ABSTRACT Wire electrical discharge machining (WEDM) is a specialized electrothermal machining process capable of producing complex shapes with close tolerances irrespective of material hardness. Zirconia (ZrO2) ceramic has higher fracture toughness and flexural strength which can be useful in a variety of applications, but the principle limiting factor is its electrical conductivity. Assisting electrode (AE) method is one of the methods to overcome the above limitation that serves the purpose without altering the basic properties of ceramic material. In the present research, the Zirconia (ZrO2) is coated with a copper layer. The kerosene dielectric suggested in past literature for machining of insulating ceramics is replaced by the graphite additive mixed distilled water to provide an environment-friendly approach. The electrical resistivity of ZrO2 imposing some restrictions for a normal machining operation, so the discharge voltage variations are analyzed at three different machining stages, namely, Assisting electrode (AE), AE-ceramic interface and insulating base ceramic. Also, the nature of the spark and its variation concerning the discharge voltage is studied with the help of images captured by a high-speed camera. The combined study of the discharge voltage pulse and the spark image helps to understand the machining phenomena.

中文翻译：

---

绝缘氧化锆线切割加工中等离子体电阻变化分析研究

摘要 电火花线切割加工 (WEDM) 是一种专门的电热加工工艺，能够生产具有紧密公差的复杂形状，而不受材料硬度的影响。氧化锆 (ZrO2) 陶瓷具有更高的断裂韧性和弯曲强度，可用于各种应用，但主要限制因素是其导电性。辅助电极（AE）方法是克服上述限制的方法之一，在不改变陶瓷材料的基本性能的情况下达到目的。在目前的研究中，氧化锆 (ZrO2) 涂有铜层。过去文献中提出的用于加工绝缘陶瓷的煤油电介质被石墨添加剂混合蒸馏水取代，以提供一种环境友好的方法。ZrO2 的电阻率对正常加工操作施加了一些限制，因此分析了三个不同加工阶段的放电电压变化，即辅助电极 (AE)、AE-陶瓷界面和绝缘基陶瓷。此外，借助高速摄像机拍摄的图像，研究了火花的性质及其与放电电压有关的变化。放电电压脉冲和火花图像的组合研究有助于理解加工现象。借助高速摄像机拍摄的图像，研究了火花的性质及其与放电电压有关的变化。放电电压脉冲和火花图像的组合研究有助于理解加工现象。借助高速摄像机拍摄的图像，研究了火花的性质及其与放电电压有关的变化。放电电压脉冲和火花图像的组合研究有助于理解加工现象。