On the bonding of porcelain on titanium

The interface structure and bond strength between Ti and porcelain were studied using various firing times and vacuum levels. During firing an interfacial oxide layer was formed between Ti and porcelain. Fracture occurred between this oxide layer and Ti. A correlation was observed between the thickness of the interfacial layer and the bond strength: the thicker the layer, the weaker was bonding. An improved vacuum was found to increase the bond strength. Oxygen was observed by ESCA to dissolve into Ti, causing brittleness in the uppermost Ti layer with prolonged firing time.     

钛专用遮色瓷研制及其性能研究

采用二氧化锡系微晶玻璃制备低熔钛专用遮色瓷,研究了遮色瓷组成与热膨胀系数的关系,通过对比烧结温度、力学性能与热膨胀系数等性能,最终确定遮色瓷配方和烧结工艺;采用XRD、SEM、细胞毒性和溶血实验分别研究了钛遮色瓷的晶相组成、显微形貌和生物相容性。结果表明所研制的遮色瓷为含有锡石晶体相的微晶玻璃;其最佳烧结温度为780℃;在25～350℃,其平均线热膨胀系数为8.9×10-6/℃;所研制的钛遮色瓷细胞毒性为0级,不引起溶血反应,具有良好的生物相容性。     

低熔纯钛用体瓷的研制及其性能研究

采用硼硅酸盐玻璃体系制备低熔钛专用体瓷,研究了体瓷组成与热膨胀系数的关系,并采用XRD和细胞毒性实验分别研究了钛体瓷的晶相组成和生物相容性。结果表明,钛体瓷为不含晶体的均质玻璃体,其热膨胀系数随SiO2含量的增加而减小;通过对比两种配方的烧结温度与力学性能,最终确定体瓷配方和烧结工艺:自制钛体瓷的烧结温度为760℃,抗弯强度、断裂韧性和维氏硬度分别为(85±4.07)MPa、(1.44±0.04)MPa/m1/2和(3904±21.71)MPa/mm2,硬度稍高于天然牙釉质。XRD结果表明自制钛体瓷为不含晶体的均质玻璃体;细胞毒性为0级,对细胞无抑制作用,可望进一步应用于临床修复。     

Preparation and characterization of nitrogen-doped titanium dioxide

To extend the absorption range of titanium dioxide into the visible-light region, the nitrogen incorporation process is investigated. This work presents a simple procedure for preparing nitrogen doped titanium dioxide nanocrystal (TiOxNy) by calcinating the mixture of Degussa P-25 (DP-25) TiO2 and NH4Cl at temperatures between 350 and 500 degrees C under airtight condition. Analysis of X-ray photoelectron spectroscopy indicated the molecular state nitrogen was incorporated into TiO2 lattice leading to the observable shift of the absorption edge to longer wavelength region with higher absorption intensity. These TiOxNy samples exhibit photocatalytic activity for methylene blue decomposition in aqueous solution under visible light irradiation. The correlation between the photocatalytic activity of TiOxNy and nitrogen content, rutile phase composition, and surface area was investigated and discussed.     

Preparation and characterization of titanium dioxide nanocomposite fibers

Titanium dioxide and polypropylene fibers were prepared by melt-compounding and sputter coating, respectively. Energy dispersive x-ray analysis (EDX) confirmed the presence of titanium dioxide in the fibers. Through the application of environmental scanning electron microscopy (ESEM) and scanning probe microscopy (SPM), it was found that incorporating the titanium dioxide by melt-compounding caused severe aggregation of the titanium dioxide nanoparticles at the polypropylene fiber surface. Indeed, coverage of the fiber surface by titanium dioxide was poor. By contrast, the coverage of the sputter coated fiber surfaces was much more consistent, although aggregation of the titanium dioxide nanoparticles still appeared quite extensive. The behavior of the nanocomposite fiber surfaces was investigated using dynamic contact angle measurements by the Wilhelmy technique. Only a small increase in hydrophilicity of the polypropylene fibers was observed after melt-compounding with titanium dioxide, but a larger increase was noted after sputter coating. UV irradiation appreciably enhanced the hydrophilicity of the fiber surfaces in both cases.     

Preparation and characterization of carbon and titanium carbide coatings

Carbon and titanium carbide coatings were deposited onto 304 and 316 stainless steel, Monel 400, molybdenum and copper substrates by the d.c. diode sputtering method. The former were prepared using a graphite target in an argon atmosphere whereas the latter were deposited using a titanium target in an argon-methane gas mixture. The coatings were characterized using Auger electron spectroscopy, X-ray photoelectron spectroscopy, Rutherford backscattering spectrometry, scanning electron microscopy and X-ray diffraction techniques. The adhesion of the coatings to the substrates and the effect of annealing on their crystallinity were studied.     

钒掺杂二氧化钛薄膜制备与材料特性分析

以钛酸四丁酯和乙酰丙酮钒（Ⅲ）为主要原料,采用溶胶-凝胶法制备了钒掺杂二氧化钛薄膜,利用XRD、紫外-可见吸收光谱、FT-IR及XPS等表征手段,将其与未掺杂二氧化钛薄膜进行了材料特性对比研究。结果表明两种薄膜均为锐钛矿结构,引入钒后二氧化钛的禁带宽度由3.28eV减小至3.15eV,吸收带边红移至可见光范围;XPS分析证实制备的钒掺杂二氧化钛薄膜中钒以四价和五价两种氧化价态存在,可能在二氧化钛禁带中引入较深的杂质能级而引起价带顶向禁带拓展,从而产生引起禁带宽度变窄效应,扩展了二氧化钛带边光吸收。理论分析还表明,钒掺杂引起的深能级杂质在二氧化钛晶界处易于形成有效的陷阱俘获光生空穴,从而抑制光生载流子的复合,尤其适于用作光催化材料。     

聚合物—金属钛纳米鳞片的制备与表征

为制备防腐性能优异的钛纳米涂料,采用高能球磨技术制备了聚合物-金属钛纳米鳞片,配制了聚合物-金属钛纳米鳞片涂料.对聚合物-金属钛纳米鳞片产物进行了多种表征,对配制的涂料进行了防腐性能测试,同时初步探讨了防腐机理.研究表明:聚合物-金属钛纳米鳞片产物片厚在80 nm以下,达到了二维纳米结构;XPS表征表明产物表面已基本被聚合物包覆,标准电极电位升高,耐腐蚀性能提高.防腐性能测试表明,加入聚合物-金属钛纳米鳞片的防腐涂料的防腐性能非常优异,形成致密的防渗层.     

Preparation and characterization of hexagonal mesoporous titanium–cobalt oxides

Hexagonal mesoporous Co–Ti oxides were synthesized via a supramolecular assembly route, using a non-ionic surfactant, polyoxyethylene fatty alcohol (AEO₉). The textural and electronic properties of the specimens were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high resolution transition electron microscopy (HRTEM) and N₂-physisorption at 77 K. The application of the mesoporous Co–Ti oxides in the catalytic oxidation of cyclohexane was explored.     

Preparation, characterization and photocatalytic activities of holmium-doped titanium dioxide nanoparticles

The objective of the proposed work was focused to provide promising solid-phase materials that combine relatively inexpensive and high removal capacity of some radionuclides from low-level radioactive liquid waste (LLRLW). Four various zeolite minerals including natural clinoptilolite (NaNCl), natural chabazite (NaNCh), natural mordenite (NaNM) and synthetic mordenite (NaSM) were investigated. The effective key parameters on the sorption behavior of cesium (Cs-134) were investigated using batch equilibrium technique with respect to the waste solution pH, contacting time, potassium ion concentration, waste solution volume/sorbent weight ratio and Cs ion concentration. The obtained results revealed that natural chabazite (NaNCh) has the higher distribution coefficients and capacity towards Cs ion rather than the other investigated zeolite materials. Furthermore, novel impregnated zeolite material (ISM) was prepared by loading Calix [4] arene bis(-2,3 naphtho-crown-6) onto synthetic mordenite to combine the high removal uptake of the mordenite with the high selectivity of Calix [4] arene towards Cs radionuclide. Comparing the obtained results for both NaSM and the impregnated synthetic mordenite (ISM-25), it could be observed that the impregnation process leads to high improvement in the distribution coefficients of Cs⁺ ion (from 0.52 to 27.63 L/g). The final objective in all cases was aimed at determining feasible and economically reliable solution to the management of LLRLW specifically for the problems related to the low decontamination factor and the effective recovery of monovalent cesium ion.     

非传统粉末冶金制备生物医用多孔钛及其性能

以生物医用球形雾化钛粉为原料,碳酸氢铵做造孔剂,采用放电等离子烧结(SPS)技术制备了生物医用多孔钛块体材料。采用XRD、SEM分别对所制备的多孔钛的物相组成、微观形貌进行分析,并研究了多孔钛的力学性能及成骨细胞在其表面的粘附生长情况。结果表明:通过调节造孔剂添加量、控制烧结工艺可制备孔隙率为50.3%～70.5%、孔径为100～300μm的多孔钛,其力学性能(抗压强度为24.40～68.96MPa、弹性模量为1.010～1.287GPa)与人体松质骨相匹配。与SD大鼠成骨细胞的联合培养结果表明,该材料的粗糙表面和多孔结构可粘附生长成骨细胞,具有良好的生物相容性。     

Preparation and characterization of APTES films on modification titanium by SAMs

In this study, the titanium plates, which were modified by NaOH alkali solution, were associated with 3-Aminopropyltriethoxysilane (APTES) films using self-assembled monolayers (SAMs). The surfaces of titanium before and after modification were characterized by scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and attenuated total refraction-Fourier transform infrared spectroscopy (ATR-FTIR). After bonding the APTES films on the modification titanium, the new peaks located around 1095 cm⁻¹ attributes to siloxane groups indicating that silane agent had been grafted onto the surface of the modification titanium substrate by SAMs. Following the deposition of APTES films on titanium, significant change were seen in the amounts of oxygen, silicon and carbon present on the titanium surface, which were consistent with the anticipated reaction steps.     

Preparation,characterization and photocatalytic activities of holmium-doped titanium dioxide nanoparticles

Holmium-doped TiO₂ nanoparticles with high photocatalytic activities were prepared by sol–gel method and characterized by X-ray diffraction, transmission electron microscopy, ultraviolet–visible diffuse reflectance spectroscopy, and surface area measurement by nitrogen adsorption in this study. Experimental results indicated holmium doping could increase the surface area of TiO₂ nanoparticles, and inhibit the growth of crystalline size and the anatase-to-rutile phase transformation. The results of photodegrading methyl orange showed holmium doping improved the photocatalytic activity of TiO₂, and the reasons could be attributed to the synergetic effects of large surface areas, small crystallite size, lattice distortion and more charge imbalance of holmium-doped TiO₂. In our experiment, the optimal doped amount was 0.3 mol.% for the maximum photocatalytic degradation ratio when holmium-doped TiO₂ was calcined at 500 °C, and the optimal calcined temperature was 600 °C when the doped amount was 0.5 mol.%.     

Preparation and characterization of a novel porous titanium scaffold with 3D hierarchical porous structures

This study aims to prepare a novel porous titanium (Ti) scaffold in order to improve the biocompatibility of the metallic implants. Porous Ti was produced by a Liquid foaming method and subsequent chemical treatments. It was found that the scaffold had three-dimensionally hierarchical porous structures with pore size ranging from nanometer to micrometer scale, and it also had activated surface. Mechanical test results showed that the scaffold also has sufficient compressive strength to meet the requirements of implantation. Protein adsorption results indicated that the novel scaffolds significantly enhanced the protein adsorption.     

Ageing reactions in a high carat gold alloy for dental porcelain bonding

The phase transformation during continuous heating of a high carat gold alloy used for porcelain bonding was investigated by electrical resistivity measurements, hardness tests, X-ray diffraction and scanning and transmission electron microscopy. Four reaction stages (I, II, III and IV) were found. Stage I corresponded to the formation of a short-range order. A discontinuous precipitation took place in stage II, which contributed to remarkable hardening. Stages III and IV were reactions to the stable phases at each temperature region, and resulted in softening. The activation energies for stages I, II and III are 27.1, 33.8 and 58.2 kcal/mol, respectively.     

Preparation and characterization of titania powders obtained via hydrolysis of titanium tetraisopropoxide

TiO₂ powders were prepared through the hydrolysis of titanium isopropoxide followed by calcination at temperatures of 200 °C to 600 °C. The obtained powders were characterized by N₂ adsorption-desorption and X-ray powder diffraction. The results confirmed strong dependence between specific surface area of the TiO₂ powders and both the conditions of the hydrolysis process and the calcination temperature. While calcination temperature strongly affected crystallinity of the product, no significant influence of the hydrolysis conditions on this parameter was observed. TiO₂ powders prepared at various conditions were examined as catalysts for photodegradation of Acid Red 18 in water. Photoactivities of the prepared powders were influenced by both the amount of water used to hydrolyze the TiO₂ precursor and the temperature of calcination process. TiO₂ samples calcined at 500 °C appeared to be the most active and the photocatalytic activities of the prepared materials increased along with the amount of water used for the hydrolysis process.     

Oxide morphology and adhesive bonding on titanium surfaces

Titanium metal was subjected to two surface treatments (alkaline peroxide etch and chromic acid anodization) and resulting oxide morphology examined by high-resolution scanning electron microscopy in a Jeol 100-CX STEM. The effects of treatment time in alkaline peroxide upon oxide morphology were followed and parallel mechanical measurements made on the strengths of adhesive bonds between the metal and an epoxy resin. These strengths were measured after a standard environmental exposure, namely 120 h in water at 80° C. As time-of-treatment increases, a micro-porous oxide layer is developed and adhesive strength rises to a maximum. Prolonged treatment with alkaline peroxide produces a drastic fall in adhesive strength accompanied by gross etching of the metal surface without changes in the oxide morphology. The loss of adhesive durability in this case is therefore attributable to surface chemistry effects rather than morphological changes.     

Age-hardening behaviors and grain boundary discontinuous precipitation in a Pd-free gold alloy for porcelain bonding

Isothermal age-hardening behaviors at 400° and 450 °C and discontinuous precipitation reaction at 450 °C in a commercial Pd-free gold alloy for porcelain bonding were investigated by hardness testing, X-ray powder diffraction, and light microscopy. Variations of electrical resistivity during continuous heating and cooling processes were also measured. The alloy exhibited pronounced age-hardening in the early stage of aging and the maximum hardness exceeded twice that of the solution-treated sample. Precise lattice parameter measurements and investigations of full width at half maximum values for the X-ray Bragg reflections implied that nonuniform strains due to the pre-precipitation or zone formation was responsible for the quick and pronounced age-hardening at 450 °C. Discontinuous precipitation reaction, producing a mixture of a small amount of Pt₃In-phase with the L1₂-type superstructure and a large amount of (Pt, In)-depleted solid solution, started at grain boundaries in the late stage of aging process at 450 °C. The growth of the grain boundary discontinuous precipitates toward the intragrain area led to a gradual decrease in hardness of the alloy.     

Acidity characterization of a titanium and sulfate modified vermiculite

A natural vermiculite has been modified with titanium and sulfated by the intercalation and impregnation method in order to optimize the acidity of the clay mineral, and characterization of samples were analyzed by X-ray fluorescence (XRF), X-ray diffraction (XRD), nitrogen adsorption isotherms, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and temperature programmed desorption with ammonia (TPD-NH₃). All the modified solids have a significantly higher number of acidic sites with respect to the parent material and in all of these, Brönsted as well as Lewis acidity are identified. The presence of sulfate appears not to increase the number of acidic centers in the modified clay. For the materials sulfated with the intercalation method, it is observed that the strength of the acidic sites found in the material increases with the nominal sulfate/metal ratio. Nevertheless, when elevated quantities of sulfur are deposited, diffusion problems in the heptane reaction appear.     

Phase transformation behaviour of a low carat gold alloy for porcelain bonding during continuous heating

The phase transformation associated with hardening in a low carat gold alloy for porcelain bonding during continuous heating was studied by resistivity measurements, hardness tests, X-ray diffraction and scanning and transmission electron microscopies. A short-range order structure, based on Au-Pd, was produced at a lower temperature. At an elevated temperature, two types of precipitation were observed. One is a nodular reaction consisting of an L1₂ ordered structure based on Pd₃Sn and a disordered FCC structure at grain boundary. The other is a formation of spherical L1₂ ordered precipitates based on Pd₃Sn within the grain followed by Ostwald ripening. A fine dispersed precipitate of the latter contributed to the remarkable hardening.