SAPS工艺中电流和电压对 HfC 涂层结构形貌的影响

采用SAPS法在包埋有SiC内涂层的C/C复合材料的表面制备了HfC抗烧蚀涂层;通过改变工艺过程中的电流和电压等参数,制备了不同的HfC涂层试样;结合XRD、SEM、声发射-载荷试验及共聚焦显微镜等表征手段,研究了在喷涂电流及电压变化时,制备出的HfC涂层结构、形貌的变化情况;通过氧乙炔火焰对不同涂层的烧蚀性能进行了测试,并研究了烧蚀后不同涂层形貌和结构的变化。结果表明,在喷涂电流为400 A、喷涂电压为130 V时制备的涂层综合性能最佳。     

Surface-induced mineralization: a new method for producing calcium phosphate coatings

Calcium phosphate coatings were nucleated and grown from aqueous solution onto titanium metal substrates via surface-induced mineralization (SIM) processing techniques. This process is based on the observation that in nature organisms use biopolymers to produce ceramic composites, such as teeth, bones, and shells. The SIM process involves modification of a surface to introduce surface functionalization followed by immersion in aqueous supersaturated calcium phosphate solutions. This low-temperature process (< 100 degrees C) has advantages over conventional methods of calcium phosphate deposition in that uniform coatings are produced onto complex-shaped and/or microporous samples. Additionally, because it is a low-temperature process, control of the phase and crystallinity of the deposited material can be maintained.     

碳化硅复合镍磷合金涂层的组织结构、显微硬度及腐蚀性能研究

镍基复合涂层是一项有望替代电镀铬涂层的先进绿色环保表面处理技术。 本文在铝合金表面制备了纯 Ni、 NiP及其与SiC复合涂层, 利用SEM、 EDS和XRD研究了Ni、 NiP及其复合涂层的微观形貌、 成分与组织结构, 利用显微硬度计与电化学工作站研究了其硬度与耐腐蚀性能。 研究结果表明： SiC 复合电镀纯镍涂层的表面较为 粗糙, SiC 复合电镀镍磷合金涂层中晶粒轮廓明显; 电沉积镍磷合金涂层的相结构包括晶体 Ni2P、 Ni12P5 和非晶 NiP。 铝合金基体表面 Ni-P 合金涂层的显微硬度显著高于纯 Ni 涂层, 引入 SiC 纳米颗粒形成复合涂层可提高其 显微硬度; SiC 颗粒有助于提高复合涂层在氯化钠溶液中的腐蚀电位, 降低腐蚀电流密度, 提高其耐蚀性能。     

人体干细胞繁殖生长能力增强超音速火焰喷涂纳米氧化钛-羟基磷灰石涂层

超音速火焰(HVOF)喷涂纳米氧化钛加10%羟基磷灰石(HA)(n-TiO2-10%HA)粉末制备的生物医学涂层有望取代大气等离子喷涂的HA涂层。选用这种方法的原因为TiO2在人体内的稳定性很高(即没有溶解),另外,在Ti-6Al-4V的基板上的结合强度超过APS-HA涂层2倍。为了探索这些新材料和涂层的生物表现,在超音速火焰喷涂的n-TiO2和n-TiO2-10%HA的涂层表面上进行了从1到21天的人体间质干细胞(hMSCs)培养,APS的HA涂层和未涂层的Ti-6Al-4V合金基体作为对照。对hMSCs的活性特征进行了以下分析:阿拉莫尔艾迪布尔细胞的繁殖;生化碱性磷酸酶(ALP)活性的分析;细胞骨架组织(通过荧光/共聚焦显微镜)及细胞/基体的互动(通过扫描电子显微镜(SEM))。细胞繁殖和生化分析表明,在n-TiO2-10%HA涂层上培养的hMSCs表现出了类似的或优于APS-HA涂层上的hMSCs生物活性。细胞骨架组织在超音速火焰喷涂n-TiO2-10%HA涂层表面上具有更高的细胞繁殖和附着程度。这些结果对下一代高性能长寿命热喷涂生物涂层具有重要意义。     

Development of CeO2 nanorods reinforced electrodeposited nickel nanocomposite coating and its tribological and corrosion resistance properties

A simple electrodeposition technique was used to prepare Ni-CeO_2 nanorods composite coating(Ni-CeO_2 NRs) using Watt's nickel plating bath containing CeO_2 nanorods(NRs) as the reinforcement phase under optimized process conditions. The X-ray diffraction analysis(XRD) was used for the structural analysis of Ni-CeO_2 NRs composite coatings and their average crystalline size is ～22 nm for pure Ni and ～18 nm,respectively. The crystalline structure is fcc for the Ni-CeO_2 nanocomposite coatings. The surface morphology of the electrodeposited Ni-CeO_2 NRs composite coatings was analyzed by scanning electron microscopy(SEM). Microhardness of pure Ni and Ni-CeO_2 NRs composite coatings are found to be 253 HV and 824 HV, respectively. The inclusion of CeO_2 NRs increases the microhardness of Ni-CeO_2 NRs composite coatings. The corrosion resistance behavior of Ni-CeO_2 NRs composite coating was evaluated by Tafel polarization and AC impedance methods. It is revealed that CeO_2 NRs reinforced Ni matrix shows higher microhardness and corrosion resistance than existing reported electrodeposited pure Ni and CeO_2 nanoparticles reinforced Ni coatings.     

微/纳米结构含锌硅酸钙基涂层成骨性能研究

骨科植入物涂层的表面形貌和化学组成对炎症反应的进程和骨形成的发生都发挥着重要调节作用。为综合利用微/纳米仿生结构和生物活性元素的优势,将含锌(Zn)的纳米结构物质引入到经水热处理后的等离子喷涂硅酸钙(calcium silicate, CS)涂层表面,对所制备涂层的物相组成、表面和截面形貌、比表面积、Zeta电位和生理环境下离子溶出等物理化学性能进行了表征。相比于常规CS涂层,具有微/纳米复合结构的CS和含锌CS涂层拥有更高比表面积和孔容,可吸附更多血清蛋白和纤维连接蛋白,通过刺激细胞内整合素以及下游vinculin和FAK基因表达,提高了骨髓间充质干细胞(BMSCs)铺展能力。涂层中锌的引入进一步提高了其表面BMSCs的增殖能力和与成骨细胞分化相关的基因表达。具有微/纳米复合结构的涂层明显上调了RAW264.7巨噬细胞中M2表型因子(CD206和ARG)基因表达,而涂层中溶出的Zn²⁺显著提高了RAW264.7细胞中抑炎症因子(IL-1ra和IL-10)基因表达,促使其向抑炎症表型转化。骨科植入物涂层表面锌元素和纳米结构的引入有利于创建良好的骨免疫微环境,促进骨...     

Biphasic calcium phosphate concept applied to artificial bone, implant coating and injectable bone substitute

The development of calcium phosphate ceramics and other related biomaterials for bone graft involved a better control of the process of biomaterials resorption and bone substitution. The bioactive concept was developed for biphasic calcium phosphate ceramics (BCP). An optimum balance of the more stable phase of HA and more soluble TCP was obtained for controlling gradual dissolution in the body, seeding new bone formation as it releases calcium and phosphate ions into the biological medium. The bone/material interface and the events occurring in the development of this dynamic interface such as cellular response, biodegradation or bioresorption of the materials and their transformation to carbonate hydroxyapatite (CHA) were described. These processes were observed in both bulk samples, implant coating and injectable bone substitute (IBS).     

Dynamics of Gradient Bioceramic Composite Coating on Surface of Titanium Alloy by Wide-Band Laser Cladding

Hydroxyapatite (HA) ,akindofbioactivematerial,haswideapplicationprospectinhardtissuereplacementandrepairbecauseofsimilarchemicalcompositionandcrystallographicstructuretothoseofbonemineral[1,2 ] .TheHAcoatingwithbioactivityandbiocompatibilityonthesur faceo…     

Formation of hydroxyapatite in new calcium phosphate cements

Tetracalcium phosphate (TTCP) has been shown previously to be an essential component of self-setting calcium phosphate cements that form hydroxyapatite (HA) as the only end-product. We report herein on a new self-setting calcium phosphate cement that does not contain TTCP. These cements consist of dicalcium phosphate anhydrous (DCPA), dicalcium phosphate dihydrate (DCPD), alpha-tricalcium phosphate, or amorphous calcium phosphate and, as an additional source of calcium, calcium hydroxide or calcium carbonate. These cements require the use of a phosphate (0.2 moll(-1) or higher) solution or a high pH solution as the cement liquid. The cements harden in relatively short time (5-30 min) and form HA as the dominant end-product in 24 h. The diametral tensile strengths of the 24-h samples are in the range of 0.2 to 7.5 MPa. Results from X-ray diffraction studies suggest that the cement setting is caused by rapid HA formation induced by the high phosphate concentration of the cement liquid. Because DCPA and DCPD are highly soluble at pH values above 12.7, which is the pK3 of phosphoric acid, high phosphate concentration in the slurry solution was also attainable by using a highly alkaline solution as the cement liquid. The physicochemical properties of these cements are comparable to those of TTCP-containing cements, and the new cements may be expected to have in vivo characteristics similar to those of TTCP-containing cements as well.     

Hydroxyapatite and Fluoridated Hydroxyapatite Coatings and Their Effects on Commercially Pure Magnesium Corrosion Response

Dicalcium-phosphate dehydrate, converted to hydroxyapatite by post-treatment in sodium hydroxide, and fluoridated hydroxyapatite were electrodeposited on commercially pure magnesium substrates that were pretreated with sodium hydroxide. The coatings’ crystalline structure, thickness, scratch hardness, morphology and chemical composition were characterised by GIXRD, microscratch testing platform, SEM and EDS. The results showed that the apatite coatings had highly crystalline structure, acceptable scratch hardness, flake-like morphology and acceptable chemical composition. Corrosion behaviour of the uncoated and coated substrates was investigated by potentiodynamic polarization and immersion tests in simulated body fluid. The coated substrates, especially fluoridated hydroxyapatite coated substrates, showed significantly lower corrosion rates compared to uncoated substrates. The polarisation curves showed that the coatings hindered anodic reactions; the corrosion potentials were shifted toward less-negative. In general, this study concluded that the corrosion rate of commercially pure magnesium could be significantly decreased to be a candidate for future cost-effective biodegradable orthopaedic implants.     

Mechanical and histological evaluation of amorphous calcium phosphate and poorly crystallized hydroxyapatite coatings on titanium implants

The effect of amorphous calcium phosphate (Ca/P) and poorly crystallized (60% crystalline) hydroxyapatite (HA) coatings on bone fixation to "smooth" and "rough" (Ti-6A1-4V powder sprayed) titanium-6Al-4V (Ti) implants was investigated. Implants were evaluated histologically, mechanically, and by scanning electron microscopy (SEM) after 4 and 12 weeks of implantation in a rabbit transcortical femoral model. Histological evaluation of amorphous vs. poorly crystallized HA coatings showed significant differences in bone apposition (for rough-coated implants only) and coating resorption (for smooth- and rough-coated implants) that were increased within cortical compared to cancellous bone. The poorly crystallized HA coatings showed most degradation and least bone apposition. Mechanical evaluation, however, showed no significant differences in push-out shear strengths between the two types of coatings evaluated. Differences between 4 and 12 weeks were significant for coating resorption and push-out shear strength but not for bone apposition. Significant enhancement in interfacial shear strengths for bioceramic coated as compared to uncoated implants were seen for smooth-surfaced implants (3.5-5 times greater) but not for rough-surfaced implants at 4 and 12 weeks. Rough implants showed greater mean interfacial strengths than uncoated smooth implants at 4 and 12 weeks (seven times greater) and to coated smooth implants at 12 weeks only (two times greater). Mechanical failure of the bone/coating/implant interface consistently occurred within the bone, even in the case of the poorly crystallized HA coatings, which had almost completely resorbed on rough implants. These results suggest that once early osteointegration is achieved biodegradation of a bioactive coating should not be detrimental to the bone/coating/implant fixation.     

Formation of Hydroxyapatite Coating on Anodic Titanium Dioxide Nanotubes via an Efficient Dipping Treatment

Hydroxyapatite (HA) depositions on metallic biomedical implants have been widely applied to generate bioactive surfaces in simulated biological environments. Meanwhile, highly ordered TiO₂ nanotubes obtained via anodization have attracted increasing interest for biomedical applications. However, the capability to grow HA coating on TiO₂ nanotubes at room temperature remains problematic. In this study, we applied a dipping treatment for biomimetic formation of an adhesive HA coating on titanium dioxide nanotubes. The coatings formed using this procedure did not require high-temperature annealing or high supersaturation of the simulated biological condition. The as-formed TiO₂ nanotubes on titanium were treated using several dip-and-dry steps, through which the TiO₂ nanotubes were filled and covered with calcium phosphate nucleation sites. The specimens readily grew HA once immersed in the original simulated biological fluid (SBF) after little more than 12 hours. The carbonated HA coating was formed with 10-??m thickness after 4 days of immersion, while only a few calcium phosphate particles were observed on annealing TiO₂ nanotubes immersed in the same solution for the same duration. Tensile testing showed that the bonding strength between HA coating and substrate was 27.2 ± 1.6 MPa. This treatment dramatically improved efficiency for promoting HA formation on anodic TiO₂ nanotubes at room temperature.     

等离子喷涂氧化钇稳定氧化锆涂层的分形特征与断裂韧性

采用超音速等离子喷涂和普通大气等离子喷涂制备了微米级氧化钇稳定氧化锆（yttria-stabilized zirconia,YSZ）基热障涂层,使用SprayWatch-2i系统测试喷涂过程中粒子飞行速度及表面温度,通过扫描电镜和图像分析技术表征涂层微观结构,利用压痕法测试了断裂韧性和弹性模量,采用基于分形思想的面积-周长幂率定量表征两种工艺条件下孔隙不规则形态,并研究了分形维数对涂层断裂韧性的影响。结果表明:超音速等离子喷涂和普通大气等离子喷涂YSZ涂层孔隙都具有分形特性;超音速等离子喷涂YSZ涂层分形维数是普通等离子喷涂涂层的1.12倍,孔隙结构更复杂,涂层断裂韧性更高。     

X-ray powder diffraction patterns of calcium phosphates analyzed by the Rietveld method

Least-square refinement of x-ray powder diffraction patterns analyzed by the Rietveld method can yield structural information which had been unattainable or at least elaborate to obtain by conventional pattern analysis. The Rietveld method calculates a powder pattern on the basis of a structural model as well as the characteristics of the instrument used, and minimizes the differences between the intensities observed and the intensities calculated. The method is applied on patterns produced powders or polycrystalline solids on conventional powder diffractometers. For materials containing more than one crystalline phase with known structures such as hydroxyapatite (HA) and whitlockite (beta-TCP), pattern analysis yields phase quantification without internal or external standards. Refinement of the lattice parameters a0 and c0 determines the degree of dehydroxylation in plasma-sprayed HA coatings. The presence of amorphous Ca phosphates in HA coatings is detected by background modeling. The calculation of entire powder patterns allows discrimination of small concentrations of poorly crystallized Ca phosphate phases against the background, and prevents gross aberrations in estimating secondary phases. Even detect structures such as an OH-deficient HA lattice can be detected through slight differences in diffracted intensity by which the pattern calculated deviates from the pattern observed.     

Quality of life and productivity in nurses reporting migraine

Calcium phosphate bone cements (CPBCs) are osteotransductive, i.e. after implantation in bone they are transformed into new bone tissue. Furthermore, due to the fact that they are mouldable, their osteointegration is immediate. Their chemistry has been established previously. Some CPBCs contain amorphous calcium phosphate (ACP) and set by a sol-gel transition. The others are crystalline and can give as the reaction product dicalcium phosphate dihydrate (DCPD), calcium-deficient hydroxyapatite (CDHA), carbonated apatite (CA) or hydroxyapatite (HA). Mixed-type gypsum-DCPD cements are also described. In vivo rates of osteotransduction vary as follows: gypsum-DCPD > DCPD > CDHA approximately CA > HA. The osteotransduction of CDHA-type cements may be increased by adding dicalcium phosphate anhydrous (DCP) and/or CaCO3 to the cement powder. CPBCs can be used for healing of bone defects, bone augmentation and bone reconstruction. Incorporation of drugs like antibiotics and bone morphogenetic protein is envisaged. Load-bearing applications are allowed for CHDA-type, CA-type and HA-type CPBCs as they have a higher compressive strength than human trabecular bone (10 MPa).     

Characterization of hydroxyapatite film with mixed interface by Ar+ ion beam enhanced deposition

Ar+ ion beam enhanced deposition (IBED) was used to produce a hydroxyapatite (HA) film on polished titanium substrates. In this study, the HA ceramic target was sputtered by an argon-ion beam with an energy of 1.5 KeV, and the sputtered film was intermittently bombarded by energetic argon-ions at 60 KeV. An effective Ca-Ti mixed layer produced by the energetic argon-ion bombardment was confirmed by using Auger electron spectroscopy. The characteristics of the deposited films were evaluated by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. XRD analysis revealed that the as-deposited film was amorphous, and a hydroxyapatite-type structure was obtained from the post-heat treatment of the deposited films. SEM observations showed that no distinct difference in surface morphology was found between the as-deposited and heat-treated samples for Ar+ IBED films, suggesting a strongly bonded HA film on the titanium substrate. In comparison with the HA target, some chemistry alterations were brought about in the deposited films, such as the incorporation of CO3, the loss of the OH groups and some distortion of the phosphate lattice.     

Synthesis and Properties of Pulse Electrodeposited Ni-CeO2 Nanocomposite

Ni-CeO₂ nanocomposite coatings were pulse electrodeposited from the Watt??s electrolyte containing different concentrations of nanosized CeO₂ particles (10, 20, 30, 40, and 50?g/L). The microhardness, thermal stability, and corrosion resistance of these coatings were evaluated and compared with those of pure nanocrystalline Ni deposited under the same conditions. The results show that the Ni-CeO₂ nanocomposite coating, synthesized from the electrolyte containing 30?g/L CeO₂, has significantly higher hardness, thermal stability, and corrosion resistance than those of the pure nanocrystalline Ni and other Ni-CeO₂ nanocomposite coatings.     

钙离子的浓度对X80钢腐蚀行为的影响

采用失重法、电化学测试、扫描电镜、X射线衍射等方法研究了钙离子浓度对X80钢在哈密土壤模拟溶液中的腐蚀行为影响.在60d浸泡期内,X80钢在不同钙离子浓度模拟溶液中的腐蚀形态均为全面腐蚀,腐蚀产物都为B-FeOOH;X80钢在模拟溶液中的腐蚀速率随钙离子浓度的降低而呈逐渐增大的趋势.在180d浸泡期内,在钙离子浓度为63.5mmol·L-1的模拟溶液中,钙盐随时间的增加在X80钢基体表面不断结晶析出;钙盐层有效阻碍了溶解氧的迁移,并促进其覆盖区域下形成氧浓差电池,最终导致基体表面点蚀的萌生.同时,在内层腐蚀产物表面连续析出的钙盐层的致密性也随时间不断得到改善,在一定程度上起到了抑制氯离子和溶解氧对基体的侵蚀作用,X80钢的全面腐蚀逐渐减缓.      

Morphology and microstructure of electrochemically deposited calcium phosphates in a modified simulated body fluid

Calcium phosphates were deposited on a pure titanium plate for various loading times under 1.3 and 12.9 mA/cm2 in a modified simulated body fluid at 52-92 degrees C. The plate-like crystals formed under 1.3 mA/cm2 were identified to be octacalcium phosphate (OCP) and/or carbonate-containing apatite. OCP converted to carbonate-containing apatite with the elapsing time of the loading current. The needle-like precipitates formed under 12.9 mA/cm2 were identified to be carbonate-containing apatite crystals elongated parallel to the c-axis direction. The degrees of crystallinity of the deposits formed under 1.3 mA/cm2 showed the highest value around 72 degrees C, whereas those under 12.9 mA/cm2 increased with the electrolyte temperature. The carbonate content of the deposits decreased with the electrolyte temperature and the flow current. The degree of crystallinity of the electrochemically deposited calcium phosphates decreased with the carbonate content.     

Galvanic powder coatings for tribotechnical purposes

The state of stress and strain is considered for composite gradient coatings, in which the basic type of structure is layered, matrix, or skeletal, and which may be loaded by static or averaged dynamic forces or tangential frictional forces. It is shown that there is high carrying capacity and adequate wear resistance in coatings of gradient type containing nanocomposite matrices and uniformly distributed macroscopic impurities. The best material for sliding friction under high loads is dispersion-hardened or diffusion-alloyed matrix deposited on oriented crystalline eutectic layer (columnar type) containing macroinclusions which are linked by diffusion interaction zones with the metal matrix and the substrate.