Influence of Surface Conditions on Wear and Friction of Hardmetals

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Dry sliding friction and wear response of WC-Co hardmetal pairs in linearly reciprocating and rotating contact

This paper presents an experimental evaluation of friction and wear properties of WC-Co cemented carbides. A comparison is made between unlubricated rotating and linearly reciprocating pin-onplate sliding pairs. The plate specimens were WC-10wt%Co grades surface finished by polishing or sequential wire-EDM steps, whereas WC-6wt%Co pins were used as counter body. The tests were carried out at room temperature using a sliding speed of 0.30m/s and mean Hertzain contact pressures of 1.76 and 2.08 GPa, i.e., normal contact loads of 15N and 25N, respectively. The worn surfaces on plate samples were quantified in terms of 2–D wear profiles obtained by means of surface topography scanning equipment. Wear mechanisms such as polishing and abrasion were identified using optical microscopy. Inferior tribological characteristics for wire-EDM surface finish compared to polishing were found. Higher friction coefficient and wear levels were measured in unidirectional rotating sliding experiments compared to linearly reciprocating test conditions

Effect of surface finishing on tribological properties of ZrO2-based composites

Laboratory-made ZrO2-based composites with 40 vol. % WC, TiCN or TiN were tested in dry sliding contact with WC-6wt%Co cemented carbide using an ASTM G133 pin-on-flat configuration. Surface characterization included profilometric measurement, scanning electron microscopy, energy disperse X-ray analysis and X-ray diffraction. ZrO2-based composites with wire-EDM surface finish displayed higher friction coefficient and wear level compared to their ground equivalents. This finding was correlated to flexural strength measurements, revealing strong discrepancy between both surface finishes. ZrO2-WC composites exhibited superior tribological characteristics compared to the ZrO2-TiCN and ZrO2-TiN grades

Influence of Electro-Discharge Machining on Tribological Behaviour of Hardmetals

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