Superscratch-resistant glass by means of a transparent nanostructured inorganic coating

Silica nanoparticles were synthesized by a reverse microemulsion method and deposited on soda-lime silica substrates. The deposition of these nanoparticles by dip-coating gave rise to close-packed layers, which significantly modify the scratch resistance of the surface. The silica nanoparticles are found to spread out the stress at the surface/indenter contact and to favor microductile behavior.     

化学气相沉积法制备二维过渡金属硫族化合物研究进展

二维过渡金属硫族化合物(TMDs)是继石墨烯之后的新型二维材料,由于其自身的独特物理化学性质在半导体、光电材料、能源储存和催化制氢等方面备受瞩目。化学气相沉积(CVD)是目前适合实现大规模制备二维材料的工艺之一,制备过程中参数的高度可控性使其具有很大优势。本文综述了近期通过CVD制备TMDs的研究进展,探讨了在CVD制备工艺中各种参数对产物生长和最终形貌的影响,包括前驱体、温度、衬底、辅助剂、压力和载气流量等。列举了一些改进的CVD制备工艺,并对其特点进行了总结。最后讨论了目前CVD制备TMDs所面临的挑战并对其发展前景进行展望。     

一步CVD法制备WS2-MoS2垂直异质结及其表征

本文主要研究了WS2-MoS2垂直异质结的制备及其光电性能.以氧化钼(MoO3)、氧化钨(WO3)、硫粉(S)作为反应物,采用改良的一步化学气相沉积法(CVD)实现高质量的WS2-MoS2垂直异质结的制备.使用拉曼光谱仪(Raman)、光致发光光谱仪(PL)、光学显微镜(OM)、原子力显微镜(AFM)、透射电子显微镜(...     

Preparation and properties of porous glass using fly ash as a raw material

The porous glasses were prepared by a conventional phase separation method using coal fly ash as a raw material, and the properties of these porous glasses were investigated. The composition of coal fly ash is basically composed of SiO₂–Al₂O₃–Fe₂O₃–CaO system and the SiO₂–B₂O₃–Al₂O₃–CaO–Na₂O system of glass was chosen as base glass composition. The pore diameter increases proportional to cube root of heating time (t^1/3), however, the early stage of phase separation is not clear. It is estimated that the rate determining step may be the diffusion process of structural units involving oxygen ions and the phase separation may take place by the nucleation and growth mechanism, and the relatively larger pores of above 1 μm can be obtained easily. The chemical composition of porous glasses is SiO₂–B₂O₃–Al₂O₃(–CaO–Na₂O). A relatively large amount of fly ash (>40%) can be used successfully for the preparation of porous glass.     

The role of MgO on thermal properties,structure and bioactivity of bioactive glass coating for dental implants

The successful application of bioactive glasses as a coating for titanium implants to improve osseointegration is dependent on achieving a thermal expansion coefficient (TEC) match between the two phases. Many studies have indicated that magnesium affects the thermal and structural properties of a glass. However, its effect on bioactivity of bioactive glasses is still under debate. In this study, we characterize the effect of magnesium on the thermal properties, structure and bioactivity of glasses containing MgO. Seven glasses with different MgO concentrations have been synthesized by melt-derived technique. All these glasses contain SiO₂, CaO, MgO, ZnO, Na₂O, K₂O and P₂O₅ and have been characterized by X-ray diffraction (XRD), differential scanning calirometry (DSC) and dilatometry. Additionally, the oxygen density and bulk density have been investigated. The bioactivity of the MgO glass series was evaluated in simulated body fluid (SBF) and Tris-buffer solution. The results indicate that magnesium suppresses crystallization and decreases TEC, glass transition temperature (T_g) and softening (T_s) temperature. Oxygen density increases proportionally with MgO content; whereas glass density decreases. After different time points, XRD and Fourier transform infra-red spectroscopy (FTIR) show that magnesium does not inhibit the apatite forming ability of the glasses, but retards the time of apatite deposition. The glass coatings of this series exhibit clear clinical application for use as a functional barrier: osteoblastic attachment and growth was poor, however, fibroblastic biocompatibility was good.     

Preparation of bioactive glass ceramic nanoparticles by combination of sol-gel and coprecipitation method

SiO₂-CaO-P₂O₅ ternary bioactive glass ceramic nanoparticles were prepared via the combination of sol-gel and coprecipitation processes. Precursors of silicon and calcium were hydrolyzed in acidic solution and gelated in alkaline condition together with ammonium dibasic phosphate. Gel particles were separated by centrifugation, followed by freeze drying, and calcination procedure to obtain the bioactive glass ceramic nanoparticles. The investigation of the influence of synthesis temperature on the nanopartilce’s properties showed that the reaction temperature played an important role in the crystallinity of nanoparticle. The glass ceramic particles synthesized at 55 °C included about 15% crystalline phase, while at 25 °C and 40 °C the entire amorphous nanopowder could be obtained. In vitro testing showed that the bioactive glass ceramic nanoparticles can induce the formation of hydroxylaptite from simulated body fluid rapidly. As a result, this bioactive glass ceramic nanoparticle with excellent bioactivity would be a promising filler material for bone tissues engineering.     

以S、Se为原料的CVD ZnS、CVD ZnSe的化学反应分析

本文详细分析了用单质硫或单质硒为原料,在Zn-S-H2-Ar体系或Zn-Se-H2-Ar体系中化学气相沉积生长 ZnS和ZnSe晶体所发生的化学反应,认为在这两种化学气相沉积过程中所发生的化学反应是以锌蒸汽与硫或硒蒸汽反应来实现的.计算出了上述反应的△H、△S和△G这些热力学函数,并将该△G与采用H2S气体(Zn-H2S-Ar体系)和H2Se气体(Zn-H2Se-Ar体系)为原料的CVD ZnS和ZnSe做了对比.实验结果表明,以单质Se为原料生长的CVD ZnSe比以H2Se为原料的CVD ZnSe的努普硬度有显著的提高.     

渗硼高速钢表面CVD金刚石膜制备研究

直接在高速钢表面生长CVD金刚石非常困难.为了克服高速钢中Fe元素对金刚石生长的不利影响,在高速钢表面利用渗硼技术先生成B、Fe的化合物的中间层然后再制备CVD金刚石膜.采用显微维氏硬度计、XRD衍射仪、扫描电子显微镜、激光拉曼光谱和洛氏硬度计对渗硼基体和金刚石膜进行检测,研究渗硼处理对高速钢基体和金刚石膜生长的影响.结果表明:渗硼热处理可以在高速钢表面形成一层致密的B、Fe化合物层,能有效降低Fe元素的不利影响,有利于金刚石的生长,在高速钢表面形成一层高附着的致密金刚石膜.     

Optical and magnetic properties of (Zn,Mn)O nanostructures synthesized by CVD method

We report on microstructural, optical and magnetic properties of (Zn,Mn)O nanostructures synthesized by a chemical vapor deposition (CVD) technique. Average diameters of the as grown (Zn,Mn)O nanorods and nanowires were ∼400 nm and ∼50 nm, respectively. X‐ray diffraction (XRD) and photoluminescence (PL) spectra provided the evidence that Mn was incorporated into ZnO lattice. PL spectra of the (Zn,Mn)O nanostructures showed shift in near band edge (NBE) emission at 396 nm together with a green band (GB) emission at 510 nm and a blue band (BB) emission at 460 nm. Magnetic measurements revealed mixed magnetic phases (ferromagnetic and antiferromagnetic) in the (Zn,Mn)O nanostructures. Vapor‐solid‐solid (VSS) mechanism was thought to be responsible for the growth of the nanostructures at low temperatures. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Mechanical properties of optical glass fibers damaged by nanoindentation and water ageing

Mechanical properties of optical glass fibers are strongly influenced by cracks on glass surface. Cracks may be generated during manufacture and handling. The chemo-mechanical effect due to water may decrease the response of glass fibers because of surface degradation. In this work glass fibers were aged in a wet chamber at humidity of 85% in temperatures lower than 90 °C, during seven weeks. After being aged, the fibers were submitted to tension tests. The fracture loads were investigated by Weibull statistics. An increase in dynamic fatigue parameter was observed. Surface analysis by AFM indicated smooth surfaces. Small cracks on optical fiber glass surface were made by Vickers indentation and nanoindentation using a Berkovich indenter. A decrease on applied load to fracture indicates that the fiber was damaged by indentation. The influence of indentation load was investigated. As the deformation rate was very low during tension tests, the cracks grow during the test and the fiber fracture at loads lower than for not indented fibers. The effect of water and small indentation fracture on glass is discussed considering the surface damage induced by both methods. The size of the cracks from the different indentations and ageing are estimated.     

Acid-base properties of glass surfaces

The adhesion of polymers to inorganic oxides such as glass is very dependent on acid-base interactions between the acidic or basic surface sites of the glass and the basic or acidic functional sites of the polymer. This paper reviews the principles of such interactions, methods of measuring the acidity or basicity of surface sites, and the enhanced mechanical properties of glass-reinforced polymer composites resulting from interfacial acid-base complexation. A new study is presented of the acid-base properties of fiberglass and of surface treatments with silane coupling agents and polyvinyl acetate. It illustrates calorimetric titration methods for assessing surface acidity and basicity, and correlates these findings with angular-dependent X-ray photoelectron spectroscopy (ADXPS).     

Optical and lasing properties of fluorophosphate glass

Neodymium-doped fluorophosphate glass is a laser material newly-developed for use in high power laser fusion systems. The low refractive index (n_d ～ 1.45) and low dispersion (Abbe number ～90) of fluorophosphate glasses give them the properties of low nonlinear refractive indices and long Nd³⁺ fluorescence lifetimes, which are desirable for the high power laser applications. We have measured the intensity gain of 1.052 and 1.064 nm laser light produced by flashlamp-pumped fluorophosphate glass amplifiers, varying in size from 4–34 clear aperture. The measured gains are compared with those measured in other laser glass types and with those predicted from the spectroscopic properties of Nd³⁺. We estimate that the peak cross section for the ${}^4\text{F}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{→}{}^4\text{I}{}_{\mathrm{<mtext>11</mtext><mtext>12</mtext>}}$ transition in commercial fluorophosphate laser glasses is ～2.2 × 10^?20 cm².     

阶梯型复合刀具CVD金刚石涂层制备工艺及应用研究

针对加工阶梯孔类的阶梯型复合刀具,采用热丝辅助化学气相沉积技术(HFCVD),通过超声辅助酸碱两步预处理法,并且采用钽丝上下两层平行布置的沉积装置,调节生长参数,研究了YG6硬质合金阶梯型复合刀具的金刚石涂层制备技术.为了研究涂层性能,以含少量石棉的复合纤维刹车片作为加工对象,分别对比实验了金刚石涂层和未涂层刀具的钻削性能.结果表明:相对传统单层热丝沉积工艺,采用双层热丝布置方式,在涂层过程中能使切削刃各个部分的温度保持平衡稳定,使得阶梯复合刀具每个切削刃都能均匀地涂上一层金刚石薄膜.采用该方法沉积的金刚石涂层阶梯复合刀具在钻削过程中具有良好的切削性能及附着强度,特别是在高速加工中金刚石涂层阶梯复合刀具在轴向钻削力及扭矩方面都小于未涂层刀具,金刚石涂层阶梯复合刀具在钻削刹车片阶梯复合孔加工中具有显著的优势.     

高功率CO2激光器CVD金刚石窗口制备研究

本文研究制备了可应用于高功率CO2激光器的CVD金刚石窗口.首先使用环形天线-椭球谐振腔式MPCVD装置沉积制备直径2英寸(1英寸=2.54 cm)金刚石自支撑膜,然后将膜片双面抛光,激光切割成矩形基片,再采用蒸镀法在基片表面制备中心波长在10.6μm的增透膜,最终制备得到金刚石光学窗口.采用傅里叶红外透射谱、热导仪、...     

Preparation of silver nanoparticles in soda-lime silica glass by an electrochemical procedure

An electrochemical technique for producing silver particles of nanometric sizes in soda-lime silica glass is presented. The procedure is based on the use of silver iodide as solid electrolyte membrane.     

Doping of a high calcium oxide metaphosphate glass with titanium dioxide

This study investigates the effect of doping a high calcium oxide containing metaphosphate glass series (CaO)₄₀(Na₂O)₁₀(P₂O₅)₅₀ with TiO₂ (1, 3, and 5 mol%). TiO₂ incorporation increased the density and glass transition temperature while reduced the degradation rate (5 mol% in particular) by twofold compared with (CaO)₃₀ system reported previously. This has been confirmed by ion release and the minimal pH changes. TiP₂O₇, NaCa(PO₃)₃ and CaP₂O₆ phases were detected for all TiO₂-containing ceramics. XPS showed that the surface is composed of Ca, P, and Ti. Ti was recognized mainly as TiO₂, but its total amount was lower than theoretical values. ³¹P magic angle spinning (MAS) NMR showed a downfield shift of the ³¹P lineshape with increasing TiO₂, interpreted as an effect of the titanium cation rather than an increase in the phosphate network connectivity. FTIR showed that incorporation of TiO₂ increased the strength of the phosphate chains, and the O/P ratio while introducing more Q¹ units into the structure at the expense of the Q² units. There were no differences, however, in surface topography roughness and free energies between these glasses. These results suggested that TiO₂ and CaO were acting synergistically in producing glasses with controllable bulk and structural properties.