Additive Manufacturing of Novel Cemented Carbides with Self-Lubricating Properties

Simple item page
dc.contributor.advisorBoakye-Yiadom, Solomon
dc.contributor.authorAgyapong, Joseph
dc.date.accessioned2020-05-11T12:54:30Z
dc.date.available2020-05-11T12:54:30Z
dc.date.copyright2019-12
dc.date.issued2020-05-11
dc.date.updated2020-05-11T12:54:29Z
dc.degree.disciplineMechanical Engineering
dc.degree.levelMaster's
dc.degree.nameMASc - Master of Applied Science
dc.description.abstractIn this research, WC-17Co and WC-Co-hBN cemented carbides were processed using Selective Laser Sintering (SLS) and heat treated at 400 C, 600 C, 800 C and 1000 C for 3 hours to understand the effect of processing and post-processing heat treatment on the structure and properties of the cemented carbide. Electron microscopy and X-ray diffraction (XRD) analysis revealed that the microstructure of the as-printed WC-17Co specimen was characterized by relatively large poly-angular WC/W2C chips, WC-Co dendritic structures, W-C-Co phase and Co-rich regions. WC-Co-hBN also revealed from the microstructure polyangular WC chips which were smaller in size with no W2C phases present in the sample. During heat treatment between 0 C to 600 C, the large poly-angular chips in both WC-17Co and WC-Co-hBN disintegrated to smaller poly-angular chips as a result of the conversion of the unstable W2C phase to the more stable WC phase and the generation of W-Co-N and Co-W-B phases respectively. Heat treatment above 600 C resulted in the coalescence and growth of relatively large WC phase chips. There was significant increase in hardness of the WC-17Co samples during heat treatment when compared with the as-printed WC-17Co sample, with the sample heat-treated at 600 C being 36% harder than the as-printed sample due to the breakdown of poly-angular WC chips and the increase in volume fraction and spatial distribution of the observed W-C-Co phase regions. The increase in hardness at 600 C was coupled with the highest fracture toughness, representing a 34% increase in fracture toughness, when compared with the as-printed sample. The high fracture toughness is attributed to the evolution of the ductile W6Co6C phase in the sample after heat treatment. Nevertheless, the as-printed sample had approximately 15% higher wear resistance than the sample heat-treated at 600 C. In the WC-Co-hBN, the heat-treated samples had lower hardness values compared to the as-printed WC-Co-hBN sample. However, the hardness values were 3 times higher than the hardness value of the WC-17Co sample. This was attributed to the lower grain sizes in the WC-Co-hBN as compared to the WC-17Co samples. The wear resistance of the WC-Co-hBN samples were much higher than the WC-17Co samples with the highest being on the WC-Co-hBN sample heat treated at 1000 C. It is concluded that post-processing heat treatment of SLS printed WC-17Co alloy at 600 C can be used to improve the structure and mechanical properties of the alloy. And a further improvement of the wear properties and hardness of the material can be done by adding a volume of hBN to the alloy.
dc.identifier.urihttps://hdl.handle.net/10315/37471
dc.languageen
dc.rightsAuthor owns copyright, except where explicitly noted. Please contact the author directly with licensing requests.
dc.subjectMaterials Science
dc.subject.keywordsAdditive Manufacturing
dc.subject.keywordsSelective Laser Sintering
dc.subject.keywordsCemented carbides
dc.subject.keywordsFracture Toughness
dc.subject.keywordsWear
dc.subject.keywordsMicro Hardness
dc.subject.keywordsX-Ray Diffraction
dc.subject.keywordsElectron Microscopy
dc.titleAdditive Manufacturing of Novel Cemented Carbides with Self-Lubricating Properties
dc.typeElectronic Thesis or Dissertation

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
Agyapong_Joseph_2019_Masters.pdf
Size:
8.03 MB
Format:
Adobe Portable Document Format
Download
License bundle
Now showing 1 - 2 of 2
No Thumbnail Available
Name:
license.txt
Size:
1.83 KB
Format:
Plain Text
Description:
Download
No Thumbnail Available
Name:
YorkU_ETDlicense.txt
Size:
3.36 KB
Format:
Plain Text
Description:
Download

Collections

Mechanical Engineering

All items in the YorkSpace institutional repository are protected by copyright, with all rights reserved except where explicitly noted.