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Quick Search     Adv Search   2017 Vol. 27, No. 01 Published: 2017-02-10   1 Study on thermoelectric properties of[Ca2.95Sm0.05Co3.995-xNi0.005FexO9+δ]by self-propagation process ZHONG Hong-hai，SHAN Na，NI Di，MU Hao-han，JIANG Yang，YU Da-bin DOI: 10.13228/j.boyuan.issn1006-6543.20160001 [Ca2.95Sm0.05Co3.995-xNi0.005FexO9+δ][(х＝0，0.10，0.15，0.20)]ceramic material was prepared by self propagation process using citric acid as chelating agent， nitrate and oxide as oxidant. The synthesized powders [Ca2.95Sm0.05Co3.995-xNi0.005FexO9+δ][（x＝0.10）]were compacted. The thermoelectric properties of[Ca2.95Sm0.05Co3.995-x][Ni0.005FexO9+δ]were explored from 473 K to 973 K. The results show that the compression law of [Ca2.95Sm0.05Co3.995-x][Ni0.005FexO9+δ]is in accordance with HUANG Pei-yun equation with compaction module of 1.86 MPa and nonlinear exponent of 2.074， respectively. The electrical conductivity and Seebeck coefficient of the material increase with the increase of temperature， while the thermal conductivity decreases with the temperature increasing. The[ZT]value of [Ca2.95Sm0.05Co3.995-xNi0.005FexO9+δ]sample is 0.13 at 973 K.[Ca2.95Sm0.05Co3.995-xNi0.005FexO9+δ]is promising thermoelectric material. 2017 Vol. 27 (01): 1-6 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 7 Process research and characterization of W-Cu composite powders prepared by hydrothermal co-reduction technology CHEN Yan-wu，LIU Xiang-jun，LU Feng-hui，LI Wei DOI: 10.13228/j.boyuan.issn1006-6543.20160005 A special W coated Cu nano-composite powder was successfully synthesized via hydrothermal reaction and calcining-continuous reduction process， and the phase， morphology and microstructure of the powder obtained at different preparation stages were analyzed using XRD， SEM and TEM， respectively. Results show that the near-spherical CuWO4·2H2O and Cu2WO4(OH)2 complexes are produced by co-precipitation between Na2WO4·2H2O and Cu(NO3)2·3H2O during hydrothermal reaction， and this complex powder has good dispersibility， a narrow size distribution of 10-15 nm without hard aggregate. After calcination， the precipitations are converted into a mixed oxide powders consisted of[CuWO4-x，]CuO and WO3 through dehydration and decomposition. After hydrogen reduction， the oxide powders turn into W-Cu composite powder completely， which presents a special near-spherical structure of W coated Cu， the particle size is 20-60 nm， at the same time， the presence of Cu plays a catalytic role on the reduction of tungsten oxide. 2017 Vol. 27 (01): 7-11 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 12 Study on the mixing process of two-component particles with big variance in shapes and densities YU Zheng-wei，LIU Hai，GUO Zhen，LIU Rui-rui，WANG Lu-quan，HUANG Jian-min DOI: 10.13228/j.boyuan.issn1006-6543.20160099 Two-component particles with big variance in shapes and densities of stainless steel microspheres and aluminum powders were mixed by the disc mixer. The influence of particle wetting agent dosage， mixing time， mixing speed and filling rate on the mixing degree of mixed powders were studied systematically. The mixing degree was discussed by variation coefficient method. Results show that optimal mixing process parameters are as follows： particle wetting agent dosage of 1.5% (mass percent)， mixing time of 90 min， mixing speed of 40 r/min and filling rate of 30%. The optimal mixing degree is 93.4%. The influence degree of four kinds of mixing factors on the mixing degree is as follows： mixing time＜filling rate＜mixing speed＜particle wetting agent dosage. 2017 Vol. 27 (01): 12-15 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 16 Influence of co-precipitation reaction parameters and dispersant on performance of Cu-Al2O3 powders SHI Yong-liang，LIN Tao，QI Cui-fen，CHEN Tao，ZHANG Jing-jin DOI: 10.13228/j.boyuan.issn1006-6543.20160015 The nano-Al2O3-dispersed strengthening copper-based powder was prepared with acidic and alkaline waste cupric liquor as raw material， polyvinyl alcohol (PVA) as dispersant， adding soluble aluminum salt to co-precipitation， calcination and hydrogen reduction. The effects of co-precipitation process parameters on the particle size of Cu-Al2O3 powder and dispersed phase Al2O3 were checked by laser particle size analyzer， SEM-EDS and X-ray diffraction. Results show that， the Cu-Al2O3 powder with particle size of less than 1.5 μm and narrow size distribution is prepared by controlling co-precipitation reaction parameters as follows， mother liquor concentration of 1.0 mol/L， precipitation ammonia concentration of 20% (volume fraction)， reaction temperature of 70 ℃ and pH value of 7. The particle size and distribution of dispersed phase is controlled by the content of dispersant. The nano-Al2O3-dispersed phase is less than 100 nm particle size and 100-200 nm particle spacing when the content ratio of PVA and copper ion is 0.4[∶]1.0. After sintered at 950 ℃ in hydrogen for 60 min， the sintered body has density of 8.45 g/cm3 and hardness of 115 HB. 2017 Vol. 27 (01): 16-21 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 22 Research on micro metal injection molding of titanium for biomedical applications LIU Chao， KONG Xiang-ji， WU Sheng-wen， KUANG Chun-jiang， DOI: 10.13228/j.boyuan.issn1006-6543.20160127 Titanium is considered to be the best biomedical material with a series of superior properties like high specific strength， low elastic modulus， very good corrosion resistance and fantastic bio-compatibility. Micro metal injection molding (Micro MIM) provides a novel near net shape technology to fabricate titanium micro-components for biomedical applications in large scale with low cost. Titanium micro-components were prepared using micro metal injection molding， followed by debinding and sintering process. Through the debinding and sintering parameters optimization， samples with oxygen mass percent of 0.240%， nitrogen mass percent of 0.028%， yield strength of 450 MPa ， ultimate tensile strength of 565 MPa， elongation of 18.0% and relative density of 97.3% were obtained. These properties meet the requirements of ASTM F2989-13 for biomedical grade 2 pure titanium. 2017 Vol. 27 (01): 22-26 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 27 Effects of (Co＋Ni)， (TiC＋TaC)?on hardness of WC-Co based cemented carbide ZHANG Yan，WANG Hong-fu，HE Ling，WANG Hai-peng，WANG Jun-yuan DOI: 10.13228/j.boyuan.issn1006-6543.20160007 Cemented carbide with high hardness and high toughness properties has become a hot research area in recent years. Seven specimens of three graded cemented carbide were investigated in detail for the element content distribution and hardness by using X-ray energy dispersive spectroscopy and rockwell apparatus. Results show that all the specimens are WC-Co based cemented carbide. The addition of Co and Ni enhances the toughness， while reduces the hardness of cemented carbide. The additives TaC， TiC enhance hardness of WC-Co based cemented carbide. The enhancing effect of TaC and TiC on the hardness of cemented carbide greatly surpasses the weakening effect caused by the addition of Co and Ni. 2017 Vol. 27 (01): 27-30 [Abstract] ( 2 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 31 Sensitivity analysis of overlap rate during DMLS processes ZHANG Juan，LI Yang-bo，MENG Xian-lei，ZHANG Shu-yuan DOI: 10.13228/j.boyuan.issn1006-6543.20160094 According to the actual sintering process of direct metal laser sintering (DMLS)， 304 stainless steel powder was used as sintering material， and the temperature field of sintering process was simulated by using Ansys finite element software. Firstly， the change of temperature field in multi pass sintering process was analyzed， and then the influence of different overlap ratio on the temperature field was analyzed. Results show that too low overlap ratio leads to non sintered area between the adjacent sintering channels， while too high overlap ratio causes excessively concentrated temperature and serious heat accumulation. The sintering effect of 304 stainless steel powder is better when the lap ratio is between 26%-33%. 2017 Vol. 27 (01): 31-36 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 3 ) 37 Study on properties of Ni based+WC coating by plasma spray welding ZENG Zhi-qiang，ZHANG Bo，WANG Jun-yuan，ZHU Xi-jing，GUI Kai DOI: 10.13228/j.boyuan.issn1006-6543.20160087 In order to reduce the severe friction and abrasion between diesel engine pistons and cylinder sleeves working under high temperature and high pressure and enhance the heat resistance and corrosion resistance， 15%， 25% and 35% (mass percent) of WC powder as the strengthening materials were mixed into the Ni45 powder and Ni55 powder to manufacture the hard-face layer on the surface of 38CrMoAl diesel engine cylinder sleeves by plasma spray welding technology， respectively. The properties of the hard-face layer including the micro-structure， micro-hardness and thermal physical parameters were analyzed and tested. Results show that all hard-face layer prepared by the above 6 kinds of powder can play the role of strengthening， but the hard-face layer with the best comprehensive performance was produced by (Ni45＋25%WC， mass percent) alloyed powder， in which the micro-hardness exceeds 600 HV， the gradient micro-hardness and the coefficient of thermal expansion match the substrate and meet the requirements of strengthening the inner wall of the cylinder sleeves. 2017 Vol. 27 (01): 37-41 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 42 Study on thermal conductivity of multivariate ceramics/Cu composite ZENG Zhao-feng DOI: 10.13228/j.boyuan.issn1006-6543.20160011 The powder metallurgy vacuum hot-pressed sintered technology was used to prepare SiC， Si3N4， B4C multivariate ceramics/Cu composite. The thermal conductivity of the composite at room temperature was tested through laser pulse method. Results show that the thermal conductivity of the composite decreases gradually with the content increase of SiC， Si3N4， B4C multivariate ceramics， especially when the mass percent of the ceramic is more than 15.0%. Pores， grain boundary， lattice distortion， dislocation and other defects are the main factors that affect the thermal conductivity of the composite. To obtain composite materials with good thermal conductivity， the mass percent of multivariate ceramics particles should be controlled below 15.0%. Moreover， annealing or two times extrusion can be used to improve the density and reduce internal defects of the composite， thus increase the thermal conductivity. 2017 Vol. 27 (01): 42-47 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 48 Analysis of heat treatment cracking of one Ni-based powder metallurgy superalloy disk LIU Ming-dong，，ZHANG Ying，，HUANG Hu-bao，，LI Ke-min，，HAN Shou-bo，，ZHAO Jing-jian，，ZHANG Yi-wen， DOI: 10.13228/j.boyuan.issn1006-6543.20160109 One cracking Ni-based powder metallurgy superalloy disk after heat treatment was analyzed. The results show that there is TIP (thermal induced pore) in the disc， and the surface micro-crack induced by TIP reduces the tensile strength of the disk. The residual stress resulted from heat treatment is beyond to the alloy strength， which means the disk cracking and failure. The formation of the pore is because of leaking of cans in the hot isostatic pressing. Improving the quality of cans is the key measure to eliminating the defect of TIP. 2017 Vol. 27 (01): 48-52 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 53 Effect of CrO3 on the quality of thin wall pipe lining coating prepared by SHS gravity method HU Shan，，，YANG Xi，，，YANG Yong-shun，，，DONG Zhi-xiang，， DOI: 10.13228/j.boyuan.issn1006-6543.20160009 Using SHS gravity method， Al-Fe2O3 as reaction system， SiO2 and CrO3 as additives， the preparation of small diameter thin wall ceramic lined pipe was studied. The results show the ceramic layer contains Al2O3， Al6Si2O13， FeAl2O4 and Fe2SiO4 phases without adding CrO3， while the diffraction peaks of FeAl2O4 and Fe2SiO4 disappear after adding CrO3. When the mass percent of CrO3 is 6%， the surface of the substrate is slightly fused， which is the most closely combined with the ceramic layer， the coating and substrate interface are mechanical anchoring， the apparent porosity is the minimum and the volume density is the highest. With the increase of CrO3 content， the apparent porosity increases and the volume density decreases gradually. When the mass percent of CrO3 is 10%， the steel pipe has partial melting； the coating with more pores， loose structure and poor quality is obtained. 2017 Vol. 27 (01): 53-58 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 59 Research progress on mechanical alloying of bearing alloy with immiscible system WU Zhi-fang，LIU Chao DOI: 10.13228/j.boyuan.issn1006-6543.20160002 The research progress on mechanical alloying (MA) of bearing alloy with immiscible system was overviewed. The transition mechanism of nano-phase composite structure， as well as thermal stability and mechanical properties of bearing alloy with immiscible system were emphatically addressed. 2017 Vol. 27 (01): 59-63 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 2 ) 64 Research progress of SiC particle reinforced aluminum matrix composites LI Shu-zhi，WANG Tie-jun，WANG Ling DOI: 10.13228/j.boyuan.issn1006-6543.20160023 The advantages of SiC particle reinforced aluminum matrix composites and its preparation methods were briefly introduced， including mixing method， infiltration method， spraying method， powder metallurgy method and solid-liquid separation method. The influence of hot deformation parameters on the properties of the composites was discussed. Finally， the developing prospects of aluminum matrix composites prepared by powder metallurgy method were discussed. 2017 Vol. 27 (01): 64-70 [Abstract] ( 1 ) HTML (1 KB)  PDF  (0 KB)  ( 1 ) 71 Effect of titanium dioxide on the performance of exterior wall coatings TONG Wei，，YIN Qing-chun，YIN Lian-hai，LIU Tao， DOI: 10.13228/j.boyuan.issn1006-6543.20160025 Titanium dioxide is an important white pigments and fillers. The adding amount， particle size and dispersion of titanium dioxide have great influence on the properties of exterior wall coating. Reasonable using of titanium dioxide can not only improve the quality of exterior wall coating， but also expand the benefits of enterprise. Properties of exterior wall coating were tested according to GB/T 9755-2014. Results show that the coating has excellent physical and chemical properties when the processing time is 80 min and addition amount of titanium dioxide is 20% (mass percent). The exterior wall coating has a hiding power of 98 g/m2， excellent solvent-resistance， weather-resistance and contamination resistance， which meets the national standards and the needs of customers for the top quality products. The enterprise takes the maximization benefit. 2017 Vol. 27 (01): 71-74 [Abstract] ( 0 ) HTML (1 KB)  PDF  (0 KB)  ( 3 )

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