The Effect of ZrO2 Nanoparticles on the Microstructure and Properties of Sintered WC–Bronze-Based Diamond Composites

Abstract

Metal matrix-impregnated diamond composites are widely used in diamond tool manufacturing. In order to satisfy the increasing engineering requirements, researchers have paid more and more attention to enhancing conventional metal matrices by applying novel methods. In this work, ZrO2 nanoparticles were introduced into the WC–bronze matrix with and without diamond grits via hot pressing to improve the performance of conventional diamond composites. The effects of ZrO2 nanoparticles on the microstructure, density, hardness, bending strength, and wear resistance of diamond composites were investigated. The results indicated that the hardness and relative density increased, while the bending strength decreased when the content of ZrO2 nanoparticles increased. The grinding ratio of diamond composites increased significantly by 60% as a result of nano-ZrO2 addition. The enhancement mechanism was discussed. Diamond composites showed the best overall properties with the addition of 1 wt % ZrO2 nanoparticles, thus paving the way for further applications.

Effect of WC Nanoparticles on the Microstructure and Properties of WC-Bronze-Ni-Mn Based Diamond Composites

“…The grinding ratio increases firstly and then decreases with nano-WC content increases and grinding ratio of sample SD3 shows an about 100% increase in comparison with SD0. The wear resistance of impregnated diamond composites is higher than other WC-based, Fe-based, Co-based and Ni-based diamond composites [7,8,[21][22][23]. The diamond retention capacity largely determines the wear resistance of impregnated diamond composite [3].…”

“…Figure 2 shows the fracture morphologies of matrix samples S0 and S5. In Figure 2a,b, the 0.5-6 µm matrix grains can be differentiated according to their shape: polygon-shaped grains consisting of micron-WC particles [7][8][9][29][30][31] and smooth round grains around, which are bonding phases bronze and Ni. As marked in Figure 2a, micro-WC particles are discerned from bronze phase grains by means of shape.…”

“…The nano-WC particles pin the crossing dislocation and promote dislocations bowing around the particles under exteral load [32,33]. In addition, the mismatch in the coefficient of thermal expansion (CET) between WC (6 × 10 −6 K −1 ) and bronze (≥18 × 10 −6 K −1 ) needs further consideration [7,34]. During the cooling from processing temperature (980 • C), thermal stresses around the nano-WC particles lead to plastic deformation, especially in the interface area [33].…”

“…The choice of the matrix materials which holds the diamond is essential to properties and service life of diamond tools [5,6]. WC-Bronze-Ni-Mn matrix, a composite mainly containing micron-WC, bronze (Cu85%-Sn6%-Zn6%-Pb3%) alloy, Ni and Mn, is widely used for diamond drilling tool manufacturing [7,8]. The micro-WC is used as framework material to enhance hardness and wear resistance, bronze is used as bonding phase, the element of Ni is used as strengthened phase because of its excellent wettability with diamond and Mn plays the role of antioxidant [9].…”

“…nanoparticles can be used as reinforcing phase. But Al 2 O 3 , ZrO 2 , TiC and TiB 2 nanoparticles have low wettability with bonding phase bronze, which decreases composites properties [7,13,[22][23][24][25][26]. WC nanoparticles have excellent wettability with bronze and have good properties, namely high hardness, high wear resistance, good thermal and chemical stability.…”