G.W. Chang
,
H.X. Wang
,
X.D.Yue
,
H.L. Zhang
金属学报(英文版)
For settling the question of feeding speed in applying the cored-wire method to spheroidize ductile iron melt, ANSYS software was applied to simulate the heat transfer and mass transfer, and the melt time of the steel strip in the iron melt was determined by linking the heat transfer and mass transfer, and then the feeding speed was calculated. Conclusions have been drawn that the iron layer was formed on the surface of the cored-wire during the wire-feeding process. The thickness is 0.073 mm when the temperature of the iron melt is 1500℃, the time from formation to remelting of the iron layer is 0.063~s. When the temperature of the iron melt is below 1500$^{\circ}$C, the time taken for the steel strip to melt is rapidly shortened. When the temperature of the iron melt is above 1500℃, the variation amplitude of the steel strip melt change with time is gradually diminished. The melt time of the steel strip is rapidly increased with the increase of the steel strip thickness. When the temperature of the iron melt is 1500℃ and the carbon content is 4 %, the melt time of a steel strip, which has a thickness of 0.5 mm, isthrice that of a steel strip whose thickness is 0.3 mm. The calculation results of the feeding speed are basically in agreement with the applied feeding speed in the factory.
关键词:
Ductile iron
,
null
,
null
,
null
G.W. Chang
,
G.C. Jin
,
S.Y.Chen
,
X.D. Yue
金属学报(英文版)
According to the nature of the periodic bending deformation of solid-liquid interface in the solidification process of continuous casting slab，The nucleation and extension of crack was analyzed by the variation of temperature gradient and dendritic spacing in the front edge of solid-liquid interface. The results indicate that the bending deformation of interface makes temperature field change in the front edge of solid-liquid interface; the occurrence of temperature gradient along drawing direction provides the condition for the growth of secondary dendrites; The crack source formed during the middle and final stage of solidification may extend to the surface of casting slab and become internal crack. The theoretical analysis is basically agreement with the experimental results.
关键词:
continuous casting
,
null
,
null
李在元
,
顾惠敏
,
翟玉春
稀有金属材料与工程
用NH4OH 把H2WO4转化成(NH4)2WO4,再以CuSO4水溶液和(NH4)2WO4水溶液为反应物,用NH4OH和H2SO4调节pH值,进行W-Cu (70 g: 30 g)共沉淀反应,考察了pH值对W-Cu共沉淀回收率的影响;理论计算了pH值对W-Cu共沉淀回收率的影响.实验结果表明:Cu的回收率随pH值增大而提高,pH值大于6.0时,Cu的回收率有下降的趋势; W的回收率随pH值增大而降低;当pH值为5.2时,W和Cu的回收率相等,且只有一个相等点,此时两者的回收率大于99%,这与理论计算结果相符合.
关键词:
H2WO4
,
CuSO4·5
,
H2O
,
共沉淀
,
pH值
,
回收率
林水东
,
吴粦华
,
丁马太
,
章汝平
,
叶雅龙
功能材料
考察了增容剂聚丙烯接枝甲基丙烯酸甲酯(PP-g-MMA)对聚丙烯/硅灰石(PP/W)复合材料力学性能和非等温结晶行为的影响.用Avrami、Ozawa、Mo、Dobreva、Kissinger等方法对非等温结晶的数据进行分析:ΔGac、ε、n、α参数表明,W自身有较强的异相成核活性,且会改变PP的结晶成核和生长机理;Kc、t1/2、F(T)、Tp、Xc参数表明,W的填充和PP-g-MMA的掺入,均会提高PP的结晶速率;ΔE和ε表明,W还起着阻碍PP大分子链或链段运动的作用,而 PP-g-MMA则会进一步增强这种阻碍作用.由于PP-g-MMA的掺入,PP/W复合材料的刚性、强度和韧性均得以提高.
关键词:
聚丙烯接枝甲基丙烯酸甲酯
,
聚丙烯
,
硅灰石
,
力学性能
,
非等温结晶
何玉林
,
尹玉珍
,
孙明军
机械工程材料
对50W800G硅钢板采用十字形试样进行了不同加载条件下的单向拉伸试验和双向拉伸试验,并运用ANSYS软件对试验结果进行了有限元模拟.结果表明:50W800G硅钢板双向等比拉伸时的应力-应变曲线位于双向非等比拉伸和单向拉伸时的应力-应变曲线之上;50W800G硅钢没有明显的各向异性行为,双向等比拉伸时轧制方向的应力-应变曲线稍高于垂直于轧制方向的,而双向非等比拉伸时垂直于轧制方向的应力-应变曲线稍高于轧制方向的;ANSYS有限元数值模拟的结果可用来预测双向拉伸过程中的应力-应变关系.
关键词:
硅钢板
,
双向拉伸试验
,
加载路径
,
有限元模拟
于婷婷
,
柳丽芬
,
杨凤林
催化学报
doi:10.1016/S1872-2067(16)62556-1
电化学或光电化学半导体催化剂广泛应用于降解污水中的有机与无机污染物,有望实现低能耗且高效的污染物降解.目前,已有多种异质结半导体光催化剂的研究报道,并且大多数的研究结果显示催化剂活性有明显提高,但仍存在着光激发后电子与空穴的复合问题.光电化学系统的构建可减少电子与空穴的复合,因光催化阳极与光催化阴极之间费米能级的不同,在两极之间形成异质结,产生内电场,自生偏压驱动电子流动.已有诸多研究报道将TiO2催化剂与g-C3N4复合形成异质结,提高光催化活性.由于g-C3N4(~–1.12 eV vs.NHE)导带位置相比于TiO2(~–0.2 eV vs.NHE)更负,因此在两者之间可形成内部偏压,驱动电子由g-C3N4转移至TiO2.WO3/W导带位置(~+0.2 eV vs.NHE)比TiO2与g-C3N4更正,因此自生内偏压促进电子由阳极流动至阴极.我们研究组发展了一种在无光条件下的自偏压电化学燃料电池系统,异质结间的电子流动可活化氧气产生自由基,自由基可用于阳极污染物的降解,但阴极未降解污染物.本文在上述研究基础上,应用TiO2/g-C3N4异质结与WO3/W分别作为阳极与阴极催化剂,构建自偏压催化燃料电池系统,在无光条件下催化阳极与阴极之间自发电子转移,活化氧气产生自由基,同时实现低能耗阳极室内污染物如罗丹明B和三氯生的氧化,且电子用于阴极室内硝态氮的还原.通过在空气中原位加热与氧化钨丝制得WO3/W阴极,由扫描电镜图可知在钨丝表面形成三氧化钨纳米粒子,此结构增大了催化剂的表面积以及催化剂与电解液的接触面积,有利于电荷转移.用循环伏安曲线(CV)与电流时间曲线(I-t)表征了电极的电化学性质.CV测试结果表明,相比于硫酸钠电解液,WO3/W阴极在含有硝态氮的电解液中存在还原峰,且紫外照射比无光条件下的电流略大,说明此电极在无光条件下可用于还原硝态氮,有光更利于激发催化剂产生电子与空穴降解和去除污染物.在硫酸钠电解液中,无光照条件下(同室),I-t曲线表明TiO2/g-C3N4相比于WO3/W电极可产生更大电流,因此选择TiO2/g-C3N4作为阳极,WO3/W作为阴极.在含污染物电解液中,无光照条件下,Pt片作为对电极时(同室),I-t曲线中的电流在曝气时比未曝气时小,说明电极上产生的部分电子用于活化氧气产生自由基,因此转移到外电路的电子减少,电流变小;相反,当TiO2/g-C3N4阳极置于阳极室,WO3/W阴极置于阴极室时(两室),阳极鼓入空气,阴极曝氮气时,电流比两室均未曝气时大,说明此系统有利于电子产生与转移,用于氧化还原去除污染物.相比于传统方法,此系统通过阳极室内曝空气与活化分子氧形成自由基,无需外加偏压,在有光与无光条件下,均可实现对阳极室与阴极室内不同污染物的同时去除或降解,同时提出了此系统中的降解机理.
关键词:
自偏压系统
,
异质结
,
无光照
,
低能耗
,
污染物降解
Doris Smith
,
Ken Lynam
环境化学
本文中使用安捷伦SPEC C18AR固相萃取膜盘成功萃取了水中的有机氯农药残留和除草剂.使用双柱配置的GC/μECD系统进行检测,安捷伦J&W DB-35ms UI超高惰性色谱柱作为分析柱,DB-XLB色谱柱为确认柱.该方法为浓度接近或低于最大污染限值的含氯有机物提供了高度灵敏的分析方法.根据预估的分析物萃取浓度,方法使用的校准范围为1-100 ng· mL-1.分别对0.01 μg·L-1的加标水样和一个自来水水样进行了萃取和分析,结果证明可满足水中的有机氯农药残留和除草剂的测定.
关键词:
有机氯农药
,
除草剂
,
色谱柱
HUANG Huimin CHEN Xinmin Central South University of Technology
,
Changsha
,
China HUANG Huimin Associate Professor
,
Department of Chemistry
,
Central South University of Technology
,
Changsha
,
China
金属学报(英文版)
The nature of the oxygen contained in β-W was investigated with DSC,X-ray analysis on quenched samples and Auger spectroscope.It was shown that the oxygen contained in nonpyrophoric β-W consists of the reversibly chemisorbed oxygen and the interstitial oxygen which could form an interstitial solid solution with β-W.It seems better to consider β-W to be a metastable phase of tungsten with the interstitial oxygen as stabilizer.
关键词:
tungsten
,
null
,
null
,
null
穆立峰
,
马永强
,
李涛
,
孙常亮
,
韩冬
钢铁研究
介绍了抚顺特殊钢公司通过快锻工艺制造φ400～700 mm大规格风电轴承钢的生产实践.通过控制钢中残余元素、VD精练结束前高拉铝、采用保护气氛浇注、使用保护气氛电渣炉生产及墩拔锻造工艺等,使渗碳轴承钢G20Cr2Ni4A的w(Ti)≤0.003％,w(A1)为0.015％～0.050％,w(O)≤0.001 5％,w(Sn)≤0.03％,w(As)≤0.04％,w(Sb)≤0.015％,w(Pb)≤0.02％,w(Ca)≤0.001％,w(Bi)≤0.02％,且钢中夹杂物及低倍组织处于较好水平,渗碳轴承钢晶粒度、性能、探伤等指标完全适合风电轴承套圈的使用要求.
关键词:
风电轴承钢
,
钛控制
,
快锻工艺
Physical Review B
The effect of W on the structural stability of TiAl intermetallic systems and the site preference of W in B2 and L1(0) TiAl were studied based on first-principles calculations. It was found find that about 15 at. % W addition, in good agreement with experiment, is required to stabilize the B2 structure in a TiAl base alloy. W was predicted to occupy Al sites in the B2 phase, but Ti sites in the L1(0) phase. The B2-stabilizing effect of W and its site preference can be explained perfectly on the basis of the pseudogap effect and the strong covalent W-Ti bonding. The strong W-Ti bonding pairs are maximized when W occupies Al sites in B2 TiAl. But when W occupies Al sites in L1(0) TiAl, the W-Ti bonding is weakened by the existence of Al in the alternating (002) plane, which can, however, strengthen the in-plane W-Ti bonding when W occupies Ti sites.
关键词:
gamma-titanium aluminides;electronic-structure;microstructure;deformation;systems;alloys
