本文選題：放電等離子燒結(jié) + 熱變形��； 參考：《南昌航空大學(xué)》2017年碩士論文

【摘要】：Nd-Fe-B基稀土永磁體以其優(yōu)異的磁性能廣泛應(yīng)用于機(jī)電、航空航天、新能源汽車(chē)、信息及醫(yī)療等領(lǐng)域。熱變形納米晶Nd-Fe-B磁體的晶粒組織細(xì)小,晶間交換耦合作用較強(qiáng),有利于提高磁體的溫度穩(wěn)定性。本文通過(guò)放電等離子燒結(jié)技術(shù)(SPS)制備了各向同性納米晶Nd-Fe-B磁體,研究了PrCu低熔點(diǎn)合金添加對(duì)SPS磁體微觀結(jié)構(gòu)和磁性能的影響�；赟PS磁體,通過(guò)熱變形技術(shù)成功制備出各向異性Nd-Fe-B磁體,利用晶界擴(kuò)散(GBDP)對(duì)熱變形磁體進(jìn)行改性研究,獲得了具有高矯頑力和高熱穩(wěn)定性的熱變形納米晶磁體�；诜烹姷入x子燒結(jié)(SPS)技術(shù),在700℃/50MPa/5min燒結(jié)條件下,制備出了具有優(yōu)異磁性能的各向同性納米晶Nd-Fe-B磁體,其矯頑力、剩磁和最大磁能積分別為:H_(ci)=1516kA/m、J_r=0.83T、(BH)_(max)=118kJ/m~3。由于放電等離子燒結(jié)所形成的暫態(tài)高溫場(chǎng),燒結(jié)磁體中存在呈層狀分布的粗細(xì)晶區(qū),細(xì)晶區(qū)由長(zhǎng)寬比不同的晶粒所組成,而粗晶區(qū)多以等軸晶為主。研究了低熔點(diǎn)Pr-Cu合金的添加對(duì)燒結(jié)磁體性能的影響,確定了在添加15wt.%含量和650℃/50MPa/5min條件下所制備的燒結(jié)Nd-Fe-B磁體的矯頑力最高,矯頑力H_(ci)=1970kA/m。以放電等離子燒結(jié)磁體作為熱變形磁體前驅(qū)體,通過(guò)熱變形技術(shù)制備出了各向異性納米晶Nd-Fe-B磁體。研究表明,變形過(guò)程中通過(guò)銅套的加入抑制了熱變形磁體周邊鋸齒狀的出現(xiàn),增大了材料的利用率。熱變形后,磁體磁滯回線的方形度有所改善,剩磁和最大磁能積均得到提高,熱變形后磁體的矯頑力、剩磁和最大磁能積分別為:H_(ci)=752kA/m、J_r=1.27T、(BH)_(max)=272kJ/m~3。通過(guò)在熱變形磁體中晶界擴(kuò)散低熔點(diǎn)PrCu合金,制備出了矯頑力高達(dá)1945kA/m的熱變形磁體,熱變形磁體矯頑力的提高可能歸因于晶界鐵磁性元素含量的降低和晶界相分布均勻性的改善。500℃/3h晶界擴(kuò)散條件下磁體的綜合磁性能最為優(yōu)異,磁體的矯頑力、剩磁和最大磁能積分別為H_(ci)=1515kA/m、J_r=1.22T、(BH)_(max)=262kJ/m~3。回復(fù)曲線研究表明,通過(guò)晶界擴(kuò)散工藝,可將磁體的回復(fù)曲線張開(kāi)程度大為降低至幾乎閉合狀態(tài),磁體矯頑力也得到大幅提高,這歸因于晶界擴(kuò)散改性所帶來(lái)的晶界相分布均勻性的改善。熱穩(wěn)定性方面,晶界擴(kuò)散熱變形磁體的矯頑力溫度系數(shù)和剩磁溫度系數(shù)分別為-0.59%%/K和-0.13%%/K,相比于初始熱變形磁體,溫度穩(wěn)定性得到大幅改善,這表明通過(guò)晶界擴(kuò)散可有效提高磁體的溫度穩(wěn)定性,促進(jìn)其在高溫領(lǐng)域的應(yīng)用。矯頑力機(jī)制分析表明,熱變形磁體的矯頑力由釘扎機(jī)制所控制。
[Abstract]:Nd-Fe-B based rare earth permanent magnets are widely used in the fields of electromechanical, aerospace, new energy vehicles, information and medical treatment due to their excellent magnetic properties. Thermal deformation nanocrystalline Nd-Fe-B magnets have fine grain structure and strong intergranular exchange coupling effect, which is helpful to improve the temperature stability of the magnets. In this paper, isotropic nanocrystalline Nd-Fe-B magnets were prepared by spark plasma sintering (SPS) technique. The effect of PrCu low melting point alloy addition on the microstructure and magnetic properties of SPS magnets was investigated. Based on SPS magnets, anisotropic Nd-Fe-B magnets were successfully prepared by hot deformation technique. Thermal deformation nanocrystalline magnets with high coercivity and high thermal stability were obtained by means of grain boundary diffusion (GBDP). Based on the spark plasma sintering (SPS) technique, isotropic nanocrystalline Nd-Fe-B magnets with excellent magnetic properties were prepared at 700 鈩，

本文編號(hào)：1922360