Applied Mechanics and Materials Vol. 161

Abstract: Decorative chromium demand in the worldwide market is more than three times of hard chromium. But chromium plating processes has long been known to hazardous. The corrosion resistance of a nano-crystalline Sn-Co-X alloy intended as an alternative for decorative chromium has been studied. The corrosion resistance of Sn-Co-X are all better than trivalent chromium, hexavalent chromium, and it is more better than coarser gained Sn-Co alloy. The microstructures of Sn-Co-X alloy were analyzed by SEM, TEM, XPS and AES. The mechanism of its excellent corrosion resistance is described.

Abstract: Flexible DCSF technology was put forward, and its forming character was described. The flexible DCSF machine was developed and related stretching experiment were carried out. The experimental photos show the DCSF technology is feasible and the DCSF machine is practicable. The FE model of flexible DCSF was set up, and extensive numerical simulations for spherical parts, saddle parts and S-type parts were carried out by Abaqus. The numerical results show that the longer the transitional length is, the more homogeneous the stretching strain and the thickness become. The smaller the friction coefficient is, the more homogeneous the stretching strain and the thickness become. The larger the clamp number is, the better the fit degree becomes. This work may provide useful guidance on the flexible DCSF process.

Abstract: Under immersed and we-dry cyclic conditions, the deterioration processes of the organic coating on carbon steel surface have been comparatively studied using electrochemical techniques. The wet-dry cycles were carried out by exposure to 4 h immersion and 4h dryness (4-4h cycles) and 12h immersion and 12h dryness (12-12h cycles) conditions, respectively. The immersion condition was carry out in a 3.5% NaCl solution and drying at 298K and 50% RH. According to the EIS characteristics, the entire deterioration processes under above three mentioned conditions can be divided into three main stages, consisting of the medium penetration, corrosion initiation and corrosion extension. Comparing with the immersed, the 4-4h wet-dry cycles greatly accelerated the entire deterioration process; especially during the corrosion initiation and the corrosion extension periods, leading the paint system lose its anti-corrosive performance in a short period. However, the 12-12h wet-dry cycles decelerated the entire deterioration process, prolonging the coatings anticorrosive ability. The acceleration mechanism of the coatings and underlying metal corrosion under wet-dry cycles was discussed based on the above results.

Abstract: Microstructure and mechanical properties of X70 pipeline steel with polygonal ferrite plus granular bainite were characterized using tensile tests, Charpy V-notch impact tests, drop weight tear tests, hardness tests and scanning electron microscopy. The results of experiment indicated that X70 pipeline steel with polygonal ferrite plus granular bainite showed an excellent combination of high strength and toughness. The base metal with polygonal ferrite plus granular bainite microstructure exhibited perfect mechanical properties in terms of the transverse yield ratio of 0.81, elongation of 46%, an impact energy of 335 J at -10 °C and a shear area of 90% at 0 °C in the drop weight tear test. The heat affected zone contained coarse grain zone and fine grain zone, which exhibited good low temperature toughness of 216 J at -10 °C. The weld metal primarily consisted of intragranularly nucleated acicular ferrites which led to the high strength and toughness.

Abstract: Multi-point holder forming (MPHF) adopts series of coupled holder punches, arranged between forming punches, to clamp the whole sheet in the forming zone. The multi-point holder forming processes of spherical parts of titanium mesh plate were simulated by finite element code, and the results were compared with those of multi-point die forming (MPDF). The influence of holder punch load on the deformation of spherical part in multi-point holder forming was investigated. The shape error analysis of titanium mesh formed by MPHF was performed in finial. The results showed that the spherical part had more excellent performance in multi-point holder forming, and the more deformation the titanium mesh was, the larger force of holder punch would be needed. In addition, there was a small shape error for titanium mesh part formed by MPHF before springback.

Abstract: Although multi-point forming (MPF) is an advanced processing technique and has been investigated comprehensively as a metal working operation, there are few papers published to deal with MPF of polymers. The present paper reviews the features of MPF and evaluates the possibility of producing polymer components by means of MPF. The experimental research work makes use of PC sheets with a thickness of 3.82 mm. Numerical simulations were performed with the software ABAQUS, then spherical and saddle-shaped components were manufactured by MPF. The geometrical deviations between shaped components and their original CAD/CAM models were obtained to investigate the forming accuracy. The results confirm that MPF of PC sheet has potential for the manufacture of complex components.

Abstract: For more efficient and economical extraction of cochineal dye, combined microwave-ultrasonic wave extraction was applied. It was approached 4 factors as microwave power, treated time, materials-to-liquid ratio and ultrasonic wave power. Results showed that the optimal condition individually for cochineal dye extraction was at 400W microwave power, 17min treated time, 1:8 materials-to-liquid ratio and 600W ultrasonic wave power. On the basis of single factor test, RSM optimization of the extraction was achieved at 464W microwave power, 18.48min treated time, 1:8.23 materials-to-liquid ratio and 627W ultrasonic wave power. The verification was very approximate to the predicted value from the modelling regression equation. And the best extraction grade was tesified as 4 times.

Abstract: In order to obtain large quantities of broadly selective receptor as one diagnose agent to detect amantadine residue, the M2 protein gene with a His-tag was ligated into pET11a and transferred into E. coli BL21 (DE3) cell. The recombinant E. coli was cultured in liquid LB culture. SDS-PAGE result showed the recombinant M2 protein (rM2) was expressed as insoluble inclusion bodies with about 18KDa in molecular size. rM2 protein was further recognized by Western blot and purified by Ni Sepharose 6 Fast Flow and then refolded. The equilibrium dialysis result showed the rM2 protein had the binding constant of 1.1×10⁵, and stoichiometry of 4.2. The above result showed the rM2 has the potential as biological diagnose agent to the detection of amantadine residue.

Abstract: For the improvement of processing and the increase of refined products of Chinese insect wax, it was carried out on the raw wax for its refining in the pilot plants. After the treatment, it was raised the melting point and reduced the acid value, iodine value, saponification value and insoluble substances of benzene significantly. The quality of final products was accord to the industrial top-grade requirement. The yield of refined wax was ranging from 72.76% to 74.30% and the whiteness was 51.8% to 56.3%. It was not observed any chemical changes of the wax during the processing.

Abstract: Objectives: Zirconia powder in nanometers can be fabricated into inter-joined abutment of detal implant system with the injection shaping technique. This study was to detect the resistance of inter-joined zirconia abutment with different angle loading for clinical applications. Materials and Methods: The inter-joined abutments were shaped with the technique of injection of zirconia powder in nanometers. Sixty 0sstem GSⅡ5.0mm×10mm implants were used with 30 zirconia abutments and 30 0sstem GSⅡtitanium abutments for fixation using 40N torque force. The loading applications included 90°, 30°, 0° formed by the long axis of abutments and pressure head of universal test machine. The fracture resistances of zirconia and titanium abutments were documented and analyzed. Results: The inter-joined zirconia abutments were assembled to the 0sstem GSⅡimplants succssfully. In the 90° loading mode, the fracture resistance of zirconia abutment group and titanium abutment group were 301.46±15.38N、736.36±120.10N respectively. And those in the 30°groups were 434.66±36.07N、1073.12±73.96N correspondingly. Significant difference in the two groups was found through T Test. No damage on the abutments of the two groups but S-shaped bending on the implants was found when the 0° loading was 1300~2000N. Conclusions: Through the assembly of Zirconia abutments and implants, all the components presented sufficient resistance acquired for the clinical application under loadings with different angle.