Advanced Materials Research Vols. 228-229

Abstract: Arc ion plating technique PVD ZrN coatings were deposited on YT15 cemented carbide. Microstructural and fundamental properties of the ZrN coatings were examined. The ZrN coated tools (DZ and GZZ) showed much better cutting performance compared to the YT15 uncoated cemented carbide, which is connected with their large hardness increase, and good abrasive wear resistance. The wear surface features of the coatings were examined by scanning electron microscopy. Results showed that the PVD ZrN coatings onto the cemented carbide substrate show high hardness and good adhesion with the substrate. Abrasive wear was found to be the predominant flank wear mechanism for the ZrN coated tools. While the mechanisms responsible for the rake wear were determined to be adhesion.

Abstract: EMD is an effective analysis method of non-stationary signal, but the end effect exists in the process of decomposition. As for the end effect problem, GM(1,1) of gray theory model is used to predict and modify the extension values at endpoints in this paper, which makes the cubic spline interpolation envelope more effective in the course of sifting. The result shows that this method is reasonable by using it to analyze gear fault signal.

Abstract: In order to analyze rotary characteristics of light type hydraulic excavator, according to prototype’s real parameters, a 3-D model of excavator was built using Pro / E design software, and import into the software ADAMS to build the virtual excavator, while using the AMEsim software to build the main components of multi-way valve characteristics model, etc.. After the simulation model of hydraulic system was developed, rotary characteristics were simulated and researched through experiments with different moments of inertia which change in the heavy-load operating mode. On the basis of the analysis and comparison with the results of simulation and experiments, the law between hydraulic system pressure variation and energy consumption about light type hydraulic excavator was obtained with different moments of inertia when excavator rotating.

Abstract: Any heat treatment technology must begin with the process of austenization, during which the holding time at austenite region is one of the critical parameters. The effect of austenization treatment holding time on the martensitic transformation in the 30CrNi3MoV ultra-high-strength steel was investigated by means of dilatometric measurements and microstructural observations. The results showed that extending the holding time at 900 oC won’t cause obvious coarsening of austenite grains due to the dragging effect of vanadium solute atoms adsorbed at austenite grain boundaries. Martensite microstructures obtained in the 30CrNi3MoV samples that were heat treated with different holding time varied a little. The austenization holding time has obvious influence on the Ms of the 30CrNi3MoV steel, because it simultaneously affect the size of prior austenite grains and the configuration of dislocation defects.

Abstract: In order to realize numerical simulation of warm forming and reasonably establish the warm formation process parameters for 6016 aluminum alloy, we study the forging process of 6016 aluminum alloy with warm compression experiments on the Gleele-1500 thermal simulation testing machine, and research the deformation flow stress behavior of the aluminum alloy sheet at different temperatures , strain rate under the warm forming. The results show that the deformation temperature and strain rate have significant influence on flow stress of 6016 aluminum alloy sheet, that is, the alloy is a temperature and strain rate sensitive materials, and the flow stress increases with the increase of strain rate and decreases with the increase of deformation temperature. The deformation constitutive equation of 6016 aluminum alloy is got by multiple linear regression analysis. The constitutive equation is consistent with the experimental curves rather well, which confirms the accuracy of the constitutive equation.

Abstract: According to the actual experimental condition of the scanning electron beam welder, a 3-D finite element model(FEM) model of the temperature field for the electron beam quenching of ductile iron QT600-3 was established by using ANSYS parametric design language. In the course of analysis, the heat transfer theory was applied. The temperature relativity of the thermal physical parameters, the phase transformation and thermal radiation were considered. The size of the hardened zone was calculated and experimented. The results show that the obtained experimental results show a good agreement with the simulation results. It indicates that the established numerical model is correct and reliable. The model provides a guide for studying the rule which it is heating and solidifying process of electron beam surface quenching. And the FEM model can be well used to obtain and optimize the processing parameters.

Abstract: Establishing the plow cutting coal seam 3D simulation model, Using finite element analysis software ANSYS/ LS-DYNA, simulating plow bit cutting coal seam process. under Through this study, obtaining the plow speed, cutting resistance of plow bit’s time process curve, analyzing the influence on cutting resistance of different cutting depth, separation distance and width.

Abstract: A novel chemical precipitation method was studied to prepare the metal cobalt powder from the precursor Co(OH)x(CO3)y powder. From XRD and IR analysis, it was proved that there were interactions between the NH4+, Cl- and the precursor powder of Co(OH)x(CO3)y. Based on DSC-TGA analysis, the influence of additive and temperature on the cobalt powder preparation process was observed during heat decomposition. The results showed that pure metal cobalt was obtained when the amount of the additive tartaric acid was about 60% and calcination temperature was 500°C.

Abstract: The thesis raises an idea of researching and developing synthetic material of wollastonite in four-molding and simple-molding method through the analysis on the energy consumption of traditional ceramic sanitary products, and comparatively studies the energy consumption and carbon emission of traditional sanitary products and low carbon sanitary products and verifies the applicable value of the latter, providing a basis for the R&D of low carbon sanitary products.

Abstract: The propagation of fatigue short crack is a fractal curve, the irregular path can be described by fractal dimension. The fractal dimension of the crack implicit in many of the physical factors, such as microstructure of material, load conditions and so on. In this paper, the short crack for low cycle at high temperature is studied. The material 20# steel in the various stress state is experimentally studied, the initiation, propagation and coalescence influence of short crack are observed. By analyzing experiment results, characters of crack fractal dimensions evolving with the cycle process are as follows, the behavior of short fatigue cracks satisfies fractal feature, with the development of the fatigue process, the fractal dimension is increased.