Papers by Keyword: Hydrogen Content

Abstract: This study was performed to improve the adhesiveness of a diamond-like carbon (DLC, a-C:H) layer film with an a-SiC interlayer. In previous studies, an a-SiC/DLC layer film was formed and changes in the DLC film structure and hardness caused by the thickness of the a-SiC layer were examined. After the a-SiC interlayer thickness increased and the G-peak position shifted to a lower frequency, the peak began shifting to higher frequencies. The G-peak position reached a minimum frequency at a film thickness of approximately 0.3 μm. In contrast, as the thickness of the a-SiC interlayer increased, the FWHM of the G-peak position increased almost monotonically and the number of sp³ bonds also increased. As the interlayer thickness increased, the hydrogen content in the DLC film increased, and then began decreasing, with the interlayer film thickness exhibiting a local maximum at approximately 0.3 μm. As for the DLC film hardness, a correlation between the hydrogen content and half width of the G-peak position was observed. When the hydrogen content was ≤40 at%, a positive correlation with the FWHM (G) was observed, and when the hydrogen content was 40 at% or above, a negative correlation with FWHM (G) was found. The adhesiveness of the DLC film and substrate was improved by forming an a-SiC thin film as an interlayer. The effects of the a-SiC thin film on DLC film quality were determined.

Abstract: On the basis of the principle of hydrogen pressure, this paper makes a comprehensive research about coupling effect of the stress field in the micropores in the condition of hydrogen pressure. According to the equation of Kazinczy Pokinger, calculation model of hydrogen pressure strength of the micropores in the heavy forgings is established with the temperature and hydrogen content. Summarize the relative position of crack in the forgings into four combinations, and use the finite element software to analyze the coupling strength of four different combinations of cracks under hydrogen pressure stress field. Analysis results show that, different relative position relationship between cracks and the size of the micro cracks have different effect on coupling effect of hydrogen pressure stress field in micro cracks.

Abstract: Impact of sample preparation on determination of hydrogen content in TC4 titanium alloys is studied through the experimental test method which was developed according to ASTM E 1447-2009. The simulation of the heating process in sample preparation process verifies the slight warming (60°C ~ 80 °C) will affect the test result of hydrogen content in TC4 titanium alloys. The heating process makes the result be lower than the actual content.

Abstract: The effect of hydrogenation on structure and properties of TC21 alloy by die forming and sintering using hydrogenated powder was researched by means of the room-temperature die forming and sintering in protection air to produce titanium alloy. The results show that the structure of TC21 titanium sintered body using hydrogenated powder with hydrogen content of 0.39 wt% by die forming and sintering is thinner and the density is higher than the others. The compression strength and compressive yield strength of TC21 sintered body with hydrogen content of 0.39 wt% are well. With hydrogen content increasing, the structure of TC21 production using hydrogenated powder by die forming and sintering gets well and the grain size becomes smaller. After annealing, the structure of TC21 titanium production gets more uniformity and refinement obviously, and the hydrogen content of TC21 alloy safety state is achieved. In the end, the density and mechanical property of TC21 titanium alloy sintered body with hydrogen content of 0.39wt % is the best.

Abstract: The essential principle of elastic recoil detection analysis (ERDA) of hydrogen content in the film and the experimental method were described briefly. The energy spectrum of the recoiled hydrogen atom can be obtained by the elastic collision of incident ion beam with hydrogen atoms in film, and the spectrum can be transferred easily into hydrogen concentration and depth profile. For illustrating the application of ERDA in hydrogen storage research, a beam of helium ion was used to recoil hydrogen in titanium hydride and deuteride film to obtain hydrogen contents and depth profiles. This technique was believed to be powerful in determining hydrogen content in hydride films.

Abstract: It has been established that hardness and density of diamond-like carbon (DLC) layers can be raised by increasing ion energy during deposition, decreasing H-content and by increasing sp³-fraction. To confirm differences in hydrogen content of hydrogen containing and hydrogen free DLC films deposited at different bias voltages, layers were etched in oxygen atmosphere in a capacitively coupled plasma device. By employing real-time ellipsometry measurements, the H-content of the hydrogen containing a-C:H layers were estimated by determining the optical constants n and k (n-real part and k-imaginary part of the refractive index). In addition, DLC layers were analyzed by X-ray photoelectron spectroscopy to estimate the ratio of sp^²- and sp^³-hybridization. The mechanical and tribological properties of the coatings were evaluated by means of nanoindentation and ball-on-disc-tests. Finally correlations between these properties, H-content and sp³/sp²-ratio were obtained in an effort to explain different tribological behaviors of DLC-layers.

Abstract: The impact specimens with different hydrogen contents were solution treated at 540±3°C for 12h; water quenched at 60-100°C; and aged at 165±1°C for 6h. The impact test was carried out at Roell450 pendulum impact testing machine. The impact test results show that the impact energy has strong relation with the hydrogen content. The total absorption energy increases with the increasing of hydrogen content. The crack propagation energy A_vp and present larger proportion than the initial crack energy A_vi in the total absorption energy A_v. The number of the pinholes increases and the pinholes turn from smaller irregular ones into sub-circular shape ones. The specimen with irregular sub-circular pinholes has larger K_I, and has more crack propagation resistance.

Abstract: The influences of alloying elements Mg, Zn and Cu and rare metals Ce, Er and mix rare metal (MRE) on the hydrogen content and inclusion in 1050 aluminum alloy were studied by optical microscope, scanning electronic microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results show that when adding 1wt.%Mg, 5wt.%Zn, 0.5wt.%Er and 0.5wt.%MRE into 1050 aluminum alloy, respectively, the decrements of density of the reduced pressure test (RPT) samples are 0.36g/cm³, 0.24g/cm³, 0.72g/cm³, and 0.24g/cm³, respectively. Mg and Er significantly increase the tendency of hydrogen adsorption in Al melt. The results of XRD analysis and microstructural observation indicate that the alloys adding Er contain more oxides and gas porosity.

Abstract: The hydrogen content was measured by HYDRIS hydrogen analyzer during ladle furnace (LF) refining process aiming to test the regular pattern of hydrogen variation in molten steel. The results showed that the hydrogen increased during temperature rising, Ca-treatment and soft blowing argon period, and the absolute increment were 0.64 ppm and 0.46 ppm respectively. The water in refining slag and submerged arc slag led to hydrogen increase during temperature rising period, and fast wire-feeding speed led to hydrogen increase during Ca-treatment and soft argon blowing period. In addition, during the desulfuration and alloying period, excessive large argon blowing caused the hydrogen content increasing by 0.22 ppm.

Abstract: The influence of hydrogenation on structure and properties of TC4 alloy by die forming and sintering using hydrogenated powder was researched and the modification mechanism was analyzed by means of the room-temperature die forming and sintering in protection air to produce titanium alloy. The results show that, with the increase of hydrogen content and sintering temperature, the structure of TC4 titanium production using hydrogenated powder by die forming and sintering was changed from Widmanstaten structure to duplex structure. The density of TC4 titanium production shows a rise trend gradually. After annealing, the structure of TC4 titanium production gets more uniformity and refinement obviously, the compress yield limit shows a rising trend gradually, and the hydrogen content of TC4 alloy safety state is achieved. The density and mechanical property of TC4 titanium alloy with hydrogen content of 0.42wt % is the best.