Development of Antiwear Shim Inserts Utilizing Segment-Structured DLC Coatings

Abstract

Wear and fretting fatigue are important technological problems in automotive, railway and aerospace fields. The purpose of this study is to find a method of reducing the wear of cast-iron (FCD)/aluminum components, which are often applied to automotives, and thus extend their lifetime. First, a stainless-steel (SUS) shim was designed, which can be inserted between an FCD plate and an aluminum plate. Second, diamond-like carbon (DLC) coatings were applied to the shim inserts to prevent the FCD and aluminum plates from wear. Then, the tribological and fatigue characteristics of the shim were evaluated by a ball-on-disk (BoD) test and a bending fatigue test of up to 1×10 6 cycles. Each substrate was coated with DLC by Plasma-Based Ion Implantation and Deposition (PBII&D). A unique feature of our shim is that a segment-structured DLC film (S-DLC) is employed as well as a continuous DLC (C-DLC) film. The effect of the DLC coating on reducing the damage to the Al plate was apparent, because the surface roughness of the Al plate abraded with the DLC-coated shim was significantly smaller than that abraded directly with the FCD plate. Moreover, the average damage fraction to the C-DLC coating is approximately 20-fold larger than that to the S-DLC coating. The C-DLC film suffers severe damage near the bolt hole, whereas the S-DLC film suffered almost no damage even after 1×10 6 bending cycles. In conclusion, an S-DLC-coated SUS shim has a marked effect on reducing the wear of Al/FCD components and improving their lifetime.

Preparation and Mechanical Characterization of Amorphous B-C Films

“…Other studies reported that the void formation on the surface of film maybe attributed from the oxidation process [10]. Those voids are expected to play roles of oil pits and accumulation of debris, like segmentstructured DLC films [11,12]. As can be seen in Figure 3a, both hardness and Young's modulus of the coatings are reduced with increasing of gas pressures from 5 Pa (sample A, B, C) to 10 Pa (Sample D, E).…”

Mechanical characterization of segment-structured hydrogen-free a-C films fabricated by filtered cathodic vacuum arc method

“…In contrast, the deposition of a hydrogen-free a-C film with a segment structure under the same deposition conditions as the continuous hydrogen-free a-C film can prevent the occurrence of delamination. The advantages of using segmentstructured DLC to prevent delamination were studied by other researchers, where the DLC was deposited by RF-plasma CVD and plasma-based ion implantation and deposition (PBII&D) [7,13]. It was claimed that segment-structured DLC can suppress the delamination of films by reducing the strain between the film and substrate.…”

Fabrication of Textured DLC Films Using Three-Dimensional Masking System

“…The S-DLC film has succeeded in coating on the softer materials such as rubber (7) , aluminum alloy (8) and polymer (9) , and shown excellent tribological properties and deformation resistance. Not only for these soft substrates, stainless steel substrates which have the almost same Young's modulus as DLC film should also have been distorted when applied to the high load, and it is expected to be able to make use of an advantage of the S-DLC film (10) . Meanwhile, conventional coating method using metal masks for the masking has difficulty to apply the S-DLC films on the intricate three-dimensional substrates.…”