Author/Editor		Navinšek, B; Panjan, P; Krušič, J
Title		Hard coatings on soft metallic substrates
Type		članek
Source		Surf Coat Tech
Vol. and No.		, št. 98
Publication year		1998
Volume		str. 809-15
Language		eng
Abstract		The application of PVD CrN coatings onto soft, electropolished nickel moulds and PVD TiN, CrN and double-coating (TiN + CrN) onto copper weilding contact tips is reported. both studies and tests were made in practical conditions, i.e. in industrial manufacturing. The first case study was on protection of the surface of a precision mould with a complicated shape and used for artificial tooth production. The substrate was 4 mm thick Ni, electrodeposited and electropolished. Such a sensitive surface is used together with polymethylmethacrylate paste in a tooth production pressure process at 150 degrees C. We found that in this case, the only feasible deposition technique was DC reactive sputtering of Cr and CrN at 140 degrees C in the SPUTRON plasma beam sputtering equipment of Balzers. A 3 micro thick CrN coating with high microhardness (1400 HV, 0.25 N on the Ni substrate), goodadhesion (Lc AE = 12 - 16 N) and excellent corosion and oxidation resistance, successfully protected the nickel mould from mechanical damage occuring during production cycles, even after its use for 18 months. The second case was improvement of copper weilding contact tips used in the MIG welding technique. TiN and CrN coatings were used both as single and double coatings, directly deposited on the copper substrate and also using 5 and 16 micro m thick Ni galvanic coatings as an intermediate layer. Good adhesion (Lc AE = 15-22 N), low scratching coefficient, high microhardness (1400-2500 HV, 0.10) and temperature resistance up to 600 degrees C (TiN) or 800 degrees C (CrN and TiN + CrN) provided an improvement in weilding contact tip life from the standard value of 10-16 h of interrupted work to 85-210 h. The best results were obtained with the "hard" tip substrate made of CuZnZr alloy.(Abstract truncated at 2000 characters.)
Descriptors		DENTAL ALLOYS NICKEL TITANIUM CHROMIUM CORROSION METHACRYLATES WELDING MICROSCOPY, ELECTRON, SCANNING HARDNESS ADHESIVENESS