The Nb2 C layer formed in the bonding interface of a niobium clad steel composite at 1023 K for 112 h was examined metallographically and analyzed using the electron microprobe technique. The mechanism of Nb2 C phase diffusion layer formation was discussed using Fick’s law assuming that stationary diffusion of carbon was established in niobium/steel diffusion couples.
Using embedded atom method and molecular static relaxation method, the core structure of 〈100〉, 〈110〉 edge dislocations, 〈100〉 screw dislocation, the interaction between point defects and 〈100〉 edge dislocation in NiAl intermetallics were investigated. The results show that 〈100〉 edge dislocation expands along [110] and orientation on the (001) slip plane. The core structure of 〈100〉 edge dislocation on (001) plane is like a ”butterfly”, while it is very compact when it lies on {110} slip plane. So NiAl will have a 〈100〉 {110} slip system in stead of 〈100〉 {100} slip system, as experiments showed. 〈110〉 edge dislocation has a more expanded core structure and the atoms of dislocation core distort more heavily. None dislocation dissociation was found in the studied dislocations. The outlines of dislocation core structures change very little after a row of point defects are introduced in them, which can be explained by point defects’ little effects on the stress field around dislocation core. The results also show that it is hard to change dislocation core structure by decreasing alloy order using the method of introducing limited point defects into the alloy.
The structure and properties of high chromium white cast iron in different treatment states were studied. Using X-ray diffraction method, observing their metallograph and measuring their microhardness, the phases involved in the iron were determined. The notch toughness, macrohardness and the fractograph of the samples are compared and their performance was determined, which mainly depends on the matrix structure. Relatively good comprehensive properties can be obtained in the tempering state. Improvements have been made on the commonly used tempering standard. Tempering for a short period at low temperature can improve the materials’ service performance obviously.
The coating of Ni-W-P was deposited as base-layer, and then the composite coating of Ni-Ti(particles)-Re(rare earth) was deposited subsequently on the surface of diamond using electroless plating by adding 2 – 3 µm Ti particles and trace rare earth salt to bath solution. Ti particles deposited on the surface of diamond were found by SEM and formation of TiC was verified by X-ray diffraction analysis after heat treatment of the coatings in vacuum at 900 °C. The binding strength between the coated diamond and the metal matrix was improved effectively in the diamond composite based on metal cement.
The invar alloy powder, mixed with different Cu powder contained different content of oxygen, was compacted and sintered into four sorts of DG™ invar-Cu low expansion and high conductivity alloy specimens. The mechanical and physical properties of the alloys were tested and analyzed. The behavior of oxygen and its effect mechanism were discussed. The results show that the ultimate strength decreases with the increase of oxygen content, so does the coefficient of thermal expansion (α) whereas the α platform is shortened.
A process of preparing ZnO voltage-sensitive ceramics doped with some oxides by coprecipitation was described in the paper. The thermal properties of ZnO nanometer powders and the current-voltage characteristics of the ceramics have been investigated. The results showed that the six-additive ZnO powders with hexagonal system were homogeneous grain size distribution in microstructure, the optimal reaction pH is 6.90±0.05, the temperature for calcining and sintering was at about 500 °C and 1100 °C, respectively. The powders were also examined by SEM, IR and XRD etc, and the effect of doping La2O3 on the electrical properties of ZnO varistor was investigated too.
Aqueous E-pH Diagram is an essential tool for analyzing hydrometallurgical and corrosion processes. Due to the requirements for environmental protection and energy saving in recent years, waste water processing and hydrometallurgical process of concentrate have been greatly developed. The construction of E-pH diagrams has turned to multi-component systems. However, there are some limits in plotting such diagrams. There is only one diagram for one multi-component system, which can not reflect the truth of the aqueous reaction. In the paper, a new computation method is proposed to construct E-pH diagrams. Component activity term is used to determine the boundary of stable areas. For the multi-component systems, different atom ratios of elements have been taken into account. M-S-H2O system is chosen to study since it is of importance in metallurgical solution. Compared with conventional methods, the algorithm is simple and conforms to real conditions.
The mechanism of synergistic extraction of gold in HCl media was researched with tri-n-octyl amine(TOA) and tri-n-octyl phospine oxide(TOPO). It was determined that the composition of synergistic extract is (TOAHTOPO) AuCl4; the constant of synergistic extracting equilibrium is 109.20; and the synergistic reaction is exothermic with − 17.187 kJ/K· mol of ΔH298. The extraction mechanism was also studied by the IR-spectra and UV-spectra. It is found that the extraction mechanism belongs to ion-association type.
A new type of antimony mercaptide heat stabilizer—antimony mono(isooctyl thioglycolate) di(n-dodecanethiol) was prepared, and its application in polyvinyl chloride (PVC) plastics is discussed. The stabilizing effect of this product is better than the complex-stabilizer of Ca/Zn when it is used in soft PVC and than the complex-stabilizer of lead and dilauratetin dibutyl when it is used in hard PVC.
A new C60 derivative—hydroxylated fullerene epoxide [C60 (OH)x(O)y] was prepared by the reaction of C60 benzene solution with aqueous NaOH and H2O2 in the presence of tetrabutylammonium hydroxide (TBAH) as the catalyzer. The structure of hydroxylated fullerene epoxide was characterized by FT-IR, NMR and MS, and it was found that it is easy to hydrolyze to fullerol.
The targets, importance, difficulties, strategies, general function frame and technology frame of Petroleum Drilling Fluid Engineering Design Expert Ssytem(PDFEDES) were discussed. A brief introduction to the special domain and application cases of the PDFEDES are given. A good prospect of artificial intelligence in petroleum exploration engineering is presented.
In order to control sintering process, improve permeability and stabilize burn through point, a control scheme which combines thermal state with permeability state is proposed, and an expert system for controlling sintering process state is developed, the software which includes about 1000 expert rules is successfully applied to off-line control of sintering process.
The center-cracked Brazilian disk subjected to diametral compressive stress uniformly distributed along parts of its cylindrical surface is used to investigate combined mode fracture of brittle material. A fracture analysis is made of this specimen configuration. Explicit formulae for mode I and mode II stress intensity factor calculation are derived based on boundary integral equation method and related numerical solution given by Atkinson. The proposed formulae are valid in wide range of crack length a/R. This configuration can avoid splitting along load line usually occuring in Brazilian test and permit one to achieve easily pure mode II crack growth (crack coplanar extension) and any combination of KI and KII by a simple alignment of crack orientation with respect to load line. SIF values from the present calculation and finite element solution are also given for comparison.
Some profile of a rock section and some isopleth of a fractured surface of the rock were divided each into three parts. Then three parts were measured by dividers method and lattice method. It was discovered that the fractal dimensions of the three parts were remarkably different, so the fractured surface of rock was not simple fractal but multi-range fractals.
Previous studies have confirmed in simulation and experiment that an improved control performance can be obtained when the optimal preview control method was applied to an active suspension system for a quarter car model. In order to investigate the effectiveness not only in riding comfort but also in road handling, an half-car model with the hydro-pneumatic active suspension system is proposed in this study. Whole preview control method and partial preview control method, in which the road information detected by the front wheel is sent to the controller to decide the input to rear suspension, are taken into design of the active suspension control system. Results of numerical simulation show that satisfactory control efficiency could be achieved in both whole preview control and partial preview control. The comparison of results suggests that whole preview control method can provide better system performance, but the partial preview control method is superior due to its lower cost.
In rigid mechanism dynamic analysis, the equivalence theorem is often used due to its simplicity and perceivability. Based on conjugation and duality between inertia energy-storing element and elastic energy-storing element, the equivalence theorem is used in elastic error analysis of planar mechanism. A set of calculation formula of elastic error is introduced, and these equations are similar in expression form to the rigid dynamic equation. To demonstrate the method developed, a computation example is given.
The stress field of the combined extra-height forging die, which was reformed from solid extra-height forging die, was calculated and analysed using finite element method (FEM). The major factors influencing the stress field of forging die and its variation law were discussed. The results demonstrated that the combined forging die could meet the working strength demand, and that the calculated results by FEM were superior to that by the general design method for die strength. The conclusion could provide evidence for improving the forging die structure and durability.
Address the design of state-feedback H∞ suboptimal controllers. Through parameterization of decentralized controllers, the design condition for the feedback gain is given in the form of a biaffine matrix inequality. An iterative algorithm based on linear matrix inequality(LMI) is proposed to obtain the decentralized controller which ensures the closed-loop system asymptotically stable and the H∞-norm less than constant number 1.
A simple fast method is given for sequentially retrieving all the records in a B-tree. A file structure for database is proposed. The records in its primary data file are sorted according to the key order. A B-tree is used as its dense index. It is easy to insert, delete or search a record, and it is also convenient to retrieve records in the sequential order of the keys. The merits and efficiencies of these methods or structures are discussed in detail.