The hydrogenated diamond-like carbon (DLCH) film with 1-µm thickness is deposited by direct hydrocarbon gas ion beam method on silicon wafer and annealed at 400 • C. Detailed Raman spectra feature are fitted from nine sets of different peak fitting functions, including Gaussian, Lorentzian and Breit-Wigner-Fano (BWF) functions. These fitting results obtained from a two-peak combination show some specific variances on the G peak position, FWHM G and I D /I G ratio for as-deposited and as-annealed DLCH films. The most popular two-peak fitting method with full Gaussian function tends to exhibit a higher ratio of the G peak position shift and higher I D /I G ratio than others fitting methods, the drastic difference among the most popular G (G) & G (D) and B (G) & L (D) schemes also have brought out in I D /I G ratio. However, for a more complex four-peak Gaussian function fitting Raman spectra, the I D /I G ratio is close to that of a two-peak fitting function with a mixture functions of BWF (G) and L (D). Furthermore, a series of systematic peak fitting procedures and comparisons of Raman spectra have been discussed in this study.
The hydrogened diamond like carbon film (DLCH) with 1 mm thickness is made by hydrocarbon gas ion beam deposition method. The relationship between I D =I G ratio fitted from visible Raman spectra and sp 2 /sp 3 ratio done from XPS spectra of DLCH film shows a trend. The I D =I G ratio of deconvoluted visible Raman spectra shows a correlation with sp 2 /sp 3 ratio from XPS spectra as annealing temperature increases, the graphitization and the disorder increase. The I D =I G ratios fitted with two-curve Gaussian functions of Raman spectra tend to be proportional to sp 2 /sp 3 ratio fitted with three-curve with 100% Gaussian function of XPS spectra when post annealed treatment is below 400 C and without severe oxidation.
The bonding and crystalline structures of oil-fried fly ash collected from a power plant were analyzed by using Raman spectroscopy and X-ray diffraction (XRD), respectively. These carbon powders underwent a series of annealing treatment for graphitization and crystallization. In Raman spectra, the refined, unburned carbon contains clearly the D, G and D peaks under 2000 or 2700 • C treatment. The Raman spectral line shape of refined, unburned carbon heated at 2700 • C is similar to that of commercial graphite made from graphitization process. In the XRD spectra, the refined, unburned carbon contains (002), (100) and (004) diffraction peaks under heating at 2000 or 2700 • C. The XRD spectral line shape of refined, unburned carbon heated at 2700 • C is similar to that of a commercial graphite bar. The quantitative graphitization level from Raman spectra and crystallization degree from XRD spectra on refined, unburned carbon powders serve as preliminary guide for the qualitative evaluation of these unburned carbon powders.
Shot peening treatment uses special steel shot media to impact the surface material at a high speed, thus resulting in a compressed and dense surface. The compressive stress provides higher resistance to thermal fatigue and stress corrosion cracking. To evaluate the effects of shot peening on thermal cracking and the mechanical properties of H13 tool steel, this study conducted impact, thermal fatigue and wear tests, as well as SEM microstructure and microhardness inspections. Experimental results showed that steel shot peening treatment, conducted for 30 min at 0?5 MPa on H13 tool steel reached the optimum for improving the microstructure and fatigue properties. The process can enhance the surface hardness to HV 561 and extend the limit of fatigue strength on H13 tool steel by two to three times. This technology can be successfully applied to die casting moulds to notably improve and extend tool life.
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