多孔碳酸钙陶瓷--人造珊瑚的研究

天然珊瑚有三维贯通的多孔网络结构，它的主要成分碳酸钙（CaCO3)在人体环境可降解。模拟珊瑚的组成与结构，研制新型的组织工程支架材料有着良好的应用前景。本文探索了多孔碳酸钙陶瓷的制备方法，并通过盐析法制备了一种多孔的碳酸钙陶瓷，有望获得高的孔隙率和孔连通性。     

多孔碳酸钙陶瓷——人造珊瑚的研究

天然珊瑚有三维贯通的多孔网络结构，它的主要成分碳酸钙(CaCO3)在人体环境可降解。模拟珊瑚的组成与结构，研制新型的组织工程支架材料有着良好的应用前景。本文探索了多孔碳酸钙陶瓷的制备方法，并通过盐析法制备了一种多孔的碳酸钙陶瓷，有望获得高的孔隙率和孔连通性。     

多孔碳酸钙陶瓷-人造珊瑚的研究

天然珊瑚有三维贯通的多孔网络结构，它的主要成分碳酸钙(CaCO3)在人体环境可降解。模拟珊瑚的组成与结构，研制新型的组织工程支架材料有着良好的应用前景。本文探索了多孔碳酸钙陶瓷的制备方法，并通过盐析法制备了一种多孔的碳酸钙陶瓷，有望获得高的孔隙率和孔连通性。     

多孔碳酸钙陶瓷--人造珊瑚的初步研究

天然珊瑚的多孔结构是从事组织工程的材料学家梦寐以求的 ,而且珊瑚的主要成分碳酸钙 (CaCO3)在人体环境可降解。模拟珊瑚的组成与结构 ,研制新型的组织工程支架材料有着良好的应用前景。本文探索了多孔碳酸钙陶瓷的制备方法 ,并通过盐析法制备了一种多孔碳酸钙陶瓷 ,有望获得高的孔隙率和孔连通性     

多孔碳酸钙的制备及应用研究进展

碳酸钙是一种稳定的无机化合物,在自然界中广泛存在。多孔碳酸钙作为无机材料,以其比表面积大、无毒、生物相容性好等优点而被广泛应用于化工、医药、冶金、食品等行业。但多孔碳酸钙的结构、性能与应用受其制备方法和工艺影响严重,不同方法制备得到的多孔碳酸钙呈现出千差万别的结构和晶型。本文主要介绍了多孔碳酸钙的常用制备方法,主要有模板法、乳状液膜法、共沉淀法、溶剂/水热法、凝胶结晶法、盐析法等,并简要阐述了各种方法的制备原理与优缺点,同时将一些较新领域应用所取得的成果进行了归纳。指出国内外研究多孔碳酸钙在制备方法和工艺方面存在产品结构与性能难精确控制、过程节能环保不到位、原料利用较局限等问题,建议开展多孔碳酸钙在废水废气方面的应用研究。     

碳化法制备多孔碳酸钙的工艺研究

以石灰石为原料，采用碳化法制备多孔碳酸钙。以多孔碳酸钙的比表面积作为评价指标，探究消化时间、消化温度、液固比、模板剂浓度、碳化温度、CO₂流量等对多孔碳酸钙比表面积的影响，得出最佳的制备工艺条件。结果表明，以十二烷基硫酸钠(SDS)为模板剂，在最佳制备条件(消化时间为1 h、消化温度为60℃、液固比(体积质量比，g/m L)为14∶1、SDS浓度为0.1 mol/L、碳化温度为30℃、碳化CO₂流量为400 m L/min)下制备的多孔碳酸钙比表面积可达60.17 m²/g。利用扫描电镜(SEM)、X射线衍射(XRD)等表征手段对所得多孔碳酸钙的颗粒形貌、晶型进行了分析，结果显示在最佳制备工艺条件下制备的多孔碳酸钙颗粒表面粗糙，孔道结构清晰可见，晶型为稳定的方解石型。     

多孔陶瓷的制备、性能及应用：（I）多孔陶瓷的制造工艺

多孔陶瓷的制备方法很多，其成孔机理主要有机械挤出、颗粒堆积、成孔剂、发泡、多孔模板、凝结结构成孔。本文根据成孔机理的不同综述了多孔陶瓷的制备工艺最新研究进展。     

多孔陶瓷的制备,性能及应用

多孔陶瓷性能特点，应用广泛，并为节能等相关行业带来进步。本文对多孔陶瓷的种类，制备，结构与性能表征，应用，国同发展等作了一个概述。     

多孔陶瓷的制备、性能及应用:(Ⅰ)多孔陶瓷的制造工艺

多孔陶瓷的制备方法很多 ,其成孔机理主要有机械挤出、颗粒堆积、成孔剂、发泡、多孔模板、凝结结构成孔。本文根据成孔机理的不同综述了多孔陶瓷的制备工艺最新研究进展。     

氧化铝多孔陶瓷制备工艺的研究

本研究了氧化铝多孔陶瓷的制备工艺，探讨了制备工艺参数对多孔陶瓷性能的影响。研究结果表明，氧化铝骨料颗粒度是得到不同孔径多孔陶瓷的关键；粘结剂含量对多孔陶瓷的孔隙率、强度有很大影响；烧 是得到性能多孔陶瓷的重要因素。通过改变工艺参数，可以得到平均孔径1至10μm，开气孔率40％的氧化铝多孔陶瓷。     

Fabrication of a Novel Calcium Carbonate Composite Ceramic as Bone Substitute

The coral, whose main composition is aragonite‐type calcium carbonate, has been widely used as bone substitute in clinic. However, the study on calcium carbonate bioceramic has not been largely reported due to difficulty in sintering calcium carbonate which is liable to evidently decompose at low temperature. In this study, a novel calcium carbonate composite ceramic was fabricated by sintering fast at a low temperature. A degradable, biocompatible phosphate‐based glass (PG) which grew liquid at a low temperature was added as sintering agent in the sintering process. The sintering schedule was explored by thermal analysis. The phase composition, microstructure, compressive strength, and biocompatibility of calcium carbonate composite ceramics were evaluated. The results revealed that the optimum holding time at the sintering temperature was 20 min. The obtained calcium carbonate composite ceramics did not produce calcium oxide but new compounds according to phase analysis. The compressive strength of calcium carbonate composite ceramics correspondingly increased with growing addition of PG ranging from 10 to 50 wt%. The cell proliferation on the calcium carbonate composite ceramic was not compromised but augmented compared to the neat calcium carbonate ceramic without adding PG as sintering agent. The novel calcium carbonate composite ceramic is a promising bone substitute for bone defects.     

硅藻土基多孔陶瓷的制备

以硅藻土为主要原料,加入天然有机细粉为造孔剂,水玻璃为高温粘合剂,轻质碳酸钙和轻质碳酸镁为添加剂,经半干压成型,常规烧成,制备出了性能优良的硅藻土多孔陶瓷。随着造孔剂的加入量和烧成制度的改变,制品的气孔率、体积密度和抗压强度等性能也随着改变。     

Calcium carbonate thermal decomposition in white-body wall tile during firing. I. Kinetic study

This study examines the thermal decomposition of calcium carbonate, contained in disk-shaped test pieces formed from a mixture of raw materials of a similar composition and characteristics to those of the mixtures customarily used for the manufacture of white-body wall tile.The experiments were conducted under isothermal conditions at different temperatures in the range 825–950 °C in an air stream free of carbon dioxide.The experimental results have been interpreted using the Shrinking Unreacted Core kinetic model, assuming that, at low conversion degrees, the process is only controlled by the chemical reaction step of CaCO₃ decomposition, while at high conversion degrees the diffusion of the resulting CO₂ through the porous structure of the reacted ceramic layer also affects the process. The derived equations, which relate the conversion degree of calcium carbonate in the ceramic body to residence time, temperature, and initial porosity of the test pieces, allow the experimental results to be satisfactorily reproduced.     

Development of composite tissue scaffolds containing naturally sourced mircoporous hydroxyapatite

The aims of this work were to investigate the conversion of a marine alga into hydroxyapatite (HA), and furthermore to design a composite bone tissue engineering scaffold comprising the synthesised HA within a porous bioresorbable polymer. The marine alga, Phymatolithon calcareum, which exhibits a calcium carbonate honeycomb structure, with a natural architecture of interconnecting permeable pores (microporosity 4–11 μm), provided the initial raw material for this study. The objective was to convert the alga into hydroxyapatite while maintaining its porous morphology using a sequential pyrolysis and chemical synthesis processes. Semi-quantitative XRD analysis of the post-hydrothermal material (pyrolised at 700–750 °C), indicated that the calcium phosphate (CaP) ceramic most likely consisted of a calcium carbonate macroporous lattice, with hydroxyapatite crystals on the surface of the macropores. Cell visibility (cytotoxicity) investigations of osteogenic cells were conducted on the CaP ceramic (i.e., the material post-hydrothermal analysis) which was found to be non-cytotoxic and displayed good biocompatibility when seeded with MG63 cells. Furthermore, a hot press scaffold fabrication technique was developed to produce a composite scaffold of CaP (derived from the marine alga) in a polycaprolactone (PCL) matrix. A salt leaching technique was further explored to introduce macroporosity to the structure (50–200 μm). Analysis indicated that the scaffold contained both micro/macroporosity and mechanical strength, considered necessary for bone tissue engineering applications.     

Mechanism of densification of calcium carbonate by cold sintering process

In general, carbonates cannot be easily hardened by the conventional ceramic sintering process due to their thermal decomposition during heating. However, when the cold sintering process (CSP) is selected, carbonates can be hardened at lower temperatures. It has been demonstrated that calcium carbonate can be hardened by CSP, but the detailed densification mechanisms of cold sintering at various temperatures have not been fully clarified. In this study, the vaterite phase of calcium carbonate was selected as the starting material. As the cold sintering temperature for calcium carbonate powder increased, the bulk density of the hardened calcium carbonate body increased. The compressive strength was maximized when cold sintered at 80 °C due to the balance between the solubility of calcium carbonate and the reactivity of cold sintering. Almost no crystal phase transformation from vaterite to calcite occurred during cold sintering, and reprecipitation of the vaterite phase though dissolution-precipitation densified the body.     

In-situ electrochemical synthesis of inorganic compounds for materials conservation: Assessment of their effects on the porous structure

This study refers to the application of in-situ electrochemical synthesis as an alternative method to improve the properties of porous materials against harmful external agents that deteriorate them. It is oriented to an understanding of the effects of crystallisation on the pore structure of different compounds commonly used in the restoration and conservation of porous materials (historical ceramics, building walls, sculptures, or biomedical applications). It analyses the microstructural, chemical details, and stability of the neo-formed phases that modify the pore network. The electrochemical synthesis was carried out at ambient temperature (20 °C), over high porous sandstone for crystallising Ca carbonate, Mg carbonate, Ca phosphate, and Ca oxalate compounds. Based on the neo-formed minerals, a comparison was made depending on their specific properties defining how they affected the pore structure. The characterisation included polarised light optical microscopy, environmental and field-emission scanning electron microscopy, digital image analysis, cathodoluminescence (CL-ESEM),energy-dispersive X-ray spectroscopy, and X-ray microdiffraction. Aragonite, hydromagnesite, hydroxyapatite, and whewellite were identified as the majority phases depending on the treatment. Phase transformation, dehydration, and dissolution-re-precipitation processes suggested different degrees of stability, including aragonite/calcite (CaCO3 treatment) and hydromagnesite/magnesite (MgCO3 treatment) transformations and simultaneous crystallisation of brushite/hydroxyapatite ((Ca₃(PO₄)₂ treatment). Electrocrystallisation induced changes in inter-granular porosity, the development of secondary porosity inherent to the minerals, and differences in pore cementation depending on its mineralogy. Among the treatments, Mg carbonate reduced porosity most effectively, followed in descending order by calcium carbonate and calcium phosphate, being the calcium oxalate the less effective.