A technique based on viscous polymer processing (VPP) was described, which can produce high ceramic content green fibers. PZT-5 ceramic powders were ball milled to get high dispersibility. The slurry prepared for VPP ...A technique based on viscous polymer processing (VPP) was described, which can produce high ceramic content green fibers. PZT-5 ceramic powders were ball milled to get high dispersibility. The slurry prepared for VPP was a composition of PZT-5 powder, PVA binder and glycerin. High ceramic content PZT-5 fibers were extruded with the slurry. The results show that the ceramic powders have fine mean particle size of 0.54 μm, high specific surface area of 3.55 m2/g and zeta potential of 8.81 mV after 16 h milling. The fibers sintered at 1 280 ℃ for 4 h have pure perovskite structure and grains of 2-5 μm in size, with little pores or cracks. The ultimate tensile strength of sintered fibers is up to 13.84 MPa compared with 2.88 MPa of green fibers. The remnant polarization (Pr) and coercive field (Ec) of the fibers are 50.65 μC/cm2 and 2.45 kV/mm, respectively. This fiber can withstand an electric field of 9 kV/mm higher than the ceramic (5 kV/mm), which shows high directional and compact qualities.展开更多
Boron was found to be a unique grain refiner in cast TiAl alloys in the beginning of 1990 s and has become an element in most of the TiAl alloys developed to date.Over the past 25 or so years,efforts to understand the...Boron was found to be a unique grain refiner in cast TiAl alloys in the beginning of 1990 s and has become an element in most of the TiAl alloys developed to date.Over the past 25 or so years,efforts to understand the role of boron in solidification,solid-phase transformation,thermal and thermomechanical processing and mechanical properties of TiAl alloys and the relevant mechanisms never ceased.As a result,abundant knowledge on boron in TiAl alloys has been accumulated but scattered in various research papers and conference proceedings.This review summarises the progress in understanding boron and its impacts on the TiAl alloy systems.展开更多
基金Project (50402014) supported by the National Natural Science Foundation of China
文摘A technique based on viscous polymer processing (VPP) was described, which can produce high ceramic content green fibers. PZT-5 ceramic powders were ball milled to get high dispersibility. The slurry prepared for VPP was a composition of PZT-5 powder, PVA binder and glycerin. High ceramic content PZT-5 fibers were extruded with the slurry. The results show that the ceramic powders have fine mean particle size of 0.54 μm, high specific surface area of 3.55 m2/g and zeta potential of 8.81 mV after 16 h milling. The fibers sintered at 1 280 ℃ for 4 h have pure perovskite structure and grains of 2-5 μm in size, with little pores or cracks. The ultimate tensile strength of sintered fibers is up to 13.84 MPa compared with 2.88 MPa of green fibers. The remnant polarization (Pr) and coercive field (Ec) of the fibers are 50.65 μC/cm2 and 2.45 kV/mm, respectively. This fiber can withstand an electric field of 9 kV/mm higher than the ceramic (5 kV/mm), which shows high directional and compact qualities.
文摘Boron was found to be a unique grain refiner in cast TiAl alloys in the beginning of 1990 s and has become an element in most of the TiAl alloys developed to date.Over the past 25 or so years,efforts to understand the role of boron in solidification,solid-phase transformation,thermal and thermomechanical processing and mechanical properties of TiAl alloys and the relevant mechanisms never ceased.As a result,abundant knowledge on boron in TiAl alloys has been accumulated but scattered in various research papers and conference proceedings.This review summarises the progress in understanding boron and its impacts on the TiAl alloy systems.
