Papers by Keyword: WC Grain Size

Abstract: In this work, WC grains in WC-Co cemented carbide were selectively electrolytic corroded and the effects of corrosion time, WC mean grain size and Co content on corrosion rate were systematically investigated. The results showed that corrosion rate decreased with the prolonging of electrolytic corrosion time. The WC-9Co cemented carbides had grain size of 2.9 μm The intensity of Co diffraction peaks was found to exceed the WC diffraction peaks when corroded for 4 hours, and the WC diffraction peaks disappeared when corroded for 8 hours. The corrosion rate increased with the decrease of WC mean grain size and the Co content. As the WC content increased in cemented carbide, it was necessary to increase corrosion time when analyzed Co phase in the cemented carbide by X-ray diffraction.

Abstract: The erosive wear resistance of manual arc welded hardfacings with low-carbon or stainless steel matrix, varied WC grain size (0.23-0.61 mm) and varied WC content (max. 40 wt. %) was studied. Electrodes were produced by JSC “Anykščių varis“ company (Lithuania). Testing was performed according to GOST 23.201-78 standard using the Centrifugal Accelerator of Kleis (CAK). Test parameters were as following: room temperature; silica sand with particles size 0-0.6 mm; particle impact velocity – 10, 30, 50 and 80 ms-1; impact angles – 30° and 90°.It was found that there is only minor (usually not more than 2 times) effect of WC grain size and content on erosive wear of studied hardfacings. There is strong effect of velocity on wear rate. The graph showing the effect of abrasive particle‘s kinetic energy on wear rate is provided. It was found that the wear rate increases 2.8 times faster than kinetic energy of abrasive particles. The wear resistance of coatings could be improved by addition of WC when hardfacing is tested with impact angle of 30°. However, for impact angle of 90° the addition of WC into hardfacing has no effect or is even detrimental (leading to the increase in wear rate). The hardfacings with WC grain size in the range from 0.14 to 0.27 mm have the lowest wear rates during testing with impact angle of 30°. A discussion of the wear mechanisms for the hardfacings is provided, based on data and observations obtained by using scanning electron microscopy.

Abstract: Three different WC grain size powder were used to prepare WC-Co coatings employing HVOF technique. The effect of WC grain size on the abrasive wear resistance and failure mechanism were analyzed. The results show that the abrasive wear resistance increases with the decrease of WC grain size. Nanostructured coating is high in surface plasticity. It can only be pressed out of prints, the opportunity of cutting is small. Micro-cutting wear dominates the main abrasive wear mechanism of nanostructured coating.

Abstract: Micro carbide endmills suffer severe abrasive friction and impact wear in high speed milling of graphite. This paper focused on the study of the effect of Co content and WC grain size on the tool wear resistance of micro carbide endmills in high speed milling of graphite. The tool wear morphologies of cutting tools were examined at the initial wear stage and severe wear stage. The results showed that the abrasive resistance of micro carbide endmill increased with the decrease of Co content and WC grain size. The best impact resistance can be obtained with medium Co content and smaller WC grain size. The fine-grained carbide 0.2WC-8%Co is considered as the optimum tool material for high speed milling of graphite.