Applied Mechanics and Materials Vols. 278-280

Abstract: The basic principle and technological methods of electroforming are briefly described. With the progress in materials, processes and equipment, electroforming has got a considerable development. It is increasingly combined with other technologies, such as assembling electrotype, fabrication of MEMS, LIGA, etc. The shortcomings of electroforming technologies at present stage are also pointed out. As an inter-disciplinary subject area, electroforming will be widely developed and applied.

Abstract: Bonnet polishing is a practical and economical polishing technology for the fabrication of precision optical components. Its removal function is controlled by many parameters, and much research has been performed on them in the past few years. However, most of the previous research has been focused on the inner pressure of the bonnet, the rotation speed of the spindle, the precession angle, the bonnet decrement, etc. The deformation of the bonnet under the inner pressure has received relatively little attention. This paper demonstrates the deformation of the bonnet under the inner pressure and its effect to the contact area and the bonnet decrement. It also proposes two solutions, one is to add an enhancement layer on the bonnet; the other is to design a novel bonnet contour which is aspheric but turns to spherical under the effect of the inner pressure. The latter one is proved that it’s effective to reduce the deformation to the polishing process.

Abstract: Running-in is an important and inevitable wear process for machine system, and it plays an indispensable role in extending service life and improving operating performance. Surface topography appears as a significant feature of friction pairs. Therefore, study on modification of surface topography in running-in is crucial to control surface quality and then achieve improvement of machine system. In this paper, to understand the evolution of surface topography in running-in process, steel dry sliding running-in experiments were conducted, and surface topographies in running-in were evaluated with the areal surface evaluation parameters. The results reveal that surface topography evaluation could provide valuable information about wear status of steel running-in process of dry sliding friction, amplitude parameters, area and volume parameters, and hybrid parameters play different and important roles in characterization of surface topography modification in running-in.

Abstract: the controlled crystallization and characterization of Li2O-Al2O3-SiO2-P2O5 glass ceramic by XRD and numerical calculus. The results indicate that the controlled model of crystallization is the process though controlling the growing size of crystallization grain by forming residual glass phase with high melting point, and proper high-melting supplement such as Y2O3、Al2O3 can reduce crystal grain size at the same time that does not change nucleation quantity. At last, transparent glass-ceramic with little crystal grain can be obtained by the theorizing analytic model.

Abstract: The Ni- ZrO₂ nanocomposite coatings were prepared by pulse electrodeposition with rotating cathode in an ultrasonic field, and the corrosion resistance of the coatings were studied in 5% H₂SO₄. The surface morphologies of composite coatings after corrosion were analyzed by scanning electron microscope (SEM). And corrosion rate was tested using an electronic balance. The results shows that, compared with pure Ni coating, pulse current composite coating and pulse current composite coating with ultrasound, the Ni-ZrO₂ nanocomposite coating prepared by pulse electrodeposition with rotating cathode in an ultrasonic field has more uniform micro-structure, more compacted grain and lower corrosion rate. Peculiarly, it exhibits excellent corrosion resistance.

Abstract: Owing to the disadvantages of traditional mortar with poor antifreeze property，low adhesive strength and short durability in the cold region of China, the facing tiles often fall off and lead to the lost of decorative effects and protective effects. In this article，a new type of mortar for exterior wall facing tile，polymer cement mortar modified by polymer, is introduced. The advantages of the new mortar are: (l) Better frost resistance，which is reflected by stability after one hundred cycles of freezing and thawing; (2) Higher adhesive strength (2.0MPa); (3) Better permeability resistance and longer durability. It is believed that an ideal building mortar for the resistance of frost damage and suitable for exterior wall facing tile.

Abstract: Through analyzing and testing the microstructure and property of ZL114A aluminum alloy castings under the condition of alternating electromagnetic field, the effects of the intensity of alternating electromagnetic field on the microstructure and property of ZL114A aluminum alloy castings are studied. The results showed the intensity of alternating electromagnetic field had a great influence on the microstructure and property of ZL114A aluminum alloy castings. With the increase of the intensity of alternating electromagnetic field, the grain size of ZL114A aluminum alloy was more and more small, under the 10A current intensity, the grain was the finest. Whereas, with the increase of the intensity of alternating electromagnetic field further, the grain is more and more big. Meanwhile, in a certain rang of current intensity, the mechanical performance of ZL114A aluminum alloy had been improved comprehensively, its tensile intensity was improved 10MPa and the elongation was increased by 30%.

Abstract: Lotus-type porous copper materials were fabricated by continuous casting technique. The relationship between porosity and external pressure were developed based on the solute mass conservation law. Theoretical values of porosity are in agreement with our experimental results. Results show that porosity decreases when the partial pressure of hydrogen increases for cases of no pressure of argon above melt, while porosity first increases and then decreases as the partial pressure of hydrogen increases for case of nonzero pressure of argon above melt.

Abstract: The influence of dosage of calcium added slag on the strength and water-repellency of Magnesium oxychloride cement was studied in this paper. The results indicated that the compressive strength of magnesium oxychloride cement enhanced while the flexural strength remained unchanged when the dosage of calcium added slag between 5%-30%. The compressive strength of magnesium oxychloride cement was 110.0 MPa when the dosage of Calcium added slag was 20%, which increased the strength of 17%. The calcium added slag significantly improved the water-repellency of Magnesium oxychloride cement. The softening coefficient of magnesium oxychloride cement was more than 0.82, and the highest is 1.07.

Abstract: In order to understand the behavior of biomass pyrolysis, a series of pretreatment biomass were prepared with acid-washing and metal impregnated methods. The effects of metal ions on the yields of tar, char and gas from straw pyrolysis were analyzed in our lab scale fixed-bed reactor. Alkali metal and alkaline earth metal ions affect biomass pyrolysis process and the products heavily. The decreasing metal ions result in declining yield of semi-char and increasing yields of tar and gas. Meanwhile, the pyrolysis temperature corresponding maxium yield of tar increases. There exist marked catalytic effect of potassium, calcium and magnesium cations on the cracking of large molecular weight parts of tar and semi-char formation via recombination reaction of tar. As cause a higher production of char while a decrease of tar and gas production.