Date of Award
8-26-2024
Publication Type
Thesis
Degree Name
M.A.Sc.
Department
Mechanical, Automotive, and Materials Engineering
Supervisor
Ahmet Alpas
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Abstract
Aluminum alloys have significantly influenced the automotive industry since the 1970s, primarily due to their lightweight properties and potential to enhance fuel efficiency and performance. Al-Si alloys have a good combination of mechanical properties and corrosion resistance and when produced using additive manufacturing (AM) techniques, exhibit a unique microstructure that further distinguishes them from traditionally manufactured alloys. Mg alloys have also gained prominence in the automotive industry over the past few decades. Specifically, Mg AE44 stands out as an attractive lightweight alloy, especially valued for its creep resistance at high temperatures, making it highly suitable for demanding automotive applications. This thesis explores the tribological properties of additively manufactured (AM) AlSi10Mg alloys (A90, A60, A120), which are differentiated by variations in AM process parameters, compared to conventionally cast Al alloy (A356-T6), age-hardened AM Al alloy (A120-T6), and Mg alloy, AE44. Dry Sliding tests were conducted using a pin-on-disk configuration at 25°C with loads ranging from 0.1 N to 5.5 N and a 4 m sliding distance for all Al alloys, where the counterface material was a ball of 52100 steel. Lubricated block-on-ring wear tests, using a ring of 52100 steel as the counterface, were carried out under a 200 N load at 93°C for sliding distances from 120 m to 5000 m. The lubricated tests were designed to evaluate the wear resistance of AM aluminum alloy (A90), and AE44 under conditions simulating continuously variable transmissions (CVT). A90, A60, and A120 were different regarding their AM scanning patterns, specifically in the orientation of their laser scan tracks (hatches). Sample A90, featured a 90-degree rotation of hatches in each layer, A60 had three distinct layers with 60-degree rotations and A120 had two layers with 60-degree and 120-degree rotations. Dry wear rate comparisons revealed that while AM alloys A90, A60, and A120 generally exhibit similar wear properties, A120 demonstrated a slightly higher wear trend in dry tests. The AM alloys exhibited wear rates that were at least three times lower than that of A356-T6. Moreover, their wear rates were less than half of that observed in the heat-treated A120 (A120-T6). In lubricated tests, A90 had wear rates 7.5 times lower than A356-T6. A90’s very fine Si particles remained intact and possibly acted as a protective layer during wear, contrasting with A356-T6, where fragmented particles led to higher wear. Lubricated tests revealed that the Mg AE44 alloy exhibited higher wear rates than Al alloys. Its wear rate was 0.0098 mm^3/m while the wear rates for A356-T6 and A90 alloys were 0.0015 mm^3/m and 0.0002 mm^3/m respectively. This high wear rate of Mg AE44 is attributed to a tendency for fragmentation of intermetallic phases and damaging the tribolayer at the contact surface.
Recommended Citation
Niknam, Zeinab, "Sliding Wear of Additively Manufactured AlSi10Mg Aluminum Alloys and a High Temperature Magnesium AE44 Alloy for Powertrain Applications" (2024). Electronic Theses and Dissertations. 9401.
https://scholar.uwindsor.ca/etd/9401