Abstract: Incompetent rock is always related to low strengths and/orto well developed discontinuities, which are often the most essential factors leading to unstable openings. This paper outlines the deformobility and failure of incompetent rock around an opening under mining disturbances, and discribes the main requirements for opening supporting under circumstances mentioned above. Two kinds of rock-bolts with superior performances which were designed for strengtheting of incompetent masses are presented and two schemes for opening supporting combined rock bolting with reinforced shotcrete which have been used successfully in mines are given.
Abstract: The interaction between Mn-bearing slag and steel during direct alloying with manganese ore is studied in presernt paper. Basicity and[Si] and/or[C] content are the main factors influencing the reaction. When using FeSi and SiC as reducing agents, the reduction rate of MnO is in 10-5 Mn/s·cm2 order. But the dessolving process of SiC has some effects on the reduction. After about 10 to 15 minutes,[Mn] tends to be stable. The rate order of SiC-MnO reaction is first order, then increases somewhat.
Abstract: In accordance with the coexistence theory of slag structure and the phase diagram, mass action concentration calculating models corresponding to various temperature ranges for CaO-SiO2 slag system are formulated. Calculated results at steelmaking temperatures show that both calculating models, considering two silicates (CaSiO3 and Ca2SiO4) and considering three silicates (CaSiO3,Ca2SiO4 and Ca3SiO6), are applicable for mass action concentration calculation. Comparison of different calculating variants has proved that using thermodynamic data obtained by the regression analysis in this paper gives better agreement between calculated NCaO and measured aCaO than using the data from references does, so the later should be investigated in detail in the future. The correspondence of maximum mass action concentrations of silicates with their congruent melting points in phase diagram tells us that silicates play very important roles in the melting temperature of the givem system. The appearance of minimum Σn in the course of its variation with basicity can be explained by the fact that several structural units can combine to form one silicate molecule.
Abstract: The phase constituent and structure of a Fe-W(Mo)-Co(Ni) age hardening tool steel were investigated by TEM-SEM, X-ray and image analysis. The mechanizm of age hardening indicated that the non-barrier precipitation-spinodal decomposition happened at the initial stage of age hardening to form a period structure, the growth of this structure was very slow, and it caused the fast hardening and slow softening in the aging process.
Abstract: The notch effect on high temperature LCF (Low Cycle Fatigue) and fatigue/creep interaction behaviour was investigated in GH33A super-alloy. LCF life was decreased dramatically because of notch and acuity of notchs. During LCF tests, dwelling at maximum stress introduces creep damage into low cycle fatigue, then decreased LCF fatigue cycles. At LCF tests with constant maximum stress and varied minimun stress, fatigue/creep interaction curve exhibits a maximum fatigue life at certain stress condition and fracture character can be gradually changed from pure fatigue into pure creep with increasing in mean stresses and decreasing in alternating stress amplitudes.
Abstract: A TEM study on the interfacial structure of M23C6/γ and VC/γ precipitated in GH36 superalloys was conducted. The misfit dislocation distribution has been clearly observed at the semi-coherent interfaces of M23C6/γ, a single array along the broadfaces at both sides with Burgers Vector a/2 <110>γ and spaced about 10 nm apart. It has been shown circular strain field constrast around the very fine dispersive VC particles of 3 to 12nm or so in size. In addition, strengthening mechanism of M23C6 and VC precipitated in GH36 superalloy, and how to identify the moire pattern or interfacial dislocations by TEM, were also discussed.
Abstract: Under temperatures (773~1023K), the results show that in early stage of annealing the coercivity increases sharply and after a peak value, it decrease again. The coercivity for the specimens under annealing state was enhanced one time compared with that of the sintered state. The matrix phase was single phase, in which no crystalline defect was found and the matrix phase was unchanged, only the grain boundaries change. The increase of the coercivity ofter annealing was connected with the changes of grain boundaries.
Abstract: By making use of low-carbon steel K08Al, 08Al, the change of surface roughness Rz,Rm value according to the forming paths of uniaxial, plane, biaxial, uniaxial-biaxial and biaxial-uniaxial deformation models was investigated. The initial value fo and the change of inhomogeneity of thickness fR with strain were measured. The results show that the surface roughness Rz, Rm increase linearly with the increase of strain while inhomogeneity of thickness fR decrease in each forming path.
Abstract: The flow field of double concentric strong swirling jets in a cylinder combustion and the distribution of its turbulent parameters were simulated. During the computation, work was done on first step for the adjust of the empirical coefficient Cμ in the hypothesis of Kolmogorov-Prandtl eddy viscosity. Cμ is considered to be various for various flow fields and for different points in a same one, and to be non-isotropic. Compared with experimental results the mathematical model and the numerical methods used were practicable for the simulation of axisymmetric strong swirling jets.
Abstract: Based on the analysis of pervious work about Coal Water Slurry (CWS), this paper considered the varying of flow velocity distribution inside pipe caused by the yield stress of CWS, analysed the pipe flow of CWS theoritically and proposed a theoritical calculating method of pipe flow drag of CWS. Also, a lot of experiments have been carried out to identify the method. The experimental results correspond to the theoritical analysis very well. This calculating method can be applied to the disign of practical engineering of CWS.
Abstract: A new fatigue test called Reliability Fatigue Test Method is advanced in the paper according to the mathematics theory on the relation of frequency distribution between fatigue strength and fatigue lifetime based on the component basic property of fatigue destroy. By means of this method, the component distribution law of fatigue strength can be easily to analyze the fatigue strength reliability of mechanical component. High effeciency of success and the short testing period are some of advantages of this method and a great number of spring parts fatigue test done by author show the feasibility of the method.
Abstract: While a computer control system is designed, it is very difficult to use the stability criterion of discrete control system-the distribu-tion of the roots in z plane-to judge the stability of the system if there aredifferent sampling times in the system. Therefore, it is a effective method to use simulation to judge its stability. This paper mainly discussed a practical variable speed control system with rotation and current closed-loops. By analyzing the system model and choosing the method of simulation, it gave out the result of the system simulation in the end.
Abstract: The boron-rich phase in Nd-Fe-B magnet was studied by means of HVEM, Mossbauer spectroscopy, X-ray diffraction and magnetic measurements. The chemical formula of the boron-rich phase can be represented by Nd1+εFe4B4. It is composed of two interpenetrating substructures, both have tetragonal symmetry. Since two substructures have different periods in $\vec C$ direction, the boron-rich phase may belong to the compositional incommensurate structure in one dimension. It is paramagnetic at room temperature and may behave as the pinning sites in the magnet. The observation results by HVEM of micrOstructure of Nd-Fe-B alloy at different temperature are also given. The coercivity mechanism is discussed coupling with the reported results.
Abstract: In fluorescent X-ray analysis of Steel sample, matrix effect must be corrected using Lachance, De Jongh and JIS models. This three correction factors exit definite relation. Lachance model's α and De Jongh model's α may exchange each other. The αB used in Lachance α and De Jongh models may transfer into d's used in JIS model. The value of Ei computed from theoretical correction factor αi. used in Lachance model is same as found from calibrate curve, and the correction factors d* used in De Jongh and JIS models covered from Lanchance mondel, αB is same as computed directly by individual ternary sample method.
Abstract: Experiments on the extraction of sulphur from the sulphides and oxysulphides such as MgS, CaS, BaS, RE2S3 and RE2O2S by hydrogen reduction have been carried out at 600~900℃ by means of hydrogen reduction-polarogra-phic analysis method. The reduction degree of various sulphides by H2 at 800℃ is in the order of decreasing as follows:FeS>MgS ≥ RE2S3>RE2O2S ≥ CaS=BaS.
Abstract: According to the thermodynamic and mathematical properties that the stable area of the substance in the phase diagram of the area of predominance is defined by the solution of linear inequalities and it's geometrical shape is convex polygen, the new computer algorithm of the calculation for the phase diagram of the area of predominance is developed in this paper by the solutions of the problems of linear programming that is made by introducing a series of optimum functions to the linear inequalities. The FORTRAN program has been made by the use of the Revised Simplex Method that is used for computer to solve the problems of linear programming. The results cal- Ciliated by this method is correspond to the papers published. The method has the following advantages, such as has definit, clear and reliabl e mathematical model; clear physical concept; appropriate for common use; high accurate in results and more convienent to the very complex systems.
Abstract: Siliconizing on carbon/carbon composite can get the cladding silicon carbide. The sample with silicon carbide coating are performed some distructible experiments at various temperatures and in different times. The result points that the carbon/carbon composites with silicon carbide coating make about two orders of improvement in antioxidation behavior.
Abstract: Based on general principle of the 2nd low of thermodynamics, methods for verifying the "Principle of Maximum Work" are summarized and same essential problems in this area are discussed. There is a main concept presented in the article, i. e. the surrounding conditions must be never forgotten when analyzing thermodynamical subjectst Some valuable conclusions are drawn to help to clear several uncertainties which usually exit in study on thermodynamics.
Abstract: This paper describes the experiments of determining many metals ions by using sensitive color reagent, called 5-Br-PADAP, in ring oven technique. The color condition of Fe (Ⅱ) ion determined, the method of eliminating disturbing ions and the optimum range of determination were studied. The method could be applied to the determination of micro-iron in zincification effluence.
Abstract: To improve thermal fatigue properties an improved mould was suggested based on thermal fatigue and simulated tests. Thermal stress changes in both the practical and the improved ingot moulds in the processes of casting steel and water bath were analyzed by the finite element method. The result shows that thermal stress is main reason to destroy the ingot mould. The effectiveness of the improved ingot mould was also explained.
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
