Sol-Gel Derived Nanocrystalline Fluoridated Hydroxyapatite Powders and Nanostructured Coatings for Tissue Engineering Applications

Nanocrystalline fluoridated hydroxyapatite (FHA) powders and coatings with a chemical composition of Ca₁₀(PO₄)₆OH_2–x F _x (where x values were selected equal to 0.0 ,0.5, 1.0, 1.5, and 2.0) were prepared through a modified simple sol-gel technique in comparison with conventional alkoxide-based sol-gel route. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), fourier transform infrared (FTIR) spectroscopy, pF-meter with a fluorine-sensitive electrode, and inductively coupled plasma–optical emission spectroscopy (ICP-OES) analysis techniques were employed in order to evaluate phase composition, particle size distribution, morphology, functional groups, fluorine content, and purity of prepared FHA nanopowders, respectively. SEM analysis was used to study the surface morphology and cross section of the FHA coatings, deposited on 316L stainless steel substrate. Results indicated that single-phase and homogeneous FHA nanopowders with carbonate peaks in the FTIR spectrum were synthesized through the modified sol-gel technique. TEM analysis revealed that fluorapatite (FA) powder was composed of nanosized particles, ~25 nm in size, with polyhedron shape and straight corners. In the modified sol-gel technique, polymerization and gelation kinetic of the sol were significantly improved without any need to use additives or pH control. Uniform, dense, well-adhered, and compacted FHA coatings were formed on the 316L stainless steel substrate after 24 hours of aging.     

Diffusion Interaction during Preparation of Nanocrystalline Powders in the System ZrO2-Y2O3

The properties of ZrO₂ - 3 mole% Y₂O₃ nanocrystalline powder prepared by diffusion impregnation are studied. The original nanocrystalline powder of M-ZrO₂ is prepared with hydrothermal treatment of aqueous zirconium hydroxychloride solution by different regimes. It is found that after diffusion impregnation for all of the powders with yttrium oxide two solid solutions are formed (F-ZrO₂ and M-ZrO₂) in mixture. It is established that the morphological features typical for the original powders are retained. The efficiency of diffusion impregnation is determined by the slightly-agglomerated powder with a high degree of crystallinity.__________Translated from Poroshkovaya Metallurgiya, Nos. 3–4(442), pp. 3–11, March–April, 2005.     

Change in the Physicochemical Properties of Nanocrystalline Powder Based on ZrO2 in the Presence of a Mineralizing Agent

The change in physicochemical properties of nanocrystalline powder of the composition ZrO₂ ― 3 mole% Y₂O₃ in the presence of aluminum fluoride is studied. The starting powder is prepared by a complex method including elements of hydrothermal synthesis and sol-gel technology. It is established that these conditions expand the temperature limits for the existence of ZrO₂ monoclinic solid solution. Transformation is connected with adsorption of fluorine at the ZrO₂ surface, diffusion in the solid phase, and a reduction in anion vacancy concentration.     

Change in the Physicochemical Properties of Nanocrystalline Powder Based on ZrO2 in the Presence of a Mineralizing Agent

The change in physicochemical properties of nanocrystalline powder of the composition ZrO₂ ― 3 mole% Y₂O₃ in the presence of aluminum fluoride is studied. The starting powder is prepared by a complex method including elements of hydrothermal synthesis and sol-gel technology. It is established that these conditions expand the temperature limits for the existence of ZrO₂ monoclinic solid solution. Transformation is connected with adsorption of fluorine at the ZrO₂ surface, diffusion in the solid phase, and a reduction in anion vacancy concentration.

     

Sintering of Refractory Compound Nanocrystalline Powders. Part 1. Storage and Preliminary Heat Treatment of Titanium Nitride Nanocrystalline Powders

Several approaches are considered for storing and processing finely-dispersed oxygen-free refractory compound powders using the example of titanium nitride nanopowder. The change in composition of nanopowders protected by a surfactant and without protection from oxidation during storage in air, and also during processing in gas atmospheres (nitrogen, hydrogen) and in a vacuum is studied.     

NiTi合金的生物医用性能及其在医学领域的应用

介绍NiTi合金作为医用材料的主要性能特点：良好的形状记忆效应最大可恢复应变达9％～10％，独特的超弹性使NiTi合金制成的医疗器件如NiTi丝等具有良好的柔顺性；较低的弹性模量弥补了传统医用金属材料作为骨植入物时容易出现应力遮挡现象从而造成骨质疏松的缺点；除此以外，NiTi合金还具有良好的抗疲劳、耐磨损和耐腐蚀性能；讨论了NITi合金的血液相容性和Ni^2＋离子毒性问题。总结了NiTi合金在医学领域的应用现状以及在新兴医学领域的发展，最后给出了一些NiTi医用性能改良的途径。     

Synthesis and Structure of Nanocrystalline Powders of Ultrahard Phases

The synthesis of ultrahard nanocrystalline phases is based on the occurrence of direct phase transformations in carbon and boron nitride at high pressures during shock compression. This survey examines the relationship between features of the initial layered structures, the mechanisms of the direct transformations (martensitic, diffusional), and the actual structure of the ultrahard phases formed during shock compression.     

化学及纳米掺杂氧化锆材料的性能与应用

对化学及纳米掺杂的ZrO2材料，从它们的晶体结构、相变规律、离子导电机制和材料性能等及其应用进行了较全面的综述，分析了不同掺杂对ZrO2材料的烧结性能、电性能以及其他热物理性能的影响。结果表明：通过化学掺杂不同价态、不同含量的氧化物使ZrO2的各项性能得到显著改善，通过纳米掺杂可以提高ZrO2材料的烧结性能，降低晶粒电阻，提高材料的离子导电性能。另外还对ZrO2作为结构和功能材料在金属熔体及气体定氧的氧传感器、脱氧剂、燃料电池以及超高温陶瓷发热元件等不同领域的应用情况进行了概述。     

Oxidation and Antioxidation of Nanocrystalline Powders of Nd-Fe-B

ＯｘｉｄａｔｉｏｎａｎｄＡｎｔｉｏｘｉｄａｔｉｏｎｏｆＮａｎｏｃｒｙｓｔａｌｉｎｅＰｏｗｄｅｒｓｏｆＮｄＦｅＢＷｅｎＤｉｊｉａｎｇ（闻荻江）（ＳｃｈｏｌｏｆＣｈｅｍｉｓｔｒｙａｎｄＣｈｅｍｉｃａｌＥｎｇｉｎｅｒｉｎｇ，ＳｕｚｈｏｕＵｎｉｖｅｒｓｉ...     

Thermal Barrier Coatings Based on ZrO2 Solid Solutions

Powder Metallurgy and Metal Ceramics - The standard material of the ceramic layer in thermal barrier coatings (TBCs)—a solid solution of ZrO2 stabilized with (6–8 wt.%) Y2O3...     

纳米结构WC—Co复合粉末的制备与应用

介绍了一种制备纳米结构ＷＣＣｏ复合粉末的方法———热化学合成法。该方法包括原始溶液制备、喷雾干燥生成化学均匀的前驱体粉末及其流化床热转化为纳米结构ＷＣＣｏ复合粉末。论述了制得的纳米结构ＷＣＣｏ复合粉末的结构、性能与应用     

Ti-Cu-Zr-Fe-Sn-Si-Ag-Pd Bulk Metallic Glasses with Potential for Biomedical Applications

Ti₄₇Cu_38−xZr_7.5Fe_2.5Sn₂Si₁Ag₂Pd_x (x = 1, 2, 3, and 4 atomic percent, at. pct) bulk metallic glasses (BMGs) with potential for biomedical applications were fabricated by copper-mold casting. The Ti-based BMGs exhibited high glass-forming ability (GFA) with critical diameters of 4 to 5 mm and a supercooled liquid region over 50 K, though the high contents of Pd slightly decreased the GFA. The additions of 2 and 3 at. pct Pd benefited the improvement of plasticity, and the resultant BMGs showed the relatively low Young’s modulus of about 100 GPa, high compressive strengths of 2174 to 2340 MPa, and compressive plastic strain of around 4 pct. The addition of Pd also decreased the passive current density and increased the pitting potential of the Ti-based BMGs in the Hank’s solution, leading to the enhanced bio-corrosion resistance of the BMGs. Furthermore, the cell adhesion, viability, and proliferation behaviors revealed that the present Ti-based BMGs possess as good biocompatibility as that of the Ti-6Al-4V alloy. These results demonstrated the potential of the Ti-Cu-Zr-Fe-Sn-Si-Ag-Pd BMGs as biomedical materials.

     

ZrO2基中温固体电解质材料的制备和性能研究

采用无机胶化工艺制备了球状的、分散性好且粒度分布较窄的几种ZrO2基粉末.经干压成型和烧结后制备成陶瓷质电解质材料.通过XRD显微结构等分析,显示所得的样品均为立方相结构.在1 450℃烧结的样品已近完全致密.1 450～1 550℃烧结的8YbSZ在450 ～700℃测试范围内具有比其他的ZrO2基材料更高的离子电导...     

Sintering of Refractory Compounds Nanocrystalline Powders. Part 2. Non-Isothermal Sintering of Titanium Nitride Powder

New approaches to the sintering of nanocrystalline powders of refractory compounds are proposed. Titanium nitride-based ceramics with a grain size of 50 nm and nanohardness 28.8 ± 2.47 GPa was obtained by sintering at a controlled rate of densification. Investigation of evolution of the block structure in the material during sintering enabled further optimization of the procedure and reduction of the sintering temperature to 1150°C.     

Sintering of Refractory Compounds Nanocrystalline Powders. Part 2. Non-Isothermal Sintering of Titanium Nitride Powder

New approaches to the sintering of nanocrystalline powders of refractory compounds are proposed. Titanium nitride-based ceramics with a grain size of 50 nm and nanohardness 28.8 ± 2.47 GPa was obtained by sintering at a controlled rate of densification. Investigation of evolution of the block structure in the material during sintering enabled further optimization of the procedure and reduction of the sintering temperature to 1150°C.

     

Data-Fusion Approaches and Applications for Construction Engineering

Data fusion can be defined as the process of combining data or information for estimating the state of an entity. Data fusion is a multidisciplinary field that has several benefits, such as enhancing the confidence, improving reliability, and reducing ambiguity of measurements for estimating the state of entities in engineering systems. It can also enhance completeness of fused data that may be required for estimating the state of engineering systems. Data fusion has been applied to different fields, such as robotics, automation, and intelligent systems. This paper reviews some examples of recent applications of data fusion in civil engineering and presents some of the potential benefits of using data fusion in civil engineering.     

Conventional Powder Metallurgy Process and Characterization of Porous Titanium for Biomedical Applications

Commercially pure titanium (c.p. Ti) is one of the best metallic biomaterials for bone tissue replacement. However, one of its main drawbacks, which compromises the service reliability of the implants, is the stress-shielding phenomenon (Young’s modulus mismatch with respect to that one of the bone). Several previous works attempted to solve this problem. One alternative to solve that problem has been the development of biocomposites implants and, more recently, the fabrication of titanium porous implants. In this work, porous samples of c.p. Ti grade 4 were obtained using conventional powder metallurgy technique. The influence of the processing parameters (compacting pressure and sintering temperature) on the microstructure features (size, type, morphology, and percentage of porosity), as well as on the mechanical properties (compressive yield strength, and conventional and dynamic Young’s modulus) were investigated. The results indicated that there is an increment in density, roundness of pores, and mean free path between them as compacting pressure and/or sintering temperature is increased. The Young’s modulus (conventional and dynamic) and yield strength showed the same behavior. Better stiffness results, in the central part of cylindrical samples, were obtained for a uniaxial compression of 38.5 MPa using a sintering temperature of 1273 K and 1373 K (1000 °C and 1100 °C). An evaluation of porosity and Young’s modulus along a cylindrical sample divided in three parts showed that is possible to obtain a titanium sample with graded porosity that could be used to design implants. This approach opens a new alternative to solve the bone resorption problems associated with the stress-shielding phenomenon.     

Functional Graded Materials Based on ZrO2 and Al2O3. Production Methods

The various methods for producing functional graded materials based on ZrO₂ and Al₂O₃ are reviewed: dry pressing followed by thermal treatment, diffusion welding, co-extrusion, chemical infiltration, electrophoretic deposition, centrifugal deposition, sedimentation, tape casting, slip casting, direct ceramic ink-jet printing.