在非水溶液体系中电泳沉积Ti6Al4V/BG/HA梯度涂层

本工作的目的是探索制备钛合金表面生物活性梯度涂层的新方法 ,提高涂层的结合强度及稳定性 .通过诱导羟基磷灰石 (HA)在生物玻璃 (BG)颗粒表面的结晶 ,改变了生物玻璃表面的带电特性 ;采用电泳沉积 (EPD)法 ,在非水溶液体系中实现了BG和HA在阴极Ti6Al4V基体上的共沉积 ,经烧结获得了生物活性梯度陶瓷涂层 ,得到了一种制备生物活性梯度陶瓷涂层的新工艺 .用XRD对涂层的相组成进行了定性分析 ,结果表明涂层由HA ,榍石和玻璃组成 ;采用粘结拉伸法测定的涂层与基体结合强度大于 18MPa,用SEM观察涂层表面及断面的形貌 ,可见涂层表面较为平整 ,没有明显的裂纹 ;涂层与基体结合紧密 ,且存在一明显的界面梯度区域 .     

冰醋酸介质中电泳共沉积制备生物玻璃/羟基磷灰石涂层

通过研究生物玻璃(bioglass，BG)微粉和羟基磷灰石(hydroxyapatite，HA)微粉在水和非水介质中的分散及带电特性，选择冰醋酸为介质，使分散在其中的BG颗粒和HA颗粒表面均带上正电荷，为电泳共沉积提供了前提条件。通过对BG颗粒和HA颗粒在冰醋酸介质中电泳共沉积以及后续低温快速热处理，在钛合金基体上成功地制备出了底层致密而表层附近多孔的BG／HA涂层。并对所制备的BG／HA涂层的力学性能和微观结构及组成进行了测试分析。     

溶胶-凝胶法在医用Ti合金表面制备SiO2-CaO-MgO-P2O5系生物玻璃涂层

在医用Ti合金表面涂覆一层生物玻璃涂层可阻止金属离子的溶出并且提高其生物活性。本文采用溶胶-凝胶法在Ti合金基体上制备了Si02-CaO-MgO-P2O5系生物玻璃涂层。利用差示量热扫描仪（DSC）、扫描电镜（SEM）、拉伸试验和模拟体液（SBF）浸泡等手段系统研究了涂层的表面形貌，粘附性能及生物活性。结果表明：热处理温度为800℃时涂层与基体间的粘附强度最大，涂层越薄涂层与基体问的粘附强度越大；在模拟体液中浸泡30天后，材料表面生成了大量磷灰石。用溶胶-凝胶法可在Ti合金基体上制备出SiO2-CaO-MgO-P2O5系生物活性高的生物玻璃涂层。     

电泳沉积和反应结合制备羟基磷灰石/氧化铝复合涂层

在金属表面用电泳沉积(electrophoretic deposition, EPD)法制备羟基磷灰石(hydroxyapatite, HA)涂层的主要问题是结合强度较低.为了提高HA涂层与基体的结合强度,先采用EPD在钛表面制得羟基磷灰石/铝(hydroxyapatite/aluminum, HA/Al)复合涂层,然后采用反应结合方法(reaction bonding process)制备羟基磷灰石/氧化铝(hydroxyapatite/aluminum oxide, HA/Al2O3)复合涂层,并与相同条件下制备的HA单一涂层进行比较研究.用扫描电镜表征涂层的表面和横截面形貌.用能量散射X射线衍射(X-ray diffraction, XRD)谱分析HA/Al2O3复合涂层的化学组成.用XRD仪研究涂层的物相组成和热稳定性.通过黏结-拉伸实验测定HA涂层与基体的结合强度.结果表明:通过850℃热处理,HA/Al复合涂层中的Al粉发生氧化反应生成Al2O3,经反应结合得到HA/Al2O3复合涂层;反应结合提高了HA涂层的致密化程度且降低了基底钛表面的氧化程度;与单一HA涂层相比,HA/Al2O3复合涂层与基底间的结合强度得到明显提高.     

钛板表面生物活性梯度陶瓷涂层的制备

采用涂覆-烧结法制备了一种以金属钛为基体的二氧化钛-羟基磷灰石梯度涂层材料.通过对其进行成分设计,从而将金属钛、羟基磷灰石这两种材料各自的优点综合起来,并弥补了相互的不足.用扫描电镜（SEM）、X射线衍射仪（XRD）及粘结拉伸试验研究了该生物梯度材料的制备、组织结构、表面形貌、化学组成以及力学性能.试验证明,该材料具有较好的结合强度以及优良的生物活性,是一种很有前景的骨替换材料.     

医用Ti合金表面生物玻璃涂层的制备与研究

在医用Ti合金表面涂覆一层生物玻璃涂层可阻止金属离子的溶出并且提高其生物活性。本文采用溶胶-凝胶法在Ti合金基体上制备了SiO2-CaO-MgO-P2O5系生物玻璃涂层。利用差示量热扫描仪(DSC)、扫描电镜(SEM)、拉伸试验和模拟体液(SBF)浸泡等手段系统研究了涂层的表面形貌、粘附性能及生物活性。结果表明:热处理温度为800℃时涂层与基体间的粘附强度最大,涂层越薄涂层与基体间的粘附强度越大;在模拟体液中浸泡30天后,材料表面生成了大量磷灰石。用溶胶-凝胶法可在Ti合金基体上制备出SiO2-CaO-MgO-P2O5系生物活性高的生物玻璃涂层。     

钛合金表面涂烧生物活性玻璃陶瓷涂层的性能与结构

采用涂烧法在钛合金表面制备出结合强度高,化学稳定性好,防组织液渗透和生物相容性良好的复合生物玻璃陶瓷涂层。用XRD,FT－IR等方法研究了涂层的组成、结构和性能。结果表明：底釉由玻璃相、FAP和榍石晶相组成;多孔生物玻璃陶瓷涂层由玻璃相、FAP和β－CaSiO3晶相组成;复合涂层能与骨组织产生骨性结合。     

溶胶凝胶法制备羟基磷灰石/TiO2复合生物活性涂层的研究

通过溶胶凝胶法在纯钛基体上制备了羟基磷灰石/TiO2复合生物活性涂层.HA可以提高钛基的生物活性,TiO2可以提高涂层与基体的物理、化学相容性和结合强度.HA和TiO2溶胶由前驱体制得,按不同物质的量比直接混合两种溶胶来制备复合溶胶.使用XRD、SEM研究了不同温度下热处理后涂层的组成和结构.实验结果表明HA的结晶度和晶粒随着温度的升高而提高和变大;涂层表面为连续多孔结构.粘结拉伸结果表明复合涂层与基体结合良好,较纯HA涂层与基体的结合强度有较大提高.复合涂层试样于SBF中浸泡2d、7d和14d的SEM分析结果表明复合涂层表面的磷灰石形成量较高.电位动力学曲线分析表明复合涂层可以提高基体的耐蚀性.     

水热电沉积法制备羟基磷灰石/氧化钛复合涂层的研究

采用水热电沉积法．在钛金属基体￡：成功制备了羟基磷灰石(hydroxyapatite,HA)氧化钛(HA／TiO2)复合涂层．对涂层的表面形貌、相组成、TiO2共沉积量、热稳定性和结合强度进iir研究。实验结果表明：复合涂层具有较均匀的微观结构。TiO2的加入明显改善了涂层与基体的结合强度．涂层中TiO2含量越高．结合强度的提高也越显著。在200℃．100g／L TiO2条件下．电沉积制备的HA／TiO2复合涂层的结合强度为21.0MPa,约为纯HA涂层的2倍。TiO2共沉积量随电解液中TiO2浓度的提高逐渐增加;随电解液温度的提高先增后降,在160C达到最大。涂层经800℃热处理后,TiO2促使HA部分分解为β-磷酸钙(β-tricalciumphosphate,β-TCP)和CaO;经1200℃热处理后,HA和TiO2发生相互作用生成α-TCP和CaTiO3。     

以葡萄糖为造孔剂制备多孔羟基磷灰石涂层

采用电泳沉积方法在钛基材表面制得羟基磷灰石(hydroxyapatite,HA)/葡萄糖复合涂层,经烧结处理得到多孔HA涂层。采用红外光谱仪、扫描电镜、X射线衍射和热重分析表征了涂层的组成、表面形貌、物相组成及热稳定性,黏结-拉伸实验测定涂层与基体的结合强度,人体模拟体液(simulated body fluid,SBF)浸泡测定涂层的生物亲合性。结果表明:经700℃烧结处理,复合涂层中的葡萄糖微粒热分解得到多孔HA涂层,孔径为2～20μm,涂层与基体的结合强度可达17.6MPa;在1.5倍SBF(各离子浓度为SBF的1.5倍)中浸泡5d后,多孔HA涂层表面碳磷灰石化,呈现良好的生物亲合性。     

Preparation and properties of poly(Nε,Nε-dicarboxymethyl-l-lysine)

A new ampholytic homopolypeptide, $\text{poly}\text{(N}{}^{\mathrm{\epsilon }}\text{,N}{}^{\mathrm{\epsilon }}\text{-}\text{dicarboxy-methyl-}\text{l}\text{-lysine}\text{)}$, which has one tertiary amino and two carboxyl groups in the side chain has been derived from a hydrochloride salt of poly(L-lysine). The polymer in aqueous solution seems to be in the coil form with locally extended structure (LES) at neutral pH. In both the acidic and alkaline regions, the molar ellipticity of the polymer changes as a result of change in net charge on the side chain. The conformational changes may be from the coil with LES to other coiled forms. 5–7 M NaClO₄ and 80% aqueous methanol induce the α-helix in the polymer at neutral pH. Divalent cations, Cu²⁺ and Ca²⁺, do not induce any remarkably ordered structures such as α-helix or β-structure in the polymer in aqueous solution at any pH. Ultraviolet absorption studies show an absorption peak of the polymer-Cu²⁺ complex near 240 nm. Dependence of the peak intensity on pH at various q values ($\text{q =}\text{[}\text{Cu}{}^{\mathrm{2+}}\text{]}\text{[}\text{residue}\text{]}$) indicates the two steps of the complex formation. At q less than 0.64, the formation is described only with the first step. An average coordination number for Cu²⁺ at the first step was calculated to be about 2 by the method of Mandel and Leyte. The association constant of Cu²⁺ with the residue at the step was determined from the absorption data to be far smaller than that for the Cu²⁺-EDTA complex. The second step of the formation occurs in the case of large q but the absorption data for the second step cannot be obtained exactly due to precipitation.     

Wet Milling of Fe/Al/Al2O3 and Fe2O3/Al/Al2O3 Powder Mixtures

Wet milling of Al₂O₃-aluminide alloy (3A) precursor powders in acetone has been investigated by milling Fe/Al/Al₂O₃ and Fe₂O₃/Al/Al₂O₃ powder mixtures. The influence of the milling process on the physical and chemical properties of the milled powders has been studied. Particle refinement and homogenization were found not to play a dominant role, whereas plastic deformation of the metal particles leads to the formation of dislocations and a highly disarranged polycrystalline structure. Although no chemical reactions among the powder components in Fe₂O₃/Al/Al₂O₃ powder mixtures were observed, the formation of a nanocrystalline, ordered intermetallic FeAl phase in Fe/Al/Al₂O₃ powder mixtures caused by mechanical alloying was detected. Chemical reactions of Fe and Al particle surfaces with the atmosphere and the milling media lead to the formation of highly porous hydroxides on the particle surfaces. Hence the specific surface area of the powders increases, while the powder density decreases during milling. The fraction of Fe oxidized during milling was determined to be 0.13. The fraction of Al oxidized during milling strongly depends on the metal content of the powder mixture. It ranges between 0.4 and 0.8.     

Participation of lewis base on vinyl chloride polymerization with Al(C2H5)3CCl4 catalyst system

The polymerization of vinyl chloride has been investigated using an $\text{Al}\text{(}\text{C}{}_2\text{H}{}_5\text{)}{}_3\text{CCl}{}_4$ catalyst system in the presence of various Lewis bases. Effective Lewis bases are γ-butyrolactone, diglyme and diethylenetriamine which are multidentate. The rate of polymerization is dependent not only on the basicity of the Lewis base used but also on a coordination number of one. The latter is the predominant factor. For the effect of polymeric amines, a tentative hypothesis is discussed.     

Sintering of Si3N4-Y2O3-Al2O3

Sintering kinetics of the system Si₃N4-Y2O₃-Al₂O3 were determined from measurements of the linear shrinkage of pressed disks sintered isothermally at 1500° to 1700°C. Amorphous and crystalline Si₃N₄ were studied with additions of 4 to 17 wt% Y₂O₃ and 4 wt% A1₂O₃. Sintering occurs by a liquid-phase mechanism in which the kinetics exhibit the three stages predicted by Kingery's model. However, the rates during the second stage of the process are higher for all compositions than predicted by the model. X-ray data show the presence of several transient phases which, with sufficient heating, disappear leaving mixtures of β ' -Si₃N₄ and glass or β '-Si₃N₄, α '-Si₃N₄, and glass. The compositions and amounts of the residual glassy phases are estimated.     

Synthesis and Characterization of Ti0.33Ta0.33Nb0.33C and Ti0.33Ta0.33Nb0.33CxN1-x Whiskers

Ta_0.33Ti_0.33Nb_0.33C and Ta_0.33Ti_0.33Nb_0.33C _x N_{1− x} whiskers were synthesized via a carbothermal vapor-liquid-solid growth mechanism in the temperature range 900°-1450°C in Ar or N₂. The optimum temperature was 1250°C. Whiskers were obtained in a yield of 70-90 vol%. The whiskers were 0.5–1 µm in diameter and 10–30 µm in length. The starting materials that produced the highest whisker yield were: TiO₂, Ta₂O₅, Nb₂O₅, C, Ni, and NaCl. C was added to reduce the oxides, and Ni to catalyze whisker growth. NaCl was used as a source of Cl for vapor-phase transportation of Ta and Nb oxochlorides and Ti chlorides to the catalyst. The catalyst metal was recycled several times during the synthesis and was transported as NiCl₂( g ) according to thermodynamic calculations. The rate of formation and the chemical composition of the whiskers depended on the synthesis temperature, the choice of catalyst, and the atmosphere. At low temperatures, the whiskers were enriched in Nb and Ta, whereas the Ti content increased with increased synthesis temperature.