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標題: Characterization of Cr2O3/CrN duplex coatings for injection molding applications
作者: Wang, D.Y.
Chiu, M.C.
關鍵字: Cr2O3;CrN;duplex coating;injection molding;unbalanced magnetron
Project: Surface & Coatings Technology
期刊/報告no:: Surface & Coatings Technology, Volume 137, Issue 2-3, Page(s) 164-169.
In this study, we deposited Cr2O3/CrN duplex coatings, consisting of a thin Cr2O3 oxide film on top of a CrN layer, with an unbalanced magnet ron (UBM) sputtering technique. Microstructure characterization was conducted with X-ray diffraction (XRD) and scanning electron microscopy (SEM). Tribological evaluations were also performed with a scratch tester and ball-on-disc tribometer. Experimental results showed a well-adherent Cr2O3/CrN duplex coating morphology. The Cr2O3 top-layer possesses an amorphous lattice structure. Gas flow rates and bias voltages had an impact upon mechanical and chemical properties of the Cr3O3/CrN coatings. To compensate the fluctuation of pumping efficiency, target poisoning and sputtering parameters, the flow rate of the reactive gas was rapidly and accurately regulated via a set of piezo valves and an optical emission monitor (OEM). OEM readings revealed the exact proportions of reactive gas consumed by metal plasma (US Patent 4 525 (1985) 417 Appl. Phys. Lett. 50 (1987) 1056; Surf. Coat. Technol. 49 (1991) 543). Gas flow rates were thus controlled, dynamically, with variations of processing conditions. At an OEM setting of 30-50% and a pulsed bias voltage of -55 V, the Cr2O3/CrN duplex coating demonstrated excellent micro-hardness (2533 Hv(25)g) and adhesion strength (L-c = 75 N). The highest contact angle between water and Cr2O3 was measured at 103 degrees at an OEM setting of 30%. An improved mold releasing capability is anticipated, especially compared with the traditional hard chrome plating. Finally, an outstanding wear Life of 4250 m was achieved on the Cr2O3/CrN duplex coating deposited at 50% of OEM setting. In summary, the enhanced properties of micro-hardness, film adhesion, mold releasing and wear life of the Cr2O3/CrN duplex coating demonstrated its potential for injection molding applications. (C) 2001 Elsevier Science B.V. All rights reserved.
ISSN: 0257-8972
DOI: 10.1016/s0257-8972(00)01109-9
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