Advanced Materials Research Vols. 306-307

Abstract: Two kinds of polymer fiber and polymer latex are used to improve the toughness and bondability of cement mortar. The influences of the fiber and latex on the compressive and flexural strength, compressive strength-flexural strength ratio (CS/FS), bond flexural strength and compactedness of the hardened mortar were studied. The results showed that both of the latex and fibre can improve the compressive and flexural strength of mortar in low content, decrease the CS/FS, and then improve the toughness significantly. The bond flexural strength of mortar can be improved by 40-50% when the latex is added. The effect of fibre-latex added together was better than that of two matters added separately. The optimized components for Fibre-Latex hybrid were: 0.28% of PVA+5% of ACE.

Abstract: Hardfacing alloys reinforced with WC/W₂C on Q235 steel plates were prepared by the method of flux-cored wire TIG and MIG welding. The interface microstructure and carbide morphology were investigated using optical microscopy and scanning electron microscopy (SEM). The effect of dissolving of WC/W₂C on the interface microstructure was discussed. It indicated that the C-W-Fe ternary brittle compound has formed on the interface due to dissolving of WC/W₂C and the dissolving degree of the particles by TIG is less than by MIG. Abrasion resistance was evaluated by wet sand rubber wear tests and the wear mechanism was studied. The results show that WC/W₂C particles play a key role in improving abrasion resistance.

Abstract: Parameters of processing (heat treatment temperature, holding time) and properties (Bending strength and Microhardness) of Ti₂AlC/TiAl compound materials were obtained through mechanical properties examination, the network model was built by BP artificial neural network. The results show that the built model can reflect the relationships between processing and properties very well and has certain accuracy. It can be used for the prediction of the properties of Ti₂AlC/TiAl compound materials after heating processing under different experiment conditions. Meanwhile, the model can also serve as a guide for the preparation technology of Ti₂AlC/TiAl compound materials.

Abstract: The SEM images of Ti₂AlC/TiAl materials with different samples showed different fractal dimension.In Multi-fractal spectrum, the parameter is calculated by the multi-fractal spectrum theory. Without r=0.00625, giving rise to the small fluctuate, lnχq(r) and lnr shows the well linear relationship in spite of the value of q. τ (q) and q show nonlinear relationship and the protuberance existed in q∈[-3,-1], D(q) and q turn to be more steep, at last the clock shape relationship between the α and f(α) reveals the good symmetry of spectrum, uneven distribution of the fracture, multi-fractal feature clearly.

Abstract: One-factor-at-a-time design and orthogonal design were used in the experimental design to optimize the process of preparation for Cefradine /Montmorillionite composites in solution intercalation. Experimental results indicate that drug initial concentration was the most significant condition for optimal preparation of composites, intercalation time and reaction temperature were not so significant. In our paper, the maximum drug load occurred at reaction temperature of 60°C with the intercalation time of 2h when the drug concentration (mass ratio of cefradine to MMT) was 2:1.

Abstract: Sulphoaluminate cement and Lead Niobium-Magnesium Zirconate Titanate ceramic (PMN) were used as matrix and functional component to fabricate 1-3-2 piezoelectric ceramic-cement composites by dicing and filling method. The influences of base thickness on piezoelectric, dielectric and electromechanical coupling properties of the composites were analyzed and discussed. The results show that with increasing the base thickness, the piezoelectric stain factor d₃₃ increases gradually, while the piezoelectric voltage factor g₃₃ decreases. The relative dielectric factor ε_r decreases initially and then increases, while the dielectric loss tan δ increases initially and then decreases. When base thickness is 0.50 mm, ε_r has the minimum value of 1406. When base thickness is 3.00 mm, tan δ reaches the minimum value of 0.251. With increasing the base thickness, the planar electromechanical coupling coefficient K_p exhibits the decreasing trend, and the thickness electromechanical coupling coefficient K_t and acoustic impedance Z show the increasing trend.

Abstract: 1-3 type cement/epoxy resin based piezoelectric composite was designed and fabricated aiming at providing a new method for cement hydration monitoring. Combining with piezoelectric impedance technology, the cement hydration reaction process was monitored by using the composite. The research results show that in the initial cement hydration period, the resistance-frequency curves of the sensor drift toward low frequency direction, while the anti-resonance resistance value decreases gradually. With increasing cement hydration time, the resistance-frequency curves of the sensor drift toward high frequency direction and the anti-resonance resistance value shows fluctuation changes. The cement hydration reaction process can be divided into different periods according to changes of anti-resonance frequency and anti-resonance resistance value of the sensor.

Abstract: A novel water soluble core material composed of alumina, quartz sand, kaolin, gypsum powder and the solution of binders was prepared. The influence of different mass concentration of Polyethylene Glycol (PEG) binder solution and sodium silicate compounded (SS) binders solution on water soluble performance and compressive strength of the core materials was investigated, respectively. The results show that the compressive strength and solubility rate of the core materials, with the concentration of 30% of SS binders solution, are 1.023MPa and 0.24g/s respectively, which is satisfied for the requirements of Resin Transfer Molding (RTM) process completely.

Abstract: The carbon fibers / rubber composite films were fabricated by compression molding method with butyl rubber (IIR) as matrix and carbon fiber as reinforced material. The mechanical properties and electromagnetic shielding effect of the thin films at different conditions were measured by the WDW electronic universal testing machine according the national standard GB13022-91 and the far-field EMC shielding effectiveness test fixture (DN1015 type) respectively. The results show that the good mechanical properties of composite films with mess ratio of IIR and carbon black of 1:6 and vulcanizing time of 1.5h were obtained at the same other condition that the tensile strength reached 534.65MPa, the elongation rate reached 87.26% and the yield point stress up to124.85MPa. Meanwhile, it is also found that the electromagnetic shielding effect of the thin films shows negative growth at low frequency area ranging from 1MHz to 300MHz. Whereas, the shielding effect increases with frequency at 300MHz ~ 1.5GHz, and the SE value is up to -25dB ~-35dB.

Abstract: To improve the mechanical properties and the MR effect of MRE, we use flexible epoxy as the matrix of MRE. It shows that both the mechanical properties and the MR effect of epoxy based MRE improved. At room temperature the highest absolute modulus increase was 203 MPa when the intensity of magnetic field was 0.2T while the carbonyl iron content was 71.4%. Temperature influenced the MR effect. When at -40°C the maximum storage modulus increased more than 2356 MPa and changed with the temperature. Meanwhile, the morphology of the epoxy based MRE was studied by scanning electron microscopy (SEM).