Comparative effects of corrosion  on electroless -nickel plated A6061  alloys in DOT3 brake fluid

Aluminium alloys used in automobile brake master cylinder pistons wear by corrosion due to contamination and chemical reaction of the contacting brake fluid. The study investigates the corrosion of electroless-nickel (EN) deposition enhanced cast aluminium alloy master cylinder piston surfaces immersed in hydraulic brake oil. Cast specimens were produced from the as-received wrought A6061 alloy scrap by sand casting. EN plated as-received and cast aluminium alloys specimens were immersed fully in brake oil for 1680 hours and corrosion rates were determined every 24 hours. Test samples were characterised using the hardness tester, atomic absorption spectrometer, metallurgical photo-microscope, x-ray diffractometer; and SEM with EDX attachment. Both surfaces corroded in the order of electroless-nickel plated cast aluminium alloy (ENCA) < electroless-nickel plated as-received aluminium alloy (ENAA) at 0.0235 and 0.0251 rates (mg/mm2/y) results which showed improvement in the corrosion resistance with significant influence of electroless-nickel coating in reducing corrosion rates of aluminium alloy in brake oil.

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Effects of Hard Surface Grinding and Activation on Electroless-Nickel Plating on Cast Aluminium Alloy Substrates

Journal of Coatings ◽

10.1155/2014/841619 ◽

2014 ◽

Vol 2014 ◽

pp. 1-10 ◽

Cited By ~ 6

Author(s):

Olawale Olarewaju Ajibola ◽

Daniel T. Oloruntoba ◽

Benjamin O. Adewuyi

Keyword(s):

Aluminium Alloy ◽

Electroless Nickel ◽

Sodium Hypophosphite ◽

Palladium Chloride ◽

Alloy Sample ◽

Sand Cast ◽

Hard Surface ◽

Cast Aluminium ◽

Surface Polishing ◽

Cylinder Piston

This work examined effects of hard surface polishing grits and activation on electroless-nickel (EN) plating on cast aluminium alloy substrates in sodium hypophosphite baths. As-received aluminium alloy sample sourced from automobile hydraulic brake master cylinder piston was melted in electric furnace and sand cast into rod. The cast samples were polished using different grits (60 μm–1200 μm) before plating. The effects on adhesion, appearance, and quantity of EN deposits on substrates were studied. Observation shows that the quantity of EN deposit is partly dependent on the alloy type and roughness of the surface of the substrates, whereas the adhesion and brightness are not solely controlled by the degree of surface polishing. The best yield in terms of adhesion and appearance was obtained from the activation in zincate and palladium chloride solutions. Higher plating rates (g/mm2/min) of 3.01E-05, 2.41E-05, and 2.90E-05 were obtained from chromate, zincate, and chloride than 8.49E-06, 8.86E-06, and 1.69E-05 as obtained from HCl etched, NaOH, and H2O activated surfaces, respectively.

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Friction Stir Welding of Elements Made of Cast Aluminium Alloys

Archives of Metallurgy and Materials ◽

10.2478/amm-2014-0064 ◽

2014 ◽

Vol 59 (1) ◽

pp. 385-392

Author(s):

B. Rams ◽

A. Pietras ◽

K. Mroczka

Keyword(s):

Friction Stir Welding ◽

Aluminium Alloy ◽

Aluminium Alloys ◽

Welding Parameters ◽

Process Conditions ◽

Friction Stir ◽

Seam Weld ◽

Cast Aluminium ◽

Weld Structure ◽

Welding Stability

Abstract The article presents application of FSW method for joining elements made of cast aluminium alloys which are hardly weldable with other known welding techniques. Research’s results of plasticizing process of aluminium and moulding of seam weld during different FSW process’ conditions were also presented. Influence of welding parameters, shape and dimensions of tool on weld structure, welding stability and quality was examined. Application of FSW method was exemplified on welding of hemispheres for valves made of cast aluminium alloy EN AC-43200.

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Effect of Processing Parameters on the Protective Quality of Electroless Nickel-Phosphorus on Cast Aluminium Alloy

Journal of Metallurgy ◽

10.1155/2015/386347 ◽

2015 ◽

Vol 2015 ◽

pp. 1-12 ◽

Cited By ~ 3

Author(s):

Olawale Olarewaju Ajibola ◽

Daniel Toyin Oloruntoba ◽

Benjamin O. Adewuyi

Keyword(s):

Aluminium Alloy ◽

Surface Condition ◽

Electroless Nickel ◽

Processing Parameters ◽

Solution Ph ◽

Cast Aluminium ◽

Time Variations ◽

Surface Morphologies ◽

Best Fit

The effects of temperature, pH, and time variations on the protective amount and quality of electroless nickel (EN) deposition on cast aluminium alloy (CAA) substrates were studied. The temperature, pH, and plating time were varied while the surface condition of the substrate was kept constant in acid or alkaline bath. Within solution pH of 5.0–5.5 range, the best quality is obtained in acid solution pH of 5.2. At lower pH (5.0–5.1), good adhesion characterised the EN deposition. Within the range of plating solution pH of 7.0 to 11.5, the highest quantity and quality of EN deposition are obtained on CAA substrate in solution pH of 10.5. It is characterised with few pores and discontinuous metallic EN film. The quantity of EN deposition is time dependent, whereas the adhesion and brightness are not time controlled. The best fit models were developed from the trends of result data obtained from the experiments. The surface morphologies and the chemical composition of the coating were studied using the Jeol JSM-7600F field emission scanning electron microscope.

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Effect of Solidification Rates at Sand Casting on the Mechanical Joinability of a Cast Aluminium Alloy

Metals ◽

10.3390/met11081304 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1304

Author(s):

Moritz Neuser ◽

Olexandr Grydin ◽

Anatolii Andreiev ◽

Mirko Schaper

Keyword(s):

Mechanical Properties ◽

Aluminium Alloy ◽

Aluminium Alloys ◽

High Strength ◽

Casting Process ◽

Sand Casting ◽

Minimum Thickness ◽

Cast Aluminium ◽

Microstructure Parameters ◽

Alloys Of The Al

Implementing the concept of mixed construction in modern automotive engineering requires the joining of sheet metal or extruded profiles with cast components made from different materials. As weight reduction is desired, these cast components are usually made from high-strength aluminium alloys of the Al-Si (Mn, Mg) system, which have limited weldability. The mechanical joinability of the cast components depends on their ductility, which is influenced by the microstructure. High-strength cast aluminium alloys have relatively low ductility, which leads to cracking of the joints. This limits the range of applications for cast aluminium alloys. In this study, an aluminium alloy of the Al-Si system AlSi9 is used to investigate relationships between solidification conditions during the sand casting process, microstructure, mechanical properties, and joinability. The demonstrator is a stepped plate with a minimum thickness of 2.0 mm and a maximum thickness of 4.0 mm, whereas the thickness difference between neighbour steps amounts to 0.5 mm. During casting trials, the solidification rates for different plate steps were measured. The microscopic investigations reveal a correlation between solidification rates and microstructure parameters such as secondary dendrite arm spacing. Furthermore, mechanical properties and the mechanical joinability are investigated.

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