Advanced Materials Research Vols. 295-297

Abstract: In the present investigation, a feasibility study is made to use Rice Husk Ash as an admixture to an already replaced Cement with fly ash (Portland Pozzolana Cement) in Concrete, and an attempt has been made to investigate the strength parameters of concrete (Compressive and Flexural). For control concrete, Indian Standard (IS) method of mix design is adopted. Five different replacement levels namely 5%, 7.5%, 10%, 12.5% and 15% were chosen for the replacement study. A range of curing periods starting from 3 days, 7 days, 28 days and 56 days are considered in the present study. Series ranging from 5% to 10% RHA concrete but better compressive strengths at later ages though showing lower compressive strengths initially. However, split tensile strengths are lower for RHA concrete when compared to normal concrete.

Abstract: Using fly ash from the power plant and SiO₂ as the main raw materials, glass-ceramic was prepared by melting method. By means of DSC, XRD and SEM, the crystallizations of CaO-Al₂O₃-SiO₂ system glass-ceramic were studied. The results show that it is more and more difficult to crystallize as the content of SiO₂ increases. When the content of SiO₂ reaches to 41.5%, the crystal nucleus form in the form of shuttle shape, the crystals develop in the same direction for a certain zone. But the crystals develop into hexagon shape finally when they are heated for 1 h at 1100°Cafter nucleation at 780°C.The developed crystals are anorthite. The sizes of crystals are between 1- 1.5μm, their microhardness can reach HV804.

Abstract: The nano-hydroxyapatite/zirconia coating of double layers on surface of titanium allay materials have been prepared using electrochemical method. The features and structures of the composite coating materials are studied and analyzed by the Scanning electron microscope (SEM) and EDAX measurement. The results show that nano-HA/ZrO₂ are densely and uniformly deposited on the surface of titanium allays in ionic form, a stable gradient composite coating, in which the nano-zirconium oxides (ZrO₂) are homogeneously distributed between HA and titanium surfaces, are obtained. The tensile strength experiment exhibits that the adhesion or combined strength of the coating with the titanium surface is higher and about 17GPa, which manifests the nano-HA/ ZrO₂ coating is successfully combined on the surface of the titanium allay materials. The biological experiments represent that this material can be used in repairing of bone and medical dental- implant of teeth.

Abstract: Ti-6Al-4V alloy castings are made by means of induction melting technology. The relationships between grain size and tensile strength, yield strength, elongation percentage, investigated for Ti-6Al-4V alloy castings. The results show that the relationships between grain size, and tensile strength, yield strength, specific elongation, meet the Hall-Petch equation.

Abstract: Owing to the diversity of green evaluation index and multiple-factor related to the process evaluation, existing green evaluation of manufacturing process lacks a set of effective knowledge management model. It leads to the high cost and inefficiency of analysis and evaluation process. A green evaluation model for manufacturing process based on multi agent is presented. Based on the model, green evaluation support system of manufacturing process based on multi agent is developed with the knowledge base introduced. The implementation strategy of green evaluation for manufacturing process is implemented by the closed-loop knowledge chain, which is composed of knowledge mining, knowledge transferring, knowledge application and knowledge feedback. The feasibility of this system is verified by an instance of the valve stem manufacturing process in a valve factory.

Abstract: The organic solar cells with a structure of ITO/Rubrene(35 nm)/C60(35 nm)/BCP (6 nm)/Al(150 nm) was fabricated and the influence of anode modifying layer(MoO3) and 3V bias voltage treatment on device performance were investigated. The experiment results show, inserting anode modifying layer, the open-circuit voltage and the power conversion efficiency were almost increased by a factor of 5.3 and 11.3, respectively. The anode modifying layer can effectively enhance the built-in electric field and improve dissociation and transport excitons. The bias voltage treatment can improve the performance of defective devices by burning partial defects, but there is little effect for too few defective devices.

Abstract: A kind of novel polytetrafluoroethylene (PTFE)-based composite filled with nano SiO₂ are developed for sliding tribological applications. The specimens are fabricated with the compression moulding technique. And the mechanical and tribological properties of the composites are investigated. It is demonstrated that these properties are influenced by the content of fillers. The wear resistances of all the developed PTFE composites are much higher than that of pure PTFE with very low coefficients of friction. Among the developed composites, the mixture of PTFE + 30% nano SiO₂ exhibits the best combination of properties. The improved tribological performance of nano-SiO₂ filled PTFE composites can be attributed to the improved structural integrity of the composites.

Abstract: A novel processing of quick spheroidizing annealing based on DET(divorced eutectoid transformation) mechanism has been presented in this paper. Spheroidized carbide microstructure could be achieved directly by austenite through phase transformation during cooling processing, which is different from the conventional spheroidization annealing where carbide was spheroidized by carbide lamellar gradually resolved and coarsened.The novel processing of spheroidizing annealing presented here will decrease the annealing time from 10-16 hours in conventional processing to around 2-3 hours, which could save about 50% of the energy consumption, comparing to the conventional annealing processing.

Abstract: To increase the mechanical properties of the metal rollers, Mo and Mo+Y₂O₃ alloy powders were designed. And a kind of coating fabricated by a continuous wave CO₂ laser surface alloying(LSA) on 40Cr steel roller was obtained. The effect of Mo and Mo+Y₂O₃ on microstructure, hardness and wearing resistance of alloying coating were studied by OM, SEM, XRD, microhardness tester and wearing tester. The experimental results indicate that the grain size in alloying coating is obviously fined, and the grain boundary is strengthened. The uniformity and density of microstructure are improved. The microhardness and wear resistance of alloying coating are significantly increased.

Abstract: Pt colloids were synthesized by a wet-chemical method. The Pt colloids were modified on the glassy carbon electrode (GCE). The electrochemical behavior and electrocatalyst for methanol of the colloidal Pt-modified electrode in H₂SO₄ medium were investigated. The results show that the as-prepared Pt colloids are good electrocatalysts for methanol oxidation and the oxidation current increases with methanol concentration in the range of 0.002 to 0.5 M. The colloidal Pt-modified electrode is simple, easy-to-use and reusable, showing promising applications in the electrocatalyst and determination of methanol.