WCCo/cBN composites produced by pulse plasma sintering method

Abstract

WCCo/cBN composites have been considered as a next-generation material for use in cutting-tool edges, being characterized by an optimal combination of hardness and toughness. They can be used instead of WCCo/ diamond composites in machining of iron-based materials. The major challenge in sintering these composites is to produce a well-bonded interface between the WCCo matrix and cBN particles. In this study, WCCo/cBN composites were fabricated by the pulse plasma sintering technique. The aim of this work is to obtain sintered parts with density near the theoretical value and with very good contact between the cBN particles and WCCo matrix. cBN/ cemented carbide containing 30 vol.% of cBN particles was produced using a mixture of 6 and 12 wt.% Co-added WC powder, with WC grain size of 0.4 lm and cBN powder with grain size ranging from 4 to 40 lm. Scanning electron microscopy (SEM) observations of the microstructure and diffraction phase examinations did not show the presence of hBN phase. The specific heating conditions used to consolidate the material using high-current pulses hamper the transformation of cBN into hBN and ensure a strong bond between the cBN particles and the cemented carbide matrix. Fractures through the WCCo/cBN composite showed that only few cBN particles were torn out from the cemented carbide matrix, with most of them having been cleaved along the fracture plane. This provides evidence that the bond at the WCCo/cBN interface is mechanically strong. Composites sintered at temperature of 1,200°C under pressure of 100 MPa for 5 min had density near the theoretical value. Increase of the sintering temperature to 1,200°C resulted in an increase of the hardness to 2,330 HK1 for the WC6Co/cBN(1/3) composite and to 2,160 HK1 for the WC6Co/cBN(37/44) composite.

Analysis of wear resistant coatings influence on tool life of cutting tools made of WCCo-cBN composite

“…W przypadku badanego materiału osnowę stanowi WCCo. Kompozyt WCCo-cBN wytworzony został przy pomocy impulsowego spiekania plazmowego [4]. Znane są zastosowania kompozytów narzędziowych opartych o cBN i inne materiały [5].…”

Evaluation of physical phenomena occurring in turning of nodular cast iron with use of the WCCo/cBN composite cutting edges

“…1c) z płytką skrawającą wykonaną z kompozytu WCCo/cBN (BNDCC) bez powłoki przeciwzużyciowej. Ostrza miały twardość ok. 2300 HV [8] Jednym z najtwardszych obecnie stosowanych materiałów narzędziowych (drugim po diamencie) jest regularny azotek boru -cBN (cubic boron nitride). Do głównych zalet tego materiału należą odporność termiczna i chemiczna, dzięki którym wykonane z niego narzędzia skrawające -w przeciwieństwie do narzędzi diamentowych -nadają się do skrawania obrobionych cieplnie stali (> 50 HRC), utwardzonych żeliw oraz stopów na bazie niklu i kobaltu.…”

“…kobaltu. Mieszaninę tę uzupełnia proszek z cBN, stanowiący 30% objętości uzyskanego kompozytu [8]. Kompozyt WCCo/cBN (BNDCC) pozostaje w fazie badań laboratoryjnych, w związku z tym jego wła-ściwości skrawne nie są jeszcze rozpoznane.…”

The influence of the diamond wheel grinding process on the selected properties of boron nitride dispersion in cemented carbide (BNDCC) composites

“…The wear resistance of cemented carbides can be significantly increased, while retaining their high fracture toughness, by replacing part of the carbide phase with cubic boron nitride grains as a dispersive phase. This composite can be produced with method of pulse plasma sintering (PPS) [4][5][6]. This method allows to carry out the sintering process at a lower temperature and in shorter time than the conventional methods for preparing WCCo composite.…”