D.G. Wang
,
Y.C. Wu
,
M.H. Jiao
金属学报(英文版)
The warm compaction process is simulated by the finite element analysis software which is MSC/MARC. The thermal mechanically coupled analysis method is applied based on the updated Lagrangian Method to simulate powder warm compaction process. The powder warm compaction process is simulated, and the influence of friction condition and pressing styles is researched on the density of powder green and the mechanics behavior at certain temperature. The results indicate that for cylindrical powder metallurgic products, with the improvement of friction condition, the uniformity of distribution of green relative density is largely improved, the pressing force and stress all decrease, and the nonconforming pressing processes influence the distribution of green density in some degree. The status of stress distribution of the process that punches firstly press and die finally press is different with other three processes, presents the figure of ‘flume’.
关键词:
Density
,
FE
,
property
,
FEM
,
property
,
Three
Feng XIAO
,
Liang FANG
材料科学技术（英文）
Density of molten Ni and Ni-W alloys was measured in the temperature range of 1773~1873 K with a sessile drop method. The density of molten Ni and Ni-W alloys trends to decrease with increasing temperature. The density and molar volume of the alloys trend to increase with increasing W concentration in the alloys. The calculation result shows an ideal mixing of Ni-W alloys.
关键词:
Density
,
null
,
null
,
null
Yuanyuan LI
材料科学技术（英文）
Fe-2Cu-2Ni-1Mo-0.8C (wt pct) elemental mixed powders were rapidly sintered within 6~min by spark plasma sintering, and the effects of sintering parameters on the densification degree and performance of the as-sintered materials were investigated. Results showed that when a proper combination of pulse electric current and constant electric current was employed for sintering, the density and bend strength of the as-sintered material reached the maxima, being 7.61×103 kg/m3 and 1540 MPa, respectively. Its corresponding fracture morphology was characterized as the mix of ductile, intergranular and cleavage fractures.
关键词:
Spark plasma sintering
,
密度
,
组织性能
,
铁基合金
Jianzhong WANG
金属学报(英文版)
doi:10.1016/S1006-7191(08)60122-2
A new method for producing higher density PM parts, high velocity compaction (HVC), was presented in the paper. Using water atomized pure iron powder without lubricant admixed as the staring material, ring samples were compacted by the technique. Scanning electron microscopy (SEM) and a computer controlled universal testing machine were used to investigate the morphologies and the mechanical properties of samples, respectively. The relationships among the impact velocity, the green density, the sintered density, the bending strength and the tensile strength were discussed. The results show that with increasing impact velocity, the green density and the bending strength increase gradually, so the sintered density does. In addition, the tensile strength of sintered material is improved continuously with the sintered density enhancing. In the study, the sintered density of 7.545~g/cm3 and the tensile strength of 190~MPa are achieved at the optimal impact velocity of 9.8 m/s.
关键词:
Powder metallurgy
,
high velocity compaction
,
green properties
,
stress wave
,
bending strength
Liang FANG
,
Feng XIAO
,
Zushu LI
,
Zainan TAO
材料科学技术（英文）
The density of Ni-Al alloys in both liquid state and solid-liquid coexistence state was measured with a modified pycnometric method. It was found that the density of Ni-Al alloys decreases with increasing temperature and Al concentration in the alloys. The molar volume of liquid Ni-Al binary alloys increases with the increase of temperature and Al concentration. The partial molar volume of Al in Ni-Al binary alloy was calculated approximately. The molar volume of liquid Ni-Al alloy determined in the present work shows a negative deviation from the ideal linear molar volume.
关键词:
Ni-Al alloy
,
null
,
null
,
null
,
null
周绍建
,
黄剑
,
吴书锋
,
嵇阿琳
,
张智
宇航材料工艺
doi:10.3969/j.issn.1007-2330.2014.06.010
以径棒法编织成型预制体,采用沥青浸渍炭化工艺制备了C/C复合材料(1.50 g/cm3),采用CT检测了试件的密度分布特征,并采用光学显微镜和压汞法分析了试件的孔隙分布特征.结果表明,在沥青浸渍炭化的工艺条件下,试件外端密度最高,由外端到中心沿径向密度递减;以坯体中心为参照点,同一圆周方向密度均匀分布;坯体开孔率沿径向由外端到中心递增;坯体大孔和中孔孔容积比率沿径向从外端到中心递增,而微孔孔容积比率则从外端到中心递减.
关键词:
C/C复合材料
,
压汞法
,
密度
,
孔隙
龙东辉
,
张洁
,
杨俊和
,
胡子君
,
李同起
,
成果
,
张睿
,
凌立成
新型炭材料
以苯酚、间甲酚和糠醛为原料,在正丙醇溶剂中以盐酸为催化剂经溶胶-凝胶过程合成了醇凝胶,直接超临界正丙醇干燥得到有机气凝胶,在氮气保护下裂解制备出富含中孔的炭气凝胶.用IR、N2吸附、SEM、TEM等表征气凝胶的结构特征,考察了问甲酚苯酚摩尔比对凝胶结构的影响.结果发现:提高间甲酚的含量能够增强聚合物的交联密度,减小聚合物与溶剂的相溶性,缩短相分离时间,有利于得到较小的纳米颗粒和孔径的炭气凝胶.所制得的炭气凝胶平均中孔孔径随间甲酚含量的增加从47 nm逐渐减小至13 nm,BET比表面积和中孔孔容在m-C/P=0.33时达到最大值.
关键词:
炭气凝胶
,
溶胶-凝胶法
,
超临界干燥
,
密度
,
孔隙
