Nd-Dy-Fe-Co-B磁体的环境加速腐蚀行为研究

Corrosion behavior of sintered Nd-Dy-Fe-Co-B magnets in different corrosive environments

研究了不同成分的烧结Nd-Fe-B磁体在恒定湿热和高压加速腐蚀环境中的腐蚀行为,对其腐蚀形貌进行宏观观察和扫描电镜微观观察,讨论了合金成分及不同腐蚀试验条件对磁体磁通损失的影响。研究结果表明,以重稀土元素Dy部分取代Nd,及微量添加Co元素等,能明显提高烧结Nd-Fe-B磁体的耐湿热腐蚀性能。在恒定湿热和高压加速腐蚀两种不同的腐蚀试验条件下,磁体的腐蚀产物不同,其宏观和微观腐蚀形貌也有明显差异。烧结Nd-Fe-B磁体在高压加速腐蚀试验时的腐蚀速率明显比恒定湿热试验缓慢,这可能是因为高压水蒸气致使供氧不足及氧的扩散受到限制所致。

Corrosion behavior of sintered Nd-Fe-B magnets was investigated in steady-state humid heat（HH） and pressure cooker testing（PCT） climates.The macroscopic and microscopic corrosion morphologies were observed through DC and SEM.The effects of alloy composition and different corrosive environments on magnetic flux loss were discussed.It shows that the damp heat resistance of sintered Nd-Fe-B magnets can obviously improved by Dy substitution for Nd partially and minor Co addition.The corrosion product and their macroscopic and microscopic morphologies have distinct difference in HH and PCT climates.The corrosion rate in PCT is much slower than that in HH climate.It is probably because that high-pressure steam leads to an oxygen-deficient supply,and the steam/liquid film on the surfaces of magnets will hinder the diffusion of oxygen.