Characterization of calcined kaolin/TiO<Subscript>2</Subscript> composite particle material prepared by mechano-chemical method

Calcined kaolin/TiO₂ composite particle material (CK/TCPM) was prepared with TiO₂ coating on the surfaces of calcined kaolin particles by the mechano-chemical method. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to investigate the microstructures and morphologies, respectively. The mechanism of the mechano-chemical reaction between calcined kaolin and TiO₂ was studied by infrared spectra (IR). The results show that TiO₂ coats evenly on the surfaces of calcined kaolin particles by Si-O-Ti and Al-O-Ti bonds on their interfaces. The hiding power and whiteness of CK/TCPM are 17.12 g/m² and 95.7%, respectively, presenting its similarity to TiO₂ in pigment properties.     

High-g impact resistance for epoxy molding compound

The behavior of resistance high-g impact of EMC (epoxy molding compound) with two package models, small outline package (POS) and Globtop, was evaluated by experimental method used Hopkinson bar. At 120,000 g (generated in the Hopkinson bar with widths about 70 μ s) no damage in either the POS devices or the Globtop devices was observed. In order to enhance the EMC’s ability of resistance high-g impact, buffering effect of epoxy resin was also studied. The experimental results above all show that EMC has a better performance of impact resistance at about 120,000 g, and epoxy resin can absorb the stress wave to have the protected ability. The study of this paper could serve as a basis for selection packaging materials and enhance its reliability in high-g impact environment.     

Effects of curing systems on properties of high volume fine mineral powder RPC and appearance of hydrates

The effects of different curing systems on the properties of high volume fine mineral powder RPC (reactive powder concrete) and the appearances of hydrates were studied. The experimental results show that dry-heating curing promotes the development of pozzolanic reactivity of fine mineral powder; due to low cement content, 0.20 water-bind ratio and high reactive fine mineral powder content, the strength of RPC increases by around 200% after steam curing and subsequent dry-heating curing. Scanning electron microscopy and energy spectrum diagram showed that: after the high volume fine mineral powder RPC with 0.16 water-bind ratio underwent steam curing and dry-heating curing, there was no significant change in the appearance of hydrates; after the RPC with 0.20 water-bind ratio, the cement content of 150 kg/m³ and more steel slag powder underwent dry-heating curing, there was a certain change in the appearance of C-S-H, the structure of gel was more compact and was uniformly distributed, and the Ca/Si of C-S-H gel decreased from 1.41 to around 1.20.     

Oily wastewater treatment by porous ceramics mediums with surface lipophilic modification

Aiming at the treatment of difficult-to-handle oily wastewater, the ceramics filter mediums made from the iron and steel plant sludge were adopted to surface lipophilic modification so as to remove oil efficiently. The hydrolysis technique by FTIR and conductivity test indicated that under acid conditions hydrogen silicon oil did not hydrolyze but release hydrogen by chemical reaction under alkaline conditions. The results of the experiments including contact angle measurement, FTIR analysis, and SEM analysis illustrate that a layer of lipophile coating indeed exists evenly on the surface of filter mediums after modification. Furthermore, the hydrogen-containing silicone oil was combined through dehydration of Si-H bond with the -OH on the surface of ceramic filter medium.     

Crystallization and conductivity mechanism of ITO films on different substrates deposited with different substrate temperatures

ITO thin films were grown on PC(polycarbonate), PMMA(polymethyl methacrylate) and glass substrates by r.f. magnetron sputtering. The electrical, structural and chemical characteristics of ITO films were analyzed by the Hall Technique, X-ray diffraction, and X-ray photoelectron spectroscopy. XPS studies suggest that all the ITO films consist of crystalline and amorphous phases. The degree of crystallinity increases from less than 45% to more than 90% when the substrate temperature increases from 80 to 300 ℃. The In and Sn exist in the chemical state of In3+ and Sn4+, respectively, independent of substrate type and temperature. The enrichment of Sn on surface and In in body of ITO films are also revealed. And, the oxygen deficient regions exist both in surface layer and film body. For ITO films deposited under 180 ℃ , the carrier concentration are mainly provided by oxygen vacancies, and the dominant electron carrier scattering mechanism is grain boundary scattering between the crystal and the amorphous grain. For ITO films deposited over 180 ℃, the carrier concentration are provided by tin doping, and the dominant scattering mechanism transforms from grain boundary scattering between the crystal grains to ionized impurity scattering with increasing deposition temperature.     

Preparation and enhanced daylight-induced photo-catalytic activity of transparent C-Doped TiO<Subscript>2</Subscript> thin films

The transparent C-doped TiO₂ nanostructure films were fabricated on the silicate glass substrates by sol-gel spin-coated method. The as-prepared films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible absorption spectra (UV-vis) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity was evaluated via the photo-catalytic oxidation of methylene blue in aqueous under daylight irradiation at room temperature. The results show that the daylight-induced photocatalytic activities of the as-prepared films are improved by the C-doping. The calcination temperatures significantly affect the morphology, microstructure and photocatalytic activity of the as-prepared samples. At 723 K, the C-doped TiO₂ films exhibit the highest photocatalytic activity due to the synergetic effects of good crystallization, appropriate oxygen vacancies and strong absorption in the near UV and visible-light region.     

Application of polymerizable surfactant in the preparation of polystyrene/nano-Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> composite

Monooctadecyl maleate, as a polymerizable surfactant, was synthesized by the mono-esterification of maleic anhydride and octadecanol, and was utilized to surface-modify nano-Fe₃O₄ particles. A polymerizable magnetic fluid was obtained by directly dispersing modified nano-Fe₃O₄ particles into styrene monomer, and the polystyrene/nano-Fe₃O₄ composite was prepared through free radical polymerization of polymerizable magnetic fluid. The structure and dispersion status in different dispersion phases of modified nano-Fe₃O₄ particles were studied by Fourier transform infrared (FTIR) spectrometry, X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The experimental results show that the nano-Fe₃O₄ particles modified by monooctadecyl maleate with the size of about 7–10 nm can be uniformly dispersed into styrene and fixed in the composite during the procedure of polymerization. Thermogravimetric analysis (TGA) and vibrating sample magnetometry (VSM) indicate that the thermal stability of polystyrene/nano-Fe₃O₄ composite is improved compared to that of pure polystyrene, and the composite is a sort of superparamagnetic materials.     

The properties of solution precursor plasma spray nanostructured thermal barrier coatings

About 300 μm thickness uniform thermal barrier coatings (TBCs) were deposited on the 1Cr18Ni9Ti samples by solution precursor plasma spray (SPPS).The analysis methods,such as TEM,SEM,and XRD were used to characterize the coatings in the aspects of microstructure and phase compositions.The samples were quenched from 1121 ℃ to room temperature by forced-air to measure the thermal cycling capability.Coatings density were measured by means of water displacement.The experimental results show that grain size of the SPPS TBCs is about 30 nm with desired tetragonal phase ZrO2,and the SPPS TBCs(with 16% porosity) consist of arcuate pores,gelatin and melted particles.The hardness of the coatings is HR45Y38.5 and bond strength between coatings and substrates is 24.2 MPa.The thermal shock test show the coatings have a average life of 500 cycles which is about 2.5 times than that of conventional air plasma spray (APS) TBCs.     

Tissue response of an osteoinductive bioceramic in bone defect rabbit model

HA/TCP and HA rods (?5 mm×10 mm) were made for implantation in New Zealand white rabbit with different condition. Sixty three rabbit were divided into three groups: group 1 (n=18), group 2 (n=27) and group 3 (n=18). In group 1, 10 mm radius was defected, and one HA/TCP rod was implanted in the muscle a distant away from the bone defect area. In group 2, also, 10 mm radius was defected, one HA rod was implanted in the muscle a distant away from the bone defect area. In group 3, two HA/TCP rods were implanted in the dorsal muscle of the rabbit with bone intact. Histological observation showed that in group 1, some new bone was found only two months after implantation (n=2), and obvious immature woven bone could be observed in these bioceramics from the 3^rd month on. However, in group 3, bone began to be found 6 months after implantation (n=2). In group 2, we could not find any bone tissue up to 9 month’s observation. These results suggest that, first, the bone defect model could significantly accelerate bone formation at non-osseous sites in rabbits; second,. HA/TCP bioceramics were confirmed with osteoinductive property while HA bioceramics without osteoinductive property nearly. Thus, bone defect might be a good animal model for further researches for osteoinductive bioceramics.     

Facile synthesis of uniform hollow hematite sub-micro spheres with controllable shell thickness

A simple method was developed to prepare the uniform hematite hollow submicro-spheres with controllable structure and different diameter based on monodisperse poly(styrene-co-acrylic acid) [P(St-co-AA)] particles. The structure and formation mechanism of the hollow spheres were investigated in detail. The control mechanism of shell thickness was also discussed. The results indicated that the shell thickness and coarseness of the synthesized core-shell hematite hollow spheres could be tuned simply by the surface carboxyl content of the P(St-co-AA) particles. This method provided a new approach for the structure control in the preparation of hollow spheres. A Brunauer-Emmett-Teller (BET) test shows that the prepared hollow spheres have large surface areas which were decreased along with the increase of the diameter. The magnetic properties of the as-obtained hematite hollow spheres were investigated. The result showed that the coercivity and saturated magnetization were increased along with the increase of the shell thickness, and the remanent magnetization was increased along with the decrease of the diameter.