Applied Mechanics and Materials Vol. 692

Abstract: Effects of La content on the infrared stealth of ZnO: (La, Al) coated cotton fabrics were studied through XRD, SEM, ICP, IR_2 dual-band emissivity measuring instrument and the infrared camera instrument, where the content of Al remained unchanged. It was suggested the doping of Al and La was favorable for providing more free electrons, improving scattering of infrared photon, and decreasing the infrared emissivity of ZnO: (La, Al) coated fabric in the range of 8-14μm wavelengths. Thermography indicated that ZnO: (La, Al) coated fabric gave as low thermal radiation as the environment.

Abstract: A novel and environmental-friendly route combining the conventional freeze casting and gel casting was proposed for the fabrication of aligned pore structures. The viscosity of the suspension increased with the increase of the addition of the Hydantion concentration. In comparison with the conventional freeze casting, the utilisation of a water-soluble Hydantion epoxy resin in the freeze casting promoted the gelation process and led to a higher compressive strength of the green body. After sintering, the freeze gelcast samples exhibited more than twice higher compressive strength and 11.5% higher porosity at the same time than those of conventional freeze cast sample. The improvements were attributed to the combination of gelation of Hydantion epoxy resin and the aligned ice growth, which led to the coexistence of aligned cylindrical and lamellar pore structures.

Abstract: The synthesis of polyaniline (PANI) doped with anionic spherical polyelectrolyte brushes (ASPB) (PANI/ASPB nanocomposite) by means of in situ chemical oxidative polymerization were presented. The PANI/ASPB nanocomposite was characterized by Fourier trans-form infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Energy dispersive x-ray detector (EDX), and Thermo-gravimetric analysis (TGA). Results showed that PANI/ASPB nanocomposite was successfully fabricated with regular morphology. Investigation of the electrical conductivity at room temperature showed that the electrical conductivity of PANI/ASPB nanocomposite was 9.03 S/cm, which was higher than that of PANI (2.7 S/cm). The measurement of dispersity demonstrated that PANI/ASPB nanocomposite had enhanced dispersity in water.

Abstract: Coaxial polyaniline/multiwalled carbon nanotubes (MWCNTs) nanocomposites were prepared by ultrasonic–assisted chemical oxidative polymerization of aniline monomers in hydrochloric acid solution, in which MWCNTs with minimal defects was used as a template. Redoping of hydrochloric acid was achieved after the as-prepared nanocomposites were treated by ammonia. The nanocomposites were characterized by field emission scanning electron microscopy, fourier transform infrared spectroscopy, thermogravimetric analysis and cyclic voltammetry, respectively. The results indicated that HCl doped nanocomposites were better than HCl redoped nanocomposites on the thermal stability and electrochemical properties.

Abstract: The hot-rolling deformation resistances of a TRIP Steel were studied by using a Gleeble-3500 thermal simulator. The true stress-true strain curves of the TRIP steel is determined under different hot-rolling deformation conditions, and the effect of deformation temperature, strain rate and deformation amount on the deformation resistance was evaluated. Based on experimental results, the mathematic model for the calculation of the deformation resistance of the TRIP Steel has been set up by the regression analysis by means of the origin software. It is found that the simulated stress-strain curves have good curve-fitting performance.

Abstract: In order to optimize the well control equipments of nitrogen drilling, the wellhead equipments have been inspected and analyzed systematically, and the failure analysis has been performed for the fracture at the through hole of two valve plates of flat valve at the side outlet of the multi-function four-way valve in this paper. The fracture reason of the valve plates is explored from macroscopic morphology analysis, chemical composition analysis, mechanical property test, SEM analysis and macroscopic analysis respectively. SEM scanning shows that more precipitates have been separated out nickel-based solid solution in Ni60 welded alloy layer. The spectrum analysis shows that these precipitate phases are rich chromium evolution phases. The valve plate cracks are originated in the welded alloy layer. The final fracture of valve plate is a cleavage fracture and the mechanism is brittle fracture.

Abstract: The hot deformation of X100 pipeline steel was studied in the temperature range of 800~1200 °C and strain rate of 0.1~40s^-1 on Gleeble-1500 thermal mechanical simulating tester. The effect of deformation conditions on the flow stress was analyzed. The constitutive equation of hyperbolic sine including Z parameter was used to describe the relationship between the peak stress and deformation conditions. The results indicate that the flow stress of X100 pipeline steel decreases with the increase of temperature and increases with the increase of strain rates. The hot deformation activation energy is 337.12kJ·mol^-1.The average error between predicted values and experimental values of the peak stress is 3.85%, which proved that the model is reliable.

Abstract: Abstract. This paper studies on the thermal decomposition analysis kinetics of nanometer powders. The DTA-TG-DTG curves obtain by SDT 2960 Simultaneous DSC-TGA analysis apparatus. Under the condition of N₂ atmosphere operation and rise temperature velocity was 10°C·min^-1. The mechanism function dα/dt=κ(1-α)ⁿ is used to calculate the kinetics factors. Reaction progression n was obtained by calculation of the kissinger peak shape factor method. The results showed that the apparent activation energy of nano-Ni(OH)₂ was 254.027 KJ·mol^-1, the pre-exponential factor was 3.062×10³⁶, the reaction progression was obtained as 1.560, the kinetic equation is dα/dt=3.062×10³⁶exp(-30554.166/T)(1-α)^1.560

Abstract: Through the analysis of the basic principles of vibration drilling, using the ultrasonic vibration drilling device to carry out the stainless steel 0Cr17Ni4Cu4Nb micro-deep-hole drilling test, and comparison between the common drilling and the ultrasonic vibration drilling in the exit burr, chip morphology, and surface roughness. The result fully reflects the superiority of the ultrasonic vibration drilling, and it has a dramatic effect of technology than the common drilling. A new method was afforded for stainless steel 0Cr17Ni4Cu4Nb micro-deep-hole drilling.

Abstract: This paper researched the test of fatigue crack propagation of grade X80 submerged arc welded pipes. According to the test results, analyzed and calculated the fatigue life of submerged arc welded pipes for X80 with half elliptical crack defects at the simulated work condition of shutdown. On a single simulated work condition, the fatigue life of submerged arc welded pipes for X80 with Ф1219×22.0mm is 62 years, which had enough safety margin for fatigue life.