Comparative study on tribology and microhardness of laser synthesized Ti-Al₂O₃/Zn coatings on Ti-6Al-4V alloy

Abstract

The study of laser cladding of 90Ti-10Al 2 O 3 , 90Ti-8Al 2 O 3 -2Zn and 90Ti-4Al 2 O 3 -6Zn coatings onto Ti-6Al-4V alloy, with intention to produce defect-less, high microhardness and wear resistant coating was carried out. The coatings were deposited onto Ti-6Al-4V alloy at 900 W laser power and 0.6 m/min laser scan speed. Microstructures and phase constituents of the developed coatings were investigated by using a scanning electron microscope (SEM) and Xray diffractometer correspondingly. Vickers microhardness tester and pin-on-disk tribometer were employed to characterize microhardness and wear behaviour of the Ti-Al 2 O 3 /Zn coatings respectively. SEM was also used to examine the worn track. It was observed that 90Ti-10Al 2 O 3 coating yielded optimal microhardness along with maximal wear resistance in comparison to the other coatings and Ti-6Al-4V alloy. It has been established that laser cladding of Ti-Al 2 O 3 coating with Zn contents on Ti-6Al-4V alloy alleviates the formation of cracks, however, microhardness and wear properties are negatively affected.

Microstructure and Wear Resistance of Ti6Al4V Titanium Alloy Laser-Clad Ni60/WC Composite Coating

“…The average friction coefficients of the Ni60/WC coatings exhibit a progressive trend, measuring 0.56, 0.52, 0.43, and 0.5 as the scanning speed increases from 8 mm/s to 14 mm/s. Mthisi et al [37,38] prepared different composite coatings on the substrate with friction coefficients ranging from 0.6-0.76; the results of this paper are similar to theirs and have lower coating friction coefficients. This pattern demonstrates an initial decrease followed by an increase in friction coefficients with the rising scanning speed, which aligns with the observed variations in microhardness.…”

Ni–WS2–Ti–6Al–4V self-lubricating coating on TC4 alloy by laser cladding

“…However, some micropores are visible in the coating (as shown in Figure 4(a–c)). It might be due to the inclusion of the gases during the cladding process [19-21]. Apart from the micropores, no other types of defects are observed in the coating-substrate interfaces and the clad portion.…”

Composite coating by TIG cladding with different rare earth oxides

“…Their investigation revealed an increase in hardness up to 4.5 times and wears resistance 3 times. Mthisi et al [13] used Ti, Al 2 O 3 and Zn powders for creating a high hardness and wear-resistant coating on titanium alloy using 900 W laser sources. The authors concluded that by increasing the Zn content, defects were mitigated, but the hardness and wear-resistant ability of the coating was decreased.…”