用冲击波合成法制备羟基磷灰石粉体

 羟基磷灰石（HA）已广泛用作人体硬组织的修复和替换材料，采用冲击波处理CaCO₃与CaHPO₄·2H₂O的混合物合成了HA粉末，并用XRD、SEM和FTIR对制得的粉末进行了表征。研究结果表明：与传统的高温焙烧法相比，冲击波法合成的HA粉末不仅有类似的晶相结构及成分，而且含有少量CO₃^2-离子，为类人骨的羟基磷灰石；其粒度更细、分布更均匀、内部存在大量的晶格畸变，有更高的活性。冲击波处理是合成HA粉末的一种新方法。     

氮化硅粉末的冲击波活化研究

 研究了经过两种不同压力15.7 GPa和25.6 GPa的冲击波活化的Si₃N₄粉末的表观和显微特性及其烧结特性。结果表明冲击波活化在烧结过程中有明显的增进密实化进程的作用。     

烧结温度对Eu3+在羟基磷灰石中发光性能的影响

采用化学沉淀法制备了一系列Eu³⁺掺杂的羟基磷灰石样品,并在不同温度下对样品进行了烧结.使用X射线衍射、红外光谱以及荧光光谱等对样品的结构及发光特性进行了研究.分析表明,烧结对Eu掺杂羟基磷灰石的结构及结晶度产生了影响.在394 nm激发下,样品出现Eu的特征发射,掺杂摩尔分数一定时,随烧结温度增加,样品的荧光发光强度先增大后减小,在500 ℃达到峰值.其荧光寿命随烧结温度的升高而延长.此外,样品中电偶极跃迁与磁偶极跃迁强度之比(I_R:I_O)也随烧结温度的增加先增大后减小.分析表明,烧结温度的改变通过晶体结构对样品的荧光特性以及掺杂取代位置产生了影响.     

PZT-95/5压电陶瓷的冲击波活化改性研究

 研究了冲击波对PZT-95/5压电陶瓷的活化改性作用，对PZT-95/5粉末及块状材料进行动态冲击波加载。实验表明：在合适的条件下，冲击波作用可提高样品的密度ρ，压电应变常数d₃₃，介电常数ε，降低介电耗损系数tg δ%。通过对样品进行X射线衍射，扫描电镜SEM、透射电镜TEM和X射线光电子能谱XPS等微观测试分析，揭示了冲击波改性的机理主要是：晶粒细化，晶界破坏，孔隙增多，缺陷增多，相变产生等，从而达到对样品改性的作用。     

PZT－95／5压电陶瓷的冲击波活化改性研究

研究了冲击波对ＰＺＴ－９５／５压电陶瓷的活化改性作用，对ＰＺＴ－９５／５粉末及块状材料进行动态冲击波加载。实验表明：在合适的条件下，冲击波作用可提高样品的密度ρ，压电应变常数ｄ３３，介电常数ε，降低介电耗损系数ｔｇδ％。通过对样品进行Ｘ射线衍射，扫描电镜ＳＥＭ、透射电镜ＴＥＭ和Ｘ射线光电子能谱ＸＰＳ等微观测试分析，揭示了冲击波改性的机理主要是：晶粒细化，晶界破坏，孔隙增多，缺陷增多，相变产生等，从而达到对样品改性的作用     

水溶性BSA-羟基磷灰石-碳酸钙复合物的形成机理

本文以傅里叶变换红外光谱为手段,对不同反应摩经的牛血清蛋白（ＢＳＡ）、羟基磷灰石、碳酸钙固体在水溶液中反应后的滤液进行了研究,谱带峰位和强度的变化表明,ＢＳＡ与羟基磷灰石、碳酸钙以多种形式的络合配位及氢键等结合,使难溶钙盐的溶解度增加,形成三元水溶性复合物,其复合物的组成随反应摩尔比的改变而有差异,具有化学计量的性质。     

TiO2的冲击波活化及其光催化活性

实验研究了金属氧化物催化剂ＴｉＯ２在经受不同的冲击波压力处理后,对Ｈ２Ｓ脱氢反应的光催化活性变化。结果表明,与未冲击样品相比,冲击波处理后ＴｉＯ２的光催化活性得到了明显提高。在１６￣３４ＧＰａ的实验压力范围内,催化活性提高了２￣３倍,初步分析认为,冲击波处理使样品晶粒中生成大量残余应变和位错缺陷,以及使ＴｉＯ２能隙宽度减小,这是光催化活性提高的主要原因。     

铽掺杂羟基磷灰石的制备及其荧光特性

在室温下采用化学沉淀法制备了铽掺杂的羟基磷灰石(Tb-HAP),通过X射线衍射分析(XRD)、傅里叶变换红外光谱(FT-IR)和荧光光谱(PL)等对其结构和荧光性能进行了表征分析。XRD和FT-IR测试表明,Tb³⁺的掺杂对羟基磷灰石的结构没有显著影响。荧光光谱分析表明:在545 nm波长监测下,测得的最佳激发波长为378 nm。样品的发光强度随Tb³⁺在样品中的掺杂摩尔分数先增大后减小,在8%时发光最强。此外,Tb-HAP样品的荧光寿命随着Tb³⁺掺杂摩尔分数的增加呈现减小的趋势。     

珊瑚水热转换羟基磷灰石中的影响因素

分别在不同的反应温度、不同的pH值、加矿化剂与否的条件下,将滨珊瑚水热转换为珊瑚羟基磷灰石。利用X射线衍射（XRD）、扫描电子显微镜（SEM）分别对产物和中间产物的物相和微结构进行了分析。发现不同条件下存在有不同的反应路径。考察了反应温度、pH值和矿化剂对珊瑚水热反应的影响。     

石墨烯/羟基磷灰石复合材料力学性能的数值研究

为了研究石墨烯/羟基磷灰石复合材料力学性能（弹性模量和泊松比）,开发了石墨烯/羟基磷灰石复合材料的随机分布模型自动生成算法及相应的计算程序;建立石墨烯/羟基磷灰石复合材料的有限元模型,计算添加不同质量分数的石墨烯对复合材料力学性能的影响,通过与实验数据对比验证算法的有效性.结果表明：添加0.25%~1.25%（质量分数）的石墨烯可使复合材料的弹性模量增加12%~50%,表明添加少量石墨烯即能有效地改善羟基磷灰石的力学性能.     

Raman Spectroscopy Investigation of Nano Hydroxyapatite Doped with Yttrium and Fluoride Ions

In this study, nano hydroxyapatite doped with yttrium (2.5, 5, and 7.5 mol%) and fluoride (2.5 mol%) ions were synthesized by precipitation method and sintered at 900°C, 1100°C, and 1300°C. Raman spectroscopy was applied to track the structural modifications in pure and doped hydroxyapatites. The results showed that the main characteristic band of pure hydroxyapatite at 963 cm^?1 was not affected significantly by ion doping but exhibited higher intensity with increasing sintering temperature. Due to fluoride substitution, the 1048 and 1034 cm^?1 bands of pure hydroxyapatites appeared with a wavenumber shift in the spectra of ion-doped hydroxyapatites. The 333 cm^?1 band of pure hydroxyapatite disappeared and an additional calcium–fluor bond at 322 cm^?1 was observable in ion-doped hydroxyapatites. Two fluorescence bands at 770 and 697 cm^?1, which were also observed in the spectra of pure hydroxyapatites, shifted to higher wavenumbers in the spectra of ion-doped hydroxyapatites. This was considered to result from the perturbation in the hexagonal structure of hydroxyapatite due to yttrium and fluoride codoping.     

Calcination of Rod-like Hydroxyapatite Nanocrystals with an Anti-sintering Agent Surrounding the Crystals

Sintering-free nanocrystals of calcined hydroxyapatite (HAp) having a rod-like morphology were fabricated by calcination at 800°C for 1 h with an anti-sintering agent surrounding original HAp particles and the agent was subsequently removed after calcination. The original HAp particles having a rod-like morphology with a size ranging from 30 to 80 nm (short axis) and 300 to 500 nm (long axis) were prepared by wet chemical process, and poly(acrylic acid, calcium salt) (PAA-Ca) was used as the anti-sintering agent. In the case of calcination without additives, the mean size of HAp crystals dispersed in an ethanol medium increased by about 4 times and the specific surface area of the crystals exhibited a 25% decrease compared to those of the original HAp particles because of calcination-induced sintering among the crystals. On the other hand, the HAp crystals calcined with the anti-sintering agent, PAA-Ca, could be dispersed in an ethanol medium at the same size as the original particles, and they preserved the specific surface area after calcination. These results indicate that PAA-Ca and/or its thermally decomposed product, CaO, surrounded the HAp particles and protected them against calcination-induced sintering during calcination. The HAp crystals calcined with PAA-Ca showed high crystallinity, and no other calcium phosphate phases could be detected after washing with water.     

高压烧结法合成致密纳米BaTiO3陶瓷结构和铁电性能研究

 在6 GPa压力、1 000 ℃温度条件下制备了致密的纳米BaTiO₃陶瓷，合成样品的平均晶粒尺寸为50 nm，理论密度在97%以上。通过介电测量，观察到了样品宽化的相变峰，它与粗晶陶瓷的相变峰大不相同。由于90°电畴的减少和退极化场的存在，观察到了细长的电滞回线，它是样品铁电性存在的有力证据，表明钛酸钡陶瓷的临界尺寸在50 nm以下。     

放电等离子烧结制备ZrB2-SiC超高温陶瓷的力学性能及氧化行为

在服役环境中,超高声速飞行器表面与空气剧烈摩擦导致温度极高。超高温陶瓷相较于一般陶瓷而言具有高熔点和良好的抗氧化烧蚀性能,是目前极具前景的热防护材料之一。采用放电等离子两步烧结工艺将ZrB2纳米粉末和SiC粉末在1700℃下制备超高温陶瓷材料ZrB2-20%SiC,通过纳米压痕微观实验、三点弯实验研究其力学性能及其在高温环境下的氧化行为,着重分析1000、1200、1400和1600℃4种不同氧化温度下ZrB2-20%SiC超高温陶瓷的氧化表面、氧化截面和氧化层厚度。结果表明:ZrB2-20%SiC超高温陶瓷的硬度为18 GPa,弹性模量为541 GPa,断裂韧性为5.7 MPa·m1/2;当氧化温度为1600℃时,超高温陶瓷内部的SiC由被动氧化转变为主动氧化,并且随着氧化温度升高,超高温陶瓷氧化层厚度与氧化温度呈正相关。     

Preparation and Characterization of Isotactic Polypropylene Reinforced with Hydroxyapatite Nanorods

Isotactic polypropylene (PP) composites filled with hydroxyapatite nanorods (nHAs) were fabricated using a melt compounding process. The effects of nHA additions on the structure, thermal, and mechanical properties as well as bioactivity of PP were investigated. Wide-angle X-ray diffraction and differential scanning calorimetry results showed that PP crystallized exclusively in the α-form when adding nHAs. Dynamic mechanical analysis showed that nHAs enhanced the storage modulus of PP. Mechanical measurements showed that nHAs stiffened and reinforced PP but reduced its tensile ductility and impact strength considerably. Furthermore, the PP/nHA nanocomposites were found to exhibit excellent bioactivity upon immersion in a simulated body fluid solution. This was attributed to the formation of apatite mineral crystals on the nanocomposite surfaces as revealed by scanning electron microscopy and energy dispersive X-ray analysis.     

Preparation and Mechanical and Tribological Properties of High-Density Polyethylene/Hydroxyapatite Nanocomposites

High-density polyethylene (HDPE) nanocomposites reinforced with hydroxyapatite nanorods (nHA) were fabricated by means of extrusion and injection molding. The thermal, mechanical, and dry sliding wear properties of HDPE-based nanocomposites filled with nHA loadings up to 20 wt% were investigated. The results of mechanical property characterization showed that nHA additions improved the hardness, elastic modulus, and yield strength of HDPE at the expense of its tensile ductility and impact strength. Thermogravimetric analysis and heat deflection temperature measurements revealed that nHA fillers are very effective to enhance the thermal stability of HDPE. The wear behavior of HDPE/nHA nanocomposites was studied using a pin-on-disk tribometer. nHA fillers of a large aspect ratio improved the wear resistance of HDPE substantially because of their load-bearing effect and the formation of a continuous transfer film on the steel counterface.     

Hydroxyapatite Nano Sol Prepared via A Mechanochemical Route

Well-dispersed sol with crystalline hydroxyapatite (HAp) was obtained directly by milling a mixture comprising Ca(OH)₂, an aqueous solution of H₃PO₄ and a dispersant, an ammonium salt of polyacrylic acid. The average crystallite size of HAp was below 20 nm. Ca/P molar ratio of the product was 1.51 ± 0.04, i.e. Ca deficient from stoichiometric HAp. Minimum apparent viscosity was attained at a dispersant concentration 0.92wt% of sol. An as-milled sol was diluted by a factor 10–2.61 solid wt% to give a Newtonian fluid of 2 mPa s. From the diluted sol, we obtained a few m thick dense film of HAp by dip coating on the slide glass precoated by chitosan.     

纳米BaTiO3陶瓷的超高压烧结

将10 nm钛酸钡粉在6 GPa超高压条件下进行烧结,得到了晶粒大小约为30 nm的钛酸钡陶瓷.用扫描电子显微镜和原子力显微镜观测了样品的微观结构.研究表明,由于超高压能够压碎纳米粉体中的团聚体,而且能增加烧结的驱动力,降低成核的势垒,从而使成核速率增加;同时由于扩散能力的降低而使生长速率减小,所以超高压烧结能在较低的...