Impact of Plasma Pre-Treatment on the Tribological Properties of DLC Coatings on PDMS Substrates

Abstract

The processes of the deposition of carbon coatings on PDMS (polydimethylsiloxane) substrates using plasma techniques are widely used in a large number of studies, in applications ranging from electronic to biological. That is why the potential improvement of their functional properties, including tribological properties, seems very interesting. This paper presents an analysis of the impact of plasma pre-treatment on the properties of the produced diamond-like carbon (DLC) coatings, including changes in the coefficients of friction and wear rates. The initial modification processes were performed using two different techniques based on low-pressure plasma (RF PACVD, radio-frequency plasma-assisted chemical vapour deposition) and dielectric barrier discharge (DBD) plasma. The effects of the above-mentioned treatments on the geometric structure of the PDMS surface and its water contact angles and stability over time were determined. The basic properties of the DLC coatings produced on unmodified substrates were compared to those of the coatings subjected to plasma pre-treatment. The most interesting effects in terms of tribological properties were achieved after the DBD process and production of DLC coatings, achieving a decrease in wear rates to 2.45 × 10−8 mm3/Nm. The tests demonstrate that the cross-linking of the polymer substrate occurs during plasma pre-treatment.

Barrier Diamond-like Carbon Coatings on Polydimethylsiloxane Substrate

“…However, the data cannot be compared with each other because the chemical structure of DLC coatings and their other properties are determined by the substrate material [ 56 , 57 ]. Other researchers obtained similar results regarding silicon and PDMS substrates [ 36 , 51 ]. Interestingly, the obtained Raman spectra also provide information on the thickness of the produced DLC coatings.…”

“…Figure 7 , Figure 8 , Figure 9 , Figure 10 and Figure 11 show the Raman spectra ranging from 900 cm −1 to 2000 cm −1 of both the PDMS modified in methane plasma with different negative autopolarization potentials and the reference material, silicon. These results are evidence of the formation of carbon coatings on PDMS substrates; therefore, further analysis was undertaken based on a model assuming curve fitting with four characteristic peaks: D1, D2, G1, and G2, in accordance with the literature [ 35 , 36 ]. Based on the analysis of the areas of the determined characteristic peaks, the ID/IG ratio for the obtained spectra was determined, in our case, to be equal to the expression (ID1 + ID2)/(IG1 + IG2).…”

“…In order to analyze changes in the chemical structure of modified or not modified PDMS substrates, spectral ranges from 100 to 3200 cm −1 were used, while the analysis of the chemical structure of DLC coatings was carried out based on the range from 900 to 2000 cm −1 . The obtained Raman spectra for DLC coatings were deconvolved into 4 characteristic peaks in accordance with the literature data [ 35 , 36 ], using the PEAKFIT 4.12 software (Version 4.12, Seasolve, San Jose, CA, USA).…”

Tribology and Anti-Ablation Properties of SiC-VN-MoS2/Ta Composite Coatings on Carbon/Carbon Composites from 25 to 800 °C

“…In order to decrease the CoFs of C/C composites, the selflubricating coatings such as graphite, PTFE and DLC (diamond-like carbon) were studied. However, their self-lubricating properties were invalid and poor at high temperature [19][20][21]. Though the CoFs of lubricants such as Ti3SiC2, Ti2AlC and CaF2/BaF2 were lower than that of C/C composites at 800 °C, their lubricating properties were poor at room temperature [22,23].…”

Effects of Self-Lubricant Coating and Motion on Reduction of Friction and Wear of Mild Steel and Data Analysis from Machine Learning Approach

“…The combined motion is used at the same time in different mechanical systems, robotics components, electronic devices, and similar real-life and industrial applications [ 22 , 23 , 24 , 25 , 26 , 27 ]. Several pieces of research have been done on friction and wear of different types of materials under different operating and processing conditions with computing approaches [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ].…”