材料期刊网

DYNAMIC SEGREGATION OF SULPHUR IN CAST IRON

QIN Ziqiang YU Zongsen University of Science and Technology Beijing , Beijing , China QIN Ziqiang Department of Metal Physics , University of Science and Technology Beijing , Beijing , China

金属学报(英文版)

The segregation of sulphur at iron/graphite interfaces in both grey and nodular iron was in- vestigated with AES.Sulphur was found to nonequilibratorily segregate at the interfaces in grey iron,but not in nodular iron.Such different behaviors of segregation,which will exagger- ate the difference of grey and nodular iron in sulphur content at iron/graphite interfaces, might be derived from the difference of solidification process between the two irons.

关键词: cast iron , null , null , null

Iron Extraction From Oolitic Iron Ore by a Deep Reduction Process

LI Ke-qing , NI Wen , ZHU Ming , ZHENG Mei-juan , LI Yuan

钢铁研究学报(英文版)

A laboratory experiment was carried out to extract iron from oolitic iron ore by a deep reduction and magnetic separation technique. The raw coal with fixed carbon of 66.54% was used as the reductant. The iron was successfully extracted from the oolitic iron ore which otherwise is nearly impossible to be separated due to its extremely fine-grain and mosaic nature. The results showed that an iron recovery rate of 90.78% and an iron content of 92.53% of iron concentrate could be obtained by such a technique. The optimized roast temperature is 1200 ℃ and time is 60 min. The subsequent magnetic separation was performed by using a magnetic field intensity of 111 kA·m-1 and a grinding fineness less than 45 μm of 96.19% for the sintered product.

关键词: oolitic hematite , deep reduction , magnetic separation

Technology of Iron Carbide Synthesis

M. Bahgat , null

材料科学技术（英）

Iron carbides are very promising metallurgical products and can be used for steelmaking process, where it plays as an alternative raw material with significant economic advantages. Also it has many other applications, e.g. catalysts, magnets, sensors. The present review investigates the different properties and uses of the iron carbides. The commercial production and the different varieties for the iron carbides synthesis (gaseous carburization, mechanochemical synthesis, laser pyrolysis, plasma pyrolysis, chemical vapor deposition and ion implantation) were reviewed. Also the effect of different factors on the carburization process like gas composition, raw material, temperature, reaction time, catalyst presence and sulfur addition was indicated.

关键词: Iron carbides , null , null , null

HYDROGEN-VACANCY INTERACTION IN IRON

WANG Xiaogang(Hunan Normal University , Changsha. China Manuscript received 3 June 1994)

金属学报(英文版)

The discrete variational method (DVM)and cluster model are used to study the electronic structure and atomic configuration of the hydrogen-vacancy complex in iron.The optimum location of hydrogen atom in the monovacancy in iron is determined by minimizing the total energy and the bond characteristic between hydrogen and iron atoms is analyzed Meanwhile, the positron annihilation characteristics of the hydrogen -vacancy complex is also calculated.

关键词: :vacancy hydrogen-vacancy complex , null , null

Nitriding iron at lower temperatures

Science

The microstructure in the surface layer of a pure iron plate was refined at the nanometer scale by means of a surface mechanical attrition treatment that generates repetitive severe plastic deformation of the surface layer. The subsequent nitriding kinetics of the treated iron with the nanostructured surface layer were greatly enhanced, so that the nitriding temperature could be as low as 300C, which is much lower than conventional nitriding temperatures (above 500degreesC). This enhanced processing method demonstrates the technological significance of nanomaterials in improving traditional processing techniques and provides a new approach for selective surface reactions in solids.

关键词: surface nanocrystallization;copper

Cooperation behavior of iron and phosphorus in electrodeposition of zinc-iron-phosphorus coating

Materials Chemistry and Physics

The co-operation behavior of iron and phosphorus in clectrodeposition of Zn-Fe-P alloy onto copper from light acid chloride solutions (LACS) was investigated by means of cyclic voltammetry and steady-state polarization techniques. It was found that, under the experimental conditions, the phosphorous and the iron promote the reduction of each other and their contents in Zn-Fe-P coating change synchronously, which has been interpreted theoretically in the view of quantum chemistry. The theoretical results showed that, because the orbital radius of 4S of iron atom is shorter than that of zinc atom, the overlapping integral of iron and phosphorus (SFe-P) is smaller than that of zinc and phosphorus (SZn-P) which resulted in the synchronous variation of the contents of the phosphorus and the iron in the electrodeposits, and which also showed that there exist the cooperative effect of phosphorus with iron series metal among their co-depositing coatings. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词: electrodeposition;Zn-Fe-P alloy;cyclic voltammetry;light acid;chloride solution;alloys

THERMODYNAMIC PARAMETERS IN THE NUCLEATION OF LIQUID IRON

C.Huang , B.Song , J.H.Mao , Q.Lin , P.Zhao

金属学报(英文版)

By using of electrolytic pure iron, the specimens containing different oxide content were made in a Mo wire furnace. The DTA method was employed to measure the undercooling of liquid iron during solidification. The relations between the cleanness of liquid iron and undercooling, thermodynamic driving force of nucleation, the nucleus forming energy, as well as the critical radius of nucleus have been investigated. The results showed that with the increase of cleanness of liquid iron the undercooling and thermodynamic driving force increased, while the nucleus forming energy and critical radius of nucleus decreased.

关键词: pure iron , null , null

Separation of Iron Droplets From Titania Bearing Slag

WANG Mingyu , LOU Taiping , ZHANG Li , SUI Zhitong

钢铁研究学报(英文版)

Owing to smelting vanadiumtitanium magnetite ore, the amount of iron entrainment in slag as droplets is far higher than that in conventional BF slag. However, the iron droplets can be easily settled by blowing air into the molten slag. The results show that more than 80% of iron droplets in titania bearing slag can be settled and separated after treatment. The temperature rise of molten slag during the oxidizing process and the decreased viscosity caused by the component change of slag as well as air stirring in slag both accelerate the iron droplets settling. The vanadium content in the settled iron droplets and the original iron droplets was obtained by chemical analysis. The possible reason for the increased vanadium in the settled iron droplets was discussed by thermodynamic principles.

关键词: titania bearing slag;oxidation;viscosity change;temperature change;phase separation

SOLUBILITY OF NITROGEN IN MOLTEN GRAY CAST IRON

ZHAI Qijie , HU Hanqi , University of Science and Technology Beijing , Beijing , China HU Hanqi , Professor , Faculty of Foundry , University of Science and Technology Beijing , Beijing 100083 , China

金属学报(英文版)

The expressions of the dependence of nitrogen solubility in molten gray cast iron on the temperature and composition of the melt were proposed under the condition of foundry practice. Three gray cast iron specimens with different compositions were examined in good agreement with the derived expression.

关键词: gray cast iron , null , null

HYDROGEN DAMAGE IN HIGH PURITY IRON

WU Yichu CHANG Xiangrong TIAN Zhongzhuo XIAO Jimei University of Science and Technology Beijing , Beijing , China

金属学报(英文版)

Hydrogen damage in iron or 99.99% purity has been investigated by Doppler broadening measurement.Experimental results show that when the iron is charged with hydrogen in 0.5mol/L H_2SO_4 solution,the critical current density to cause hydrogen damage is 20mA/cm~2.While a little As_2O_3,saying 250mg/L,added to H_2SO_4 solution,even rather small current density.≤0.2mA/cm~2,would cause hydrogen damage.With the help ofi slow tensile test,it revealed that the hydrogen damage occurred in the specimen may be influential to the subsequent process of deformation and fracture.

关键词: hydrogen damage , null , null , null