In this paper, Ti-C-N nanocomposite films are deposited under different nitrogen flow rates by pulsed bias arc ion plating using Ti and graphite targets in the Ar/N2 mixture gas. The surface morphologies, compositions...In this paper, Ti-C-N nanocomposite films are deposited under different nitrogen flow rates by pulsed bias arc ion plating using Ti and graphite targets in the Ar/N2 mixture gas. The surface morphologies, compositions, microstructures, and mechanical properties of the Ti-C-N films are investigated systematically by field emission scanning electron mi- croscopy （FE-SEM）, x-ray photoelectron spectroscopy （XPS）, grazing incident x-ray diffraction （GIXRD）, Raman spectra, and nano-indentation. The results show that the nanocrystalline Ti（C,N） phase precipitates in the film from GIXRD and XPS analysis, and Raman spectra prove the presence of diamond-like carbon, indicating the formation of nanocomposite film with microstructures comprising nanocrystalline Ti（C,N） phase embedded into a diamond-like matrix. The nitrogen flow rate has a significant effect on the composition, structure, and properties of the film. The nano-hardness and elastic modulus first increase and then decrease as nitrogen flow rate increases, reaching a maximum of 34.3 GPa and 383.2 GPa, at a nitrogen flow rate of 90 sccm, respectively.展开更多
Soil organic carbon （SOC） and soil inorganic carbon （SIC） are important C pools in the Loess Plateau of Northwest China, however, variations of SOC and SIC stocks under different cultivation practices and nitrogen...Soil organic carbon （SOC） and soil inorganic carbon （SIC） are important C pools in the Loess Plateau of Northwest China, however, variations of SOC and SIC stocks under different cultivation practices and nitrogen （N） fertilization rates are not clear in this area. A long-term field experiment started in June 2003 was conducted to investigate the SOC and SIC stocks in a calcareous soil of the Chinese Loess Plateau under four cultivation practices, i.e., fallow （FA）, conventional cultivation （CC）, straw mulch （SM）, and plastic film-mulched ridge and straw-mulched furrow （RF）, in combination with three N fertilization rates, i.e., 0 （NO）, 120 （N120）, and 240 （N240） kg N/hm2. Results indicate that the crop straw addition treatments （SM and RF） increased the contents of soil microbial biomass C （SMBC） and SOC, and the SOC stock increased by 10.1%-13.3% at the upper 20 cm soil depth in comparison to the 8-year fallow （FA） treatment. Meanwhile, SIC stock significantly increased by 19% at the entire tested soil depth range （0-100 cm） under all crop cultivation practices in comparison to that of soil exposed to the long-term fallow treatment, particularly at the upper 60 cm soil depth. Furthermore, moderate N fertilizer application （120 kg N/hm2） increased SOC stock at the upper 40 cm soil depth, whereas SIC stock decreased as the N fertilization rate increased. We conclude that the combined application of crop organic residues and moderate N fertilization rate could facilitate the sequestrations of SOC and SIC in the calcareous soil.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.51271047)
文摘In this paper, Ti-C-N nanocomposite films are deposited under different nitrogen flow rates by pulsed bias arc ion plating using Ti and graphite targets in the Ar/N2 mixture gas. The surface morphologies, compositions, microstructures, and mechanical properties of the Ti-C-N films are investigated systematically by field emission scanning electron mi- croscopy （FE-SEM）, x-ray photoelectron spectroscopy （XPS）, grazing incident x-ray diffraction （GIXRD）, Raman spectra, and nano-indentation. The results show that the nanocrystalline Ti（C,N） phase precipitates in the film from GIXRD and XPS analysis, and Raman spectra prove the presence of diamond-like carbon, indicating the formation of nanocomposite film with microstructures comprising nanocrystalline Ti（C,N） phase embedded into a diamond-like matrix. The nitrogen flow rate has a significant effect on the composition, structure, and properties of the film. The nano-hardness and elastic modulus first increase and then decrease as nitrogen flow rate increases, reaching a maximum of 34.3 GPa and 383.2 GPa, at a nitrogen flow rate of 90 sccm, respectively.
基金supported by the National Natural Science Foundation of China (41671295)the National Technology R&D Pillar Program in the 12th Five Year Plan of China (2012BAD15B04)
文摘Soil organic carbon （SOC） and soil inorganic carbon （SIC） are important C pools in the Loess Plateau of Northwest China, however, variations of SOC and SIC stocks under different cultivation practices and nitrogen （N） fertilization rates are not clear in this area. A long-term field experiment started in June 2003 was conducted to investigate the SOC and SIC stocks in a calcareous soil of the Chinese Loess Plateau under four cultivation practices, i.e., fallow （FA）, conventional cultivation （CC）, straw mulch （SM）, and plastic film-mulched ridge and straw-mulched furrow （RF）, in combination with three N fertilization rates, i.e., 0 （NO）, 120 （N120）, and 240 （N240） kg N/hm2. Results indicate that the crop straw addition treatments （SM and RF） increased the contents of soil microbial biomass C （SMBC） and SOC, and the SOC stock increased by 10.1%-13.3% at the upper 20 cm soil depth in comparison to the 8-year fallow （FA） treatment. Meanwhile, SIC stock significantly increased by 19% at the entire tested soil depth range （0-100 cm） under all crop cultivation practices in comparison to that of soil exposed to the long-term fallow treatment, particularly at the upper 60 cm soil depth. Furthermore, moderate N fertilizer application （120 kg N/hm2） increased SOC stock at the upper 40 cm soil depth, whereas SIC stock decreased as the N fertilization rate increased. We conclude that the combined application of crop organic residues and moderate N fertilization rate could facilitate the sequestrations of SOC and SIC in the calcareous soil.
