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71.
《Ceramics International》2016,42(3):4333-4346
Modifying the properties of modern concrete highlights the decoding the molecular structure of C–S–H gel, which is the main binding phase in the cementitious materials. In this paper, the structural, dynamical and mechanical properties were investigated by using C–S–H glassy model and its crystal analog tobermorite 11 Å to represent the disordered and ordered molecular structure. By using reactive force field molecular simulation, the structural discrepancy for ordered and disordered phase was illustrated in respect of silicate chain skeletons, local structure of the calcium oxygen octahedrons and hydroxyl distribution. In the glassy model, the local structure of C–S–H gel, with defective silicate chains and distorted calcium sheet, is similar to the silicate glass phase of metallic ions. Furthermore, to predict the mechanical properties of the C–S–H gel and tobermorite, uniaxial tension testing by the reactive force field coupled with both the mechanical response and chemical response during the large tensile deformation process. During the tensile process, water molecules, attacking the Si–O and Ca–O bond, are detrimental to the cohesive force development in the C–S–H gel. 相似文献
72.
Biodiesel Production Using Calcined Waste Filter Press Cake from a Sugar Manufacturing Facility as a Highly Economic Catalyst
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Behzad Aghabarari M. V. Martinez-Huerta 《Journal of the American Oil Chemists' Society》2016,93(6):773-779
For the first time, a low cost, high performance and environmentally friendly heterogeneous catalyst derived from waste filter press cake (FPC) from a sugar manufacturing facility was used for the production of biodiesel. This industrial waste was calcined in air at 900 °C for 2 h to convert it into an active CaO‐based catalyst (FPC‐HT). In addition, the calcium oxide nanoparticles (FPC‐NAC) were synthesized by surfactant‐hydration treatment of FPC‐HT. The synthesized catalysts were characterized by XRD, FTIR, SEM, TEM and BET analysis. These calcium oxide catalysts were used for a transesterification reaction between canola oil and methanol to produce biodiesel. The results show that the FPC‐NAC has higher catalytic activity than FPC‐HT under optimized reaction conditions. Therefore, this economic catalyst is able to catalyze the transesterification of canola oil to its methyl esters in 1.5 h with yields above 96 %. 相似文献
73.
石灰石资源的开发利用 总被引:1,自引:0,他引:1
本文比较系统地介绍了我国优势资源石灰石的性质,一般用途和矿床的工业要求,列举了主要产品17种;简述了10种(类)钙盐产品的工业生产方法,并绘出了工艺流程示意图;对当前石灰石利用前景和可能开发方向提出了参考建议,可供石灰石储量丰富地区有关企业和当地政府在规划开发资源时作参考。 相似文献
74.
《Journal of the European Ceramic Society》2022,42(14):6713-6720
It is highly challenging to fabricate bioceramic scaffolds mimicking architecture and mechanical strength of cancellous bone. Gyroid structure, which is based on triply periodic minimal surface, highly resembles the architecture of cancellous bone. Herein, β-tricalcium phosphate (β-TCP) bioceramic scaffolds with gyroid structure were fabricated by stereolithography (SLA) 3D printing. The SLA 3D printing ensured high precision of ceramic part. The porosity (51–87%), pore size (250 – 2400 µm), pore wall thickness (< 300 µm) and compressive strength (0.6 – 16.8 MPa) of gyroid bioceramic scaffolds were readily adjusted to match various sites of cancellous bone. The gyroid bioceramic scaffolds were more favorable for cell proliferation than the grid-like bioceramic scaffolds. The cancellous-bone-mimicking gyroid bioceramic scaffolds with tunable architecture and mechanical strength were expected to efficiently repair the target bone defects. 相似文献
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78.
《Journal of the European Ceramic Society》2014,34(15):3993-4000
Polycrystalline calcium phosphate ((Cl/OH)Ap = Ca5(PO4)3(OH/Cl); TCP = Ca3(PO4)2) fibres were prepared from aqueous solutions of calcium chloride and phosphoric acid using poly(ethylene oxide) (PEO) as spinning aid. Generation of nonwoven materials was accomplished via rotary jet spinning. Polycrystalline (Cl/OH)Ap fibres 10–25 μm in diameter were obtained with 37% ceramic yield by pyrolysis of the green fibres followed by sintering at 1150 °C in air. X-ray diffraction (XRD) analysis provided evidence for apatite formation starting at 650 °C while (Cl/OH)Ap ceramic fibres were obtained at 1100 °C via transformation through intermediate dicalcium dichloride hydrogen phosphate (Ca2Cl2(HPO4)) and calcium pyrophosphate (Ca2P2O7) phases. A glass-forming Al-based additive was applied to enhance the mechanical properties of the Cl/OH)Ap ceramic fibres and indeed resulted in the formation of (Cl/OH)Ap/Al2O3 fibres with improved mechanical stability. Finally, TCP, (Cl/OH)Ap and (Cl/OH)Ap/Al2O3 fibres were subjected to seeding with mesenchymal stem cells. Negligible cytotoxicity is observed. 相似文献
79.
分析了碳硫硅酸盐(thaumasite)对水泥混凝土结构的破坏机理及对实际工程建筑所带来的危害。并针对其破坏产生的条件与作用机理,从水泥品种、水灰比、矿物掺合料的选择以及对环境因素的控制等方面阐述了有效的、可行的抗TSA侵蚀的技术。 相似文献
80.
在相同的结晶条件下,采用微波加热与传统加热所形成的硫酸钙晶体形貌有明显差异。通过蒙特卡罗模拟对此现象进行了分析和解释,模拟结果显示,微波辐射影响了硫酸钙晶体的生长过程,从而影响了硫酸钙晶体形貌。 相似文献