Multilayer Diamond Coatings Applied to Micro-End-Milling of Cemented Carbide

Cobalt-cemented carbide micro-end mills were coated with diamond grown by chemical vapor deposition (CVD), with the purpose of micro-machining cemented carbides. The diamond coatings were designed with a multilayer architecture, alternating between sub-microcrystalline and nanocrystalline diamond la...

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Main Authors: Eduardo L. Silva, Sérgio Pratas, Miguel A. Neto, Cristina M. Fernandes, Daniel Figueiredo, Rui F. Silva
Format: Article
Language:English
Published: MDPI AG 2021-06-01
Series:Materials
Subjects:
Online Access:https://www.mdpi.com/1996-1944/14/12/3333
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author Eduardo L. Silva
Sérgio Pratas
Miguel A. Neto
Cristina M. Fernandes
Daniel Figueiredo
Rui F. Silva
author_facet Eduardo L. Silva
Sérgio Pratas
Miguel A. Neto
Cristina M. Fernandes
Daniel Figueiredo
Rui F. Silva
author_sort Eduardo L. Silva
collection DOAJ
description Cobalt-cemented carbide micro-end mills were coated with diamond grown by chemical vapor deposition (CVD), with the purpose of micro-machining cemented carbides. The diamond coatings were designed with a multilayer architecture, alternating between sub-microcrystalline and nanocrystalline diamond layers. The structure of the coatings was studied by transmission electron microscopy. High adhesion to the chemically pre-treated WC-7Co tool substrates was observed by Rockwell C indentation, with the diamond coatings withstanding a critical load of 1250 N. The coated tools were tested for micro-end-milling of WC-15Co under air-cooling conditions, being able to cut more than 6500 m over a period of 120 min, after which a flank wear of 47.8 μm was attained. The machining performance and wear behavior of the micro-cutters was studied by scanning electron microscopy and energy-dispersive X-ray spectroscopy. Crystallographic analysis through cross-sectional selected area electron diffraction patterns, along with characterization in dark-field and HRTEM modes, provided a possible correlation between interfacial stress relaxation and wear properties of the coatings. Overall, this work demonstrates that high adhesion of diamond coatings can be achieved by proper combination of chemical attack and coating architecture. By preventing catastrophic delamination, multilayer CVD diamond coatings are central towards the enhancement of the wear properties and mechanical robustness of carbide tools used for micro-machining of ultra-hard materials.
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spelling doaj.art-d96ecd2d4b93428ba3425a09495ae7342023-11-22T00:24:14ZengMDPI AGMaterials1996-19442021-06-011412333310.3390/ma14123333Multilayer Diamond Coatings Applied to Micro-End-Milling of Cemented CarbideEduardo L. Silva0Sérgio Pratas1Miguel A. Neto2Cristina M. Fernandes3Daniel Figueiredo4Rui F. Silva5Department of Materials and Ceramics Engineering, CICECO—Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, PortugalDepartment of Materials and Ceramics Engineering, CICECO—Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, PortugalDepartment of Materials and Ceramics Engineering, CICECO—Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, PortugalPalbit S.A., P.O. Box 4, Branca, 3854-908 Albergaria-a-Velha, PortugalPalbit S.A., P.O. Box 4, Branca, 3854-908 Albergaria-a-Velha, PortugalDepartment of Materials and Ceramics Engineering, CICECO—Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, PortugalCobalt-cemented carbide micro-end mills were coated with diamond grown by chemical vapor deposition (CVD), with the purpose of micro-machining cemented carbides. The diamond coatings were designed with a multilayer architecture, alternating between sub-microcrystalline and nanocrystalline diamond layers. The structure of the coatings was studied by transmission electron microscopy. High adhesion to the chemically pre-treated WC-7Co tool substrates was observed by Rockwell C indentation, with the diamond coatings withstanding a critical load of 1250 N. The coated tools were tested for micro-end-milling of WC-15Co under air-cooling conditions, being able to cut more than 6500 m over a period of 120 min, after which a flank wear of 47.8 μm was attained. The machining performance and wear behavior of the micro-cutters was studied by scanning electron microscopy and energy-dispersive X-ray spectroscopy. Crystallographic analysis through cross-sectional selected area electron diffraction patterns, along with characterization in dark-field and HRTEM modes, provided a possible correlation between interfacial stress relaxation and wear properties of the coatings. Overall, this work demonstrates that high adhesion of diamond coatings can be achieved by proper combination of chemical attack and coating architecture. By preventing catastrophic delamination, multilayer CVD diamond coatings are central towards the enhancement of the wear properties and mechanical robustness of carbide tools used for micro-machining of ultra-hard materials.https://www.mdpi.com/1996-1944/14/12/3333micro-end-millingCVD diamondmultilayer coatingcemented carbidetransmission electron microscopy
spellingShingle Eduardo L. Silva
Sérgio Pratas
Miguel A. Neto
Cristina M. Fernandes
Daniel Figueiredo
Rui F. Silva
Multilayer Diamond Coatings Applied to Micro-End-Milling of Cemented Carbide
Materials
micro-end-milling
CVD diamond
multilayer coating
cemented carbide
transmission electron microscopy
title Multilayer Diamond Coatings Applied to Micro-End-Milling of Cemented Carbide
title_full Multilayer Diamond Coatings Applied to Micro-End-Milling of Cemented Carbide
title_fullStr Multilayer Diamond Coatings Applied to Micro-End-Milling of Cemented Carbide
title_full_unstemmed Multilayer Diamond Coatings Applied to Micro-End-Milling of Cemented Carbide
title_short Multilayer Diamond Coatings Applied to Micro-End-Milling of Cemented Carbide
title_sort multilayer diamond coatings applied to micro end milling of cemented carbide
topic micro-end-milling
CVD diamond
multilayer coating
cemented carbide
transmission electron microscopy
url https://www.mdpi.com/1996-1944/14/12/3333
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