Advanced Materials Research Vols. 291-294

Abstract: A method of double-side displacement-rotation flat-lapping with solid abrasives is proposed and a CNC machine tool is developed in this document. By analyzing the lapping principle and the structural characteristic of common solid abrasives flat-lapping method, the deficiencies of this method are indicated. The new method changes the motion pattern of workpiece in principle, the relative position between the workpiece and abrasive disks (lapping tools) are changed while the workpiece rotates. Therefore those deficiencies are made up radically, the lapping trace and velocity distribution of the relative motion between the workpiece and abrasive disks are more reasonable, the stress and wear states of isolating plate are improved as well. Finally, the driving moment and the speed of workpiece rotary are analyzed, and the relative velocity between the abrasive disks and workpiece is researched.

Abstract: In this paper, ultra-precision shaping and polishing experiments have been done to research the shaping and polishing characters of nanoparticle colloid jet machining. A high-purity quartz glass sample with aspheric surface profile was employed as workpiece and polished by nanoparticle colloid jet machining. We utilized surface profilometer to measure the surface profiles of workpiece before and after shaping by nanoparticle colloid jet machining. The measurement results indicate that the nanoparticle colloid jet machining has good shaping ability to satisfy the demands for surface shape correction in ultra-precision machining. Atomic force microscopy (AFM) was utilized to observe the surface microscopic morphological characteristics of the workpiece surface polished by nanoparticle colloid jet machining. The observation results show that the roughness of the workpiece surface has been reduced from 1.919 nm RMS to 0.784 nm RMS by nanoparticle colloid jet machining. Based on the atomic force microscopy observation results, power spectral density analyses have been done to evaluate the polishing performance of the nanoparticle colloid jet machining.

Abstract: This paper introduced a polishing process for planarization of gallium nitride (GaN) wafer by polishing slurry that is made up by the chemical reaction with H₂O₂ solution and iron. Some different polishing parameters in the polishing process has been analyzed, which affect the surface quality of wafers, such as slurry particle size, polishing times, polishing slurry etc., and trying to improve the polishing process by optimization of the polishing parameters. The experimental result showed that this polishing method has an effect on the surface quality of GaN wafers, finally, the efficient and precision machining with surface roughness of GaN wafers of Ra0.81 nm has been gained by the CMP polishing process.

Abstract: Due to particular structural design, the error of manufacturing and other factors, the tool system will have more or less residual imbalance. The spindle-tool system’s vibration signals and its frequency response structure were made as reference under the testing of machine raising speed idle running, firstly the tool system’s amount of imbalance was adjusted with the aid of the special balancing ring, then the spindle-tool system’s vibration characteristic was obtained under various amount of imbalanced in idle running condition, finally making use of frequency spectrum analysis the influence of unbalanced quantity to spindle-tool system’s vibration characteristics was studied and compared, the results and the researching approach can help to find the rules about the influence of tool system imbalance to its vibration characteristics in higher speed condition.

Abstract: This paper focuses on the feasibility of the hanging-weight method in bridge deflection test of high speed rail. Firstly, it explains principles and component part. And then it proposes steps to determine test parameters. Lastly, it demonstrates the feasibility and reliability of this method by numerical simulation. The result shows the hanging-weight method satisfies the precision of bridge deflection measurement in high speed rail.

Abstract: A simulation-based system dynamics (SD) model was developed for allocating the waste load and supporting river quality management. Panjin section of Liaohe River in China was used as a study case to demonstrate the feasibility of the proposed methodology. The national surface-water environment function zoning of Liaoning Province was presented as a constraint in order to calculate the maximum allowable waste quantity for COD, which is expressed as interval format of both upper bound and lower bound. Then allocate the waste load to each point source responses within these quantities. The study results simulated from SD model, together with the intervals-format uncertainties of allowable COD level is valuable for supporting decision makers in optimizing water quality management.

Abstract: This paper introduced the idea of environmental carrying capacity (ECC) to the planning of watershed’s environmental-economic optimization. And a case study in Lake Fuxianhu is utilized from year 2008 to 2028. The results are: based on the water environment carrying capacity of lakes, with the adjustment of industrial internal structure, distribution and development speed of three major industries, the water quality of the basin will be I class. This adjustment will not only keep a rapid development of economy, but also can make sure the improvement of Lake Fuxianhu Basin environment. Thus, the development of society and environment will be coordinated. The application of water environment carrying capacity of lakes to instruct the scale of social development is very significant to the sustainable development among economy, society and environment.

Abstract: Pyrolysis oil derived from sewage sludge is considered as one of the substitute of crude in the world confronting energy shortage. Before the utilization of pyrolysis oil in industry, comprehensive investigation of its physico-chemical characters is needed. Through detailed analyze of its fuel properties and other characters including metal content, solid content and stability, the pyrolysis could not used as No. 4 fuel before improving its fuel characters, decreasing its metal and solid content, and increasing its stability. The detailed analyze of the pyrolysis oil could provide basic data for the process and use of it in future.

Abstract: The Al₂O₃-Cr₂O₃ slag as raw material was analyzed by scanning electron microscopy (SEM). The effects of different size distribution of MgO-Al₂O₃ spinel grain on physical properties of refractory bricks made from Al₂O₃-Cr₂O₃ slag was studied according to YB/T376.1-1995（water quenching）, GB/T 5072－1985, GB/T 2997-1982 criterion. The results show that the main crystal phase of the refractory bricks were chromium corundum, corundum. The refractory bricks containing 10 wt% of the maximum size of 3.0 mm of MgO-Al₂O₃ spinel grain can significantly improve the thermal shock resistance of this refractory bricks. At the meanwhile, This kind of refractory bricks can be absolutely satisfied with the requirements about cold crushing strength, bulk density and apparent porosity.

Abstract: Utilization of waste refractory material has attracted much attention due to the development of metallurgical industry and the requirements of environmental protection. This article mainly researched on the Al₂O₃-ZrO₂-C sliding nozzle that prepared using its recovery refractory and some other new materials. The addition of the recovery material leads to the formation of ZrO₂ compound. The performance of the sliding nozzle is enhanced by controlling its microstructure, including the improvement of strength under cold and high temperature, and increase in slag resistance.