镗轴是落地式铣镗床的关键核心部件,主要起支撑传动和传递转矩的作用,其直接影响着机床的精度和寿命。我公司采用38C r M o A l钢作为镗轴用钢,经过氮化处理达到服役条件,要求镗轴氮化后的表面硬度尽可能高,变形尽可能小。为获得较好的...镗轴是落地式铣镗床的关键核心部件,主要起支撑传动和传递转矩的作用,其直接影响着机床的精度和寿命。我公司采用38C r M o A l钢作为镗轴用钢,经过氮化处理达到服役条件,要求镗轴氮化后的表面硬度尽可能高,变形尽可能小。为获得较好的氮化硬度及氮化层深度,分别采用等温氮化、二段氮化及三段氮化工艺进行试验,研究氮化温度及时间等参数对镗轴氮化质量的影响,找出镗轴氮化最优的工艺。展开更多
Nitric oxide （NO） deep oxidation to dinitrogen pentoxide （N2O5） by ozone together with wet scrub-bing has become a promising technology for nitrogen-oxide （NOx） removal in industrial boilers. Catalysts wer...Nitric oxide （NO） deep oxidation to dinitrogen pentoxide （N2O5） by ozone together with wet scrub-bing has become a promising technology for nitrogen-oxide （NOx） removal in industrial boilers. Catalysts were introduced to enhance the N2O5 formation rate with less ozone injection and leakage. A series of monometallic catalysts （manganese, cobalt, cerium, iron, copper, and chromium） as pre-pared by the sol-gel method were tested. The manganese oxides achieved an almost 80% conver-sion efficiency at an ozone （O3）/NO molar ratio of 2.0 in 0.12 s. The crystalline structure and porous parameters were determined. The thermodynamic reaction threshold of NO conversion to N2O5 is oxidation with an O3/NO molar ratio of 1.5. Spherical alumina was selected as the support to achieve the threshold, which was believed to improve the catalytic activity by increasing the surface area and the gas-solid contact time. Based on the manganese oxides, cerium, iron, chromium, cop-per, and cobalt were introduced as promoters. Cerium and iron improved the deep-oxidation effi-ciency compared with manganese/spherical alumina, with less than 50 mg/m3 of outlet NO ＋ nitro-gen oxide, and less than 25 mg/m3 of residual ozone at an O3/NO molar ratio of 1.5. The other three metal oxides inhibited catalytic activity. X-ray diffraction, nitrogen adsorption, hydrogen tempera-ture-programmed reduction, and X-ray photoelectron spectroscopy results indicate that the cata-lytic activity is affected by the synergistic action of NOx oxidation and ozone decomposition.展开更多
文摘镗轴是落地式铣镗床的关键核心部件,主要起支撑传动和传递转矩的作用,其直接影响着机床的精度和寿命。我公司采用38C r M o A l钢作为镗轴用钢,经过氮化处理达到服役条件,要求镗轴氮化后的表面硬度尽可能高,变形尽可能小。为获得较好的氮化硬度及氮化层深度,分别采用等温氮化、二段氮化及三段氮化工艺进行试验,研究氮化温度及时间等参数对镗轴氮化质量的影响,找出镗轴氮化最优的工艺。
基金supported by the National Natural Science Foundation of China(51422605)the Provincial Natural Science Foundation of Zhejiang,China(LR16E060001)~~
文摘Nitric oxide （NO） deep oxidation to dinitrogen pentoxide （N2O5） by ozone together with wet scrub-bing has become a promising technology for nitrogen-oxide （NOx） removal in industrial boilers. Catalysts were introduced to enhance the N2O5 formation rate with less ozone injection and leakage. A series of monometallic catalysts （manganese, cobalt, cerium, iron, copper, and chromium） as pre-pared by the sol-gel method were tested. The manganese oxides achieved an almost 80% conver-sion efficiency at an ozone （O3）/NO molar ratio of 2.0 in 0.12 s. The crystalline structure and porous parameters were determined. The thermodynamic reaction threshold of NO conversion to N2O5 is oxidation with an O3/NO molar ratio of 1.5. Spherical alumina was selected as the support to achieve the threshold, which was believed to improve the catalytic activity by increasing the surface area and the gas-solid contact time. Based on the manganese oxides, cerium, iron, chromium, cop-per, and cobalt were introduced as promoters. Cerium and iron improved the deep-oxidation effi-ciency compared with manganese/spherical alumina, with less than 50 mg/m3 of outlet NO ＋ nitro-gen oxide, and less than 25 mg/m3 of residual ozone at an O3/NO molar ratio of 1.5. The other three metal oxides inhibited catalytic activity. X-ray diffraction, nitrogen adsorption, hydrogen tempera-ture-programmed reduction, and X-ray photoelectron spectroscopy results indicate that the cata-lytic activity is affected by the synergistic action of NOx oxidation and ozone decomposition.
