A. Ganda, Diah Wulandari, Firman Yasa Utama, W. Warju, Dyah Riandadari, Dewi Puspitasari, Lena Citra Manggalasari
Cassava starch bioplastics have been known well as an alternative plastic replacing conventional petrochemical plastics, which have difficulty degrading rapidly in the environment. Cassava peels as waste is a potential eco-friendly starch source for biodegradable plastic. This study investigated the effect of graphene as a nanofiller on the hydrophobic properties of cassava peel starch film. Bioplastic was synthesized using the melt blending method by adding graphene in various amounts, which were 3 wt%, 5 wt%, and 7 wt%. Graphene was found to be able to increase the contact angle of the films up to 93° with the addition of 5 wt%. Graphene also affects water absorption properties. These results indicate that the hydrophobic properties of cassava peel starch films could be modified by adding graphene nanofiller.
{"title":"Incorporating Graphene Nanofiller for the Improvement of Hydrophobic Properties of Cassava Peel Starch Bioplastic","authors":"A. Ganda, Diah Wulandari, Firman Yasa Utama, W. Warju, Dyah Riandadari, Dewi Puspitasari, Lena Citra Manggalasari","doi":"10.4028/p-9fcqbm","DOIUrl":"https://doi.org/10.4028/p-9fcqbm","url":null,"abstract":"Cassava starch bioplastics have been known well as an alternative plastic replacing conventional petrochemical plastics, which have difficulty degrading rapidly in the environment. Cassava peels as waste is a potential eco-friendly starch source for biodegradable plastic. This study investigated the effect of graphene as a nanofiller on the hydrophobic properties of cassava peel starch film. Bioplastic was synthesized using the melt blending method by adding graphene in various amounts, which were 3 wt%, 5 wt%, and 7 wt%. Graphene was found to be able to increase the contact angle of the films up to 93° with the addition of 5 wt%. Graphene also affects water absorption properties. These results indicate that the hydrophobic properties of cassava peel starch films could be modified by adding graphene nanofiller.","PeriodicalId":18262,"journal":{"name":"Materials Science Forum","volume":"32 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141113599","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}
Teguh Suprianto, Muhammad Kasim, Akbar Ela Heka, D. Darmansyah
Wood waste biomass has emerged as an abundant source of alternative energy. This alternative energy source holds significant potential in the industrial sector, particularly in the field of metal casting. The development of aluminum melting equipment aims to provide invaluable support to aluminum craftsmen by harnessing wood waste as an easily accessible fuel source. The approach employed in this research involves the design of a wood waste combustion chamber capable of reaching the aluminum melting point. Two types of wood, Ulin (Eusideroxylon zwageri) and Gelam (Melaleuca cajuputi), were utilized in the study. The research achieved a temperature of 863°C in 28 minutes with Ulin wood, whereas with Gelam, a temperature of 821°C was reached in 29 minutes. This study makes a significant contribution to the efficient utilization of wood waste biomass in the aluminum casting industry, offering remarkable environmental and economic benefits.
{"title":"Optimizing Aluminum Melting with Sustainable Biomass Fuels: A Case Study of Ulin (Eusideroxylon zwageri) Wood and Galam (Melaleuca cajuputi) Wood","authors":"Teguh Suprianto, Muhammad Kasim, Akbar Ela Heka, D. Darmansyah","doi":"10.4028/p-j1jl2n","DOIUrl":"https://doi.org/10.4028/p-j1jl2n","url":null,"abstract":"Wood waste biomass has emerged as an abundant source of alternative energy. This alternative energy source holds significant potential in the industrial sector, particularly in the field of metal casting. The development of aluminum melting equipment aims to provide invaluable support to aluminum craftsmen by harnessing wood waste as an easily accessible fuel source. The approach employed in this research involves the design of a wood waste combustion chamber capable of reaching the aluminum melting point. Two types of wood, Ulin (Eusideroxylon zwageri) and Gelam (Melaleuca cajuputi), were utilized in the study. The research achieved a temperature of 863°C in 28 minutes with Ulin wood, whereas with Gelam, a temperature of 821°C was reached in 29 minutes. This study makes a significant contribution to the efficient utilization of wood waste biomass in the aluminum casting industry, offering remarkable environmental and economic benefits.","PeriodicalId":18262,"journal":{"name":"Materials Science Forum","volume":"20 17","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141118697","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}
Tsuyoshi Takahashi, Son Thanh Nguyen, Masaaki Kimura
In this study, the Al2O3 round bar and Al-Si12CuNi (AC8A) round bar were joined by friction welding. AC8A is a typical piston material treated by the heat treatment T6. The parameters of the joining condition are friction time and upset pressure. SEM observed the microstructure at the interface region of joined materials. 1) Judging from these photographs, the damages to the microstructures at the interface region of joined materials by upset pressure are more significant than those caused by friction time. 2) The relationship between the joint conditions and mechanical characteristics from three points of bending test results for the joint material specimens. 3) The residual stresses around the interface were measured by the Raman spectroscopy method. There is a possibility that the friction welding conditions are correlated to the residual stresses.
{"title":"Microstructure and Mechanical Characteristics of Friction Welded Joint between Alumina and Aluminum Casting Alloy","authors":"Tsuyoshi Takahashi, Son Thanh Nguyen, Masaaki Kimura","doi":"10.4028/p-9esrhc","DOIUrl":"https://doi.org/10.4028/p-9esrhc","url":null,"abstract":"In this study, the Al2O3 round bar and Al-Si12CuNi (AC8A) round bar were joined by friction welding. AC8A is a typical piston material treated by the heat treatment T6. The parameters of the joining condition are friction time and upset pressure. SEM observed the microstructure at the interface region of joined materials. 1) Judging from these photographs, the damages to the microstructures at the interface region of joined materials by upset pressure are more significant than those caused by friction time. 2) The relationship between the joint conditions and mechanical characteristics from three points of bending test results for the joint material specimens. 3) The residual stresses around the interface were measured by the Raman spectroscopy method. There is a possibility that the friction welding conditions are correlated to the residual stresses.","PeriodicalId":18262,"journal":{"name":"Materials Science Forum","volume":"38 21","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141113708","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}
{"title":"Advanced Materials and Materials Application","authors":"F. Gapsari, Bruno Castanie, Ramesh K. Agarwal","doi":"10.4028/b-uliu8t","DOIUrl":"https://doi.org/10.4028/b-uliu8t","url":null,"abstract":"","PeriodicalId":18262,"journal":{"name":"Materials Science Forum","volume":"31 19","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141118120","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}
Cahyo Hadi Wibowo, D. Ariawan, E. Surojo, Sunardi Sunardi
In order to enhance diverse composites and foster sustainable development, it is essential to use strategic measures. Microcrystalline cellulose (MCC) has the desirable characteristics of being both renewable and biodegradable. The characteristics above provide MCC with a favorable option for enhancing the structural integrity of composite materials. This study examines the literature on using MCC as a composite reinforcement to identify its primary characteristics. This evaluation explores the properties and potential future advancements of the naturally derived materials under investigation. This work comprehensively reviews scientific publications to guide future research efforts. Based on empirical investigations, using MCC as a composite reinforcement has enhanced various mechanical and tribological characteristics. This study provides a comprehensive reference for implementing sustainable MCC as a composite reinforcement.
{"title":"Microcrystalline Cellulose as Composite Reinforcement: Assessment and Future Prospects","authors":"Cahyo Hadi Wibowo, D. Ariawan, E. Surojo, Sunardi Sunardi","doi":"10.4028/p-viyb6d","DOIUrl":"https://doi.org/10.4028/p-viyb6d","url":null,"abstract":"In order to enhance diverse composites and foster sustainable development, it is essential to use strategic measures. Microcrystalline cellulose (MCC) has the desirable characteristics of being both renewable and biodegradable. The characteristics above provide MCC with a favorable option for enhancing the structural integrity of composite materials. This study examines the literature on using MCC as a composite reinforcement to identify its primary characteristics. This evaluation explores the properties and potential future advancements of the naturally derived materials under investigation. This work comprehensively reviews scientific publications to guide future research efforts. Based on empirical investigations, using MCC as a composite reinforcement has enhanced various mechanical and tribological characteristics. This study provides a comprehensive reference for implementing sustainable MCC as a composite reinforcement.","PeriodicalId":18262,"journal":{"name":"Materials Science Forum","volume":"43 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141117367","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}
Alexandre Pereira Dall'Oglio, W. Haupt, K. Riffel, R. H. Gonçalves e Silva
Superduplex stainless steels have great mechanical and corrosion properties. However, its chemical composition makes it prone to intermetallic phase precipitation during thermal processing. Sigma (σ), chi (χ), and chromium nitrides (Cr2N) remove Cr and Mo from the matrix, reducing the corrosion and mechanical resistance. Understanding the effects of thermal processing on the secondary phase’s precipitation and depletion of the material’s performance is crucial to its applications. Thus, this work aims to analyze the behavior of the corrosion performance of the UNS S32750 after thermal treatment at 800°C, for 60, 180, 300, and 420 minutes, in comparison to the as-received material. Optical emission spectrometry, X-ray diffraction, and SEM with backscattered electrons (BSE) were used to evaluate the material. The corrosion performance was evaluated with the cyclic potentiodynamic polarization technique. The main results and conclusions obtained in the study were a decomposition of the ferrite phase into the χ and σ phases, with the formation of the χ phase being predominant in shorter times, while for longer aging times σ formed in greater quantities. It was also possible to verify a more aggressive corrosion trend for aged samples in the regions adjacent to the formation of the χ and σ phases. It was also possible to observe that the losses generated in corrosion resistance were greater for aging times longer than 60 minutes. The aging treatment significantly reduced the material’s corrosion resistance in conjunction with the formation of precipitates.
{"title":"Effect of Artificial Aging in the Microstructure and Corrosion Performance of Superduplex UNS S32750 Stainless Steel","authors":"Alexandre Pereira Dall'Oglio, W. Haupt, K. Riffel, R. H. Gonçalves e Silva","doi":"10.4028/p-ibs0sh","DOIUrl":"https://doi.org/10.4028/p-ibs0sh","url":null,"abstract":"Superduplex stainless steels have great mechanical and corrosion properties. However, its chemical composition makes it prone to intermetallic phase precipitation during thermal processing. Sigma (σ), chi (χ), and chromium nitrides (Cr2N) remove Cr and Mo from the matrix, reducing the corrosion and mechanical resistance. Understanding the effects of thermal processing on the secondary phase’s precipitation and depletion of the material’s performance is crucial to its applications. Thus, this work aims to analyze the behavior of the corrosion performance of the UNS S32750 after thermal treatment at 800°C, for 60, 180, 300, and 420 minutes, in comparison to the as-received material. Optical emission spectrometry, X-ray diffraction, and SEM with backscattered electrons (BSE) were used to evaluate the material. The corrosion performance was evaluated with the cyclic potentiodynamic polarization technique. The main results and conclusions obtained in the study were a decomposition of the ferrite phase into the χ and σ phases, with the formation of the χ phase being predominant in shorter times, while for longer aging times σ formed in greater quantities. It was also possible to verify a more aggressive corrosion trend for aged samples in the regions adjacent to the formation of the χ and σ phases. It was also possible to observe that the losses generated in corrosion resistance were greater for aging times longer than 60 minutes. The aging treatment significantly reduced the material’s corrosion resistance in conjunction with the formation of precipitates.","PeriodicalId":18262,"journal":{"name":"Materials Science Forum","volume":"35 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140981385","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}
Maria Eleni Mamassi, D. Ioannidou, Stavros Deligiannis, P. Tsakiridis
Steel hydrogen embrittlement (HE), a complex and multifaceted issue, can lead to sudden and catastrophic failure, without significant plastic deformation, making it a critical concern in the industrial sector. The present investigation focuses on the evaluation of HE effects regarding microstructure, mechanical properties degradation and type of fracture of AISI 1010 low-carbon steel, after accelerated hydrogen cathodic charging. Hydrogen was diffused electrolytically in 0.2 Μ H2SO4 solution, containing 3g/L of NH4SCN, using a cathodic current density of 10 and 20 mA/cm2, for 6 and 18 h. Mechanical properties were investigated through slow-rate tensile tests, as well as Charpy V-notch (CVN) impact tests, to determine the value of fracture toughness, both in uncharged and electrochemically pre-charged specimens. Vickers microhardness tests were conducted on the cross-sections of the hydrogen charged samples to evaluate embrittlement susceptibility, due to the presence of dissolved hydrogen. The microstructure modification was carried out through light optical (LOM) and scanning electron microscopy (SEM), in conjunction with an energy-dispersive X-ray detector (EDS). Slow scan X-ray diffraction (SSXRD) was also conducted for crystal structure analysis. The microstructure analysis showed the presence of large amounts of secondary cracks and cavities into the steel matrix, due to hydrogen diffusion and its accumulation at various sites. Hydrogen charging caused a significant gradual elongation decrease of the parent material, from 25% to 6.73%, in case of embrittlement at 20 mA/cm2 for 18h. Accordingly, after 18 h of exposure, the impact energy decrement was determined at 31.5%, at a current density of 10 mA/cm2, whereas the corresponding reduction at 20 mA/cm2 reached 68%.
{"title":"Investigation of Hydrogen Embrittlement Effect on Microstructure Mechanical Properties and Fracture of Low-Carbon Steels","authors":"Maria Eleni Mamassi, D. Ioannidou, Stavros Deligiannis, P. Tsakiridis","doi":"10.4028/p-zame7f","DOIUrl":"https://doi.org/10.4028/p-zame7f","url":null,"abstract":"Steel hydrogen embrittlement (HE), a complex and multifaceted issue, can lead to sudden and catastrophic failure, without significant plastic deformation, making it a critical concern in the industrial sector. The present investigation focuses on the evaluation of HE effects regarding microstructure, mechanical properties degradation and type of fracture of AISI 1010 low-carbon steel, after accelerated hydrogen cathodic charging. Hydrogen was diffused electrolytically in 0.2 Μ H2SO4 solution, containing 3g/L of NH4SCN, using a cathodic current density of 10 and 20 mA/cm2, for 6 and 18 h. Mechanical properties were investigated through slow-rate tensile tests, as well as Charpy V-notch (CVN) impact tests, to determine the value of fracture toughness, both in uncharged and electrochemically pre-charged specimens. Vickers microhardness tests were conducted on the cross-sections of the hydrogen charged samples to evaluate embrittlement susceptibility, due to the presence of dissolved hydrogen. The microstructure modification was carried out through light optical (LOM) and scanning electron microscopy (SEM), in conjunction with an energy-dispersive X-ray detector (EDS). Slow scan X-ray diffraction (SSXRD) was also conducted for crystal structure analysis. The microstructure analysis showed the presence of large amounts of secondary cracks and cavities into the steel matrix, due to hydrogen diffusion and its accumulation at various sites. Hydrogen charging caused a significant gradual elongation decrease of the parent material, from 25% to 6.73%, in case of embrittlement at 20 mA/cm2 for 18h. Accordingly, after 18 h of exposure, the impact energy decrement was determined at 31.5%, at a current density of 10 mA/cm2, whereas the corresponding reduction at 20 mA/cm2 reached 68%.","PeriodicalId":18262,"journal":{"name":"Materials Science Forum","volume":"18 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140981992","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}
The utilization of the Miedema semi-empirical model has proven to be an effective approach for the estimation of Gibbs free energy in solid solutions within binary and ternary systems. Research findings indicate that in systems such as FeAl, FeMn, FeB, FeV, FeGa, AlMn, AlGa, and AlV, the Gibbs free energy exhibits highly negative values. Conversely, systems FeSn, AlB, and AlSn demonstrate positive Gibbs free energy values, with the most negative observing at a molar fraction of 50% for Fe. These results have been corroborated through studies involving the mechanosynthesis of binary and ternary FeAl based alloys. It is thus inferred that the Miedema model can be reliably employed for predictive purposes, facilitating the estimation of Gibbs free energy and the exploration of potential multicomponent system formations.
{"title":"Calculation of Gibbs Free Energy of Iron Based Alloys Using Miedema's Model and Comparison with Experiment","authors":"Ali K. Kadhim","doi":"10.4028/p-6ykus2","DOIUrl":"https://doi.org/10.4028/p-6ykus2","url":null,"abstract":"The utilization of the Miedema semi-empirical model has proven to be an effective approach for the estimation of Gibbs free energy in solid solutions within binary and ternary systems. Research findings indicate that in systems such as FeAl, FeMn, FeB, FeV, FeGa, AlMn, AlGa, and AlV, the Gibbs free energy exhibits highly negative values. Conversely, systems FeSn, AlB, and AlSn demonstrate positive Gibbs free energy values, with the most negative observing at a molar fraction of 50% for Fe. These results have been corroborated through studies involving the mechanosynthesis of binary and ternary FeAl based alloys. It is thus inferred that the Miedema model can be reliably employed for predictive purposes, facilitating the estimation of Gibbs free energy and the exploration of potential multicomponent system formations.","PeriodicalId":18262,"journal":{"name":"Materials Science Forum","volume":" 22","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141128234","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}
Hai Tao Wang, Yu Zhang, Lin Lin Liu, Yue Xin, Kun Ren
At present, adding solid waste in plant substrate to replace part of planting soil has become a new direction in the field of ecological slope protection substrate research. In this paper, 16 groups of indoor orthogonal experiments were carried out with fly ash and sludge as the components of vegetation substrate and tall fescue as the planting object to explore the influence of ecological slope protection substrate on vegetation growth. Based on the range analysis method, the three functions of substrate planting performance, mechanical properties and substrate properties were used as references, and the entropy weight method (EWM) was used to assign weights to the proportion of each index in the total score, and the ratio was optimized. The results show that the optimal substrate ratio is 10% sludge content, 30% fly ash, 4% cement, 6% fiber, 50% planting soil (the ratio of loess and peat soil is 1:3). Fly ash has a great influence on the height of plants and vegetation coverage, and has a significant effect on the internal friction angle and fertility of the substrate. Sludge mainly affects the growth height of plants and the pH value and fertility of the substrate. The importance of factors affecting the growth of plants from large to small is: fly ash, the ratio of loess and peat soil, sludge, rice husk, cement.
{"title":"Study on the Optimization and Experimental of Fly Ash and Sludge in Ecological Slope Protection Substrate","authors":"Hai Tao Wang, Yu Zhang, Lin Lin Liu, Yue Xin, Kun Ren","doi":"10.4028/p-z1hrog","DOIUrl":"https://doi.org/10.4028/p-z1hrog","url":null,"abstract":"At present, adding solid waste in plant substrate to replace part of planting soil has become a new direction in the field of ecological slope protection substrate research. In this paper, 16 groups of indoor orthogonal experiments were carried out with fly ash and sludge as the components of vegetation substrate and tall fescue as the planting object to explore the influence of ecological slope protection substrate on vegetation growth. Based on the range analysis method, the three functions of substrate planting performance, mechanical properties and substrate properties were used as references, and the entropy weight method (EWM) was used to assign weights to the proportion of each index in the total score, and the ratio was optimized. The results show that the optimal substrate ratio is 10% sludge content, 30% fly ash, 4% cement, 6% fiber, 50% planting soil (the ratio of loess and peat soil is 1:3). Fly ash has a great influence on the height of plants and vegetation coverage, and has a significant effect on the internal friction angle and fertility of the substrate. Sludge mainly affects the growth height of plants and the pH value and fertility of the substrate. The importance of factors affecting the growth of plants from large to small is: fly ash, the ratio of loess and peat soil, sludge, rice husk, cement.","PeriodicalId":18262,"journal":{"name":"Materials Science Forum","volume":"2 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140982218","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：