The paper "Aluminium Casting Alloys" is a wonderful example of a report on engineering and construction. Aluminium in its pure form is a malleable, silvery element of belonging to the boron group (Kaufman, 2000, P. 116). This element has a symbol Al and atomic number 13. Research suggests Aluminium as the most plentiful metal on the crust of the earth but very reactive to naturally establish in element form. It is though established in over more than 275 different minerals, the major source found to be bauxite ore, which has 52% Al203, 27.5% Fe203 and 20.55 of H20 (Campbell, 2008).
Aluminium alloys are categorized into three groups including wrought heat-treatable alloys, wrought non-heat-treatable alloys and casting alloys. However, this report will only focus on what is aluminium casting alloys, its production, its fabrication and its recycling. 2.0 Aluminium production Kaufman (2000, p. 116) state that bauxite mining is regarded as the first stage of aluminium production. In this stage, alumina which is raw material is mined and processed. Processing of aluminium oxide (alumina) must be done by electrolysis in order to convert it to aluminium.
Degarmo, Paul, Black & Kohser (2003) claim that this process is realized by the application of the Bayer chemical procedure in the alumina processing plant. The aluminium oxide is discharged from the various materials in bauxite in the solution of caustic soda, which is sorted out to get rid of all insoluble elements. The aluminium hydroxide is thus precipitated from this a caustic soda solution, cleaned and dried whilst the caustic soda solution is then recycled. Calculations are then carried out which give aluminium oxide (Al2O3) as the end-product, which as fine particles white powder (Kaufman, 2000, p. 117). Primary aluminium is manufactured in smelters.
In this stage, alumina is processed to extract pure aluminium. The alumina reduction into liquid form is carried out at nearly 950c in the fluorinated bath under the higher powerful electrical current (Campbell, 2008). The process occurs in electrolytic cells in which carbon cathodes makes the bottom pot forms the negative electrode. Positive electrodes (Anode) are maintained as the top pot and are used in the process at the time it reacts with the oxygen arising from alumina (Kaufman, 2000, p. 117). 3.0 Aluminium casting alloys Campbell (2008) claims that Aluminium casting alloy is a production process where the liquid aluminium is poured into other elements containing a hollow cavity with a defined desired and given time to solidify.
The solidified piece is referred to as a casting. Aluminium casting alloys consist of both heat treatable and non-heat-treatable alloys. Shankar (2000) argues that the main forms comprise of 2xx. x series (Al-Cu), 3xx. x series (Al-Si + Mg or Cu), 4xx. x series (Al-Si), 5xx. x series (Al-Mg), 7xx. x series (Al-Zn) and 8xx. x series (Al-Sn).
The 2xx. x; 3xx. x; 7xx. x, and 8xx. x alloys could be made stronger by precipitation hardening; however, the properties that are established are not as high as for those of wrought heat-treatable alloys (Check figure 1). Figure 1: aluminium and alloying elements Source: (Esabna, 2013) According to Esabn (2013), the alloys of aluminium-copper ((Cu) 2xxx) alloys generally contain up to 10 per cent copper. The copper offers a considerable boost in strength and allows for hardening of precipitation. The alloying of copper into aluminium also reduces corrosion resistance and ductility. The most common use of alloys in the 2xxx series is aerospace, rocket fins and military vehicles.
The alloying of manganese ((Mn) 3xxx) into aluminium adds strength fairly by means of strengthening the solution and enhances stress hardening whilst not noticeably corrosion resistance or decreasing ductility (Esabna, 2013). These are fair strength non-heat-treatable components which maintain strength at raised temperatures and are rarely applied for key structural applications. The alloying of silicon and aluminium decrease melting temperature and enhances fluidity.