Key Engineering Materials Vol. 667

Abstract: As a new kind of manufacturing technology developing rapidly, Material Increasing Manufacturing, scilicet 3D printing technology is that the popularity of various fields. In this paper, under the background of the desktop 3D printing gradually enter the family. To solve the printing material problem scilicet 3D printing technology development bottleneck, come up with a bamboo-plastic composite made of Bamboo powder and poly lactic acid (PLA), can be used on desktop 3D printing. Due to bamboo resources is abundant, low cost, and also have the advantages of friendly of environment, have a good potential for development. In this paper, the right formula is used in the study on preparation of materials, through the material blending; extrusion process to produce the 3D printing wire can meet the requirements. Through further studies on the ratio of bamboo and plastic, the amount of additives added, extrusion processing temperature and material situation, optimizing the ratio of bamboo and plastic, the amount of Additives, adjust the extrusion temperature in the formulation. Tests showed that through the improved technology, wires have further enhanced performance, continuous printing more than 300 meters, the printing effect is smooth, jam does not appear, and the molded parts have good quality.

Abstract: Jet electrodeposition is one of electrochemical machining methods, which is able to increase cathodic current density, therefore having high deposition rate, good locality and nanocrystalline structure. These advantages enable jet electro-deposition to integrate with rapid prototyping technology in an effort to achieve selective electro-deposition on the cathode surface. This paper combine both methods to prepare nanocrystalline copper parts. The equipment system is developed, which is mainly composed of computer control system, machine body, electrolyte circulation system, nozzle and its hoisting mechanism and other parts. Deposition rate, locality, deposit thickness distribution and forming accuracy are analyzed. A group of nanocrystalline copper parts having good shape and size precision have been prepared. Influencing factors on forming accuracy are analyzed.

Abstract: The continuously improving of the performance of ultra-precise machine bed is claimed for, including not only the better tolerance stiffness, strength, shock and wear resistance, but also the further shock-damping and acoustic-absorbing performance. In this paper, the acoustic absorption for continuous network SiC ceramic as the laying of ultra-precise machine bed is investigated. By way of the constitutive relation of the network SiC ceramic, the flexibility matrix of such structural body is obtained. In line with the virtual loading application, the balance equation of the unit cell of the network structure is constructed, as well as the effective stress and effective Yang’s modulus. While the elastic flexibility matrix of the structure body can be re-construct with the results above, the bulk strain of the material under the infinitesimal strain would be derived from the modified matrix. The mechanism induced the deformation of network SiC structure is revealed by means of the combination of the dynamic porosity model with the bulk strain. The sensitivities of all kinds of effective factors to the dynamic porosity is analyzed and the order of parameters’ sensitivities to the dynamic porosity of 3D triangle structure is: pressure < temperature < initial porosity < network rod length < network rod radius. The results lay the theoretical foundation of the micro-mesh structure design of the network ceramics as the ultra-precise machine beding.

Abstract: Gold-based alloys are widely used in electrical contact environment which requires small contact resistance, and friction pair components consisting of electrical contact has a direct impact on the properties of electrical contact. In this thesis, an experiment of AuNI9 brushes/AuCuAgZn gold sheets in a organization is designed to show the elastic properties of the brush, friction pair wear properties and environmental adaptability of the contact resistance, whose result indicates that the elastic properties of the brushes are stable, alloy sheets mainly produce wear when the brushes and gold sheets are used in matched pair and environmental assessment tests do not significantly increase the degree of wear of the friction pair components in low load condition.

Abstract: The amorphous-nanocrystal Ni-Mo deposits were obtained by electrodeposition in alkaline nickel carbonate solution. X-ray diffraction (XRD), scanning electron microscopy (SEM) and modern technologies were used to describe the content, microstructure and morphology of the deposits. The electrochemical characteristics of Ni-Mo deposits were electrolyzed in 33°C, 7 mol/L NaOH electrolytic solutions. The results showed that when I was 100 mA·cm⁻², the hydrogen evolution potential of Ni-Mo_21.76 was lower than amorphous Ni-Mo_26.36 and 250mV lower than the nanocrystal Ni cathode. And the Ni-Mo deposits with more amorphous phase content would be in lower hydrogen evolution overpotential, a higher exchange current density, and a better electrolytic stability. These due to the amorphous combined with nanocrystal, lager contact surface and binding energy of Ni-Mo structure.

Abstract: In this paper, according to the principle of building the constitutive model of polymer material, the one-dimensional structure of the ZWT material constitutive model is added to dashpot element in parallel, and in which strain rate and coefficient of viscosity is introduced and the nonlinear viscoelastic constitutive model of Polycarbonate material is achieved. Additionally, tensile test at low strain rate and Hopkinson test at high strain rate of polycarbonate material are carried out, and the change rule of yield strength of polycarbonate material is obtained both at high strain rate and low strain rate. According to the experimental data, the parameters of the constitutive model have been optimized and fitted using ant colony algorithm, and then the fitted results are compared with experimental results. The comparative results show that the improved ZWT constitutive model can reasonably represent the nonlinear characteristics of polycarbonate material at different strain rate.

Abstract: In this paper a new kind of finite element analysis model towards metallic microstructure of titanium alloy is established based on a common metallic microstructure picture. By the simulation of tensile test on this new kind of FEA model performed by finite element analysis software Abaqus, the tensile curve in the state of simulation is obtained. Meanwhile, in order to verify the accuracy of the simulation results, a series of tensile tests are designed and performed and the tensile curves under experimental conditions are obtained. Comparing the experimental results with the simulation results, the conclusion can be verified that the new microstructure FEA model can illustrate the metallic microstructure very well. And this model provides a new perspective to study the mechanical properties of metallic materials.

Abstract: A kind of rotating step motor is used in special environment, which has the character of single step angle great,single step rotating speed rangeing widely and output turque rangeing widely. To adapt the using environment and its working characteristics, the motor’s main parts of shell and front-backcovers are all made up of the stainless steel 1Cr18Ni9Ti, which has a good performance in diamagnetic and comperhensive mechanics. During the manufacture process, the 1Cr18Ni9Ti was found can be absorded by magnet. This paper researchs the influence of elements components and metallographic structure to the 1Cr18Ni9Ti by analyzing the element components and metallographic structure of several batches of materials.

Abstract: For its light quality, good thermal conductivity, and excellent electricity shielding performance, Magnesium alloy has been used in industry, agricultural and so on, for rare earth elements can improve the mechanical performance of magnesium alloy, the study of powder metallurgy is influence by rare earth magnesium is few at present. so, in this paper, by mixing powder metallurgy method the Y89 element was added in Mg17Al12 magnesium alloy, the influence of Y89 on microstructure, hardness and compression performance of Mg17Al12 magnesium alloy was studied, The experimental results show that when amount of Y89’s addition, the mechanical performance is more then and when is 1.22%, its mechanical performance is best, hardness is 66.7 HV, compressive strength is 113.6 MPa,increased respectively by 19.7% and 29.3% compared the Mg17Al12 magnesium alloy substrate, and the grain refinement effect of Mg17Al12 magnesium alloy is the best at this time.

Abstract: The pyrolysis kinetics parameters of material had an great importance on estimating material degradation during laser transmission welding. The PA66/CB was produced using a twin-screw extruder, and thermogravimetric experiment of PA66/CB was performed at different heating rate of 5, 10, 15 and 20 °C/min, then the pyrolsis behavior and pyrolysis kinetics parameters of material were investigated based on the Kissinger, Starink and Freeman-Carroll three methods. The results showed that the pyrolsis process of PA66/CB was one step reaction. With the increase of heating rate, the initial reaction temperature and final pyrolsis temperature of TG curve and the peak temperature of DTG curve were shift to higher temperature. Temperature hysteresis was appeared but the final pyrolsis rate was not affected by heating rate. The activation energy on the biggest pyrolsis rate was not affected by the addition of carbon black. The activation energy calculated using Starink method was increased by the increase of conversion rate. The activation energy calculated using Freeman-Carroll method was bigger than Kissinger and Starink methods. The activation energy was calculated using Freeman-Carroll method, then using the n^th model, and the pyrolsis kinetic equation was expressed as: dα/dt=2.053×10¹⁹[exp (-245.32×10³/RT)](1-α)^2.22.