Abstract: This article briefly introduces traditional repair technical defects of the aeroplane aluminium alloy and the current situation of FSW. It demonstrates FSW technique feasibility using for aeroplane repair, and makes a initial research some damage forms adopting FSW repair technique, such as cracks, blow holes, and gaps, and so on. Besides, it indicates several development directions on the large-scale application of FSW in aeroplane repairing.
Abstract: An analytical model is developed to study the effects of operation conditions and micro-pore geometry parameters on the friction performance of the mechanical seals with a laser-textured micro-pore face. Seal opening forces at various operation conditions and micro-pore geometry parameters are obtained from the solution of the Reynolds equation by the finite difference method. A derivative expression of the friction torque of the mechanical seals with a laser-textured micro-pore face is calculated and contributing factors of the friction torque are analyzed. It is shown that fiction torque increases with increase of the rotating speed. An optimum pore size that corresponds to minimum friction torque is found and is consistent with experimental results.
Abstract: In order to systematically study the influence of surfacing current and magnetic field current on hardness and wear resistance of surfacing layer, longitudinal DC magnetic field was applied during plasma arc surfacing Co-based alloy on low-carbon steel. The hardness, wear resistance, microstructure and phase constitution of the surfacing layer were investigated through the tests of hardness, wear, SEM and XRD analysis. The results show that the surfacing current and magnetic field current must be matched properly to achieve the optimal properties of surfacing layer. The optimal values are obtained when the surfacing current is 160A and the magnetic field current is 3A, where the hardness is 43.7 HRC and the wear loss is 0.5493g. The proper electromagnetic stirring induced by electromagnetic field can not only refine the microstructure but also improve the hardness and wear resistance of the surfacing layer.
Abstract: In recent years, the hydrophobic and self-cleaning surface has aroused extensive attention due to its special nature such as waterproof, pollution prevention, antioxidant nature, and so on. In this paper, sol-gel was used to prepare the hydrophobic coating on ceramic surface. Ethanol and TEOS were mixed to prepare the sol as 1:1 volume ratio, and the sol would be coated on the ceramic surface treated by some ways. Then the samples were dried in a certain temperature, then calcined. At last the samples were modified with a certain percentage modifier. In this article, three different factors were discussed, such as vacuuming times, modifing time, and calcining temperatures, eventually it is gotten that the optimal experimental conditions are using 20min to vacuum, 1h to modify and 550 to calcine.
Abstract: In order to be considered as a material for semi-solid processing, an alloy has to possess solid spheroids within liquid matrix. Therefore, it is important to investigate the structure of the candidate alloy prior to forming process by conducting partial melting experiment. In this research, the partial melting was conducted for XW-42 steel directly from as annealed condition without any pre-treatment (Direct Partial Remelting). Liquid Fraction Profile obtained from Differential Thermal Analysis (DTA) showed that temperature of 1340°C was located in a low temperature sensitivity region, hence making it as a candidate for processing temperature. Direct Partial Remelting at this temperature for 0, 2 and 5 minutes revealed near spheroidal structure with average grain size between between 45-51 µm which can be considered suitable for semi-solid processing.
Abstract: A356/Al2O3 metal matrix composites produced by means of conventional stirring and cooling slope casting have been investigated and their microstructures were compared. The microstructure of conventional stirring cast samples are fully dendritic in contrast to equiaxed morphology of the cooling slope cast samples. The image analysis was carried out to characterize the effective volume percent of Al2O3 particles in the ingot, and the shape factor and the size of α-Al crystals. The cooling slope casting produces higher effective volume percent, having microstructures with smaller α-Al crystal size and a greater shape factor than the conventional stirring.
Abstract: Nowadays, due to strict environmental requirements, the automotive industry has been reducing vehicle weight in order to minimize the CO2 emission. This had led to an increase in the demand for plastic car parts as a replacement for formerly metal components. Poly ether-ether-ketone (PEEK) has a high glass transition temperature of 143°C, good friction and heat resistance, and can be easily machined. Due to these characteristics, PEEK is already being widely applied in the production of various car parts, such as seat adjustment parts, transmission parts, oil-pump parts etc. In the present study, PEEK bearings were produced by machining and their rolling contact fatigue (RCF) under non-lubricated conditions was investigated. Under high radial load, seizure in the inner bearing part occurred while under low radial load, there was failure by adhesive wear. Exposed to medium load between 85.6N and 93.1N, however, the bearings achieved relatively long lives of over 1.0x10E6 cycles, as well as a unique feature of self-lubrication that rid the raceway of micro depressions, deposits or smearing.
Abstract: Based on the theory of space meshing, the paper deduces the equation of tooth traces on the surface of the pitch cone of Gleason spiral bevel gears. The equation of tooth traces on the surface of the cone with given cone angles would be gained consequently. The 3-D models of a pair of Gleason spiral bevel gears used in the transmission system of a type of vehicle was built by the way of Pro/E parameter design software and spherical involutes function was adopted in this progress. The kinematical flank interference inspection of the gear pair was made and the satisfying gear pair was obtained through the adjustment of tangent modification coefficient. The work in this paper provides conditions for much more FEM analysis of Gleason spiral bevel gears.
Abstract: The objective of this research was to study effect of sintering time, sintering temperature and aluminum addition on pin-on-disc wear behavior of Cu-10wt%Sn bearing that was produced from powder metallurgy method. It was found that, for the as-sintered samples, the larger addition of aluminum, the greater reduction in density and hardness in all sintering conditions. Density and hardness of samples sintered at 900°C decreased with increasing sintering time. Density and hardness of samples sintered at 830°C increased with increasing sintering time. Maximum hardness was obtained when the samples were sintered at 900°C for 30 min or sintered at 830oC for 60 min. Heat treating the samples by annealing at 750oC for 1 h, and quenching in water improved the hardness of the samples alloyed with aluminum significantly. Hardness of 5wt%Al sample increased by 37% to 69.2 HV. Wear mode of samples without aluminum addition was abrasive with accumulation of α-phase wear debris on worn pin surface. For samples with aluminum addition, wear mode was abrasive-oxidative producing clean worn surface which was preferred for self-lubrication mechanism of this type of bearing.
Abstract: This paper mainly focuses on how the silicate liquid composition of chromium-free color passivation affects on passivation result, and confirmes the optimum passivation conditions, and uses two zinc plating system of alkaline and acid deposition. Silicate passivation system is compared with hexavalent chromium passivation technology and the results showed that: the appearance and corrosion resistance of passive films formed on zinc coatings plated with alkaline system are better than samples plated with acid system, and have the same corrosion resistanc with hexavalent chromium passivation. The silicate passivation films can keep 200 hours with no white rust in neutral salt spray test.