Tribological behaviour of hard Tribological behaviour of hard wear resistant layers at high wear resistant layers at high temperatures temperatures Ing. Jiří Hájek Ing. Jiří Hájek Dr. Ing. Antonín Kříž Dr. Ing. Antonín Kříž Ing. Petr Beneš Ing. Petr Beneš WBU Plzeň, Univerzitní 22, 306 14 Plzeň, ČR, hajek@kmm.zcu.cz WBU Plzeň, Univerzitní 22, 306 14 Plzeň, ČR, kriz@kmm.zcu.cz WBU Plzeň, Univerzitní 22, 306 14 Plzeň, ČR, pbenes@kmm.zcu.cz
University of West Bohemia in Pilsen Tribological analysis „PIN-on-DISC“ ribological analysis „PIN-on-DISC“ T Equipment parameters: Load 1N - 60N. Rotation speed from 10 to 500 revolutions/min. „ PIN-on-DISC “ Temperature range 20°C – 1000°C. Data processing with the use of PC. „PIN-on-DISC“ test is provided on CSEM Instruments tribometer. During the test tightly griped „PIN“ (shape of ball) is loaded onto the test sample („DISC“) with a constant force (chosen radius). The sample rotates with a constant speed. 1/18 Matrib 2005
University of West Bohemia in Pilsen Experimental materials Experimental materials On substrate from high-speed steel X82WMoCrV654 were deposited three On substrate from high-speed steel X82WMoCrV654 were deposited three various types of PVD layers. These are AlTiN, TiAlSiN, CrAlSiN AlTiN, TiAlSiN, CrAlSiN. . various types of PVD layers. These are Thin wear resistant layers were deposited on substrates by the PVD low- Thin wear resistant layers were deposited on substrates by the PVD low- voltage arc evaporating in vacuum. Deposition temperature did not exceed voltage arc evaporating in vacuum. Deposition temperature did not exceed 500°C, so the substrate was not thermally influenced. 500°C, so the substrate was not thermally influenced. 2/18 Matrib 2005
University of West Bohemia in Pilsen Wear resistance at room temperature Wear resistance at room temperature Friction coefficients, „PIN“-Al 2 O 3 , F = 10N, r = 8mm, T = 20°C, n = 12 000 cycles Against hard Al 2 O 3 ball - most wear resistant layer is CrAlSiN. This resistance is evident for example from course of friction coefficient, which does not show strong deviation of friction coefficient values. By AlTiN and TiAlSiN layers is wear of "PIN" ball covered by transfer layer . 3/18 Matrib 2005
University of West Bohemia in Pilsen Transfer layer ransfer layer T This layer inhibits contact of "PIN" ball with surface of thin layer. These layers are strongly adhesively connected with the ball surface. By CrAlSiN layer this phenomenon did not arise. Depends on the type of thin layer and on conditions load /frictional speed. Layer sticks (adheres) on ceramics during friction and forms on it a transfer film influences the results. Most important factors: adhesion TiAlSiN and friction between surfaces (important is toughness of the layer). Adhesion is influenced by presence of impurities. AlTiN CrAlSiN 4/18 Matrib 2005
University of West Bohemia in Pilsen Comparison of friction coefficient Comparison of friction coefficient with other layers with other layers 1 0,9 0,80 0,79 0,78 0,9 0,86 0,8 0,83 0,73 0,82 0,8 0,7 0,75 0,60 0,67 0,7 0,6 koeficient tření koeficient tř 0,6 0,5 0,5 0,4 0,4 0,3 0,3 0,2 0,2 0,1 0,1 0 0 TiN TiAlN AlTiN TiAlSiN CrAlSiN TiN TiAlN AlTiN TiAlSiN CrAlSiN Friction coefficients PIN-Al 2 O 3 ,T=20°C,12 000 cycles Friction coefficients PIN-Si3N4,T=20°C,10 000 cycles Measured values „PIN“ball material H it We[%] Al 2 O 3 30,83 ± 0,70 57,41 Si 3 N 4 27,60 ± 1,84 65,38 5/18 Matrib 2005
University of West Bohemia in Pilsen Resistance of system thin layer - substrate at thermal influence Resistance of system thin layer - substrate at thermal influence Temperatures were chosen according to steady thermal field during the machining process. Distribution of steady thermal field during the machining process. Chosen parameters were constant for AlTiN, CrAlSiN, TiAlSiN layers. Temperature n F [N] r [mm] v [cm/s] "PIN" ball [°C] [number of cycles] Si 3 N 4 700 4 10 3 500 2 500 Si 3 N 4 2 5 3 500 6/18 Matrib 2005
University of West Bohemia in Pilsen Layer AlTiN Layer AlTiN T= 500°C, 700°C, F= 2N, 3 500 cycles At 500°C there are evident two increases of friction coefficient values. Friction coefficient at 700°C is stationary. Higher friction coefficient at 500°C is probably caused by adhesive wear. During this test the oxidation of wear debris creates compact unit - glaze. It is probable that the time to the glaze creation is connected with increasing friction coefficient. After its creation only slight wear appears. This claim confirms the fact, that the wear of "PIN" ball is very low. At 700°C is friction coefficient influenced by thick oxidised film, whose plasticity at 700°C is lower than at 500°C, which may result in decrease of friction coefficient. 7/18 Matrib 2005
University of West Bohemia in Pilsen Layer AlTiN Layer AlTiN At 500°C there was no exposure of the substrate, while at 700°C there was complete damage of the layer. At 500°C only very small a) T= 500°C with marked area of “ plastic flow of the layer“ b) T= 700°C wear of “PIN” ball appeared. Spot, which was created on the “PIN” ball at 700°C, had irregular shape. At its margin of the spot is caught small debris from the layer. Wear of „PIN“ ball: a) T= 500°C, b) T= 700° 8/18 Matrib 2005
University of West Bohemia in Pilsen Layer TiAlSi AlSiN N Layer Ti Courses of friction coefficients, T= 500°C, 700°C, F= 2N Friction coefficient also in this case was higher at 500°C than at 700°C. At 500°C happens similar phenomenon as in the case of layers AlTiN (creation of "glaze"), but in case of TiAlSiN there is no such a high ploughing of “PIN” ball in the thin layer. This documents the SEM analysis. It is possible to think, that even microhardness of thin layer TiAlSiN is at these temperatures higher than microhardness of AlTiN layer. At thermal stress of 700°C there is frequent failure of oxidised film, thereby “PIN” ball gets in the contact with thin layer and marked deviation of friction coefficient follows. 9/18 Matrib 2005
University of West Bohemia in Pilsen Layer TiAlSi AlSiN N Layer Ti Wear tracks from SEM: a) T= 500°C, b) T= 700°C At temperature 500°C is wear track covered by oxidised layer throughout whole perimeter. Track is created by debris from damaged thin layer and from oxidised film. This oxidised film is very fast adhesively connected with TiAlSiN layer. 10/18 Matrib 2005
University of West Bohemia in Pilsen Layer TiAlSi AlSiN N Layer Ti Wear track T= 500°C Wt [%] Point N O Al Si Ti Fe Σ [%] 1 0,48 4,11 8,37 1,26 70,49 15,28 100 2 1,07 0,90 7,43 0,79 63,00 26,81 100 11/18 Matrib 2005
University of West Bohemia in Pilsen Layer CrAlSiN CrAlSiN Layer Courses of friction coefficients, T= 500°C, 700°C, F= 2N Friction coefficient is at temperature 700°C lower than at 500°C. However differences between friction coefficients are smaller than by other layers. During thermal exposition of CrAlSiN layer creates on its surface highly efficient oxidised protective layer Cr-Al-O, which prevents further oxidation of the layer. 12/18 Matrib 2005
University of West Bohemia in Pilsen Layer CrAlSiN CrAlSiN Layer Wear tracks from SEM: a) T= 500°C, b) T=700°C Wear depth is by both tracks minimal. Resulting from calottes, there was no substrate exposure at any temperature. Wear spots of “PIN“ balls have almost circular shape and their surface is plane without any noticeable abrasive ploughing. 13/18 Matrib 2005
University of West Bohemia in Pilsen Formation of glaze Formation of glaze 14/18 Matrib 2005
University of West Bohemia in Pilsen Tribological measurements after the thermal load Tribological measurements after the thermal load Thermal load „ PIN-on-DISC “ Parameters are the same like by test at room temperature „PIN“-Al 2 O 3 , F = 10N, r = 8mm, T = 20°C, n = 12 000 cycles 15/18 Matrib 2005
University of West Bohemia in Pilsen Tribological measurements after the thermal load Tribological measurements after the thermal load Layer Load AlTiN TiAlSiN CrAlSiN „PIN“ Al 2 O 3 F= 10N X/2 N/2 N/1 Si 3 N 4 r=4mm N/1 N/1 N/1 F= 2N Si 3 N 4 r=2mm N/1 N/1 N/1 Layer Load AlTiN TiAlSiN CrAlSiN „PIN“ Al 2 O 3 F= 10N X/3 X/3 X/3 Si 3 N 4 r=4mm N/2 N/2 N/1-2 F= 2N Si 3 N 4 r=2mm N/2 N/2 N/1-2 Detection of the substrate/damage area of the layer: X detection occures, N – detection doesn´t occure 3 - extensive wear, 2 - middle-sized wear, 1 - slight wear 16/18 Matrib 2005
University of West Bohemia in Pilsen Tribological measurements after the thermal load Tribological measurements after the thermal load Wear track - layer AlTiN, „PIN“ Al 2 O 3 Detail of wear track - layer AlTiN, „PIN“ Al 2 O 3 Wear track - layer TiAlSiN, „PIN“Al 2 O 3 Wear track - layer CrAlSiN, „PIN“Al 2 O 3 17/18 Matrib 2005
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