Dry sliding wear behaviour of stir-cast aluminium matrix composites(AMCs)containing LM13 alloy as matrix and ceramic particles as reinforcement was investigated.Two different ceramic particle reinforcements were used ...Dry sliding wear behaviour of stir-cast aluminium matrix composites(AMCs)containing LM13 alloy as matrix and ceramic particles as reinforcement was investigated.Two different ceramic particle reinforcements were used separately:synthetic ceramic particles(B_(4)C),and natural ceramic particles(ilmenite).Optical micrographs showed uniform dispersion of reinforced particles in the matrix material.Reinforced particles refined the grain size of eutectic silicon and changed its morphology to globular type.B_(4)C reinforced composites(BRCs)showed maximum improvement in hardness of AMCs.Ilmenite reinforced composites(IRCs)showed maximum reduction in coefficient of friction values due to strong matrix−reinforcement interfacial bonding caused by the formation of interfacial compounds.Dry sliding wear behaviour of composites was significantly improved as compared to base alloy.The low density and high hardness of B_(4)C particles resulted in high dislocation density around filler particles in BRCs.On the other hand,the low thermal conductivity of ilmenite particles resulted in early oxidation and formation of a tribo-layer on surface of IRCs.So,both types of reinforcements led to the improvement in wear properties of AMCs,though the mechanisms involved were very different.Thus,the low-cost ilmenite particles can be used as alternative fillers to the high-cost B_(4)C particles for processing of wear resistant composites.展开更多
Presently,ilmenite concentrates from Odisha Sands Complex at Chhatrapur,India are utilized to produce TiO2 slag by direct smelting in an electric arc furnace.However,the process involves the consumption of excess elec...Presently,ilmenite concentrates from Odisha Sands Complex at Chhatrapur,India are utilized to produce TiO2 slag by direct smelting in an electric arc furnace.However,the process involves the consumption of excess electrical energy and difficulty in handling the arc furnace due to frothing effects.A more efficient process of pre-reducing the ilmenite before smelting has been proposed in the present communication.In particular,studies have been undertaken on the reduction process of ilmenite-coke composite pellets.The difference in the reduction behaviour of raw ilmenite and ilmenite-coke composite pellets has been established and compared with that of the pre-oxidized raw pellets.The effects of various processing parameters like temperature,residence time,and reductant percentage on the metallization of composite pellets in a static bed have been investigated.Metallization of about 90%has been achieved at 1250°C for a reduction period of 360 min with a 4%coke composition.Furthermore,the reduced pellets have been characterized through chemical analysis,optical microscopy,field emission scanning electron microscopy and X-ray diffraction analysis.The reduction behaviour of composite pellets has also been found better than that of pre-oxidized pellets indicating the former to be more efficient.展开更多
Iron-based perovskite-type compounds modified by Ru were prepared through sol-gel process to study its catalytic activity of NOx direct decomposition at low temperature and evaluate the conversion of NO under the expe...Iron-based perovskite-type compounds modified by Ru were prepared through sol-gel process to study its catalytic activity of NOx direct decomposition at low temperature and evaluate the conversion of NO under the experimental conditions. The catalytic activity of La 0.9Ce 0.1Fe 0.8-nCo 0.2RunO3 （n=0.01,0.03,0.05,0.07,0.09）series for the NO, NO-CO two components, CO-HC-NO three components were also analyzed. The catalytic investigation evidenced that the presence of Ru is necessary for making highly activity in decomposition of nitric oxide even at low temperature（400 ℃）and La 0.9Ce 0.9Fe 0.75Co 0.2Ru 0.05O3 （n=0.05） has better activity in all the samples, the conversion of it is 58.5%. With the reducing gas（CO,C3H6）added into the gas, the catalyst displayed very high activity in decomposition of NO and the conversion of it is 80% and 92.5% separately.展开更多
文摘Dry sliding wear behaviour of stir-cast aluminium matrix composites(AMCs)containing LM13 alloy as matrix and ceramic particles as reinforcement was investigated.Two different ceramic particle reinforcements were used separately:synthetic ceramic particles(B_(4)C),and natural ceramic particles(ilmenite).Optical micrographs showed uniform dispersion of reinforced particles in the matrix material.Reinforced particles refined the grain size of eutectic silicon and changed its morphology to globular type.B_(4)C reinforced composites(BRCs)showed maximum improvement in hardness of AMCs.Ilmenite reinforced composites(IRCs)showed maximum reduction in coefficient of friction values due to strong matrix−reinforcement interfacial bonding caused by the formation of interfacial compounds.Dry sliding wear behaviour of composites was significantly improved as compared to base alloy.The low density and high hardness of B_(4)C particles resulted in high dislocation density around filler particles in BRCs.On the other hand,the low thermal conductivity of ilmenite particles resulted in early oxidation and formation of a tribo-layer on surface of IRCs.So,both types of reinforcements led to the improvement in wear properties of AMCs,though the mechanisms involved were very different.Thus,the low-cost ilmenite particles can be used as alternative fillers to the high-cost B_(4)C particles for processing of wear resistant composites.
基金Project(MLP-52)supported by the Council of Scientific and Industrial Research(CSIR),India。
文摘Presently,ilmenite concentrates from Odisha Sands Complex at Chhatrapur,India are utilized to produce TiO2 slag by direct smelting in an electric arc furnace.However,the process involves the consumption of excess electrical energy and difficulty in handling the arc furnace due to frothing effects.A more efficient process of pre-reducing the ilmenite before smelting has been proposed in the present communication.In particular,studies have been undertaken on the reduction process of ilmenite-coke composite pellets.The difference in the reduction behaviour of raw ilmenite and ilmenite-coke composite pellets has been established and compared with that of the pre-oxidized raw pellets.The effects of various processing parameters like temperature,residence time,and reductant percentage on the metallization of composite pellets in a static bed have been investigated.Metallization of about 90%has been achieved at 1250°C for a reduction period of 360 min with a 4%coke composition.Furthermore,the reduced pellets have been characterized through chemical analysis,optical microscopy,field emission scanning electron microscopy and X-ray diffraction analysis.The reduction behaviour of composite pellets has also been found better than that of pre-oxidized pellets indicating the former to be more efficient.
基金Sponsored by the National Natural Science Foundation of China(Grant No.20271019 and 20576027), Natural Science Foundation of Heilongjiang Prov-ince(Grant No.B200504), Postdoctoral Foundationof Heilongjiang Province(Grant No.LBH-Z05066) and Education Department Foundation of Hei-longjiang Province(Grant No.11511270).
文摘Iron-based perovskite-type compounds modified by Ru were prepared through sol-gel process to study its catalytic activity of NOx direct decomposition at low temperature and evaluate the conversion of NO under the experimental conditions. The catalytic activity of La 0.9Ce 0.1Fe 0.8-nCo 0.2RunO3 （n=0.01,0.03,0.05,0.07,0.09）series for the NO, NO-CO two components, CO-HC-NO three components were also analyzed. The catalytic investigation evidenced that the presence of Ru is necessary for making highly activity in decomposition of nitric oxide even at low temperature（400 ℃）and La 0.9Ce 0.9Fe 0.75Co 0.2Ru 0.05O3 （n=0.05） has better activity in all the samples, the conversion of it is 58.5%. With the reducing gas（CO,C3H6）added into the gas, the catalyst displayed very high activity in decomposition of NO and the conversion of it is 80% and 92.5% separately.
