doi":"10.1680/jemmr.23.00001","DOIUrl":"https://doi.org/10.1680/jemmr.23.00001","url":null,"abstract":"Mineral additives are preferred to improve the physical, mechanical and durability properties of cement-based composites and to reduce the use of cement in order to prevent environmental pollution and high production costs. Within the scope of this study, a new pozzolanic material, Ground Profillite Powder (GPP), was evaluated by comparing it with Granular Ground Blast Furnace Slag (GGBFS), and it was used as a substitution with cement at rates of 5%, 10% and 15% by weight. The effects of these two mineral additives on the mechanical and physical properties of mortars and their resistance to Sulfuric Acid (SA) were investigated. In the production of the mortar samples, CEM I 42.5/R type Portland Cement (OPC) was used as the binder, and 0-4 mm crushed sand was used as the aggregate. Mineral additive and non-additive mortars produced in the laboratory environment in dimensions of 40x40x160 mm; spreading values, bending and compressive strengths, water absorption and porosity values and weight and strength loss values under the effect of SA were examined comparatively. It was determined that the mortar samples produced using GPP showed higher resistance to SA attacks than the pure and GGBFS added mortars, reducing weight losses up to 21% and compressive strength losses up to 30%.","PeriodicalId":11537,"journal":{"name":"Emerging Materials Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138608932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Sasidharan, C. Rajendran, Tushar Sonar, Mikhail Ivanov
The advanced variant of gas metal arc welding (GMAW) known as cold metal transfer (CMT) developed by Fronius in Austria is used to overcome the heat input and fusion related issues such as porosity and cracking in welding of AA8011-H18 alloy sheets. The 3 mm thick sheets of AA8011-H18 alloy were welded using normal CMT-GMAW and pulsed CMT (PCMT-GMAW) processes. The microstructure of weld metal (WM) and heat affected zone (HAZ) was analysed using optical microscope. The tensile properties and hardness of joints were evaluated and compared. Results revealed that the PCMT-GMAW joints showed 26.45%, 48.97% and 40.42% improvement in tensile strength, yield strength and elongation compared to CMT-GMAW joints. The superior tensile performance of PCMT-GMAW joints compared to CMT-GMAW joints is due to the current pulsing effects along with wire retraction mechanism which aids in reducing the heat input and controlled droplet transfer.
{"title":"Investigation on tensile strength of CMT and P-CMT joints of AA8011 aluminum alloy","authors":"R. Sasidharan, C. Rajendran, Tushar Sonar, Mikhail Ivanov","doi":"10.1680/jemmr.23.00102","DOIUrl":"https://doi.org/10.1680/jemmr.23.00102","url":null,"abstract":"The advanced variant of gas metal arc welding (GMAW) known as cold metal transfer (CMT) developed by Fronius in Austria is used to overcome the heat input and fusion related issues such as porosity and cracking in welding of AA8011-H18 alloy sheets. The 3 mm thick sheets of AA8011-H18 alloy were welded using normal CMT-GMAW and pulsed CMT (PCMT-GMAW) processes. The microstructure of weld metal (WM) and heat affected zone (HAZ) was analysed using optical microscope. The tensile properties and hardness of joints were evaluated and compared. Results revealed that the PCMT-GMAW joints showed 26.45%, 48.97% and 40.42% improvement in tensile strength, yield strength and elongation compared to CMT-GMAW joints. The superior tensile performance of PCMT-GMAW joints compared to CMT-GMAW joints is due to the current pulsing effects along with wire retraction mechanism which aids in reducing the heat input and controlled droplet transfer.","PeriodicalId":11537,"journal":{"name":"Emerging Materials Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138617283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Babak Mousavi, Mohammad Farvizi, Ali Shamsipoor, Mohammad Reza Rahimipour, Ahmad Keyvani
In this research, a NiCrAlY bond coat was applied using two methods – namely, conventional air plasma spraying (APS) and new spark plasma sintering (SPS) technique – on an Inconel-738 substrate. The ceria-stabilized zirconia (CSZ) topcoat was similar in both samples and deposited using the APS method. The hot corrosion performance of the fabricated thermal barrier coatings (TBCs) was studied at 950°C in a sodium sulfate (Na2SO4)–55 wt.% vanadium (V) oxide (V2O5) corrosive salt environment. The results showed that the hot corrosion resistance of the coating system with an SPS-processed NiCrAlY bond coat and a CSZ topcoat was much better than that of the conventional TBC sample because the adhesion of the bond coat to the substrate was very good in this sample, and the interface was free of any defects such as cracks and porosities. According to these results, no spallation was observed in the SPS-processed coating up to 38 h, while for the CSZ topcoat with an APS-processed bond coat, spallation occurred after 24 h.
{"title":"Role of bond coat deposition method in the hot corrosion behavior of CSZ thermal barrier coatings","authors":"Babak Mousavi, Mohammad Farvizi, Ali Shamsipoor, Mohammad Reza Rahimipour, Ahmad Keyvani","doi":"10.1680/jemmr.22.00187","DOIUrl":"https://doi.org/10.1680/jemmr.22.00187","url":null,"abstract":"In this research, a NiCrAlY bond coat was applied using two methods – namely, conventional air plasma spraying (APS) and new spark plasma sintering (SPS) technique – on an Inconel-738 substrate. The ceria-stabilized zirconia (CSZ) topcoat was similar in both samples and deposited using the APS method. The hot corrosion performance of the fabricated thermal barrier coatings (TBCs) was studied at 950°C in a sodium sulfate (Na<sub>2</sub>SO<sub>4</sub>)–55 wt.% vanadium (V) oxide (V<sub>2</sub>O<sub>5</sub>) corrosive salt environment. The results showed that the hot corrosion resistance of the coating system with an SPS-processed NiCrAlY bond coat and a CSZ topcoat was much better than that of the conventional TBC sample because the adhesion of the bond coat to the substrate was very good in this sample, and the interface was free of any defects such as cracks and porosities. According to these results, no spallation was observed in the SPS-processed coating up to 38 h, while for the CSZ topcoat with an APS-processed bond coat, spallation occurred after 24 h.","PeriodicalId":11537,"journal":{"name":"Emerging Materials Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138528412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Enzyme-induced calcium carbonate precipitation (EICP) through the urea hydrolysis pathway has been widely studied for various applications. The EICP solution comprises urea, a calcium source (usually calcium chloride) and the enzyme urease. This study addressed the effect of the chemical concentration of the EICP solution on the morphology of the calcium carbonate product. This was achieved by varying the concentration of urea–calcium chloride and urease activity. The duration of the reaction was the third variable. The precipitation efficiency and the interface shearing resistance were reported. Precipitation efficiency decreased as the concentration of urea–calcium chloride reached beyond 0.75 mol/l. The calcium carbonate polymorph was predominantly calcite. Its crystal size and shape did, however, vary, depending on the precipitation conditions. The findings showed that the urease activity promoted the formation of rhombohedral calcite in the presence of adequate calcium ions and urea. Spherical calcite was formed when the urease activity was further increased. The morphology of calcite evolved from a single, uniform, smooth spherical crystal to a polycrystalline formation with orthorhombic protrusions. The crystals tended to grow as the reaction time increased, resulting in aggregation, when the urease levels crossed 30 kU/l. It was noted that spherical crystals exhibited stronger interface shearing resistance than rhombohedral crystals.
{"title":"Impact of solution chemistry on morphology of enzyme-induced calcium carbonate precipitate","authors":"Aishwarya Thirumalairaju, Ashish Juneja","doi":"10.1680/jemmr.23.00022","DOIUrl":"https://doi.org/10.1680/jemmr.23.00022","url":null,"abstract":"Enzyme-induced calcium carbonate precipitation (EICP) through the urea hydrolysis pathway has been widely studied for various applications. The EICP solution comprises urea, a calcium source (usually calcium chloride) and the enzyme urease. This study addressed the effect of the chemical concentration of the EICP solution on the morphology of the calcium carbonate product. This was achieved by varying the concentration of urea–calcium chloride and urease activity. The duration of the reaction was the third variable. The precipitation efficiency and the interface shearing resistance were reported. Precipitation efficiency decreased as the concentration of urea–calcium chloride reached beyond 0.75 mol/l. The calcium carbonate polymorph was predominantly calcite. Its crystal size and shape did, however, vary, depending on the precipitation conditions. The findings showed that the urease activity promoted the formation of rhombohedral calcite in the presence of adequate calcium ions and urea. Spherical calcite was formed when the urease activity was further increased. The morphology of calcite evolved from a single, uniform, smooth spherical crystal to a polycrystalline formation with orthorhombic protrusions. The crystals tended to grow as the reaction time increased, resulting in aggregation, when the urease levels crossed 30 kU/l. It was noted that spherical crystals exhibited stronger interface shearing resistance than rhombohedral crystals.","PeriodicalId":11537,"journal":{"name":"Emerging Materials Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138528408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The production of graphene oxide by the electrochemical method is more environmentally friendly, faster and suitable for mass production than the chemical method. Although this technique is very practical, the correct parameters must be selected to produce graphene oxide. Therefore, it is very important to investigate the factors affecting graphene oxide synthesis in the electrochemical process. In this study, the effect of pretreatment on graphene oxide produced by the electrochemical method was investigated. Structural characterization of the produced graphene oxide was carried out using X-ray diffraction, Raman spectroscopy and energy-dispersive X-ray spectroscopy, while morphological research was performed using scanning electron microscopy. Due to the increase in the electrochemical oxidation performance of dilute nitric acid with the effect of the pretreatment process, an effective increase in the oxygen content in the structure of graphene oxide was detected.
{"title":"Pretreatment impact on electrochemically synthesized graphene oxide","authors":"Tamer Güzel","doi":"10.1680/jemmr.23.00011","DOIUrl":"https://doi.org/10.1680/jemmr.23.00011","url":null,"abstract":"The production of graphene oxide by the electrochemical method is more environmentally friendly, faster and suitable for mass production than the chemical method. Although this technique is very practical, the correct parameters must be selected to produce graphene oxide. Therefore, it is very important to investigate the factors affecting graphene oxide synthesis in the electrochemical process. In this study, the effect of pretreatment on graphene oxide produced by the electrochemical method was investigated. Structural characterization of the produced graphene oxide was carried out using X-ray diffraction, Raman spectroscopy and energy-dispersive X-ray spectroscopy, while morphological research was performed using scanning electron microscopy. Due to the increase in the electrochemical oxidation performance of dilute nitric acid with the effect of the pretreatment process, an effective increase in the oxygen content in the structure of graphene oxide was detected.","PeriodicalId":11537,"journal":{"name":"Emerging Materials Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138528413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper highlights the engineering behavior of an expanded-polystyrene (EPS)-bead-based fly ash geomaterial (FAGM). The proposed geomaterial was prepared by blending EPS beads of different densities and fly ash contents with cement as a binding agent. The effects of three different EPS bead densities (25, 30 and 35 kg/m3), four EPS mix ratios (0.5–2.0%) and two cement contents (15 and 20%) on density, compressive strength at three different curing periods, 7, 28 and 90 days; and elasticity modulus were studied. It was concluded that the behavior of FAGM prepared with low-density and low-content EPS is analogous to that of FAGM prepared with high-density and high-content EPS. To evaluate the performance of FAGM as a lightweight and strong material, an empirical ratio of strength to density is defined. FAGM with low-density and high-content EPS can be used as an efficient lightweight filling material, whereas FAGM with high-density and low-content EPS can be used as a strong filling material. Moreover, the geomaterial, which is mainly formed from a freely available industrial byproduct, can be strongly used as a replacement for EPS geofoam blocks.
{"title":"Engineering performance of lightweight geomaterial influenced by EPS density and mix ratio","authors":"Anupam Yogendra Pande, Amit Harihar Padade","doi":"10.1680/jemmr.23.00041","DOIUrl":"https://doi.org/10.1680/jemmr.23.00041","url":null,"abstract":"This paper highlights the engineering behavior of an expanded-polystyrene (EPS)-bead-based fly ash geomaterial (FAGM). The proposed geomaterial was prepared by blending EPS beads of different densities and fly ash contents with cement as a binding agent. The effects of three different EPS bead densities (25, 30 and 35 kg/m<sup>3</sup>), four EPS mix ratios (0.5–2.0%) and two cement contents (15 and 20%) on density, compressive strength at three different curing periods, 7, 28 and 90 days; and elasticity modulus were studied. It was concluded that the behavior of FAGM prepared with low-density and low-content EPS is analogous to that of FAGM prepared with high-density and high-content EPS. To evaluate the performance of FAGM as a lightweight and strong material, an empirical ratio of strength to density is defined. FAGM with low-density and high-content EPS can be used as an efficient lightweight filling material, whereas FAGM with high-density and low-content EPS can be used as a strong filling material. Moreover, the geomaterial, which is mainly formed from a freely available industrial byproduct, can be strongly used as a replacement for EPS geofoam blocks.","PeriodicalId":11537,"journal":{"name":"Emerging Materials Research","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138528435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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