Materials Science Forum Vols. 471-472

Abstract: Two kinds of Al2O3 /SiC nanocomposites with different alumina powder are developed, one is fabricated only by nano-scale alumina powders, the other is by micro-scale with partial nano-scale alumina powders. Both of the two composites may get higher flexural strength and fracture toughness than that of micro-scale monolithic alumina ceramics, but the latter is more preferable than the former. The microstructure and the strengthening and toughening mechanisms of the new ceramic tool materials are investigated, the improvement of mechanical properties may be mainly attributed to the transgranular fracture mode induced by the added nano-scale SiC, while adding nano-scale alumina powder to micro-scale powder, both of the nano-scale Al2O3 and nano-scale SiC may strengthen the micro-scale Al2O3 matrix, that means the nano-scale Al2O3 acted as the dispersed phase.

Abstract: The features of a newly developed multi-dimension squeezed penetration piling machine are presented in this paper. The simulation model is built and the squeezing mechanism is tested under simulation environment. With the simulation method key design parameters are predicted at the early design stage; the development cycle can be shortened; and the product quality can be improved.

Abstract: Nano-scale ceramic materials are very suitable to be used as the high speed cutting tool owing to their excellent properties. The incorporation of nano-scale second phase, such as SiC and Ti(CxN1-x) particles, into a ceramic matrix can lead to an improvement in mechanical properties, which is contributed to a change in microstructure. However, the differences between nano-scale ceramic materials and monoclinic ceramic materials can be found through fabricating these two kinds of materials. Firstly the changes in microstructure that will affect the mechanical properties of the nano-scale ceramic materials are investigated as the nano-ceramic tools are compared with the monolithic ceramic tools. Secondly the effect of microstructure on the mechanical properties is discussed. Finally the microstructure formation mechanism of nano-ceramic materials is given on the bases of some hypotheses.

Abstract: In order to eliminate the non-linearity of a grinding auxiliary workpiece table, a hybrid fuzzy PID controller has been developed. The two-dimensional fuzzy control with self-tuning factor is utilized to improve the performance. The Max-Min inference mechanism and COG defuzzification method are used to obtain the crisp output of the fuzzy controller. To eliminate the oscillation at balance position, the conventional PID controller is used in the small range of the error and the switch between two controllers can automatically realize according the preset value. Simulation and experimental testing have been carried out to validate the performance of the hybrid fuzzy PID controller.

Abstract: Gear profile modification is an important method for reducing system vibration and noise of a gear transmission. In this paper, three kinds of gear profile modification curves are studied, and relevant experiments are conducted. Some useful conclusions based on the theoretical analysis and experimental results have been obtained. Line, parabola and sinusoid modification curves are very useful in improving the dynamic performance of a gear transmission system by reducing system vibration and noise. In order to design the optimal tooth profile modification curve, the curve type must be decided firstly according to the specific working condition, and the curve parameters can be determined by means of optimum programming.

Abstract: This study descripts processing of biphasic calcium-phosphate (BCP) and poly-L-lactide (PLLA) biocomposite implant material. The composite was obtained by mixing completely dissolved PLLA with granules of high crystalline BCP and was compacted by hot pressing using cylindrical dies at 450 K temperature and 98.1 MPa pressure, for 30 and 60 minutes. Wide-angle Xray structural (WAXS) analyses of BCP, PLLA and BCP/PLLA composite blocks were made followed by calorimetric (DSC) tests in the 320-520 K temperature range. Compression tests revealed that Young’s modulus and compressive strength of the composite increased with extended hot pressing time and were found to be within the bounds of the cortical bone values.

Abstract: In this paper, the character of profile material cutting is analyzed; the dynamic alliance structure of plastic window production and its quick response to the varied and individualized requirements are introduced; the formation of network manufacturing environment and the practice of NC technology in the environment are illustrated; and then the method of improving the material utilization and the ability of flexible manufacturing are put forward.

Abstract: By changing the molecular weight and concentration of dispersant, PH value of dispersion solution and treat process, this paper focuses on the optimization parameters of the TiCp-reinforced ß-sialon nanocomposites suspensions. Zeta potentials, sedimentation tests have been carried out to prepare a well reagglomerated and uniform suspensions. The optimum molecular weight of PEG is 1540 for Al2O3 powder and 4000 for others, while the concentration is 0.5wt% to 0.8wt% with the pH values range from 9.5 to 10. After addition of dispersant, PEG (polyethylene glycol), the surfaces of the TiC particles and Sialon contents were selectively covered with long organic molecular chains by soaking within solution. The resulting powders not only resisted reagglomeration, but were also readily dispersible within the mixed solution. Optimum dispersion conditions, i.e. the surfactant molecular weight and the concentration, the PH value of the suspens ions and the soaking time were determined.

Abstract: A new method for fabricating the thin-walled diamond core drill by brazing technology and the optimum grain distribution was proposed in this paper. Machining performance experiments have been carried out, including contrast tests about drill life and machining efficiency for the thin- walled monolayer brazed diamond core drill and electroplated one. The testing results show that thin-walled monolayer brazed diamond core drill has certainly super-excellent machining performance. Wear mechanism of diamond grits was studied in tho se drilling processes. No pulling out for the thin-walled monolayer brazed diamond core drill grits is the key factor of its longer life, and the optimum grain distribution and less wear flat of grits during drilling decrease the drilling spindle direction force, and improve the machining efficiency. It can be concluded that the new technology can radically improve the bonding strength at the grains interface, and make every grain effective during drilling.