Abstract
A diamond-like carbon (DLC) film, coated on an SKD11 (alloy tool steel) substrate, was shaped by plasma oxidation to form an assembly of DLC macro-pillars and to be used as a DLC-punch array that is micro-embossed into aluminum sheets. First, the SKD11 steel die substrate was prepared and DLC-coated to have a film thickness of 10 μm. This DLC coating worked as a punch material. The two-dimensional micro-patterns were printed onto this DLC film by maskless lithography. The unprinted DLC films were selectively removed by plasma oxidation to leave the three-dimensional DLC-punch array on the SKD11 substrate. Each DLC punch had a head of 3.5 μm × 3.5 μm and a height of 8 μm. This DLC-punch array was fixed into the cassette die set for a micro-embossing process using a table-top servo-stamper. Furthermore, through numerically controlled micro-embossing, an alignment of rectangular punches was transcribed into a micro-cavity array in the aluminum sheet. The single micro-cavity had a bottom surface of 3.2 μm × 3.2 μm and an average depth of 7.5 μm. A heat-transfer experiment in boiling water was also performed to investigate the effect of micro-cavity texture on bubbling behavior and the boiling curve.
Highlights
Carbon-based materials have been utilized in various applications
Experimental Results and Discussion The thick Diamond-like carbon (DLC)-coated SKD11 substrate with a size of 100 mm × 100 mm was fabricated via plasma enhanced chemical vapor deposition (PECVD) and shaped into a DLC-coated SKD11 die with a size of 10 mm × 80 mm by precise machining
This textured aluminum sheet was utilized in heat transfer experiments to demonstrate that the boiling heat transfer is uniquely affected by the micro-textured aluminum
Summary
Carbon-based materials have been utilized in various applications. Diamond-like carbon (DLC) and diamond films are coated onto metallic substrates and silicon wafers as protective coatings or as structural layers [1]. Carbon nanotubes as well as graphene films are used [2] Such carbon-based materials have industrial applications for their marginable electrical resistivity and thermal conductivity, high strength and hardness, chemical inertness, environmental friendliness, etc. The authors have been concerned with plasm oxidation printing to fabricate multi-DLC-punch assembly dies for micro-stamping [5,6,7]. In their studies, DLC-punch height was limited to a film thickness of 5 μm. A fine micro-pillared punch is necessary to fabricate micro-cavity metallic sheets for engineering applications
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