Applied Mechanics and Materials Vol. 692

Abstract: Silicalite-1 membranes with high-thermal stability were prepared on silica tubes by two-step hydrothermal synthesis after filling the tubes with water and glycerol mixtures. It was found that the filling method can improve the membrane separation performance effectively. After filling the silica tubes with mixed solution, the average flux of silicalite-1 membranes was improved by 23% while keeping the separation selectivity nearly unchanged. The results showed that the silicalite-1 membrane still showed high separation performance towards ethanol/water mixture after the repeated calcination at 400°C for 5 h, even with a calcination rate of 4 °C/min, which suggested that silica tubes may be very suitable to synthesize high-performance silicalite-1 membranes in large area.

Abstract: The activated carbon was prepared by the two-steps carbonization-activation process with printed circuit board (PCB), using KOH, K₂CO₃, NaOH and Na₂CO₃ as activators. The influence of temperature, reaction time and the ratio between activator and material on methylene blue value was discussed. Box-behnken design was applied using Design-Expert software to optimize the conditions of preparation according to Response Surface Methodology (RSM).Results showed that activated carbon prepared by chemical activation with KOH or NaOH achieved higher adsorption of methylene blue.

Abstract: This paper presents conclusions the machined surface precision of holes for steel DIN 1.4301. Based on the cutting tests, cutting speeds of 40 to 100 m/min, feed rate of 0.05 to 0.5 mm and screw drill carbide monolite. The results of the article are conclusions for working theory and practice for drilling of steel DIN 1.4301.

Abstract: This paper presents the conclusions of the cutting tool wear during the drilling of steel DIN 1.4301. Based on the cutting tests, cutting speeds of 40 to 100 m/min, feed rate of 0.05 to 0.5 mm and screw drill carbide monolite. The results of the article are conclusions for working theory and practice for drilling of steel DIN 1.4301.

Abstract: This paper is based on the heating furnace of Zhao-feng Steel Works, Chengde, and according to the characteristics of the research object, use the method that the mechanism analysis combining with the discrete state space method to build billet one-dimensional mathematical model of steady-state heat conduction. Setting up the objective function of the minimum fuel consumption, taking billet baked surface temperature, the maximum cross-sectional temperature, heating rate and furnace temperature settings as constraints obtained and using a variable tolerance method to obtain the furnace temperature settings for each segment. When the output is constant, the optimal allocation of heat load along the longitudinal direction can be obtained by this model, which has a good guidance for the actual production.

Abstract: Frontal polymerization is an fast, energy saving approach to prepare polymers and its composites. nanoCarbon /epoxy composite were prepared by frontal polymerization in this study. The composite was prepared using test-tube, and the reacting front was triggered by hot air gun. It was found that increasing the amount of hardener from 10wt% to 20wt%, the reacting frontal propagating velocity of pure epoxy system increased from 0.11mm/s to 0.34mm/s. With the increasing amount of nanocarbon black, the electrical conductivity of the composite was improved. Along the direction of the frontal polymerization, the conductivity of the composite did not change obviously which indicating the forming of uniform nanocarbon black/epoxy composite by frontal polymerization.

Abstract: While the flow rates (in unit of particles/s) of the ions in aqueous solution depend on the cross sections of the channels they pass through, the flux (in unit of particles/(m²s)) is usually independent of them. However, if the diameter of the channel becomes extremely small and comparable to the effective size of the ions, there can be the dependence of the flux on the channel diameter. The finite size effect of solute ions through such small channel is relevant to the physical process of other nanofluidic technologies such as the DNA translocation through nanopore for the sequencing technologies. In this study, we examine the flow of K⁺ and Cl^- ions in water through nanopores made of graphene structure by molecular dynamics method. The results show that there is a transition of zero to nonzero flux when the pore diameter is around the effective size of the ions. Furthermore, there is a dependence of the flux on the nanopore diameter around this regime.

Abstract: The fatigue property of the butt welded joint has significant influence to hoisting equipment’s design, manufacture and using safety for its extensive application. This paper conducted a study on the fatigue properties of a series of the most commonly used thickness steel Q345 butt welded joints. Through fatigue tests and fracture analysis, the fatigue pattern and fracture law of the joints were revealed. Combining with the finite element modeling, the all field stress distribution situation was obtained. This has profound reference significance to hoisting machinery research.

Abstract: The Ni-base alloy coatings of Derolo60 were prepared on the surface of carbon steel by electro spark deposition. The tribological properties of the coatings were investigated in a tribometer under dry sliding friction conditions. The results show that the coatings exhibit excellent properties of wear resistance because of their unique microstructure with a rational combination of hard phases and tough matrix. With the increase of the normal loads and sliding speeds, the friction coefficients of the coatings decrease, while the wear losses increase. The main wear mechanisms of the coatings are micro-cutting wear and multi-plastic deformation wear at low speed and light load conditions, and then gradually change into micro-cutting wear and adhesive wear as well as fatigue fracture accompanied by some oxidation wear at high speed and heavy load conditions.

Abstract: Carbon dioxide CO₂ could corrode the oil well cement paste matrix under agreeable moisture and pressure condition in deep oil wells, which could decrease the compressive strength and damage the annular seal reliability of cement paste matrix. The problem of oil well cement paste matrix corrosion by CO₂ was researched in the paper for obtain the feasible corrosion prevention technical measures. The microstructure and compressive strength of corroded cement paste matrix were examined by scanning electron microscope SEM and strength test instrument etc. under different corrosion conditions. The mechanism and effect law of corrosion on oil well cement paste matrix by CO₂ were analyzed. And the suitable method to protect CO₂ corrosion in deep oil wells was explored. The results show that the corrosion mechanism of cement paste matrix by CO₂ was that the wetting phase CO₂ could generate chemical reaction with original hydration products produced from cement hydration, which CaCO₃ were developed and the original composition and microstructure of cement paste matrix were destroyed. The compressive strength of corrosion cement paste matrix always was lower than that of un-corrosion cement paste matrix. The compressive strength of corrosion cement paste matrix decreased with increase of curing temperature and differential pressure. The corroded degree of cement paste matrix was intimately related with the compositions of cement slurry. Developing and design anti-corrosive cement slurry should base on effectively improving the compact degree and original strength of cement paste matrix. The compounding additive R designed in the paper could effectively improve the anti-corrosive ability of cement slurry.