Electro Discharge Machining – A Suitable Fabrication Process for High‐Pressure/High‐Temperature Equipment

Abstract

Electro discharge machining (EDM) is an important manufacturing process for hard‐to‐cut materials like nickel‐based alloys, e.g., alloy 718. Its high yield strength at high temperature make it a suitable material for vessels for high‐pressure/high‐temperature applications, in particular for ammonothermal pressure vessels. This report first summarizes the relationship between microstructure and properties of alloy 718 for practitioners. Second, it focuses on the metallographic description of alloy 718 surfaces proceeded by EDM and its behavior during use as equipment for ammonoacidic systems. Furthermore, the finding of suitable post‐processing, namely honing, to achieve high stability of the surface at high‐pressure atmosphere is included.

Ammonothermal Synthesis of the Mixed‐Valence Nitrogen‐Rich Europium Tantalum Ruddlesden‐Popper Phase EuIIEuIII2Ta2N4O3

“…All syntheses were performed in supercritical ammonia with custom‐built autoclaves made of nickel based superalloy (Haynes 282) sustaining a maximum pressure of 170 MPa at 1070 K , . The peripheral devices consist of the hand valve (SITEC), pressure transmitter (HBM P2VA1/5000 bar) and a safety head with an integrated rupture disc (SITEC).…”