Papers by Author: Qi Wang

Abstract: The effect of aging treatment on the aging hardening of 0% Yb and 0.4% Yb modified A356.2 alloy was investigated by hardness measurements and optical microscope. In this work, A356.2 was first subjected to 535°C for 5h and then subjected to 150°C, 180°C for 2h-12h hours. Results show that during aging process, there was a hardness peak along the increasing of aging temperature and time. With increasing aging progress, the morphology of Si phases became shorter and spherical. After optimum time, Si phases was coarse and the dendritic grain was broken. The peak-aged of unmodified alloys was 150°C for 10h and 180°C for 6h，and corresponding hardness values were 62.35HB and 77.10HB, respectively. With Yb addition, the hardness reached 87.58HB and 98.28HB on peak aging of 150°C/8h and 180°C/ 6h, respectively. The greatest degree of hardness was increased by 40.46% and 27.47%, combined with no Yb addition. XRD shows the interplanar crystal spacing of A356.2 with 0.4% Yb addition, which was larger than fresh A356.2 alloy. When adding 0.4%Yb under 180°C for 6h aging progress, the ultimate tensile strength was 284 MPa 12.7% increasing compared with former work.

Abstract: Porous structures represent a unique class of functional nanomaterials with many applications. In this work, porous SnO₂ with 3D networks structures were synthesized by a facile Lewis acid catalytic template method. Techniques of X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the structure and morphology of the products. The porous SnO₂ posses large macroscopic scale and porous nanostructure with huge pore volume and large surface exposure area. The sensor based on SnO₂ with porous structures exhibited high response to acetone gas (CH₃COCH₃). It suggests that the as-prepared porous SnO₂ is promising candidate for good performance acetone sensor.

Abstract: The La-doped porous In₂O₃ nanospheres were prepared by a simple hydrothermal method, and La³⁺ accounted for 3 mol% of the In³⁺. The La exists and has been doped in the lattice of In₂O₃ characterized respectively by the means of energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD), the morphology of the samples with uniform nanospheres observed by field-emission scanning electron microscopy (FESEM). Moreover, the sensor exhibits higher response properties compared with pure porous In₂O₃ nanospheres towards different acetone concentration at operating temperature 300 °C. The response and recovery times is about 13 s and 8 s to 50 ppm acetone.

Abstract: In this paper, we studied the effect of preparation on standard dry density and strength of foamed cement by orthogonal test. The results indicate that the more excellent combination is A₁B₁C₁, namely G1, the standard dry density is 376 kg/m³, the flexural and compressive strengths are 0.43 MPa and 0.8 MPa respectively, and the thermal conductivity is 0.074 W/(m·K), which conforms to the characteristics of light weight and high strength. Fewer Ca (OH)₂ crystals and more C-S-H gel generated in G1 through scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis is the reason for its high strength.

Abstract: In this paper, the hydration process and strength of calcium acrylate (CA) modified cement under the effects of different additives, such as, initiator-hydrogen peroxide, accelerator-triethanolamine, and cross-linking agent-butyl acrylate, were studied. Through comprehensive analysis, the optimal content of additives of initiator, cross-linking agent, and accelerator is ascertained 3%, 10% and 3%, respectively. On the condition of optimal content of additives and CA, it can be obtained that CA can increase the exothermic rate of cement within one hour and accelerate the exothermic rate in the induction period, shorten the time of the induction period, and speed up the initial setting time of cement. Besides, CA can inhibit the transformation of AFm from AFt, improve the dispersion of cement paste, make later hydration more fully, and promote later strength.

Abstract: Biomorphic porous LaFeO₃ samples were prepared using aspen leaves as biotemplates. The structural and microscopy characterization has been carried out with X-ray diffraction, scanning electron microscopy and transmission electron microscopy. XRD patterns confirm thatLaFeO₃ shows perovskite phase with orthorhombic structure. The results of SEM and TEM revealed that the the obtained LaFeO₃ with hollow and porous structure. And the porous LaFeO₃ is composed of spherical particles with the size of 50-80 nm The gas sensing performance of as-prepared LaFeO₃ nanocrystlas was investigated. It is found that porous LaFeO₃ calcined at 700°C exhibit good sensitivity to acetone with rapid response.

Abstract: There were different heat treatments to Cu-Zn-Al shape memory alloy. Cement-based smart lost-circulation control material was prepared by the method of rolling agglomeration. And indoor simulation experiment was carried out. The results show that the heat treatment temperature is 800°C, the quenching medium is the boiling water; the leakage is decreased with the increase of the cotton fiber content. When the cotton fiber content is 4%, the leakage is the minimum; the best volume percent of the lost-circulation control material is 20% in the grout.

Abstract: In this paper, perovskite LaFeO3 nanoparticles were synthesised by a sol-gel method. Then, polypyrrole (PPy)/LaFeO3 nanocomposites were prepared by a simple in situ chemical polymerization method. By means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM), the microstructure of PPy/LaFeO3 nanocomposites was characterized. The XRD patterns indicated that LaFeO3 nanoparticles have a perovskite phase with orthorhombic structure, and incorporation of PPy did not change the crystalline structure of LaFeO3. The PPy was evenly dispersed on the surface of LaFeO3 particles, which was endorsed by FTIR spectral analyses. And SEM images indicate that the PPy was evenly dispersed on the surface of LaFeO3 particles without apparent agglomeration. And we found that the nanocomposites exhibited a higher response to CO gas.

Abstract: Different heat-treatments were carried out on the Ti-Ni shape memory alloy, alloy thread was made to straight line with the self-made alignment on 500 °C and then self-made angle training meter was used to train the alloys. Cement-based smart materials were prepared by the method of rolling agglomeration. Finally, indoor simulation experiment was carried out. The results show that the shape recovery ration becomes lower when quenching medium are hot-oil, hot-water, cold-oil and cold-water. The smart lost-circulation control material response quickly to external environment, the time from contact with external environment to the begin of distortion is less than or equal to five seconds, and to the end of distortion is less than or equal to sixty seconds.The best volume fraction for cement-based smart plugging material in cement slurry is 20%. Furthermore, the lost-circulation control material possesses the characteristics of a short time plugging and a strong pressure-bearing capability after plugging. And it improves the capacity of the ordinary cement-based smart lost-circulation control material.

Abstract: Porous materials were prepared by sintering using C as place holder and SiO2 as based, mixed with paraffin. Then Organic-inorganic Core-shell Particles were made by crushed. With the help of XRD and SEM, on the 60°C Study on Sulfate-Corrosion Resistance of cement Mixed with Organic-inorganic Core-shell of Preparation. The Organic-inorganic Core-shell Particles made by accounted of C 15% and heat preservation 4h in 920°C were the best. The results showed that when the content of Organic-inorganic Core-shell Particles was 15%, the Sulfate-Corrosion Resistance reached the climax.