Investigation on the sliding of aluminium thin foils against PVD-coated carbide forming-tools during micro-forming

Interaction of Al with O2 exposed Mo2BC

“…3, and the discussion above the weakest bond is clearly Al Al bond. Thus, an Al layer will adhere to the native oxide layer which is in agreement with experimental observation on the macroscopic scale: The adhesion of Al to various carbon-based thin films during sheet forming has been reported by Taube [61] while Fuentes et al [4] observed Al adhesion at elevated temperatures in dry sliding conditions on WC-C coatings. Hence, the here reported results are relevant for tool surfaces that form native oxide layers and which are subsequently utilized during Al alloy forming processes.…”

“…The adhesion of Al stemming from the workpiece to the forming [4] or machining tool surface [5,6] is a well-known phenomenon which leads to galling and results in imperfections of the workpiece surface. This has been reported for many investigated surfaces such as steel [7][8][9], TiN [9,10], TiAlN [10], TiCN [10], TaC [11] and B 4 C [12] based on experimental works.…”

Molecular Coverage Determines Sliding Wear Behavior of n-Octadecylphosphonic Acid Functionalized Cu–O Coated Steel Disks against Aluminum

“…The sliding wear behavior against aluminum was investigated using a ball-on-disk test (CSM Instruments SA, Peuseux, Switzerland, Figure 1a) [16,41,42], where aluminum balls (Al 99.5) of 6 mm in diameter loaded with 0.242 N normal force were rubbed over the functionalized Cu-O coated steel disks with a sliding speed of 1 mm/s for 5 m on a 14 mm wide circular track ( Figure 1b) to resemble the contact pressure in Al cold forging [22,43,44]. As great challenges in liquid lubricant-free Al-forming processes are Al-sticking and adhesion [15,19,21], ball-on-disk tests were carried out for 5 m of sliding distances to appraise the influence of molecular coverage on the tribological behavior. Each molecular coverage was tested once using a separately functionalized disk of 22 mm diameter.…”

“…However, adhesion between tool and workpiece needs to be prevented. Particularly, this is true for forming of aluminum, where the strong interaction between workpiece and tool surface causes rapid material transfer as well as sticking increasing friction and wear observed for aluminum-steel combinations [16][17][18] as well as for coated surfaces in contact with aluminum without liquid lubrication [19][20][21]. As already emphasized in a previous study [22], functionalizing a tool steel surface with a monolayer (ML) of n-octadecylphosphonic acid (C18PA) helps to reduce friction and adhesion by the distal hydrocarbon ML-moieties weakly interacting with the aluminum surface, while the ML-molecules are chemisorbed on the steel surface by P-O-Fe bonds.…”

Scale Dependence of Adhesion Behavior under Dry Friction in Progressive Micro-Deep Drawing

“…Under the dry friction condition, while the applied researches on dry forming with a hard coating technology have been well progressed (7)(8)(9)(10) , basic research on the tribological behavior of dry friction is not well discussed, especially for the micro-sheet metal forming (11) . Investigations of the scale dependence under dry sliding friction were reported by Messner et al, (12) and Krishnan et al (13,14) .…”