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Soldering, brazing and welding
Published in Andrew Livesey, Bicycle Engineering and Technology, 2020
The various grades of pure aluminium and certain alloys are amenable to brazing. Aluminium–magnesium alloys containing more than 2% magnesium are difficult to braze, as the oxide film is tenacious and hard to remove with ordinary brazing fluxes. Other alloys cannot be brazed because they start to melt at temperatures below that of any available brazing alloy. Aluminium–silicon alloys of nominal 5%, 7.5% or 10% silicon content are used for brazing aluminium and the alloy of aluminium and 1.5% manganese.
Aluminium and its alloys
Published in William Bolton, R.A. Higgins, Materials for Engineers and Technicians, 2020
Aluminium-silicon alloys have applications in the automotive and aerospace industries due to their unique combination of high specific strength and good wear performance. They have a low thermal coefficient of expansion and this makes them used for pistons where alloy tighter tolerances are involved. The presence of so much silicon greatly improves the fluidity of the Al-Si melt and so improves the castability of the alloy. However, the specification requires microscopic examination of a test sample to check on the distribution of silica crystallites in the eutectic matrix, with the average size not to exceed 40 µm and the maximum size of an individual particle not to exceed 70 µm.
Current trends in additively manufactured (3D printed) energy absorbing structures for crashworthiness application – a review
Published in Virtual and Physical Prototyping, 2022
Chukwuemeke William Isaac, Fabian Duddeck
Aluminium-silicon alloys (AlSi10Mg) are used as a base material powder during metal additive manufacturing owing to their low density, high strength-to-weight ratio and easiness in casting (Mohamed et al. 2019; Kempen et al. 2015). When utilised for making 3D printed EAS, their energy absorption characteristics can be improved further by heat treatment processes. Stainless steel alloy especially steel 316L (Tancogne-Dejean, Spierings, and Mohr 2016; Wang et al. 2021) have been widely used for EAS owing to their good mechanical behaviour. However, in recent years, innovative approaches of fabricating 3D printed EAS made from titanium alloy (i.e. Ti6Al4V) have emerged (Drücker et al. 2021; Bai et al. 2021). Titanium alloy has higher specific stiffness and strength over aluminium and steel alloys. In Table 2, it is shown that the yield strength of titanium alloy is higher than for steel and aluminium alloys. Moreover, the investigation carried out by Baroutaji et al. (2021) showed that the energy absorption capacity of graded titanium alloy specimen outperformed that of graded aluminium alloy specimen; and was 79% higher in SEA value compared to their uniform thickness counterpart. One of the drawbacks of fabricating metallic 3D printing parts via the SLM technology is their poor ductility resulting from residual stresses. As a result, fracture usually occurs at weak zones where high loading with less material resistive force is experienced. Some probable panacea for this low ductility is by optimising the process parameters of the SLM technique and performing heat treatment on the 3D printed EAS (Mohamed et al. 2019).
Erosion of cold sprayed aeronautical coatings*
Published in Surface Engineering, 2019
D. Cruz, M. A. Garrido, C. J. Múnez, A. Rico, P. Poza
Aluminium-Silicon alloys (Al–Si), like Al C355, are extensively used in aeronautical applications where light metals are necessary. They have been used in gear boxes and fuselage parts operating in extreme conditions due to their high specific strength and low density [1,2]. Maintenance, repair and overhaul in the aeronautic industry is of great importance due to the high manufacturing costs of the increasingly performance of the metallic aircraft components. In addition, actually airline companies are extending the service life of the aircrafts and their components. For these reasons, it is necessary to look for new maintenance and overhaul strategies to extend the life of aeronautical metallic components. These strategies should include the development of safe and reliable repairing technologies, which, if possible, should be economically affordable and respect the environment. Damaged aluminium alloy components should be repaired avoiding their replacement if the aircraft’s life is extended [3,4]. Welding [5–7], laser cladding [6,8] and high temperature thermal spray techniques, like Plasma Spraying (PS) and High Velocity Oxi Fuel (HVOF) [6,9], are the most extended methods used to repair Al components. However, these high temperature technologies could affect the original components, as Al alloys are quite sensitive to the effect of temperature and temperature gradients combined with the presence of oxygen [5–9]. The original component and the repaired parts could be oxidised during maintenance if high temperatures are involved. For these reasons, it is necessary to develop low temperature alternatives able to fix the objectives of the aeronautical sector.