The effects of heat treatment temperature on the hardness, wear resistance and structure of a coating material consisting of Ni-0.45wt% RE4.8wt% B-6.2wt% Al2O3 have been discussed. The results showed that the hachess ...The effects of heat treatment temperature on the hardness, wear resistance and structure of a coating material consisting of Ni-0.45wt% RE4.8wt% B-6.2wt% Al2O3 have been discussed. The results showed that the hachess and wear resistance of the composite material reach the optimal values when heating temperature rises to 350℃ and 500℃ respectivelg. X-ray diffraction and scanning electron microscopy indicate that the composite material is amorphous in the as-coating state. The crystallized temperature of Ni-B alloy is increased when RE and Al2O3 particles are inserted. The hardness and wear resistance of the composite are raised obviously with addition of RE and Al2O3 particles.展开更多
A Ni-Cr/BN composite was produced by a active sintering process. The powder of nickel carbonyl,Cr2O3 and C were used as the original materials,and a hexagonal BN(h-BN) powder was added as a solid lubricant. The influe...A Ni-Cr/BN composite was produced by a active sintering process. The powder of nickel carbonyl,Cr2O3 and C were used as the original materials,and a hexagonal BN(h-BN) powder was added as a solid lubricant. The influence of sintering temperature,heating rate and holding time on the properties of Ni-Cr/BN were studied. The composition and microstructure of Ni-Cr/BN were analysed by X-ray diffraction(XRD) and the optical microscopy(OM). The frictional behavior and hardness were measured with ring-block friction testing machine and Brinell hardness tester respectively. The results show that Ni-Cr is the matrix and a low-melting eutectic compound is the bonding phase in the composite. The porosity reaches 48% and the value of hardness reaches HB18 when the composite is fabricated at 1 100 ℃ for 1 h. Its wear rate is 7.44×10-5 g/min,and the average friction coefficient is 0.266. These properties make such composite suitable for use as self-lubricating material.展开更多
Hydrogen absorption composite powder of Mg incorporated with Ni and CrCl3 （88∶10∶2 in mass ratio） was prepared by reactive milling in hydrogen atmosphere. Hydriding/dehydriding performances were measured by self-m...Hydrogen absorption composite powder of Mg incorporated with Ni and CrCl3 （88∶10∶2 in mass ratio） was prepared by reactive milling in hydrogen atmosphere. Hydriding/dehydriding performances were measured by self-made apparatus. The results show that reactive milling and multi-component addition of Ni and CrCl3 reduce the stability of hydride and improve the sorption performance of Mg-based materials. With powder milled for 60h, hydriding basically completes within 300s （250℃, 2.0MPa） and phase transformation fraction reaches 0.78. The phase transformation rate of hydriding/dehydriding progress increases significantly with the reduced particles size of powder while good kinetics of dehydriding at a relatively low temperature is gained with small grain size of hydride. Rapid temperature variations in a short span of time resulted from remarkable calorific effects of rapid phase transformation are detected in hydriding/dehydriding progress. The results of thermogravimetric and differential scanning calorimetric（TG/DSC） indicate that the onset temperature of desorption of composite milled for 100h is 272℃.展开更多
Direct carbon solid oxide fuel cells(DC-SOFCs)are promising,green,and efficient power-generating devices that are fueled by solid carbons and comprise all-solid-state structures.Developing suitable anode materials for...Direct carbon solid oxide fuel cells(DC-SOFCs)are promising,green,and efficient power-generating devices that are fueled by solid carbons and comprise all-solid-state structures.Developing suitable anode materials for DC-SOFCs is a substantial scientific challenge.Herein we investigated the use of La_(0.75)Sr_(0.25)Cr_(0.5)Mn_(0.5)O_(3)-δ−Ce_(0.8)Gd_(0.2)O_(1.9)(LSCM−GDC)composite electrodes as anodes for La_(0.9)Sr_(0.1)Ga_(0.8)Mg_(0.2)O_(3)-δelectrolyte-based DC-SOFCs,with Camellia oleifera shell char as the carbon fuel.The LSCM−GDC-anode DC-SOFC delivered a maximum power density of 221 mW/cm^(2) at 800℃ and it significantly improved to 425 mW/cm^(2) after Ni nanoparticles were introduced into the LSCM−GDC anode through wet impregnation.The microstructures of the prepared anodes were characterized,and the stability of the anode in a DC-SOFC and the influence of catalytic activity on open circuit voltage were studied.The above results indicate that LSCM–GDC anode is promising to be applied in DC-SOFCs.展开更多
文摘The effects of heat treatment temperature on the hardness, wear resistance and structure of a coating material consisting of Ni-0.45wt% RE4.8wt% B-6.2wt% Al2O3 have been discussed. The results showed that the hachess and wear resistance of the composite material reach the optimal values when heating temperature rises to 350℃ and 500℃ respectivelg. X-ray diffraction and scanning electron microscopy indicate that the composite material is amorphous in the as-coating state. The crystallized temperature of Ni-B alloy is increased when RE and Al2O3 particles are inserted. The hardness and wear resistance of the composite are raised obviously with addition of RE and Al2O3 particles.
文摘A Ni-Cr/BN composite was produced by a active sintering process. The powder of nickel carbonyl,Cr2O3 and C were used as the original materials,and a hexagonal BN(h-BN) powder was added as a solid lubricant. The influence of sintering temperature,heating rate and holding time on the properties of Ni-Cr/BN were studied. The composition and microstructure of Ni-Cr/BN were analysed by X-ray diffraction(XRD) and the optical microscopy(OM). The frictional behavior and hardness were measured with ring-block friction testing machine and Brinell hardness tester respectively. The results show that Ni-Cr is the matrix and a low-melting eutectic compound is the bonding phase in the composite. The porosity reaches 48% and the value of hardness reaches HB18 when the composite is fabricated at 1 100 ℃ for 1 h. Its wear rate is 7.44×10-5 g/min,and the average friction coefficient is 0.266. These properties make such composite suitable for use as self-lubricating material.
文摘Hydrogen absorption composite powder of Mg incorporated with Ni and CrCl3 （88∶10∶2 in mass ratio） was prepared by reactive milling in hydrogen atmosphere. Hydriding/dehydriding performances were measured by self-made apparatus. The results show that reactive milling and multi-component addition of Ni and CrCl3 reduce the stability of hydride and improve the sorption performance of Mg-based materials. With powder milled for 60h, hydriding basically completes within 300s （250℃, 2.0MPa） and phase transformation fraction reaches 0.78. The phase transformation rate of hydriding/dehydriding progress increases significantly with the reduced particles size of powder while good kinetics of dehydriding at a relatively low temperature is gained with small grain size of hydride. Rapid temperature variations in a short span of time resulted from remarkable calorific effects of rapid phase transformation are detected in hydriding/dehydriding progress. The results of thermogravimetric and differential scanning calorimetric（TG/DSC） indicate that the onset temperature of desorption of composite milled for 100h is 272℃.
基金Project(2019YFC1907405)supported by the National Key R&D Program of ChinaProject(GJJ200809)supported by the Education Department Project Fund of Jiangxi Province,ChinaProject(2020BAB214021)supported by the Natural Science Foundation of Jiangxi Province,China。
文摘Direct carbon solid oxide fuel cells(DC-SOFCs)are promising,green,and efficient power-generating devices that are fueled by solid carbons and comprise all-solid-state structures.Developing suitable anode materials for DC-SOFCs is a substantial scientific challenge.Herein we investigated the use of La_(0.75)Sr_(0.25)Cr_(0.5)Mn_(0.5)O_(3)-δ−Ce_(0.8)Gd_(0.2)O_(1.9)(LSCM−GDC)composite electrodes as anodes for La_(0.9)Sr_(0.1)Ga_(0.8)Mg_(0.2)O_(3)-δelectrolyte-based DC-SOFCs,with Camellia oleifera shell char as the carbon fuel.The LSCM−GDC-anode DC-SOFC delivered a maximum power density of 221 mW/cm^(2) at 800℃ and it significantly improved to 425 mW/cm^(2) after Ni nanoparticles were introduced into the LSCM−GDC anode through wet impregnation.The microstructures of the prepared anodes were characterized,and the stability of the anode in a DC-SOFC and the influence of catalytic activity on open circuit voltage were studied.The above results indicate that LSCM–GDC anode is promising to be applied in DC-SOFCs.
