FEM application in studies of mechanical properties of the C-Pd film - Biblioteka UMCS

A N N A L E S

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ABSTRACT

Comparison of numerical simulation and experimental data for nanoindentation studies of QDQRVWUXFWXUDOFDUERQDFHRXVSDOODGLXPILOPV&3GLVSUHVHQWHG

)LQLWH(OHPHQW0HWKRG)(0DQG$16<6SURJUDP$QV\V,QFZHUHXVHG7UDGLWLRQDO2OL- ver–Pharr method for cone and spherical shaped indenter were applied for FEM modelling of nano- LQGHQWDWLRQH[SHULPHQW)(0VLPXODWLRQVVKRZHGWKDW3GQDQRJUDLQVDUHPRYHGLQFDUERQPDWUL[

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Mechanical properties of new nanomaterials are particularly interesting due WRWKHSRVVLELOLW\LQQRYDWLYHDSSOLFDWLRQV3URSHUWLHVRIVXFKPDWHULDOVRQWKHQD- QRPHWHUVFDOHPLJKWGLIIHUIURPWKRVHRIDEXONPDWHULDORIWKHVDPHFRPSRVLWLRQ

Nanoindentation investigations of films containing Pd nanograins are difficult be- FDXVHWRSRJUDSK\DQGRUVWUXFWXUHRIILOPVDQGFRQWHQWVRI3GLQWKHILOPVVLJQLIL- FDQWO\DIIHFWWKHLUQDQRPHFKDQLFDOSURSHUWLHV6XFKILOPVFRXOGEHDSSOLHGDVDQ

DFWLYHOD\HULQPDQ\W\SHVRIVHQVRUV&3GILOPVFKHPLFDOPHFKDQLFDODQGSK\VL- cal properties depend on palladium nanograins and carbonaceous matrix structure

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mechanical properties such as nanohardness and reduced modulus of elasticity

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film composed of palladium nanograins embedded in carbonaceous matrix is pre- VHQWHG7KHPRGHODOORZVSUHGLFWLQJVRPHPHFKDQLFDOSURSHUWLHVRIWKHILOP7KH

preliminary FEM studies demonstrated that this method can be applied to simula- tion of nanoindentation experiment and is used to fit experimental load-displace- PHQWGDWDIRUQDQRLQGHQWDWLRQWHVW

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out in a dynamic vacuum of ~ 10^-5 PEDU7KHGHSRVLWLRQUDWHZDVDERXWQPPLQ

and the temperature of the substrate was 180^o&>@)LJSUHVHQWVW\SLFDO7(0

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Nanoindentation experiments were performed using the electrostatic trans- ducer of the Hysitron Nanoindentor Triboscope attached to a scanning force mi- FURVFRSH6)07KHLQGHQWHUFDQEHXVHGIRUVFDQQLQJRYHUWKHVDPSOHVXUIDFH

IRULPDJLQJ,IQDQRLQGHQWDWLRQLVFRPELQHGZLWKVXUIDFHLPDJLQJWKHQQDQRPH- FKDQLFDOSURSHUWLHVFDQEHORFDOO\GHWHUPLQHG7UDGLWLRQDOO\WKHORDGRILQGHQWHUWLS

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DUHDPD\KDYHDIHZVTXDUHPLFURPHWUHVRUHYHQQDQRPHWUHV7KHGHSWKRISHQ- etration versus a force is obtained and then the area of the indent is determined with WKHNQRZQJHRPHWU\RIWKHLQGHQWHUWLS$UHFRUGRIWKHVHYDOXHVFDQEHSORWWHGRQ

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The indenter tip is made of diamond and has 90^oS\UDPLGVKDSH6FKHPDWLF

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max F F K

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where )_PD[ is the maximum applied force and A_F is the cross-sectional area cor- responding to the contact depth K_F7KHFRQWDFWGHSWKK_FLVJLYHQE\

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where 6LVWKHFRQWDFWVWLIIQHVV

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with G)GK being the slope of the unloading curve at the initial point of unload- LQJ

The reduced modulus (_U is a measure of the elastic properties of the tip- sample system and can be calculated from the force-depth curves according to the IRUPXOD

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displacement boundary conditions in the y-direction to the nodes along the upper VXUIDFHRIWKHWLS7KHWRSVXUIDFHRIWKHWLSZDVFRQVWUDLQHGLQDOOGLUHFWLRQV6LQFH

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The plastic deformation after unloading for the model of C-Pd film is shown in )LJD,Q)LJEWKHGLVSODFHPHQWRISDOODGLXPQDQRJUDLQVGXHWRWLSUHDFWLRQLV

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Spherical shape of the tip becomes important when one wishes to perform QDQRLQGHQWDWLRQVRQWKLQILOPVZLWKDWKLFNQHVVRIOHVVWKDQQPDQGZKHQWKH

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In nanoindentation experiment the SFM is used to give the contact area of the WLSZLWKWKHVXUIDFHXVLQJWKHEHDULQJIXQFWLRQPRGH,QWKHFDVHRIa FRQHindenter with a perfect VSKHULFDOWLS the total cross-section area $_FLVJLYHQE\

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the C-Pd film model in the FEM simulated nano-indentation experiment with the VSKHULFDOO\VKDSHGWLSLVVKRZQLQ)LJ

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surface and create piling-up on the surface of the film in a contact area of the tip’s SHQHWUDWLRQUHJLRQ'HIRUPDWLRQLQVLGHWKHILOP¶VGHSHQGVRQWKHGLVWULEXWLRQRI

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This compatibility of experimental and simulated data allow to predict of Pd QDQRJUDLQV EHKDYLRU LQVLGH WKH &3G ILOP SDOODGLXP GLVSODFHPHQW LQ FDUERQD- FHRXVPDWUL[VWUHVVGXULQJWKHQDQRLQGHQWDWLRQWHVW

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C-Pd carbonaceous film has completely different mechanical properties in com- parison to pure C₆₀ILOPVDVZHOODVWRSXUHSDOODGLXPILOP)URP)(0UHVXOWVRQH

can conclude that Pd nanocrystals are moving in carbon matrix toward the film VXUIDFHGXHWRDQH[WHUQDOVWUHVV

FEM simulation also shows that deformation of the model of the C-Pd film LVQRWV\PPHWULFDO3GQDQRJUDLQVPRYHWRZDUGWKHILOP¶VVXUIDFHLQWKHFDUER- QDFHRXVPDWUL[7KH\DOVRFUHDWHSLOLQJXSRQWKHVXUIDFHRIWKHILOPLQDFRQWDFW

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REFERENCES

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