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Jian Wang,Jun Li,Shengen Zhang,Xiaochuan Mi,Alex A. Volinsky 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.3
This paper presents a classic process-structure-properties approach for optimizing the magnetic properties of electrical steels. Cold-rolled non-oriented electrical steel (Fe; 0.001wt% C; 0.2 wt.% Mn; 1.3 wt% Si) was subjected to extremely short 3-30 seconds annealing cycles in a range from 880°C to 980°C with a heating rate varying from 15°C to 300°C/sec. The resulting microstructure was studied by means of optical microscopy and X-ray orientation distribution function analysis. Recrystallized grains were refined with increased heating rate, caused by the nucleation rate increase, which is faster than the growth rate due to rapid heating. The optimal grain size of 60 to 80 mm in terms of magnetic properties was obtained by increasing the annealing temperature range to 920°C to 940°C with a higher heating rate of 300°C/sec and an annealing time of 6 to 9 seconds. With the heating rate increase, the characteristic {111} recrystallization fiber of cold-rolled steel was depressed, but the beneficial {110}<001> Goss texture component was significantly strengthened. The recrystallized grain size and texture were enhanced by rapid annealing, and, as a result, the magnetic properties of non-oriented electrical steel improved. This paper presents a classic process-structure-properties approach for optimizing the magnetic properties of electrical steels. Cold-rolled non-oriented electrical steel (Fe; 0.001wt% C; 0.2 wt.% Mn; 1.3 wt% Si) was subjected to extremely short 3-30 seconds annealing cycles in a range from 880°C to 980°C with a heating rate varying from 15°C to 300°C/sec. The resulting microstructure was studied by means of optical microscopy and X-ray orientation distribution function analysis. Recrystallized grains were refined with increased heating rate, caused by the nucleation rate increase, which is faster than the growth rate due to rapid heating. The optimal grain size of 60 to 80 mm in terms of magnetic properties was obtained by increasing the annealing temperature range to 920°C to 940°C with a higher heating rate of 300°C/sec and an annealing time of 6 to 9 seconds. With the heating rate increase, the characteristic {111} recrystallization fiber of cold-rolled steel was depressed, but the beneficial {110}<001> Goss texture component was significantly strengthened. The recrystallized grain size and texture were enhanced by rapid annealing, and, as a result, the magnetic properties of non-oriented electrical steel improved.
Recoating slurry process effects on the SiC-based casting foam filter properties
Fengzhang Ren,Gangjun Zhai,Zhanhong Ma,Alex A. Volinsky,Baohong Tian 한양대학교 세라믹연구소 2014 Journal of Ceramic Processing Research Vol.15 No.2
Polyurethane foam was used as a precursor for fabricating SiC-based ceramic foam filters. Two recoating slurry processes were adopted to enhance the strength of ceramic foam. One was the recoating slurry of stoved green body and another was the recoating slurry of pre-sintered green body. The differences in weight increase and thermal shock resistance of ceramic foams fabricated by the two recoating slurry processes were investigated. The effects of pre-sintering temperature on weight increase and thermal shock resistance are discussed. Thermal shock resistance of ceramic foams fabricated by two recoating slurry processes is lower than that by the single coating slurry process. Compared with recoating slurry of pre-sintered green bodies, with the same slurry, the weight increase of ceramic foams fabricated by recoating slurry of the stoved green bodies is less, but the number of thermal cycles to failure is much higher. For ceramic foams fabricated by recoating slurry of presintered green bodies with the same slurry, the weight increase and the number of thermal cycles to failure decreased with the pre-sintering temperature.
Microstructure and quality of SiC foam filters for casting
Fengzhang Ren,Gangjun Zhai,Zhanhong Ma,Xiaobo Chen,Alex A. Volinsky 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.6
Maximum compressive strain at high temperature was introduced as a new quality indicator of ceramic foam filters used in metal casting. Maximum compressive strain at high temperature, number of thermal cycles before failure, room temperature compressive strength and bulk density of SiC-based ceramic foam filters with the same pore size produced by four manufacturers were measured. The best quality product exhibited the highest number of thermal cycles before failure and minimum strain at high temperature. Differences in properties were elucidated based on X-ray diffraction and scanning electron microscope microstructural characterization. The best quality filter has less glass phase and more quartz phase, while lower quality filters have more glass and cristobalite phases. The glass phase increases the maximum strain at high temperature, while both glass and cristobalite phases reduce the number of thermal cycles before failure. The maximum compressive strain at high temperature can be utilized as the main indicator for evaluating the quality of ceramic foam filters.