Huanwu Cheng

Grain growth and thermal stability of nanocrystalline Ni–TiO 2 composites

Abstract The grain growth and thermal stability of nanocrystalline Ni–TiO2 composites were systematically investigated. The nanocrystalline Ni–TiO2 composites with different contents of TiO2 were prepared via electroplating method with the variation of TiO2 nano-particles concentration. The effect of TiO2 content on the grain size, phase structure and microhardness was investigated in detail. The corresponding grain growth and diffusion mechanisms during the heating process were also discussed. The optimal microhardness of HV50 270 was achieved for the composite with addition of 20 g/L TiO2 nano-particles after annealing at 400 °C for 90 min. The calculation of the activation energy indicated that lattice diffusion dominated at high temperatures for the nanocrystalline Ni–TiO2 composites. It was indicated that the increase of TiO2 nano-particles content took effect on restricting the grain growth at high temperatures by increasing the grain growth activation energy.

Surface Modification of Quartz Fiber by Aqueous Plasma Electrolysis

The mechanical properties of quartz and ceramic fiber are easily destroyed at high temperature. There are many process methods for continuous fiber surface treatment, commonly used in a chemical vapor deposition method and sol gel method. In this work, a method of preparing surface coating is proposed to protect the mechanical properties of fiber at high temperature, at the same time to achieve high efficiency, low cost, and to meet the requirements of Engineering production. Treatment of quartz and ceramic fibers in a continuous liquid equal plasma, plasma bombardment of the fibers is carried out, in order to achieve the purpose of preparation of coatings. After coating the surface of the quartz fiber, the ceramic coating is coated by the liquid plasma process, and the breaking strength is tested after the high temperature treatment.

Rapid Deposition of Al 2 O 3 /SiO 2 Composite Coating on Carbon Fiber Fabric

In the paper, a uniform and continuous Al2O3/SiO2 composite coating was prepared on each fiber of carbon fiber fabric via room-temperature aqueous plasma electrolysis technique. The micromorphology and anti-oxidation property of the Al2O3/SiO2-coated carbon fiber fabric were systematically investigated. The dense and continuous Al2O3/SiO2 composite coating was uniformly deposited on each fiber of carbon fiber fabric. The thickness of coating was 120–150 nm. The Al2O3/SiO2 composite coating could protect the carbon fiber fabric from oxidation above 1000 °C. In addition, it could be seen 300 m carbon fiber fabric were coated continuously by high-quality Al2O3/SiO2 composite coating.

Synthesis of In-Suit Ti 46.8 Zr 19.5 Nb 11.7 Cu 5 Be 14.5 Ag 2.5 Amorphous Composite Materials with High Tensile Ductility

A high tensile ductility in-suit Ti46.8Zr19.5Nb11.7Cu5Be14.5Ag2.5 amorphous composite materials was prepared successfully by arc melting and injection casting into a water cooling copper mold. The composition and microstructure were characterized by X-ray diffraction (XRD) with Cu Kα radiation and scanning electron microscope (SEM). The results showed the fully developed dendritic structure of the β phase with green color was uniformly distributed in the amorphous matrix, while, the size and proportion of second phase were 30 μm and 78% respectively. Standard size of tensile specimen was designed to test its tensile mechanical properties. The occurrence of rare necking deformation in amorphous materials showed the Ti46.8Zr19.5Nb11.7Cu5Be14.5Ag2.5 amorphous composite materials possessed a good ductility ability. The fracture contained the fiber area, radiation area and shear lips. Large proportion dimple area showed the dendritic phase distributed uniformly played a great role in the process of deformation.