Search

A new coordination polymer {[Cd(BIPA)(DCPS)](H2O)} n (1) was constructed with bis(4-(1H-imidazole-1-yl)phenyl)amine and 4,4′-sulfonyldibenzoate ligands. The complex 1 features (BIPA–Cd–BIPA) n and (DCPS–Cd–DCPS) n helical chains in a 3D architecture assembled via hydrogen bonds. A spectroscopic study of complex 1 in the crystalline state showed an intense red-shifted photoluminescence as compared with the ligands BIPA and DCPS2−, which can be attributed to the ligand-to-metal charge transfer (LMCT) transitions.

In the DPST (Direct Prototype Spray Tooling) sprayed directly prototype tooling technology of Huazhong University of Science and Technology , due to brittle characteristics of ceramic materials, there was low efficient in the processing of large mold .The study would obtain sprayed ceramic prototypes through Industrial robots directly milling of ceramic rough technology, However, clay ceramic prototype embryos after milling would occur large shrinkage in the high-temperature drying and consolidation. In the paper it has established a clay material mathematical model of heat and mass transfer in the high-temperature drying process, and carried out finite element simulation in the ABAQUS, obtained shrinkage deformation law of the clay material.

In this article, a drawing die is researched in order to obtain the dynamic load and stress distributions and determine the potential fatigue location in it. The stress fields of the drawing die in the drawing process and their changing rules were studied through finite element method. The dynamic simulation of stress changing state has been realized, and the potential fatigue locations in the die were also determined. Based on the conclusion, the cavity die was divided into the substrate part and the wear-resistant part according to the stress distribution. Fatigue life estimations were made on the homogeneous die and the die with bi-materials. The example showed that bi-materials design can increase the service life while greatly reduces the cost of die material. The conclusions drawn conform to reality and have realistic significance.

Crack is the common drawback in deposition manufacturing process with high energy beam, which usually leads to the manufacturing process being given up halfway. So it is important and urgent to investigate the generating principle of crack and establish relative means to prevent crack appearance. In this paper, the principle of crack generating in the process of hybrid plasma and laser manufacturing was studied experimentally and systematically. The influences of power system and shielding atmosphere on crack were researched. The results were summarized as follows: (1) The crack generating in the course of manufacturing is mainly heat crack. (2) Excessive energy density and temperature will result in crack. (3) The best method preventing part being manufactured from oxidation is to put the whole part into the inert gas.

A two dimension value simulation was carried out for studying the electromagnetic force effect on melting pool in plasma powder deposition process. As the process is a layer-laminated deposition process, the gravity and the fluid motion of molten metal in melting pool during the layer-laminated deposition process without supporting, it will difficult to form complex shape parts. So a new scheme which using the magnetic field to restrict the melting metal flow was proposed. The method designed a restricted equipment of magnetic field in order to prevent and reduce the fluid flow and collapse of the melting pool. Compared with traditional method, as the height of the deposition shape increased, the process restricted with electromagnetic force can make the shape of parts more complex and more accurate. The changes of the electromagnetic force field were simulated with the finite element analysis, while the effects of electromagnetic force on forming process were discussed. Simulation show that the method is feasible and practicable. The electromagnetic force will decrease the post-treatment procedure and could contribute to the process of plasma powder deposition manufacture.

The present study is a continuation of the previous research on direct metal part fabrication with hybrid plasma-laser deposition manufacturing (PLDM). It is remarkably important for manufacturing high accurate part to investigate the factors influencing the precision of deposited layer and obtain the influence rules. Many factors perhaps affect the layer precision, such as average power of laser, repetition frequency, pulse width, hybrid angle between laser beam and plasma beam, speed of powder feed, deposition speed, and amount of feed along Z direction and so on. In this paper, the factors except laser parameters published in other paper were researched experimentally. The results were concluded as follows: (1) The width of the layer increases and the thickness decreases with the increasing of hybrid angle. (2) The depth of layer increases with the increasing of the amount of powder feed but the width of layer is nearly unchanged. (3) The width and thickness of layer reduces with the increasing of deposition speed. (4) The deviation between the amount of feed along Z direction and the depth of depositing layer makes the part precision decrease.

The present study is a continuation of the previous research on direct metal component fabrication by hybrid plasma and laser deposition manufacturing (PLDM). The overall performance of component depends not only on the plasma but also on the laser. The purpose of this paper is to study the influence of laser parameters, such as average power, repetition frequency and pulse width, on the precision of single layer and analyze the influence rule. The results of this research are presented as follows: (1) The width of single layer decreases with the enhancing of average power and the thickness increases with the enhancing of average power. (2) The width of single layer minishes with the increasing of repetition frequency until it reaches a minimum value, and the thickness increases with the increasing of repetition frequency until it reaches a maximum value. (3) The width of single layer decreases with the increasing of pulse width and the thickness increases with the increasing of pulse width.

Metal products were widely used at a variety of industry, so it is essential to predict the security and the usability without the destructive testing for the desired production efficiency under the different their working conditions. Recently, the plasma deposition dieless manufacturing process (PDM) is an innovative and promising application of plasma heat source with extensive industrial potential for refractory and intractable material part or prototype, rebuilding of worn components and especially the direct rapid fabrication of functionally graded materials (FGMs). However, Residual stress and distortion induced by the highly localized transient heat and strongly nonlinear temperature distributions would likely promote undesired and unpredictable warps and cracks in this process. Thus, to distinguish the internal defect from the significant discontinuities during the nondestructive testing of the metal parts, in this paper, the finite-element method (FEM) was applied to predict the electromagnetic distribution. According to the difference the magnetic flux leakage analysis, distinction threshold was built by the ratio of the peak-to-peak amplitudes of the raw inspecting signal anomaly. Computational results show that it is potential to decrease the testing period and improve the security of metal parts, in particular, the micro-raw and hole in the metal parts can be predicted, thus the possiblyintended breakage would be improved.

In the rapid spray metal tooling, metal film is spray-formed on the substrate and supported under the back, which will act as the working surface of the rapid metal tool finally. So the finishing process for the sprayed metal film is important to the quality and the lifecycle of the rapid metal tool. The finishing of the metal mould is frequently carried out manually, these kinds of operations are iterative, time consuming and require experience. Automation can introduce cost reduction minimizing production times on such manual finishing operations. This paper presents a robotic polishing system with free abrasive for the finishing of the rapid spray metal tool, which is consisted of a six-degree-of-freedom industrial robot manipulator, a high speed electrical polishing spindle and a numerical swivel table. Soft polishing pad and free abrasive are also selected for the robotic polishing system. The path planning is so important to the robotic polishing system that a partition & flexible path mapping method basing on UG CAM is developed to generate the uniform robotic polishing path on the complex mould surface. UG/Open GRIP programming module is used to generate the driving paths with different path intervals on the predesigned plane for each partitioned part. When the driving paths are projected to the mould curved surface, the uniform polishing paths with NC code can be generated by the multi-axis CAM module of the UG. And the path with NC code can then be transformed to the robotic polishing path. According to the elastic deformation and the abrasion of the soft polishing tool, the robotic polishing path should be adjusted to keep the smooth polishing process by offsetting the pre-compressed value and the abrasive compensation value along the polishing axis direction. Technical parameters of the robotic polishing process are also optimized through the experiments. Finally, the rapid metal punch mould is finished to test the robotic polishing system.

During atmospheric plasma spraying (APS), to control the time dependent D.C. plasma jet behavior requires the comprehensive understanding of its electric, magnetic, thermal, thermodynamic phenomena. In this paper, influence of particles injection with the form of suspension on the fluctuation of plasma jet is analyzed, and a control approach is presented to eliminate the effect. Moreover, an integrated robotic plasma spraying system for advanced materials processing, i.e., rapid metal tooling and solid oxide fuel cell (SOFC), is developed, which combines a PC-based controller with a six-aids robot. The intelligent adaptive adjustment of robot spraying trajectories and self-dispatch of manufacturing strategies were carried out by the resultant system according to the feedback of the temperature and thickness of sprayed coatings and other information during plasma praying. The flexibility of the forming system was promoted by integrating plasma spray forming with robot motion control. Excellent control performance is observed and this system can be effective to meet the requirements of different materials processing techniques.

In order to explore the effect of extracelluar polymeric substances (EPS) on resistance and removal of heavy metals, the production of EPS, secreted by cadmium-resistant strain (SCSE425-7) and cadmium-removal strain (SCSE709-6) was investigated combined with Fourier transform infrared spectroscopy (FTIR). The results showed that the high resistance to cadmium of strain SCSE425-7 was related to the high production of soluble EPS, whereas SCSE709-6 secreted more insoluble EPS resulting in better cadmium removal performance. It was indicated that soluble extracellular carbohydrates may help the bacteria to enhance resistance to Cd2+, and insoluble EPS could contribute to Cd2+ removal effectively. The FTIR spectra showed that the peaks of amide and carboxyl were main functional groups for Cd2+ adsorption.

Based on the remote sensing data of Landsat TM (1985, 1995, and 2000) and CBERS (2006), and by using landscape pattern method and index model of regional land use change in combining with eco-function regionalization, this paper analyzed the dynamic characteristics of forest landscape in Chengdu City in 1985-2006. In the study period, over 17,000 hm2 of forest land lost, and the number and area of small- and medium-size patches changed significantly, indicating the apparent conversion and fragmentation of forest land. Forest land was mainly distributed in mountainous area, accounting for 70% of the total. In contrast, more number of patches was found in plain region, amounting to 70% of the total. The most rapid change of forest land area occurred in 1985-1995, especially in mountainous region. The relative change rate of forest land area in different eco-function regions also varied in different periods. Forest land, converted to or converted from, was mainly related to cropland and grassland. In 2000-2006, forest land was quite stable. Survival-oriented economic welfare, environmental security, and fast urbanization process were the main driving forces of the temporal dynamic change of forest landscape, whereas geographical division and socio-economic layout were the main constraints to the spatial dynamic change of forest landscape.

The surface of pulse septum magnet in HLS was specially coated with Al/sub 2/O/sub 3/ powder by plasma spraying. It was found with such magnet in the injection vacuum chamber the pressure was relatively low. To investigate the mechanics 20 sheets of coating were made (120 /spl times/ 80 /spl times/ 20 mm/sup 2/), adsorption capacity was tested. Pore constitution was studied by N/sub 2/ isotherm method. Results indicated ultimate pressure reduced obviously from 6.4 /spl times/ 10/sup -5/ Pa to 8.6 /spl times/ 10/sup -6/ Pa. Coat adsorption capacity is about 3.68 /spl times/ 10/sup -4/ Pa /spl middot/ 1/cm/sup 2/. BET surface area is 201 m/sup 2//g, Coat is porous and pore is closed at one end. XPS results indicate there are hydroxyl, carboxyl etc., on the surface, and they are most probably related with adsorption.