Tribological behaviour of hard Tribological behaviour of hard wear - - PowerPoint PPT Presentation

Tribological behaviour of hard Tribological behaviour of hard wear resistant layers at high wear resistant layers at high temperatures temperatures

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

• Ing. Jiří Hájek
• Ing. Jiří Hájek
• Dr. Ing. Antonín Kříž
• Dr. Ing. Antonín Kříž
• Ing. Petr Beneš
• Ing. Petr Beneš

Matrib 2005 University of West Bohemia in Pilsen

„PIN-on-DISC“ test is provided on CSEM Instruments

• tribometer. During the test tightly griped „PIN“ (shape
• f ball) is loaded onto the test sample („DISC“) with a

constant force (chosen radius). The sample rotates with a constant speed.

T Tribological analysis „PIN-on-DISC“ ribological analysis „PIN-on-DISC“

Equipment parameters:

• Load 1N - 60N.
• Rotation speed from 10

to 500 revolutions/min.

• Temperature range 20°C

– 1000°C.

• Data processing with the

use of PC.

„PIN-on-DISC“

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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 various types of PVD layers. These are AlTiN, TiAlSiN, CrAlSiN AlTiN, TiAlSiN, CrAlSiN. .

• 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.

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Matrib 2005 University of West Bohemia in Pilsen

Wear resistance at room temperature Wear resistance at room temperature

Friction coefficients, „PIN“-Al2O3, F = 10N, r = 8mm, T = 20°C, n = 12 000 cycles

• Against hard Al2O3 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.

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Matrib 2005 University of West Bohemia in Pilsen

T Transfer layer ransfer layer

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.

AlTiN TiAlSiN CrAlSiN 4/18

• Depends on the type of thin layer and
• n 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

and friction between surfaces (important is toughness of the layer).

• Adhesion is influenced by presence of

impurities.

Matrib 2005 University of West Bohemia in Pilsen

0,79 0,80 0,78 0,73 0,60 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9

TiN TiAlN AlTiN TiAlSiN CrAlSiN

koeficient tření

0,86 0,83 0,82 0,75 0,67 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 TiN TiAlN AlTiN TiAlSiN CrAlSiN koeficient tř

Comparison of friction coefficient Comparison of friction coefficient with other layers with other layers

Friction coefficients PIN-Al2O3,T=20°C,12 000 cycles Friction coefficients PIN-Si3N4,T=20°C,10 000 cycles 65,38 27,60 ± 1,84 Si3N4 57,41 30,83 ± 0,70 Al2O3 We[%] Hit Measured values „PIN“ball material

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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

Distribution of steady thermal field during the machining process.

Temperatures were chosen according to steady thermal field during the machining process. Chosen parameters were constant for AlTiN, CrAlSiN, TiAlSiN layers.

Si3N4 3 500 500 5 2 Si3N4 3 500 700 10 4 2 "PIN" ball n [number of cycles] Temperature [°C] v [cm/s] r [mm] F [N]

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Matrib 2005 University of West Bohemia in Pilsen

Layer AlTiN Layer AlTiN

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.

T= 500°C, 700°C, F= 2N, 3 500 cycles

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Matrib 2005 University of West Bohemia in Pilsen

Layer AlTiN Layer AlTiN

a) T= 500°C with marked area of “ plastic flow of the layer“ b) T= 700°C Wear of „PIN“ ball: a) T= 500°C, b) T= 700°

• 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

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.

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Matrib 2005 University of West Bohemia in Pilsen

Layer Ti Layer TiAlSi AlSiN N

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.

Courses of friction coefficients, T= 500°C, 700°C, F= 2N

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Matrib 2005 University of West Bohemia in Pilsen

Layer Ti Layer TiAlSi AlSiN N

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.

Wear tracks from SEM: a) T= 500°C, b) T= 700°C

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Matrib 2005 University of West Bohemia in Pilsen

Layer Ti Layer TiAlSi AlSiN N

100 26,81 63,00 0,79 7,43 0,90 1,07 2 100 15,28 70,49 1,26 8,37 4,11 0,48 1 Σ [%] Fe Ti Si Al O N Wt [%] Point

Wear track T= 500°C

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Matrib 2005 University of West Bohemia in Pilsen

Layer Layer CrAlSiN CrAlSiN

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.

Courses of friction coefficients, T= 500°C, 700°C, F= 2N

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Matrib 2005 University of West Bohemia in Pilsen

Layer Layer CrAlSiN CrAlSiN

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.

Wear tracks from SEM: a) T= 500°C, b) T=700°C

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Matrib 2005 University of West Bohemia in Pilsen

Formation of glaze Formation of glaze

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Matrib 2005 University of West Bohemia in Pilsen

Tribological measurements after the thermal load Tribological measurements after the thermal load

„PIN-on-DISC“ Thermal load

Parameters are the same like by test at room temperature „PIN“-Al2O3, 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

N/1 N/1 N/1 Si3N4 r=2mm N/1 N/1 N/1 Si3N4 r=4mm F= 2N N/1 N/2 X/2 Al2O3 F= 10N „PIN“ CrAlSiN TiAlSiN AlTiN Layer Load N/1-2 N/2 N/2 Si3N4 r=2mm N/1-2 N/2 N/2 Si3N4 r=4mm F= 2N X/3 X/3 X/3 Al2O3 F= 10N „PIN“ CrAlSiN TiAlSiN AlTiN Layer Load

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

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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“ Al2O3 Detail of wear track - layer AlTiN, „PIN“ Al2O3 Wear track - layer TiAlSiN, „PIN“Al2O3 Wear track - layer CrAlSiN, „PIN“Al2O3

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Matrib 2005 University of West Bohemia in Pilsen

Conclusion Conclusion

Obtained results show significant influence of silicium on tribological properties, but above all, replacement of titanium by chromium seems to be really revolutionary, because layer CrAlSiN proves several times higher wear resistance. Also generation of

• xidised barrier Cr-Al-O at these layers is highly efficient. In cases of TiAlSiN and

AlTiN generated thermal barrier was not so effective. Part of the experiment was also the comparison of tribological properties at normal temperatures where the samples were before the tribological test thermally loaded. Results show that at temperatures above 500°C thin layer loses markedly its adhesion to substrate. Up to which certain point it is, will be the subject of further research. Text of this contribution and the presentation will be available at website http://www.ateam.zcu.cz. This contribution was solved under the support of PhD. grant. 921/2005/G1 and post-PhD. grant 106/03/P092.

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Matrib 2005 University of West Bohemia in Pilsen

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, beenndy@seznam.cz

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Contact: www.ateam.zcu.cz