Research on microstructure evolution and surface quality of WEDM for magnetic refrigerant rare-earth gadolinium

Abstract

Rare-earth gadolinium (Gd) is preferable for manufacturing regenerators of the core components of room-temperature magnetic refrigeration owing to its unique magnetocaloric and mechanical properties. However, the surface quality of the regenerator plays a crucial role in the heat transfer effect and service life of magnetocaloric systems during wire electrical discharge machining (WEDM) when fabricating rare-earth Gd array microstructure regenerators. In this study, different process parameters were used to conduct a process experiment of the WEDM of rare-earth Gd. First, the evolution of the surface microstructure and its causes were analyzed using a single-factor experiment, while a corrosion test was conducted on the samples. The analysis showed that the pulse-on time and open voltage considerably affected the surface quality of the processed samples, while the samples with better surfaces exhibited good corrosion resistance. Additionally, a Taguchi experiment was designed, and a regression analysis used to establish regression models between the process parameters (pulse-on time, pulse-off time, peak current, open voltage, and water pressure) and both surface roughness (SR) and material removal rate (MRR). The results showed that the average prediction errors of SR and MRR were only 5.34 % and 5.48 %, respectively.