No abstract

Metal matrix composites（MMCs）is applied widely in recent years because of its excellent performances, but the machining is very difficult due to the rigidity of reinforced-phase in it, so, the application of MMCs is restricted much. In this paper the experiment of common and ultrasonic vibration drilling is performed to SiC particulate reinforced Al matrix composites （SiCp/Al）by use of carbide-alloy-twist-drill, and the surface roughness of hole is compared, furthermore, the wearing of twist drill and the feature of chips are analyzed by scanning electron microscope (SEM). From above, we can draw aconclusion that ultrasonic vibration drilling may meliorate the mechanism of drilling to some extent and it takes on much superiority that the common drilling is unmatched, so this method could provide a certain foundation for the posterior study and application.

The nano-powder of Al2O3-SiO2-CaF2 bio-glass was prepared by the homo-precipitation method with some inorganic salts containing Al3+, Ca2+, Na+, F-, SiO3 2+, Cl- as starting-reagents. The composition and characteristics of the powders were studied with XRD, EDAX, TEM and DTA. The results indicate that the prepared powder belongs to amorphous compounds containing Al, Ca, Si, O and F atoms and the size of particle is in the range of 30 ~ 70 nm. Adding citric acid and the well-controlled desiccation process can slightly improve the dispersing effect of the powders; the mixture ratio of the reagents rarely affects the characteristic of powder. The crystal phase CaF2 was precipitated firstly from the amorphous structure when the temperature is above 600°C, with the temperature rising, Al2SiO5 and Al4.4Si1.2O9.5 etc. crystal phases were precipitated sequentially.

A monolithic glass-ceramic lined steel elbow with 900-bend angle was fabricated using a self-propagating high-temperature synthesis gravitational-thermite process (SHS G-T process). The manufacture principle and some technologies were introduced. Experiment results showed that the inner surface of the composite elbow was smooth and there were no visible cracks and pores in it. The coating layer was symmetry and was of ~ 2.5 mm thick. It consisted of two zones (glass-like zone, columnar zone) and that there existed three phases (Al2O3, glass and Fe particles) in both of the two zones. However, the Al2O3 grains were different evidently in the two zones. XRD results showed that there was no hercynite phase in the coating layer.

Nano ceramics possessed ascendant mechanical property and physical characteristics contrast with engineering ceramics, so it has extensive application prospect in various industries. On the basis of applying the indentation fracture mechanics to analyze the removal mechanics of ceramic material, this paper analyzed the critical ductile grinding depth of the nano ZrO2 ceramics. Adopting ultrasonic composite processing we describe the influence of different processing parameters and grain size of diamond wheel on the grinding forces and surface roughness. Based on the grinding forces and surface roughness the grinding process with and without vibration is analyzed. By means of SEM and AFM the surface character and critical ductile grinding depth of nano ZrO2 ceramics are also discussed. The paper supplied the theoretical and experimental basis for the grinding of the large-sized ultraprecision plate structure of nano ZrO2 ceramics (nm).