Development of aerostatic porous bearings manufactured using metal 3D printing technology

Aerostatic porous bearings have been applied widely in precision devices to achieve higher accuracy of motion. Conventional aerostatic porous bearings are made of porous graphite, porous ceramics or sintered metal porous material, having a thickness of several millimetres and a surface-restricted layer. However, during mass production of porous bearings, the time required for the production of the porous materials and the surface restriction treatment leads to an increase in the manufacturing time and cost of the porous bearings. Accordingly, to overcome this problem, an aerostatic porous bearing with a layer thickness of several hundred µm and a support member, manufactured using metal 3D printing technology, is proposed. In this study, the optimum conditions for manufacturing the proposed aerostatic porous bearings with a direct metal laser sintering method 3D printer were investigated, and characteristics of the prototype of the proposed bearings were investigated experimentally.

Production of high thermal conducting aluminum-graphite composite materials by the press-squeeze method utilizing porous graphite preforms and aluminum alloys

Consideration is given to the technological process of producing high thermal conducting aluminum-graphite composite materials by press-squeeze method utilizing porous graphite preforms and aluminum alloys. It is shown that the rate of press-squeeze process, aluminum alloy composition provide dense, defect-free and non-porous thermal interface between graphite and matrix alloy, it is noted the absence of crystal inclusions of third phases, such as SiC, Al4C3. An example of evaluation of thermal conductivity of the sample of composite material is given with consideration of graphite particles orientation and matrix-filler thermal interface heat conductivity.

Research On The Fractal and Percolation Characteristics of Coal-Based Porous Media For Filtration and Impregnation

In order to distinguish the difference in the heterogeneous fractal structure of porous graphite used for filtration and impregnation, the fractal dimensions obtained through the mercury intrusion porosimetry (MIP) along with the fractal theory were used to calculate the volumetric FD of the graphite samples. The FD expression of the tortuosity along with all parameters from MIP test was optimized to simplify the calculation. In addition, the percolation evolution process of mercury in the porous media was analyzed in combination with the experimental data. As indicated in the analysis, the FDs in the backbone formation regions of sample vary from 2.695 to 2.984, with 2.923 to 2.991 in the percolation regions and 1.224 to 1.544 in the tortuosity. According to the MIP test, the mercury distribution in porous graphite manifested a transitional process from local aggregation, gradual expansion, and infinite cluster connection to global connection.