Advanced Materials Research Vols. 154-155

Abstract: Ni-WC-MgO compound coatings were made by way of Vacuum Fusion Sintering (VFS). Effects of MgO addition level on the microstructures of coating surface and longitudinal section, element diffusion in fusion sintering area and wear resistance were analyzed through scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results showed as the following: MgO addition made coating and matrix combined closely; there existed obvious transition region. When the addition level of MgO was 0.5%, the coating had the fewest defects and best combination. Ni, Cr, W, C and other elements in the coating diffused to the direction of the base metal while Fe in the base metal diffused to the coating, during which the diffusion of Fe and Ni was most obvious at the junction. Therefore, when the addition level of MgO was 0.5%, the surface microstructure of the coating was the densest and finest, and the wear resistance of the coating was the best.

Abstract: Chalcohalide glasses become ideal infrared optical fiber materials because of its isotropy, homogeneousness and high transmittance in visible and infrared region. This paper reported an experimental study on micro aspherical lens using ultra-precision single-point diamond turning technology. Turning test of a GeSe2 sulfur-base glass aspheric lens using form error compensation technique is conducted and investigated in turning process. The experimental results show that micro aspheric lens surfaces with form (PV) around 0.167 µm and a roughness (Ra) less than 2 nm is achieved successfully.

Abstract: A three-dimensional model was proposed to simulate high power laser clad TiC/NiCrBSiC composite coatings on Ti6Al4V alloys. Molten pool depth and dilution rate were obtained and compared with the experimental results. The calculated molten pool depth in the sample is about 0.76 mm and dilution rate is 21 %. The experimental data molten pool depth and dilution rate were 0.81 mm and 26%, respectively. There is a good agreement between the numerical and experimental results. A good quality laser clad TiC/NiCrBSiC coating with low dilution rate and excellent metallurgical bond can be prepared under the optimal parameters.

Abstract: In the present work, a two-dimensional finite difference model is built to realize the online control of the aluminum ingot tapered cooling process. The temperature evolution of aluminum ingot in the tapered cooling process is analyzed. According to the feature of the tapered cooling process, an efficient and simple algorithm of cooling time is developed. Online application shows that the efficiency and the accuracy of the control model can meet the production requirements.

Abstract: This paper presents an experimental research on the metal parts manufactured by laser cladding. The present studies showed two processes were conducted ,including coaxial powder-feed cladding and pre-placed powder cladding. The effect of processing parameters were studied and optimum set of parameters for the superior surface quality was established by employing the orthog -onal design. The manufactured parts were subjected to metallographic examination and micro -hardness measurement. Results showed that the microstructure of coaxial cladding parts was better than that of pre-placed powder cladding parts. The micro-hardness of the manufactured specimen along and vertical the scanning direction were measured using a HVS-1000 micro-hardness tester with a 200g applied load. Analysis of the physical properties provided further evidence of differences in micro-hardness produced by different process conditions, and the average micro -hardness value of pre-placed power cladding layer was lower than that of the coaxial powder-feed cladding layer.

Abstract: On the basis of continuous medium theory, computer simulation analysis of metal-powder injection molding was carried out with the help of FLOTRAN hydro-analysis module of ANSYS software. The effects of the gates with different dimension and location were testified. The impact of gate system on the filling process is discussed. The dynamic display of the flow leading edge in the cavity, and temperature field of the melt were researched. A result was obtained that we can modify the design of runner system if we make a full use of existing equipment resource.

Abstract: With the example of rod, this paper introduces principal stress method in the analysis and calculation of deformation force in complex parts manufactured by closed multi-ram forging. The relationship between deformation force and stroke is simulated by rigid-plastic finite element software, and then verified by experiment .It has been shown that principal stress method are accurate in calculating the deformation force of multi-ram forging by comparing and analyzing the results of these three ways.

Abstract: The technology of low temperature cool-air & minority of oil conditions (cool-air cutting technology) is employed to cut three materials— Steel 45, the alloy of titanium and 2WCrNi, then the results are contrasted with the normal cutting method. Firstly, Steel 45 and the alloy of titanium are tested with cool-air cutting and dry cutting method. Then 2WCrNi is tested by employing both cool-air cutting and oil solution cutting method. Finally, the effect of cool-air cutting technology on the life of cemented carbide tools is discussed after contrast test, and the impact of those methods on environment is also evaluated.

Abstract: A dynamic size control model during cylindrical grinding is built. The model consists of Elman neural network, fuzzy control subsystem and deformation optimal adaptive control subsystem. To improve the size prediction accuracy, the first and the second derivative of the actual amount removed from the workpiece are added into the Elman network input; To self-adapt and adjust the quantification factor and scale factor in the fuzzy control, the flexible factor is introduced to the fuzzy control model. Simulation and experiment verify that the developed prediction control model is feasible and has high prediction and control precision.

Abstract: The process of long fiber reinforced reaction injection molding (LFR-RIM) was introduced in this paper, which was used to prepare Long glass fiber reinforced foam composite materials based on polyurethane, and the bending properties of the composites were studied by this experiment. The results show that the optimal combination of technology is basically the same through the range analysis of bending strength and elastic modulus of the products, that is the fiber content A=30%, fiber length B=25mm, mold temperature C=45 °C, mixture temperature D=30 °C, the module time E=12min, ratio of material A and material B F = 1:1.85, and through the verification of the optimal combination, the bending strength was 414.96Mpa, and the bending modulus was 17.81Gpa. Though the variance analysis of bending strength and modulus of elasticity, it is found that fiber content and fiber length is the most significant factor, and the mold temperature is the least significant factors.