A study of structural and wear properties of PACVD deposited a‐C:H thin films for application as protective layers on Al alloys

Abstract

Due to the high strength-to-weight ratio, aluminum alloys are commonly used materials in aircraft and automotive industries. However, the low hardness and wear resistance and high friction coefficient limit their applications. In this study, we deposited a-C:H thin films on 7075 Al alloy substrates without an interlayer by direct current PACVD method. Negative substrate bias was varied to improve the surface mechanical properties. We obtained smooth, homogenous, and well adhered up to 28 mm thick a-C:H layers on the Al alloy substrates. The structural and mechanical properties were analyzed using Raman spectroscopy, SEM, nanoindentation and Pin-on-disc test. Raman spectroscopy showed a higher content of trans(CH) x within the films deposited with low bias and increased sp 2 bonding for higher bias depositions. Adhesion test has shown the adhesion grade HF1 to HF4. Coefficient of friction was measured in the range 0.05-0.15 and wear rates of a-C:H covered samples were significantly reduced in comparison to uncovered substrates. The obtained results show a promising potential of the a-C:H as wear resistant coatings for the 7075 Al alloy.

Impact of high‐velocity oxy‐fuel sprayed TiAlN surface coating on mechanical and slurry erosion performance of aluminium alloys

“…In this regard, surface coating can be a feasible option to improve the strength and hardness of these alloys. Extensive studies have been reported which highlight an improvement in hardness and wear performance of aluminium alloy by the application of various thermal spray techniques [22][23][24][25]. A remarkable improvement in surface hardness was achieved by the application of binary TiN/TiAl coatings and witnessed almost 10 times higher hardness than the uncoated AA5083 [26].…”

Preparation of hydrogenated amorphous carbon films using a microsecond-pulsed DC capacitive-coupled plasma chemical vapor deposition system operated at high frequency up to 400 kHz

“…There are various deposition methods employed to produce DLC films, such as sputtering, [5][6][7] filtered-arc deposition, 8) pulsed laser ablation, 9) and plasma-enhanced chemical vapor deposition (PECVD). 10,11) Among these method, PECVD is widely used to prepare a-C:H films from hydrocarbon discharges owing to its advantages of considerably low deposition temperature, higher throughput, and uniform deposition area. 12,13) PECVD involves chemical processes that occur in the vapor phase on the substrate surface to form films.…”