Applied Mechanics and Materials Vol. 576

Abstract: The present work is focused on electroless coating of copper nanolayer onto boron carbide (B₄C) particle surfaces by using copper activation method. The B₄C particles used are approximately 18.25μm in average size. B₄C particle surfaces were washed by acetone and activated through copper activation method. In the electroless coating bath, copper sulfate, EDTA-2Na and seignette salt, hydrazine hydrate were used as the copper catalytic centers source, complexing agent and reducing agent respectively. The structure and morphology of the coating layers were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). XRD and SEM observations show that B₄C particle surfaces were successfully coated by a homogeneous and continuous copper layer.

Abstract: The key factors for activity of asbestos tailings acid leaching residue (ATALR) and activated process were researched by the way of orthoplan, so as to make a new type of high-active mineral admixture in cement-based material, named as porous silica fume (PSF). Then with the strength loss indexes designed, the sulfate attack resistance of cement-PSF mortars was evaluated, which was dunked in solution of sodium sulfate during from 6 to 12 months. The results indicated that thermal activated temperature and holding time was the key factor for compressive strength, while holding time and grinding time for flexural strength. The optimal activated process was the thermal activated temperature at800°C needing to hold for 1 hour before grinding for 20minuteswhilethe appropriate amount of PSF was 5%~12% in cement mortar. When 5%~8% PSF contained, the sulfate attack resistance of cement mortar can be improved obviously, and the role was similar to silica fume (SF). PSF activated from ATALR is helpful for resource utilization of asbestos tailings, in order to improve ecological environment in the asbestos mine town and promote cement-based material development.

Abstract: Stress relief on thick and large welded components is greatly needed in various applications, such as large oil transporting pipes and offshore oil platforms. Vibration stress relief (VSR) is an relatively new method for this purpose. The efficiency of this method is a key subject, especially when the components are extremely large and it is difficult to trigger sufficient vibration amplitude in the structures. In this study, additional heating on the area near the weld line was used to promote the efficiency of VSR. Both VSR and thermal-vibration compound stress relief (TVCSR) were used to 50mm thick DH 36 steel welded plates. The Longitudinal and transverse stresses near the weld lines before and after the treatments were investigated. Comparing to VSR, the TVCSR was more effective in decreasing the residual stress. Effects of additional heating was discussed.

Abstract: Crystal bar hafnium prepared by the iodide process was studied. The influences of three important factors (filament temperature, retort materials and feed types) on the removal of iron from hafnium crystal bar under iodide process were investigated. Results show that the impurity contents of iron in the hafnium crystal bar decreased with the rising K value. Both the retort materials and feed types have obvious influence on the iron impurity contents of hafnium crystal bar. It is proposed that the optimal condition was attained when hafnium turnings was used as feed, stainless steel with molybdenum cylinder liner as retort materials, and K value was at a relatively high level.

Abstract: the numerical control milling process that commonly use tool length compensation function instruction, correct and reasonable use of tool length compensation function instruction can improve efficiency and machining accuracy. This article mainly studies the three methods of application of tool length compensation function instruction, which can provide a reference for correct application of tool length compensation function instruction.

Abstract: The effects of coiling temperature and cold rolling reduction on planar anisotropy of Ti-alloyed low carbon steel were investigated. The results show that as the coiling temperature increases from 509°C to 633°C, the strength and elongation have little change, and the planar anisotropy trends to decrease. When coiling at 580°C to 640°C, the value of planar anisotropy index (△r) can be reduced to no more than 0.15. As the total cold rolling reduction increasing from 55% to 85%, the plastic strain ratio values (r-values) perpendicular to rolling direction increase firstly, then decrease; the change regulation of rolling direction is reverse, and the values of 45°direction nearly have no change. And the planar anisotropy can reach 0.07 as cold rolling at 75%.

Abstract: A set of hot-air curing device for phosphate sand was designed, processed and assembled, samples were made by the device, and their properties were studied. Result shows that design principle of the device is correct, hot-air remains stable; Phosphate sand can be hardened by blowing hot-air, it is suitable to assembly line like clay sand molding line because of short blowing time, for φ30mm×30mm sample, suitable blowing time is 15s when blowing temperature is 200°C,its dry compressive strength is up to 2.1MPa; The sample is not suitable for storage, because storage strength is declined sharply with high humidity although it is improved slightly with falling humidity; Compare to no-bake phosphate sand and heat-cured phosphate sand, crack on fracture surface of hot-air cured phosphate sand is invisible nearly, but fracture mode is adhesive fracture mainly, so its dry compressive strength is lower slightly.

Abstract: Cold-rolling process is an important stage in Ti+P-IF steel manufacturing process, and cold rolling reduction is a main parameter. The research of recrystallization microstructure change and texture evolution of Ti+P-IF steel in cross cold rolling reductions has important meaning in study of high strong IF steel. In this paper, hot rolled Ti+P-IF steel in austenite was studied, cold rolling reduction was used as the effect factor, The study was carried out on the basis of microstructure observation, TEM analysis and texture measurement. The sizes of the grains within the recrystallization organizations were gradually diminished as the cold rolling reduction increased. At the same time, the second phase particles had showed an aggregated distribution, and there is a rule in the components of the texture that the Goss texture and the Rotating cube texture are transformed intoγtexture evolution rule.

Abstract: With the rapid development of superconducting technology, electrical properties of insulating materials in the low temperature have recently gained more and more attention. In this paper, the Alternating Current (AC) and negative Direct Current (DC) breakdown strength of polyimide (PI), polyester (PET) and polytetrafluoroethylene (PTFE) have been tested in room temperature and liquid nitrogen environment respectively by using different electrode system. The results show that the negative DC breakdown strength of these three kinds of material in the liquid nitrogen is lower than that in room temperature, and the AC breakdown strength of PTFE and PI in liquid nitrogen has a little increase than that in room temperature,but PET slightly decreases.