S.H. Tantawi (Building Research Institute
,
Dokki
,
Cairo
,
Egypt)I.Z.Selim (Physical Chemistry Dept.
,
National Research Center
,
Dokki
,
Cairo
,
Egypt (To whom correspondence should be addressed)
材料科学技术（英文）
The use of a natural white juice, taken from magrabe banana stem, as concrete admixture to improve mechanical and physicrvchemical properties of concrete has been studied. The compressive strength, bulk density the free lime liberated during hydration and the combined water content were determined. The results indicate that the admixture acts as a retarder in most cases and as accelerator in some ones. Also, the admixture effect on the corrosion resistance of the reinforcing steel against surrounding aggressive media has been investigated using galvanostatic polarization technique. The addition of 0.2% admixture leads to the more inhibition of the steel
关键词:
WADSWORTH Jeffrey and FLUSS Michael(Chemistry and Materials Science Directorate
,
Lawrence Livermore National Laboratory
,
Livermore
,
CA 94551)
金属学报(英文版)
The role of the National Laboratories is summarized from the era of post World War II to the present time. The U.S. federal government policy for the National Laboratories and its influence on their materials science infrastructure is reviewed with respect to .determining overall research strategies, various initiatives to interact with industry (especially in recent years),building facilities that serve the nation, and developing leading edge research in the materials sciences. Despite reductions in support for research in the U.S. in recent years, and uncertainties regarding the specific policies for Research &Development (R&D) in the U.S., there are strong roles for materials research at the National Laboratories. These roles will be centered on the abilities of the National Laboratories to field multidisciplinary teams, the use of unique cutting edge facilities, a focus on areas of strength within each of the labs,increased teaming and partnerships, and the selection of motivated research areas. It is hoped that such teaming opportunities will include new alliances with China, in a manner similar, perhaps, to those recently achieved between the U.S. and other countries.
关键词:
: U.S. Materials Science. U.S. National Laboratories and Facilities
,
null
M.J.Stott
,
L.M.Molina
,
J.A.Alonso
材料科学技术（英文）
Ab initio total energy calculations are used to simulate the building of equiatomic solid Apb alloys (A=Li, Na, K) with A4Pb4 clusters which are particularly stable in the gas phase. The eight clusters per unit cell were drawn together by shrinking the cell in stages, and allowing full atomic relaxation at each stage. Charged Pb4 tetrahedral units dominate the structural and electronic properties, and these units are remarkably robust and insensitive to their alkali environment. The stability of the Pb4 units diminishes as we progress from K to Li and lead to their absence in the LiPb alloy in accordance with experiment. The distance between Pb4 units seems to be the critical factor responsible for the structural trends, which is determined by the atomic size of the alkali.
关键词:
张清
,
李全安
,
文九巴
,
白真权
腐蚀学报（英文）
1974-），男，硕士研究生，研究方向为腐蚀与防护.〖ZK)〗
Tel：0379-4231846〓E-mail：FQ)〗〖HT〗〖HJ〗〖HT5”SS〗
〖JZ(〗〖HT2H〗〖STHZ〗〖WTHZ〗
采用高温高压釜，辅以失重法和扫描电镜，对不同H2S分压下(1.4 kPa,20 kPa,60 kPa,120 kPa)油管钢N80、P110的CO2/H2S腐蚀进行了研究.结果表明，在试验H2S分压范围内，随着H2S分压的升高，两种钢的腐蚀速率先增后降，且都在H2S分压为20 kPa时取得最大值.
关键词:
H2S分压
,
null
,
null
,
null
张清
,
李全安
,
文九巴
,
白真权
腐蚀学报（英文）
doi:10.3969/j.issn.1002-6495.2004.06.015
采用高温高压釜,辅以失重法和扫描电镜,对不同H2S分压下(1.4 kPa,20 kPa,60 kPa,120kPa)油管钢N80、P110的CO2/H2S腐蚀进行了研究.结果表明,在试验H2S分压范围内,随着H2S分压的升高,两种钢的腐蚀速率先增后降,且都在H2S分压为20 kPa时取得最大值.
关键词:
H2S分压
,
N80钢
,
P110钢
,
CO2/H2S腐蚀速率
