Knowledge of radioactivity present in polishing materials enables one to assess any possible radiological risks to human health. In this work, the radioactivity due to the presence of <sup>226</sup>Ra, <...Knowledge of radioactivity present in polishing materials enables one to assess any possible radiological risks to human health. In this work, the radioactivity due to the presence of <sup>226</sup>Ra, <sup>232</sup>Th, <sup>40</sup>K, and <sup>37</sup>Cs has been measured in polishing materials con-sumed in Saudi Arabia using gamma spectrometry with HPGe. The activity concentra-tions of <sup>226</sup>Ra, <sup>232</sup>Th, <sup>40</sup>K and <sup>137</sup>Cs ranged from 13.61 ± 0.005 to 0.60 ± 0.002, 18.43 ± 0.003 to 0.78 ± 0.001, 342.59 ± 0.009 to 2.47 ± 0.001 and 1.47 ± 0.001 to 0.55 ± 0.001 Bq/l, respectively. For <sup>226</sup>Ra and <sup>40</sup>K, the highest values are measured in stainless steel polisher. The highest values also measured in metal polisher (copper-chrome) and disinfectant cleaner and polisher sample for <sup>232</sup>Th and <sup>137</sup>Cs. Radium equivalent activ-ity due to the natural radioactivity of the investigated samples ranged from 51.37 to 1.24 Bq/l. This value is less than the recommended values in the established standards. The evaluated data were compared with the literature data. Our results indicate that no significant radiological hazards arise from using investigated samples hence quite safe to be used as polishing materials.展开更多
The paper firstly analyzes the influence factor on material removal rate of curved optical work-pieces in the bonnet polishing. Then the experiments are conducted to reveal the effects of several polishing parameters ...The paper firstly analyzes the influence factor on material removal rate of curved optical work-pieces in the bonnet polishing. Then the experiments are conducted to reveal the effects of several polishing parameters on the material removal rate when the spherical optical glasses are polished with different curvature radius, such as the decrement of the bonnet, the rotational speed of the bonnet and the curvature radius of the work-piece＇s surface using a bonnet trial-manufacturing machine developed by our assignment groups. In the end, the curvilinear relationships between these parameters and the material removal rate are acquired and the laws of the effects on material removal rate in bonnet polishing by several parameters are given. When the spherical-pieces are polished with smaller curvature radius, it is not proportional to either bonnet decrement or bonnet rotational speed as described by the Preston equation although the removal rate increases as the relative velocity or the applied pressure increases. Therefore, for the purpose of calculating more accurately the material removal of the spherical work-pieces, the Preston equation should be modified and studied further.展开更多
文摘Knowledge of radioactivity present in polishing materials enables one to assess any possible radiological risks to human health. In this work, the radioactivity due to the presence of <sup>226</sup>Ra, <sup>232</sup>Th, <sup>40</sup>K, and <sup>37</sup>Cs has been measured in polishing materials con-sumed in Saudi Arabia using gamma spectrometry with HPGe. The activity concentra-tions of <sup>226</sup>Ra, <sup>232</sup>Th, <sup>40</sup>K and <sup>137</sup>Cs ranged from 13.61 ± 0.005 to 0.60 ± 0.002, 18.43 ± 0.003 to 0.78 ± 0.001, 342.59 ± 0.009 to 2.47 ± 0.001 and 1.47 ± 0.001 to 0.55 ± 0.001 Bq/l, respectively. For <sup>226</sup>Ra and <sup>40</sup>K, the highest values are measured in stainless steel polisher. The highest values also measured in metal polisher (copper-chrome) and disinfectant cleaner and polisher sample for <sup>232</sup>Th and <sup>137</sup>Cs. Radium equivalent activ-ity due to the natural radioactivity of the investigated samples ranged from 51.37 to 1.24 Bq/l. This value is less than the recommended values in the established standards. The evaluated data were compared with the literature data. Our results indicate that no significant radiological hazards arise from using investigated samples hence quite safe to be used as polishing materials.
基金Foundation of Harbin Institute of Technology,China(No.HIT.2001.10)Harbin Municipal Youth Foundation of China(No.2002AFQXJ040).
文摘The paper firstly analyzes the influence factor on material removal rate of curved optical work-pieces in the bonnet polishing. Then the experiments are conducted to reveal the effects of several polishing parameters on the material removal rate when the spherical optical glasses are polished with different curvature radius, such as the decrement of the bonnet, the rotational speed of the bonnet and the curvature radius of the work-piece＇s surface using a bonnet trial-manufacturing machine developed by our assignment groups. In the end, the curvilinear relationships between these parameters and the material removal rate are acquired and the laws of the effects on material removal rate in bonnet polishing by several parameters are given. When the spherical-pieces are polished with smaller curvature radius, it is not proportional to either bonnet decrement or bonnet rotational speed as described by the Preston equation although the removal rate increases as the relative velocity or the applied pressure increases. Therefore, for the purpose of calculating more accurately the material removal of the spherical work-pieces, the Preston equation should be modified and studied further.
