多孔聚磷酸钙生物陶瓷的研究与应用

本文阐述了聚磷酸钙的国内外研究现状,初步揭示了聚磷酸钙生物陶瓷（CPP）的生物相容性和降解特性。现有的研究表明,聚磷酸钙的聚合度和晶型不同,降解速率也不同,为生物陶瓷可控降解提供了新的途径。聚磷酸钙属直链状无机聚合物,具有不完全结晶性。聚磷酸钙材料在生物相容性、降解性和力学性方面的综合优势,使其在骨修复材料领域格外受到青睐。     

纳米磷酸钙在口腔护理产品中的应用初探

纳米磷酸钙与人体骨、牙齿等硬组织的化学成分相似,具有很高的生物相容性和生物降解性,已被应用于治疗骨缺损、牙齿修复等领域.本文主要介绍了纳米磷酸钙的种类、合成方式及在生物医学领域应用的研究现状,探讨了纳米磷酸钙在口腔护理产品中的应用前景.     

稀土氧化钇改性磷酸钙骨水泥的研究

磷酸钙骨水泥是一种新型的自固化的非陶瓷羟基磷灰石人造骨材料,具有良好的生物相容性、自固化能力、易于塑形、与成骨活性相协调的溶解性能可作为药物、生物活性因子缓释载体等优越的性能。稀土掺杂羟基磷灰石,对羟基磷灰石的合成有促进作用,并且使其具有更稳定的性质。钇的加入有助于羟基磷灰石生物活性的提高。笔者利用钇掺改善羟基磷灰石生物活性作为探讨。其采用氧化钇对磷酸钙骨水泥进行改性研究,考察磷酸钙骨水泥凝结时间、可注射性和孔隙率等基本性能。采用X射线衍射分析骨水泥粉末在水化过程中的变化及其最终产物。采用电镜观察产物的微结构和表面形貌。研究结果表明:钇加入没有影响磷酸钙骨水泥的水化,并且随着钇含量的增加磷酸钙骨水泥的固化体凝结时间逐渐延长,其中氧化钇含量在5%时凝结时间最短;骨水泥浆体的可注射性变大,其中氧化钇含量在1.5%时可注射性最大(壳聚糖溶液)。磷酸钙骨水泥水化最终产物为片状或棒状的羟基磷灰石,其结构呈紧密联系,但表面有较多的孔隙,且随着钇含量的增加孔隙率有增加的趋势。     

磷酸钙骨水泥作为药物缓释载体的研究

论述了磷酸钙骨水泥作为药物缓释载体承载不同药物以及载药前后的特征变化，分析了药物缓释载体的动力学原理及其影响药物释放率的因素，磷酸钙骨水泥生物相容性和药物控释性好，可最大限度地治疗和预防外科手术感染，在临床上已成为应用最多的药物缓释载体。     

非陶瓷羟基磷灰石人工骨的研究

磷酸钙骨是一种非陶瓷的新型骨修复材料，它是由几种磷酸钙盐组成的混合物，用水调和后呈糊状物，能在人体的环境和温度下自行固化，其成分最终转化为羟基磷灰石，高的生物相容性和能根据缺损部位塑形的特性使其成为研究的热点。本文综述了磷酸钙骨水泥的组成与特性，涉及磷酸钙的制备，骨水泥自行水化硬化的化学变化过程及其生物相容性研究的等的研究进展。     

磷酸钙骨水泥复合材料研究进展

磷酸钙骨水泥以其良好的生物相容性、骨传导性被作为重要的骨修复材料。但其存在固化时间较长、机械性能不足和低塑性等缺点,使其应用受到限制,故需对其进行提高性能研究。本文就近年来磷酸钙骨水泥复合改性的研究做一综述,随着对其改性研究的深入,其性能不断得到提高。     

高性能化磷酸钙骨水泥的研究进展

磷酸钙骨水泥（CPC）作为一种新型的自固化型骨修复材料,因其具有良好的生物相容性、骨传导性、可降解性及可塑性等优点,受到了国内外众多学者的广泛关注,具有广阔的应用前景。本文从磷酸钙骨水泥高性能化着手,综述了CPC的复合物及其外添加剂的研究成果,并对新型CPC的研制进展做了介绍。     

磷酸钙生物陶瓷新工艺

磷酸钙陶瓷中羟基磷灰石是骨和齿的主要成分,具有良好的生物亲合性,广泛用作人造骨、人造齿等医用生物材料。使用这种生物陶瓷,不仅力学强度要高,而且生物适应性要好。     

骨组织工程聚磷酸钙生物陶瓷的研究进展

聚磷酸钙具有优异的细胞相容性、生物降解性、力学强度和细胞无毒性,骨传导性和骨诱导性,是一种新型的骨组织工程修复材料。这里就聚磷酸钙的结构、合成方法、多孔体的制备、纤维及其复合材料进行了综述性的介绍。     

骨组织修复用生物骨水泥的研究现状及进展

在骨组织修复材料领域,可任意塑形并能在特定条件下快速自固化的生物骨水泥已成为生物医学工程研究的重要内容。该文综述了聚甲酯丙烯酸甲酯、磷酸钙、磷酸镁等生物骨水泥,并介绍了不同生物骨水泥的主要成分、固化机理及目前存在主要问题。     

Oxidation protection of aluminum metaphosphate coating prepared by cathodic electrochemical treatment for graphite

In order to provide a short-term oxidation protection system for graphite at high temperature, an aluminum metaphosphate coating was prepared on the surface of graphite by cathodic electrochemical treatment, and its oxidation protective ability was investigated using an isothermal oxidation test. The microstructure, chemical composition, and phase components of the aluminum metaphosphate coating were respectively analyzed through scanning electron microscope, dispersive X-ray analysis, and X-ray diffraction. The results showed that aluminum metaphosphate coating with a thickness of about 24 μm provides good oxidation resistance for graphite at 1250 °C, and it reduces the oxidation rate of graphite in a 5-h period by a factor of two. The good oxidation protective ability of the as-prepared coating at 1250 °C is related to the formation of a layer consisting of aluminum metaphosphate and aluminum orthophosphate phases.     

Metastable-Phase Formation During the Crystallization of Magnesium Metaphosphate Glass

We have observed a previously unreported metastable intermediate phase during the crystallization of magnesium metaphosphate (Mg(PO₃)₂) glasses to the equilibrium ring phase, Mg₂P₄O₁₂. Our current hypothesis is that the metastable phase contains metaphosphate chains, as in other crystalline alkaline-earth metaphosphates. This type of phase could form by low-energy rearrangement of the polyphosphate chains in the glass structure. Thus, its formation might be favored at low temperatures where there is insufficient thermal energy to break the metaphosphate chains and form tetrametaphosphate rings.     

Internal Friction in Metaphosphate Glasses

The internal friction of metaphosphate glasses was measured as a function of temperature by a free torsional vibration method. In the high-temperature region metaphosphate glasses (MO/P₂O₅=l)for which M=Ca, Sr, or Ba exhibit high-temperature peaks in plots of internal friction vs temperature, whereas for M =Mg or Zn this peak is missing.     

窑法磷酸中磷酸钙对P2O5反吸过程

窑法磷酸生产中,气体产物P₂O₅与磷矿发生副反应（俗称P₂O₅反吸）生成大量低熔点物料,导致窑内结圈堵料,造成生产装置不能稳定运行。以磷酸钙与P₂O₅的反应为研究对象,采用化学分析与SEM、XRD、IR、Raman、TG及DSC等表征手段对不同温度下该反应产物的P₂O₅含量、形貌、物相组成、结构及热稳定性能等进行研究,探讨磷矿对P₂O₅的反吸行为。研究表明,反吸过程与反应温度密切相关,磷酸钙与P₂O₅在500℃以上发生反应,在500～900℃时,磷酸钙与P₂O₅反应生成偏磷酸钙,900℃反吸产物几乎为纯偏磷酸钙;在1000～1300℃时,反吸产物偏磷酸钙分解为稳定的焦磷酸钙,同时释放出P₂O₅气体,1300℃时反吸产物几乎为纯焦磷酸钙。     

Phase Evolution during the Formation of α-Tricalcium Phosphate

The formation of α-tricalcium phosphate from monobasic ammonium phosphate and calcium carbonate was investigated using a number of complementary techniques. Differential thermal analysis showed five distinct thermal events attributed to melting of the ammonium phosphate, decomposition of acidic calcium orthophosphate into an amorphous calcium metaphosphate, crystallization of β-calcium metaphosphate, crystallization of β-calcium pyrophosphate, and calcination of calcium carbonate. X-ray diffraction analyses as a function of temperature supported the evolution of these events and phases and also showed the formation of other intermediates, including an amorphous phase, apatite, lime, and β-tricalcium phosphate. Thermal gravimetric analysis (TGA) showed a large weight loss occurring between 150° and 250°C due to reaction between the acidic phosphate liquid and the calcium carbonate. This resulted in an amorphous intermediate with a Ca/P ratio between 0.5 and 1.0 from which both β-calcium metaphosphate and β-calcium pyrophosphate crystallized. Mass spectroscopy indicated that the ammonia and carbon dioxide were evolved in four different steps, while water was evolved in at least five steps. These decomposition steps correlated with those observed by TGA. Scanning electron microscopy indicated the formation of an intermediate phase that coated the calcium carbonate by 250°C. The proposed mechanistic reaction path to alpha-tricalcium phosphate involves the formation and consumption of the following sequence of intermediates: an acidic amorphous condensed phosphate; β-calcium metaphosphate and β-calcium pyrophosphate; lime, apatite, and β-tricalcium phosphate.     

偏磷酸钾肥料生产工艺

介绍用元素磷 (或磷酸或磷肥 )和氯化钾生产偏磷酸钾肥料的工艺及产品肥效。     

阳离子淀粉包覆改性硅藻土制备及在造纸中应用研究

以阳离子淀粉和硅藻土为主要原料,采用阳离子淀粉对硅藻土进行改性,并将其用于造纸填料中.研究了阳离子淀粉改性硅藻土颗粒形态、Zeta电位、粒径、阳离子淀粉沉积率和改性硅藻土留着率的变化.结果表明,采用阳离子淀粉和三偏磷酸钠能有效对硅藻土进行改性,使硅藻土粒径增大,Zeta电位升高,淀粉沉积率达98％以上.在同一加入量的条件下,与加入未改性硅藻土纸张相比,加入改性硅藻土纸张的抗张指数、撕裂指数、耐折度和耐破度均有所提高和改善,改性硅藻土留着率超过85％.     

The Influence of Silicon Oxide on the Mechanical Properties of Metaphosphate Glasses

The possibility of improving the mechanical properties of potassium aluminum metaphosphate glasses through the introduction of silicon oxide into the glass composition is analyzed. It is shown that the elastic moduli (Young modulus, shear modulus, Poisson ratio) and the hardness remain almost unchanged with an increase in the content of silicon oxide in the glass. At the same time, the structural strength increases by a factor of 1.7 and the fracture toughness increases by a factor of 1.3. The assumption is made that the observed increase in the structural strength is associated with the incorporation of silicon ions into the structure of the metaphosphate glass in the octahedral coordination.     

Luminescence of Fe3plus; in Metaphosphate Glasses: Evidence for Four- and Six-Coordinated Sites

Ferric iron-substituted sodium metaphosphate and calcium metaphosphate glasses exhibit a very weak luminescence that can be observed under laser excitation. Broad emission bands at 16 000 cm⁻¹ and at 12 000 cm⁻¹ are assigned to the ⁴T₁→⁶A, transitions of Fe^3plus; in four- and six-coordinated sites respectively. The interpretation is supported by crystal field theory calculations based on known absorption spectra of Fe^3plus;.     

Aluminum Phosphates Derived from Alumina and Alumina-Sol–Gel Systems

Aluminum phosphate products formed by the reactions of alumina and alumina-gel systems with acidic phosphates were analyzed. Drying of alumina-gel to form microcrystalline boehmite and conversion to γ-alumina by thermal treatment was indicated by the appearance of octahedral, pentacoordinate, or tetrahedral sites, which were established using ²⁷Al magic-angle-spinning solid-state nuclear magnetic resonance spectroscopy. Crystalline aluminum phosphate products and amorphous material were identified using this technique. α-alumina and heat-treated alumina-gel that were reacted with phosphate in an Al:P ratio of 1:1 yielded dramatically different aluminum orthophosphate:aluminum metaphosphate product ratios of 8.2:1 and 1:1.1, respectively. When alumina-gel was heat-treated with phosphate, an abundance of aluminum orthophosphate, aluminum metaphosphate, and hydrated aluminum phosphate products were affected by varying conditions of temperature and time of heat treatment and by the amount of phosphate present. An α-alumina/alumina-gel composite sol–gel phase that was reacted with phosphoric acid (H₃PO₄) in a Al:P ratio of 1:1 exhibited an increased quantity of aluminum metaphosphate products compared with an α-alumina:H₃PO₄ ratio of 1:1 and a higher percentage of reaction (79%) compared with the reactions of an α-alumina:H₃PO₄ ratio of 1:1 or an alumina-gel:H₃PO₄ ratio of 1:1. The morphologies of aluminum triphosphate hydrate and aluminum metaphosphate product phases were observed using scanning electron microscopy.