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Evaluation of scratch resistant properties of electroless Ni-P-Al2O3 composite coatings
Gobinda Gyawali,Dhani Ram Dhakal,Bhupendra Joshi,Jin-Hyuk Choi,Soo Wohn Lee 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.1
Ni-P-Al2O3 composite coatings were prepared from electroless plating method on copper substrate with different contents ofAl2O3 powder. Thus obtained composite coatings were heat treated at 400 oC for 1 h in an inert environment and subjectedto scratch tests. Compared to Ni-P coating, codeposition of Al2O3 exhibited the nodular structure and slightly increased surfaceroughness of the composite coatings. Low P nickel coating with approximately 4 wt% of codeposited Al2O3 into the depositwas obtained with 10 g/L Al2O3 concentration into the plating bath. Enhanced Vickers microhardness of the composite coatingwas due to the synergistic effects of the precipitation hardening by Ni3P phase and co-deposited hard Al2O3 particles. Furthermore, Ni-P-Al2O3 composite coatings have shown considerable improvement in load-bearing capacity of the coatingmatrix, thereby, enhancing the scratch resistant properties of the composite coating.
Jin-Hyuk Choi,Gobinda Gyawali,Dhani Ram Dhakal,BINHUMAMS,Bhupendra Joshi,Soo Wohn Lee 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.2
Ni-Al2O3-h/BN composite coatings were prepared by dispersing different contents of Al2O3 nanoparticles and h/BN nanosheetsin the plating bath. The prepared composite coatings were then characterized for surface morphology, surface roughness,elemental composition, Vickers microhardness, X-ray diffraction, and wear and coefficient of friction test by using moderninstruments. Compared to the nickel coating, composite coatings have revealed an increase in Vickers microhardness,improved surface roughness, and tribological properties. Increasing the h/BN content into the deposit improved the coefficientof friction, whereas increase in Al2O3 content improved wear rate. Among the different samples, the composite coatingprepared by dispersing 10 g/L of each Al2O3 nanoparticles and h/BN nanosheets improved both wear and coefficient of frictionunder dry condition. In addition, the coefficient of friction was also investigated under different loadings during the wear test. The result showed that the lowest coefficient of friction was observed at 5 N load.