晶界擴散法強化燒結NdFeB磁石量產化製程之配合技術研究

本實驗以塗覆DyCu 合金粉進行晶界擴散強化燒結NdFeB磁石之矯頑磁力，並探討量產之可行性。第一部分對5 mm厚磁石塗佈不同粒徑之Dy70Cu30 合金粉，探討進行晶界擴散對其磁特性之影響。隨著合金粉之粒徑縮短，合金粉有些微氧化致使晶界擴散後磁石磁特性明顯衰退。第二部分嘗試使用不同底層克服合金粉高溫液化後與模具的沾黏現象。結果顯示使用E作為底層，合金粉無任何沾黏痕跡；使用高純度F基板發現有殘留合金粉痕跡，但磁石未與模具產生沾黏。從循環使用及成本上考量，高純度F基板應適合量產使用。又合金粉粒徑愈細愈能在磁石面上塗覆均勻，比較滾筒式及高效能研磨之合金粉粒尺寸，以高能球磨所磨製之合金粉粒較細且較接近等軸。第三部分研究使用定量合金粉對提升擴散後磁石矯頑力之影響。對5 mm厚NdFeB磁石而言，轉印不同重量之合金粉膜B進行定量實驗，當合金粉刮刀膜中Dy重量比為0.63 wt%時能提升矯頑達7.4 kOe，與磁石過量塗覆合金粉進行擴散之矯頑力提升量(ΔiHc=7.7 kOe)相當。另一方面，轉印不同厚度DyF3刮刀膜A進行擴散之成果1，轉印Dy重量比為0.54 wt%時能提升矯頑達4.4 kOe。比較結果顯示，合金粉因熔點較低較易擴散之緣故所能擴散進入磁石內部的Dy量比氟化物(DyF3)來的多。另一方面，黏結劑 C較D來得容易趕除，能趕除量高出一個數量級之重量。M等級(iHc=17-18kOe)之磁石經轉印合金粉刮刀膜B並擴散處理後，其iHc可達25 kOe以上。 "關鍵字 : 晶界擴散,NdFeB"

關鍵字

晶界擴散法；釹鐵硼

並列摘要

In order to meet the need of mass production of grain boundary diffusion (GBD) treated NdFeB magnets, the effect of various Dy alloy powders on the diffusion efficiency and the magnetic properties are investigated. At first, various diameter Dy70Cu30 alloy powders have been coated on NdFeB magnets and annealed at two different temperatures. The results showed that the magnets coated with larger size Dy70Cu30 alloy powders have higher diffusion efficiency than those of magnets coated with smaller size powders. The coercivity (iHc) of the formers is higher than those of the latters, accordingly. Secondly, different underlayer materials between Dy alloy powders and the mold were adopted for the experiments. The result showed that underlayer materials E, high density F and DyF3 were all not sticked with the mold after grain boundary diffusion (GBD). From the stand point of resuage and the cost reduction, high density F is more suitable than the others for the usage in mass production of grain boundary diffusion (GBD) treated NdFeB magnets. At last, the screen printed B films were adopted to study the effect of Dy usage and the diffusion efficiency in GBD-treated NdFeB magnets. For 5-mm thickness NdFeB magnet, 0.63 wt% Dy is sufficient for giving the GBD-treated NdFeB magnet 7.4 kOe in ΔiHc and 11.7 kOe/% in ∆iHc/wt%Dy. In comparison with the effect of using A films, 0.54 wt% Dy could only have 4.4 kOe in ΔiHc and 8.1 kOe/% in ∆iHc/wt%Dy, adopting B film for GBD process is much effective in enhancing the coercivity of sintered NdFeB magnets, which hints a suitable solution for mass production of GBD-treated NdFeB magnets. "Key words : GBD,NdFeB"

並列關鍵字

grain-boundary-diffusion ； NdFeB

參考文獻

1 余逸哲. 以定量RF3 (R=Dy 及Tb) 塗佈層進行NdFeB 燒結永磁體擴散及磁性強化之研究碩士 thesis, 國立中正大學, (2014).

5 Nesbitt, E. A., Wernick, J. H. & Corenzwit, E. Magnetic Moments of Alloys and Compounds of Iron and Cobalt with Rare Earth Metal Additions. Journal of Applied Physics 30, 365-367, (1959).

6 Hubbard, W. M., Adams, E. & Gilfrich, J. V. Magnetic Moments of Alloys of Gadolinium with Some of the Transition Elements. Journal of Applied Physics 31, S368-S369, (1960).

7 Strnat, K., Hoffer, G., Ostertag, W. & Olson, J. C. Ferrimagnetism of the Rare‐Earth‐Cobalt Intermetallic Compounds R2Co17. Journal of Applied Physics 37, 1252-1253, (1966).

8 Strnat, K. J. Cobalt, 133 (1967).

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晶界擴散法強化燒結NdFeB磁石量產化製程之配合技術研究

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