Abstract: Under high speed preheat in blast furnace and gasification in iron-bath for smelting reduction the pyrolysis of pulverized coal injection is the first important stage. For study of this pyrolysis of coal in 1160-1750℃, an apparatus was designed. The heated rate by a plasma torch was as high as 4.3×103-2.4×104 K/s and even more than 105 K/s. The results show that increasing temperature gives more effect on the pyrolysis of bituminous coal than anthracite, but atmosphere seems to be no effect on pyrolysis process. This conclusion shows that in iron-bath process, the solid coal particles and oxydizing agent can be blown in separately. These will be good for controlling over the heat in front of the nozzles and eliminating heavy fume generation.
Abstract: Accorhing to the analogue theory, a cold experimental model for simulating the swirl pulverized coal-oxygen burner used in the industrial test was designed and established. By one dimension LDV, the distribution of axial velocity in the swirling field given was measured. Depending upon the measurement datum by the LDV, the mathematic model for showing the swirling field given was developed, and the measurement value was in good agreement with the calculation value of the model. It is considered that the approch was more satifactory than other methods at present as the axial velocity distribution in the reverse flow area was shown by cosine function. Hence, the some problems on the gas dynamics of the swirling field was also discussed in this paper.
Abstract: Based on ionic theory, a constitutional model is established for calculation of activity of CaO in basic slag. The concept of gross interaction effect and self-action effect of CaO in melten slag is also presented, and the gross interaction coefficient and self-action coefficient of CaO are determined from the experimental data after Talor and Chipman. Finally, the model is checked by the activities of CaO measured by experiments in different slag systems. The results show that the activity of CaO calculated from the model well agrees with the experimental data.
Abstract: Behaviour of grain boundaries segregation and precipitate in Fc-Cr-Mn and Fe-Cr-Mn-W-V alloys were investigated during thermal againg and irradjation by electron beam. Experiments show that Cr, Mn are depleted on grain boundaries during thermal aging in Fe-Cr-Mn-W-V alloy. It is depended on chemical composition of M23C6 type chromium-carbides. Cr and Mn in both alloys mentioned above are depleted on grain boundaries during irradiation. It is depended on concentration of radiation-induced cavity and void swelling. Radiation-induced segregation effects on chemical composition of precipitate M23C6 in both alloys.
Abstract: This investigation indicates that the primary dendritic particles lower significantly the property of low cycle fatigue in K136 ECD (Est-Cast-to-Shape Disc). The possible reason for this phenomenon is as following: (1) Arousing the main crack to early form; (2) Acting as internal source of fatigue cracks. These both effects depend on the fatigue stress and fatigue crack growth rate. Under the condition of high fatigue stress or higher crack growth rate this detrimental effect can be reduced. However, if the fatigue stress is lower, the primary dendritic larger particles decrease the fracture life significantly. Increasing solid solution temperature can decrease the number of primary particles resulting in the improvement of fatigue porperty.
Abstract: After the Ag-Cu and Ag-H62 electric contact materials arc made by cold press-rolling (or sputtering in magnetic field) and annealed, the quantitative and semi-quantitative analysis are carred out by scanning electron microscope. The results show that the interfaces are of metallic bonding. The diffusion coefficients and the activation energies are also calculated.
Abstract: The effects of Co and Al on magnetic properties and microstructure of Nd-Fe-B alloys are studied in this paper. A magnet with energy product of 278.6~318.4 kJ/m3 (35~40 MGOe) and reversible temperature coefficient (α), of -0.06~-0.08%/K at 293~373 K is abtained. Cobalt atoms enter in the tetragonal phase, increasing Curie temperature and decreasing the reversible temperature coefficient. A new phase Nd(Fc, Co)2 with MgCu2 type structure forms in the alloy containing higher Co content. It causes the decrease of the coercivity. Alumium atoms are mainly in the tatragonal phase, it makes the grains become smaller, and rises the coercivity of the alloy. When Al content further increase, a new phase forms, which destroy the coercivity of the alloys.
Abstract: Based on proposing a new equation B=Bo + BI In (t+1) +B11 1n2 (t + 1) for fitting the relaxation curve, a new relaxation parameter, which can characterize the curve comprehensively, is put forword. Byexperimentally investigating a number of rats exposed to 80 mg SiO2+20mg Fe3O4 particles, the variation law; of α* vs. the time after exposure &/or death are gained. A highly significant linear negative correlation between the α* values and the grade data got from the pathologic sections is discovered.
Abstract: White Cast irons that contain amount of massive cementite show poor plasticity and toughness, which limited their wide applications in industry. Four methods of plastic deformation and heat-treatment were adopted in this paper to improve cementite's bad morphology and distribution. An ideal structure of fine cementite particle distributing within the matrix of ferrite was obtained. The refined structure white cast iron is of excellent superpla- sticity at the range from 650 to 350℃, and its room temperature mechanical properties also have a great improvement. This kind of white cast iron can be used as wear-resistant die material.
Abstract: In order to reduce the production cost of rod and wire rolling, a high-speed horizontal wheel caster for billet of 52-85 mm square has been developed. The wheel axis of the new caster is inclined from vertical centerline by a small angle of 3°~5°. The liquid steel is flowing from tundish to mold cavity through an enclosed nozzle so that the oxidation of steel stream can be prevented and the meniscus detecting and control devices can be eliminated. With the pilot caster of 3 m in diameter, billet of 50 mm×63/67 mm has been cast with speed of 18~22 m/min. Both surface and internal quality of the strand are satisfactory. Based on the result of pilot experiment, a wheel caster for billet of 70~85 mm square in cross-section is designed, the expected casting speed will be 28m/min, and it can match with high-speed rod mill for direct rolling.
Abstract: This paper discusses the basic principle which the inverted firing angle of thyristor inverter has the influence on power factor of a cascade connected device. On the basis of this principle, if it adopts a PWM type of cascade connected device, the power factor is improved to a certain extent. The tested results fully prove that the thcoritical analysis is correct. Because the construction and control of this PWM type of cascade connected device are comparatively simple and the economic benefit by using of this device is got.
Abstract: The paper introduces the principle of least-tact rippless following system implemented by a TP-801B single board microcomputer. The program block-scheme and the experimental results are also given.
Abstract: The effect of different rare earth element additions in conductive copper is studied. The results show that rare earth element added can change the morphology of the nonmetallic inclusions and refine the grain in conductive copper, so that its mechanical properties are increased. If moderate rare earth elements add in conductive copper, the regular of impurties distribution is changed and growth rate of the grain is suppressed, resulting in improving of conductive properties of copper.
Abstract: Titanium nitride can be coated on the steel-base and cemented-carbides to improve the resistant to wear and corrosion. The effect of different N2/H2 ratios on the lattice parameter, hardness and the rate of the TiN deposition are researched in this paper. The results show that when optimum N2/H2 ratio appriximates to 0.5, the stoichiometric TiN will be formed. The hardness and the deposition rate of TiN film reach their maximum, and the lifetime of the treated surface increases by three times as compared with that of untreated ones.
Abstract: Making carbon fibres from low-cost petroleum pitch is the most attractive mcthod to produce commercial carbon fibres. Isotropic carbonaceous pitch-base continuous and short carbon fibres have made successfully at both laboratory and pilot plant. The pretreatment of petroleum sludge to make precursor, the spinning process, infusibiliza tio n and carbonization treatment are described. The tensile strength of carbon fibres is about 686.5 MPa.
Abstract: The experiments have been performed to investigate the grain growth, the characterization of grain boundary migration and the interfacial phenomena at high temperature for Fe-25Cr-5Al-RE alloy. The results show that the rare earth (landium is main) has a certain effect on the grain growth of alloy; La2O3 may be the nuclear center of titanium nitride phases that precipitate in the matrix of the alloy; for Fe-Cr-Al-RE (RE<0.1%) fine titanium nitride may precipitate on the grain boundaries and inhibite the migration of grain boundaries; by repeated heating and cooling, the rare earth increases the permeation of O2- ions through the oxide scale, lanthanum atoms diffuse towards the interfaces and precipitate as lanthana. There is no doubt that the precipitates lanthana and alumina in matrix as a trapping of vacancies greatly increase the oxidation resistance and the life of the electric heating alloy.
Abstract: The crystal structures of R1+εFe4B4 compounds which were found in the permanent magnets R-Fc-B systems arc all built based on the two interpenetrating substructures. Fe-B substructure and R substructure, both have tetragonalsymmetry. Since the two substructures do not have the same periodicities in c direction, R1+εFe4B4 compounds form the so called Chimney-Ladder structureor Vernier structure which may belong to the incommensurate composite crystal structure. The translation symmetry of the incommensurate structure do not exist in three dimensional space and the superspace group theory has been developed for the description of the symmetry of incommensurate structure. In this paper, the superspace group theory is applied to the R1+εFe4B4 compounds. The result shows that the symmetry of R1+εFe4B4 compounds can be descripted by the general form PS1S1P4/nmm
Abstract: Based on the results in small floating cell and in a series of three round bottom flasks, the experiments on the leaching of oxidized manganese ore using SO2 were carried out in an experimental pachuca tank. The tested datum well agree with ones obtained mentioned above. The average recovery of Mn, Co and Ni are 94.80%, 89.70% and 81.50% respectively. The SO2 content in the waste gas lowers less than 0.01%, which is below the allowed standard of SO2 content in the waste gas in China.
Abstract: Gallium forming a chalete compound with morin at pH 5 adsorbs on hanging mercury drop electrode and gives a sensitive reducing wave when scanned cathodically. In this paper, the optimum conditions were sought, and the interference of co-existing ions is investigated. Its peak current is proportional to the concentration of gallium in the range of 1~120 ppb; the limit of detection is 0.3ppb. The proposed procedure is applied to the determination of galliumin in steels, iron, ores and slags in Pan Zhi Hui Steel and Iron Plant.
Abstract: In this paper, a mathematical model for structure of ideal quasicrystal lattices is set up. This Model describes very beautifully the following phenomena which is shown in the electron micrograph of the Mn-Al quasicrystal obtained by Hiraga et al. In some local areas, ten bright dots groups are distributed in concentric circles; sixteen bright dots are distributed the surroundings of every two neighbourhood righs of bright dots; and fourteen bright dots arc distributed the surroundings of every double overlapping rings of bright dots. Therefore, it seems that this model can explain more phenomena in Mn-Al alloy quasicrystal than those reported by Hiraga et al, and could offer some new ideas for the theoretical research of structure of quasicrystal.
Monthly, started in 1955 Supervising institution：Ministry of Education Sponsoring Institution：University of Science and Technology Beijing Editorial office：Editorial Department of Chinese Journal of Engineering Publisher：Science Press Chairperson：Ren-shu Yang Editor-in-Chief：Ai-xiang Wu ISSN 2095-9389CN 2095-9389
