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Wear mechanisms of uncoated and coated cemented carbide tools in machining lead-free silicon brass

Bushlya, Volodymyr LU ; Johansson, Daniel LU ; Lenrick, Filip LU ; Ståhl, Jan Eric LU and Schultheiss, Fredrik LU (2017) In Wear 376-377. p.143-151
Abstract

Free-machining brass containing 2–3% of lead is a preferred industrial material as it shows excellent machinability where low cutting forces, short chips and reduced tool wear are attained. However this addition of lead, a highly toxic and hazardous material, leads to health and environmental issues. Alternative lead-free brasses are known for poor chip control and accelerated tool wear. The current study focuses on wear mechanisms of uncoated and coated cemented carbide tools when high-speed machining lead-free CuZn21Si3P silicon brass. The study shows that severe crater formation on the rake is the dominant tool failure mode. Microscopy observations indicate the diffusion wear mechanism to be driven by diffusion of cobalt binder into... (More)

Free-machining brass containing 2–3% of lead is a preferred industrial material as it shows excellent machinability where low cutting forces, short chips and reduced tool wear are attained. However this addition of lead, a highly toxic and hazardous material, leads to health and environmental issues. Alternative lead-free brasses are known for poor chip control and accelerated tool wear. The current study focuses on wear mechanisms of uncoated and coated cemented carbide tools when high-speed machining lead-free CuZn21Si3P silicon brass. The study shows that severe crater formation on the rake is the dominant tool failure mode. Microscopy observations indicate the diffusion wear mechanism to be driven by diffusion of cobalt binder into the chips and minor cross-diffusion of copper and zinc. Loss of the binder in cemented carbide is accompanied by adhesive pluck-out of WC grains. As a way to hinder the loss of Co, the diffusion preventing capacity of a-C:H diamond like carbon and (Ti,V,Zr,Nb,Hf,Ta)N nitride coating were tested. SEM, EDX and TEM data show that formation of amorphous SiO2 and stoichiometric β-SiAlON stable layers was observed on the nitride coating, thus preventing diffusional tool wear. O-rich and N-rich glassy amorphous layers in Si-Al-O-N system with ZnS inclusions were found on the DLC coating. Partial delamination of the DLC coating and removal of the glassy phases resulted in localized crater formation associated with diffusional wear.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Cemented carbide, Chemical wear, Diffusion wear, Lead-free brass, Machining
in
Wear
volume
376-377
pages
9 pages
publisher
Elsevier
external identifiers
  • scopus:85020002343
  • wos:000403904000019
ISSN
0043-1648
DOI
10.1016/j.wear.2017.01.039
language
English
LU publication?
yes
id
ebe64041-53e7-49d0-a2a2-074f42ee6123
date added to LUP
2017-06-22 09:11:26
date last changed
2018-01-07 12:08:40
@article{ebe64041-53e7-49d0-a2a2-074f42ee6123,
  abstract     = {<p>Free-machining brass containing 2–3% of lead is a preferred industrial material as it shows excellent machinability where low cutting forces, short chips and reduced tool wear are attained. However this addition of lead, a highly toxic and hazardous material, leads to health and environmental issues. Alternative lead-free brasses are known for poor chip control and accelerated tool wear. The current study focuses on wear mechanisms of uncoated and coated cemented carbide tools when high-speed machining lead-free CuZn21Si3P silicon brass. The study shows that severe crater formation on the rake is the dominant tool failure mode. Microscopy observations indicate the diffusion wear mechanism to be driven by diffusion of cobalt binder into the chips and minor cross-diffusion of copper and zinc. Loss of the binder in cemented carbide is accompanied by adhesive pluck-out of WC grains. As a way to hinder the loss of Co, the diffusion preventing capacity of a-C:H diamond like carbon and (Ti,V,Zr,Nb,Hf,Ta)N nitride coating were tested. SEM, EDX and TEM data show that formation of amorphous SiO<sub>2</sub> and stoichiometric β-SiAlON stable layers was observed on the nitride coating, thus preventing diffusional tool wear. O-rich and N-rich glassy amorphous layers in Si-Al-O-N system with ZnS inclusions were found on the DLC coating. Partial delamination of the DLC coating and removal of the glassy phases resulted in localized crater formation associated with diffusional wear.</p>},
  author       = {Bushlya, Volodymyr and Johansson, Daniel and Lenrick, Filip and Ståhl, Jan Eric and Schultheiss, Fredrik},
  issn         = {0043-1648},
  keyword      = {Cemented carbide,Chemical wear,Diffusion wear,Lead-free brass,Machining},
  language     = {eng},
  month        = {04},
  pages        = {143--151},
  publisher    = {Elsevier},
  series       = {Wear},
  title        = {Wear mechanisms of uncoated and coated cemented carbide tools in machining lead-free silicon brass},
  url          = {http://dx.doi.org/10.1016/j.wear.2017.01.039},
  volume       = {376-377},
  year         = {2017},
}