Wire electrical discharge machinability and load-bearing capacity of ATZ-WC composite ceramics

Abstract

Electrically conductive and thereby electrical discharge machinable ceramics may gain further relevance for tooling applications and in chemical industry. They combine high chemical and thermal durability with high hardness and strength. While these properties represent a significant advantage for application, they are a major challenge for conventional machining. Due to the thermophysical removal principle, wire electrical discharge machining (WEDM) is a suitable manufacturing process for hardness-independent machining and may broaden the use of ceramics especially in case of customized complex parts. Up to now, there are only a few investigations on WEDM of electrically conductive ceramics, especially with regard to the surface integrity and the influence of the EDM process on the mechanical properties. A previous study investigated the influence of different WEDM technologies on the surface integrity and the resulting load-bearing capacity of a zirconia-tungsten carbide (TZP-WC) ceramic. Based on this investigation, the heat flow in this ceramic composite was calculated with the use of a heat simulation model and compared with the analyzed rim zone, in order to predict a priori reliable process parameters. Furthermore, the wire electrical machinability and the bending strength of alumina-zirconia-tungsten carbide (ATZ-WC) composite ceramics with different fractions of the respective phases were investigated to identify the correlations and verify the simulation model.

Electrical Discharge Machinable Ytterbia Samaria Co-Stabilized Zirconia Tungsten Carbide Composites

“…Highest strength, hard- Small cracks as shown in Figure 9 would therefore not result in a significant reduction in strength (see Figure 2a). A comparison with strength data for ED-machined bending bars published by Olivier, which are in the range of 900-1150 MPa but based on tougher (K IC = 7-9 MPa √ m) wire-cut 1.5Y1.5Nd-TZP-WC composites, results in the assumption that ED-induced critical flaw sizes of 20 µm seem realistic [39].…”