Search

Owing to the native character of the coefficient of thermal expansion (CTE) mismatch between Al2O3 and 304 stainless steel, obtaining high strength for Al2O3/304 stainless steel joints remains challenging. In this study, the residual stress of an Al2O3/304 stainless steel brazed joint was relieved using the Ag‐Cu‐Ti + boron nitride (BN) composite filler. The results indicated that the elements between the filler and base metals on both sides were mutually diffused. Moreover, reaction layers formed at the interface, connecting the Al2O3 ceramic and 304 stainless steel. The microstructure of the joint was as follows: Al2O3/Cu3Ti3O + TiCu/Ag (s, s) + Cu (s, s) + TiN + TiB2 + TiCu/Cu0.8Fe0.2Ti/TiFe2/Fe‐Cr/304 stainless steel. When the.1 wt% BN was added, the average strength of the joint reached 151 ± 10 MPa, 15% higher than the average strength of the joint only using Ag‐Cu‐Ti filler (131 ± 9 MPa). The improvement in the shear strength and reduction in the residual stress was attributed to the formation of TiN and TiB2, reducing the CTE difference and refining the microstructure. [ABSTRACT FROM AUTHOR]

The surfacing layer of cobalt-based alloy is prepared using the tungsten inert gas welding (TIG) process and employing the UMCo50, St1 and St6 filler materials. the metallographic testing, hardness, wear and corrosion testing of different surfacing layers have been carried out. each area of the surfacing layer is characterized using the optical and scanning electron microscope (SEM). Cellular and a few columnar dendrites have been observed near the fusion line of the UMCo50 surfacing layer, and cellular structure is observed in the central region. Dendrites and cellular crystals have been observed in the ST1 and St6 surfacing layers. the average hardness of UMCo50, ST1 and ST6 surfacing layers are 320 HV, 672.3 HV and 497.5 HV, respectively. the wear loss of the ST1, ST6 and UMCo50 surfacing layer is 2.71 mg, 4.35 mg, and 14.57 mg, respectively. the corrosion weight loss of the ST1, St6 and UMCo50 surfacing layers are 0.0388 g, 0.0477 g and 0.0833 g, respectively. [ABSTRACT FROM AUTHOR]

Nanosize TiO2 particles were added directly into welding molten pool through electrode for the difficulty of accurate control of oxygen potential and production processing parameters. The characteristics of phase transformation and thermal behavior of inclusions for Fe-C-Mn-Si-Ti-O system and Fe-C-Mn-Si-TiO2 system were analyzed. Results show that the added TiO2 particles aremore helpful for the formation of Mn-Ti-Ocomplex inclusion and can induce the decrease of phase transformation temperature of austenite to ferrite. Intragranular ferrite can be obtained under the condition of continuous cooling transformation with cooling rate of 293 K/s-373 K/s. The inclusions in steel welds are spherical in shape and mainly composed of TiO2, Ti3O5, Ti2O3, MnO, and SiO2. The mean size of inclusions is 0.67 µm. These complex inclusions can supply a large number of nucleating cores for their precipitation at higher temperature, which will disturb the growth of columnar crystal during solidification. Moreover, Mn-containing titanium oxides will promote the transformation of austenite to intragranular ferrite for the formation of manganese depleted zones in steel welds around oxides. So it can be concluded that nanosize titanium oxide added directly in welding molten pool can be effectively used to control phase transformation and achieve fine and favorable microstructure. [ABSTRACT FROM AUTHOR]

The source rock sample of the Shahejie Formation (upper E s4) in Jiyang Sag was pyrolyzed under open system with the Rock-Eval-II apparatus, and then kinetic model parameters were calibrated for investigating the effect of uncertainty of pro-exponential factors on kinetic parameters and geological applications, where the parallel first-order reaction rate model with an average pre-exponential factor and discrete distribution activity energies was used. The results indicate that when the pre-exponential factor changes from low to high, an extreme value for residual errors occurs. And with the increasing pre-exponential factor, the distribution shape of activation energies are nearly the same, but the values of activation energies move higher integrally, and the average activation energy increases about 12 kJ/mol for every 10-fold of the pre-exponential factors. Extrapolating the geological heating rate of 3.3 °C/Ma, the results show that with the increases in pre-exponential factor, the geological temperature corresponding to TR0.5 (transforming ratio of hydrocarbon generation is 50%) increases gradually, and the additional temperature gradually decreases. Combined with geochemical data of source rock, the kinetic parameters with different pre-exponential factors are used to calculate the transformation ratio of hydrocarbon generation, and the result indicates that kinetic parameters corresponding to the better optimized pre-exponential factor are more suitable. It is suggested that the risk assessment of hydrocarbon generation kinetic parameters should be enhanced when using the kinetic method to appraise the oil-gas resources. Meantime, the application result of different kinetic parameters should be verified with geological and geochemical data of source rock in the target area; therefore, the most suitable kinetic parameters for target can be obtained. [ABSTRACT FROM AUTHOR]

In order to recognize the impact of aqueous medium on gas yields and the kinetic behaviors of hydrogen isotope fractionation during organic matter thermal degradation, the gold tube apparatus was used to conduct thermal simulation experiments by mixing the nC18 with the water of different properties and proportions. The yields of natural gas components, the relation among hydrogen isotope composition of each component and the experimental temperatures vs. heating rates have been obtained, and the results indicate that under the higher temperature conditions, the hydrous experiment has obvious impact on gas yields, such as when more water is added, higher amounts of hydrocarbon gas and H2 are yielded, and the existence of water obviously prolongs the temperature interval with the existence of heavy hydrocarbon gas. It also shows that the hydrogen isotope of hydrocarbon gas generated by the hydrous experiment is obviously lighter than that generated by the anhydrous experiment, and with the increasing amount of added water, the δD value of hydrocarbon gas gradually decreases. Compared with gas yields, the variation of δ5D value is more sensitive to aqueous medium in the thermal simulation experiment. However, compared with the amount of the added water, the aqueous medium property has smaller impact on the gas yields, which still shows the inherit effect on hydrogen isotope composition of aqueous medium. Through the model simulation and the isotope fractionation behavior analysis, it is validated that the hydrogen isotope fractionation process can be well described by the chemical kinetic model. The difference of reaction fraction of normal methane and D-containing methane is large, corresponding to the same activation energy. The content of normal methane is obviously higher in the part with lower activation energy, while the content of D-containing methane is higher in the part with higher activation energy. Therefore, it will result in larger hydrogen isotope fractionation amplitude, and the δD values will be more sensitive to the variation of maturity. Meanwhile, the average activation energy of methane generation from nC18 in the hydrous experiment is higher than that in the anhydrous experiment, and the greater amount of added water, the larger the average activation energy of methane generation reaction. This has laid foundation for its exploratory application in the study of gas reservoir forming history and the gas-source correlation, which indicates the research and application prospects in this orientation. [ABSTRACT FROM AUTHOR]

Adsorption of hydrocarbons may significantly affect hydrocarbon migration in unconventional reservoirs. Clay minerals form the primary adsorbent surfaces for hydrocarbons adsorbed in mudstone/shale. To study the adsorption properties of hydrocarbons (n-decane (C10H22), methyl cyclohexane (C7H14) and toluene (C7H8)) on clay minerals (i.e., cookeite, ripidolite, kaolinite, illite, illite/smectite mixed-layer, Na-montmorillonite and Ca-montmorillonite), hydrocarbon vapor adsorption (HVA) tests were conducted at 298.15 K. The results showed that (i) the adsorption amounts of C10H22, C7H14 and C7H8 ranged from 0.45-1.03 mg/m², 0.28-0.90 mg/m² and 0.16-0.53 mg/m², respectively; (ii) for cookeite, ripidolite and kaolinite, the adsorption capacity of C10H22 was less than C7H14, which was less than C7H8; (iii) for illite, Na-montmorillonite and Ca-montmorillonite, the adsorption capacity of C10H22 was greater than that of C7H8, and the adsorption capacity of C7H14 was the lowest; (iv) for an illite/smectite mixed-layer, C7H14 had the highest adsorption capacity, followed by C10H22, and C7H8 had the lowest capacity. Adsorption properties were correlated with the microscopic parameters of pores in clay minerals and with experimental pressure. Finally, the weighted average method was applied to evaluate the adsorption properties of C10H22, C7H14 and C7H8 on clay minerals in oil-bearing shale from the Shahejie Formation of Dongying Sag in the Bohai Bay Basin, China. For these samples, the adsorbed amounts of C7H14 ranged from 18.03-28.02 mg/g (mean 23.33 mg/g), which is larger than that of C10H22, which ranges from 15.40-21.72 mg/g (mean 18.82 mg/g). The adsorption capacity of C7H8 was slightly low, ranging from 10.51-14.60 mg/g (mean 12.78 mg/g). [ABSTRACT FROM AUTHOR]