Advanced Materials Research Vols. 383-390

Abstract: In order to explore the effect of removing siliceous components on acid resistance of fracturing proppants, acid resistance of fracturing proppants in a new silicon-free system was studied in this paper. The fracturing proppants were made by pressureless sintering using high-purity alumina and barium carbonate as the basic raw material. Acid resistance test was carried out in 12 wt% HCl + 3 wt% HF at 65 oC for 30 minutes according to The Petroleum and Gas Industrial Standards of China (SY/T5108-2006) and morphology, structure and chemical analysis of the samples were investigated using X-ray diffraction and scanning electron microscopy. Experiments show that fracturing proppants that contain barium aluminates have better acid resistance. The acid solubility of the samples is less than 3%, especially when the content of barium carbonate is about 10% (mass fraction, the same below), the acid solubility of the sample reaches 0.52% which is far beyond the demands (5%) of the Standards of SY/T5108-2006. Results prove that the removal of siliceous components of raw materials can prominently improve the acid resistance of fracturing proppants. It can provide a new referential thought for improving the acid resistance of fracturing proppants.

Abstract: The effect of hydrogen on the properties of amorphous carbon nitride films deposited onto Si substrates by magnetron sputtering device has been studied. The influence of hydrogen to roughness, porous character of films, composition and residual stress was investigated by atomic force microscopy, thermal desorption mass spectroscopy, X-ray photoelectron spectroscopy, scanning low energy electron microscopy and by goniometer equipped with Cu X-ray tube. The adding of hydrogen to nitrogen discharge a causes decrease in the high value of compressive stress (elimination of delamination of the films, increasing of nitrogen content in the bulk). On the other hand hydrogen increases roughness and porosity.

Abstract: The properties of self compacting ultra high performance fiber reinforced concrete (UHPFRC) are investigated by eliminating the coarse aggregates; optimizing the granular mixture; using a pozzolanic admixture combining with superplasticizers to decrease the water to cement ratio; setting steam heat curing to improve the microstructure; and incorporating steel fiber (about 2% by volume). The properties of UHPFRC specimens, cured by steam curing at 90oC, are investigated. This paper presents some results of studying on the strength, durability and microstructure of UHPFRC with compressive strength above 140MPa.

Abstract: The purpose of this research is to investigate the mechanical and corrosion characteristics of Ni-Cu alloyed Austempered Ductile Iron before and after austempering process. Specimens of ductile iron and 0.5% Cu-Ni ductile iron were produced through conventional CO2 sand casting method. The specimens were then austenitized at 9000C before austempered at 3500C at three different holding times which were 1 hour, 2 hours and 3 hours subsequently. The corrosion characteristics of newly developed material were obtained by means of polarization test and the mechanical testing involved tensile test (TS 138 EN1002-1), Rockwell hardness test and Charpy Impact test (ASTM E23). Density test as well as microstructure and SEM observations were also done to ductile iron and Cu-Ni alloyed ductile iron samples. All the testing was done to both as cast and austempered specimens. Addition of copper and Nickel was found to slightly increased the mechanical properties due to solid strengthening effect of Copper and Nickel. The results also indicated that austempering process at 1 hour gives the optimum mechanical properties in term of tensile strength and impact properties compared to other specimens. Increasing the austempering holding times to 2 hours and 3 hours, in contrast had resulted in decrement of the mechanical properties. There are however only slight improvement in hardness properties and no significant effect on density properties of the specimens.

Abstract: Deep cryogenic treatment produces a significant enhancement in the mechanical properties of metals. In this research paper, the mechanical properties of Aluminium Silicon composite were studied when they were subjected to deep cryogenic treatment. Samples were prepared from two different compositions of Aluminum silicon composites (Al 2024_5%SiC & 10%SiC). The samples were given controlled cryogenic treatment at -186oC. Treated samples were compared with un-treated samples for their compressive strength, hardness and metallurgical changes. The treated samples have shown an improved compressive strength. The improvement is supplemented by the hardness survey and micro-structural changes.

Abstract: The research is conducted to analyze the micro structure of TiC/7075, a composite material and to study its wear properties. TiC/7075 composites produced under different sintering temperatures and with different particle contents are prepared with the help of the powder metallurgy technology. The result shows that with the increase of the TiC content, the microstructure of TiC/7075 composites tend to have the form of equiaxed crystal. The microstructure of the composite material with 8% of TiC shows the uniform and fine properties, making it have the properties of the equiaxed crystal. The hardness and the wear resistance increase with the increase of the content of TiC. Also with the increase of the sintering temperature, the sharp edge of the hole becomes smooth. The wear resistance of TiC/7075 composites is superior to 7075 matrix alloy, and the wear mechanism of TiC/7075 composites is adhesive wear and abrasive wear.

Abstract: Ti1-xAlxN films have been shown to exhibit superior mechanical and thermal properties and are thus widely used for industrial applications. We have studied the structural and mechanical properties of fcc-TiN and fcc-Ti1-xAlxN solid solution (x=0.25 and x=0.5), using first principles calculations based on the density functional theory. These calculations provide the lattice parameter, total energy, cohesive energy, elastic constants, etc, of the TiN lattice and when Al atoms replace Ti atoms in the TiN lattice. With regard to the cohesive energy of TiN and fcc-Ti1-xAlxN, we can obtain that the fcc-Ti1-xAlxN is metastable. Via comparation and analysis, it’s shown that the lattice parameter, cohesive energy and elastic constants decrease with increasing the content of Al. However, ductile behavior is promoted by Al addition.

Abstract: Boron-doped diamond (BDD) electro- catalysis is one of the advanced oxidation processes (AOPs) can be widely applied in water treatment, because the unique physical and chemical properties enable BDD to be an ideal anode material in electrochemical oxidation of aqueous organic pollutants. In this work, electrocatalysis is conducted in research of treating isopropyl alcohol model wastewater and real wastewater of low molecular organics on BDD electrode. Experiments are performed both in static and dynamic mode with a batch reactor and a circulation cell, and the effect of current density is investigated. The results reveal the superiority of dynamic mode in treating model wastewater and real wastewater. And the optimum working currency density of dynamic electrocatalysis for model wastewater and real wastewater are 1.29mA/cm2 and 3.84mA/cm2, respectively.

Abstract: This study investigated the properties of lightweight sludge-flyash-clay ceramic by different sintering temperature. Different ratios of dry sewage sludge and fly ash with 50 wt% of clay were mixed and pressed into raw pellets. After drying and preheating treatment, the raw pellets were sintered at temperatures ranging from 1050 to 1150 °C, in 25 °C increments for 10 min. The physical properties (bulk density, grain density, water absorption and rate of expansion) were the indexes used to determine the technical parameters for the preparation of lightweight sludge-fly ash ceramic pellets. The results suggested that temperature was the key control factor of sintering process, and 1150 °C was the starting point of the bloating reaction. In the case of a small fraction in the raw material configuration, the mass ratios of sludge to fly-ash had little effect on the properties.

Abstract: On the basis of analysis of the component of the sludge from Lingzhuang waterworks and the technological process was studied which use the sludge for raw material to produce the sludge ceramsite. Through a lot of experiments, the several factors affecting the nature of ceramsite were developed and the technological parameters were confirmed. A performance test of the ceramsite shows that when the optimized temperature is 1130°C~1170 °C, the optimized baking time is 5 min, strength of tube pressure of the ceramsite is 8 MPa, bulk density of it is 1200 kg/m3compressive strength of concrete blocks is 40 MPa. So the products could meet the demand on high strength ceremsite. It is gained that the way of waterworks sludge for ceramsite is feasible and can bring certain economical profits, social profits and environmental profits. The products can be used widely to load bearing structure in construction profession.