CN111952032A - 一种低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法 - Google Patents
一种低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法 Download PDFInfo
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- QJVKUMXDEUEQLH-UHFFFAOYSA-N [B].[Fe].[Nd] Chemical compound [B].[Fe].[Nd] QJVKUMXDEUEQLH-UHFFFAOYSA-N 0.000 title claims abstract description 19
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- LMEHHJBYKPTNLM-UHFFFAOYSA-H terbium(3+);tricarbonate Chemical compound [Tb+3].[Tb+3].[O-]C([O-])=O.[O-]C([O-])=O.[O-]C([O-])=O LMEHHJBYKPTNLM-UHFFFAOYSA-H 0.000 description 1
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Abstract
本发明提供一种低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法,包括以下步骤:(1)主相合金(Nd,R)a‑(Fe,M)b‑Bc,其中,c<0.9%,采用速凝薄片工艺制成速凝薄片后磨破碎成1.5~3.5μm的粉末;(2)添加相[Nd,R,RH2(CO3)3]d‑(Fe,M)e,采用速凝薄片工艺制成速凝薄片后磨破碎成0.06~0.3μm的粉末;(3)将添加相粉末加入主相合金粉末中,添加比例为总粉末的0.1~2.0%,后在氩气保护下混合均匀;(4)在磁场中取向并压制成型,再进行冷等静压;(5)高真空低温取向预烧结得到生坯;(6)将生坯浸入由重稀土碳酸盐纳米粉末制成的浆料中浸泡;(7)加压低温烧结。本发明制得的磁体的硼、重稀土含量低,在保证磁体剩磁Br、最大磁能积(BH)max等磁性能不下降的前提下,具有高的矫顽力HcJ/HcB。
Description
技术领域
一种低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法,属于稀土永磁材料技术领域。
背景技术
烧结钕铁硼系永磁材料是一种综合磁性能十分优异的永磁材料,已广泛用于电子、电力机械、医疗仪器、包装、五金机械、计算机、新能源及航空航天等领域。烧结钕铁硼系磁体的正常使用温度为±40~80℃,工作场所的温度、时间、电磁场、机械(振动与冲击)、射线、化学作用等都会影响其性能,特别是在航空航天、海洋工程、化学工程、新能源汽车驱动电机等恶劣环境下使用,其性能衰减十分严重,寿命缩短,从而在很大的程度上限制了该材料的使用。
为了提高烧结钕铁硼系磁体在各种恶劣环境下的性能稳定性及使用寿命,从现有研究来看,较有效的解决方案有三:一是,添加含量较高的铽、镝等重稀土元素取代钕等轻稀土元素;二是,细化烧成毛坯的晶粒;三是,晶界熔渗铽、镝等重稀土元素优化晶界结构。这些方案在提高磁体的矫顽力方面取得了巨大的成功。但是,添加含量较高的铽、镝等重稀土元素取代钕等轻稀土元素,首先,铽、镝等重稀土元素价格十分昂贵,铽、镝含量的提高,势必大大增加生产成本,其次,随着铽、镝含量的提高,磁体的剩磁Br和最大磁能积(BH)max等磁性能降低较多,使该法受限,再者,从稀土资源方面看,添加更为稀少的铽、镝等重稀土元素,势必加剧稀土元素利用的不平衡。细化烧成毛坯的晶粒,对整个生产的控氧、烧结温度、烧结时间等工艺参数的控制要求十分苛刻,对设备的要求很高,在实际生产难以实现;晶界熔渗铽、镝等重稀土元素优化晶界结构方案是近年来十分热门的研究方向,晶界渗铽、镝等重稀土氟化物已在很多磁体生产厂家应用,奈何该技术的知识产权被日本等国外企业掌控,按此工艺进行生产需缴纳高昂的专利费用,加之该技术在熔渗过程,其熔渗的扩散深度较浅,对尺寸较大的磁体的效果不明显等不足,仍然限制其使用。国内,已开发出磁控溅射等替代晶界渗铽、镝等重稀土氟化物的技术,其各项技术指标均优于后者,但因对设备、工艺控制要求极高,特别是成本太高,目前还难以大范围推广。
本发明即针对现有技术存在的问题而研究提出的。
发明内容
本发明的目的是解决上述现有技术存在的问题,提供一种低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法。
本发明公开了一种低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法,包含以下步骤:
一种低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法,包括以下步骤:
步骤1:主相合金(Nd,R)a-(Fe,M)b-Bc,以纯度高于99.5%、氧含量低于300ppm的原料进行成分设计,采用速凝薄片工艺制成速凝薄片后,再采用氢破法破碎并通过气流磨破碎,制成1.5~3.5μm的粉末;
步骤2:添加相(Nd,R,RH2(CO3)3)d-(Fe,M)e,以纯度高于99.5%的原料采用速凝薄片工艺制成速凝薄片后,再采用氢破法破碎并通过气流磨破碎,制成0.06~0.3μm的粉末;
步骤3:将添加相粉末加入主相合金粉末中,添加比例为总粉末量的0.1~2.0%,后在氩气或氮气保护下混合2~4h,混合均匀;
步骤4:取向并压制成型,压制压力40~80MPa,再进行冷等静压,压力60~120MPa;
步骤5:高真空低温取向预烧结,温度500~850℃、炉内压力低于10-1Pa、取向磁场强度0.3T以上、烧结时间1~3h,制得生坯;
步骤6:将生坯浸入由重稀土碳酸盐纳米粉末制成的浆料中,浸泡时间6~36h;
步骤7:加压低温烧结,压力0.5~6Mpa、温度800~1050℃、烧结时间1~2h;
步骤8:热处理,温度400~650℃,时间4~8h,制得本发明的烧结钕铁硼系永磁体。
优选的,步骤1中的主相合金(Nd,R)a-(Fe,M)b-Bc,R指取代稀土Nd的轻稀土元素,不包括重稀土元素;M指取代Fe的Ga、Co、Al、Cu、Nb、Ti、W、Mo等元素中的一种或几种;
优选的,步骤1中的主相合金(Nd,R)a-(Fe,M)b-Bc,采用c<0.9%的低硼配方;
优选的,步骤2中的添加相(Nd,R,RH2(CO3)3)d-(Fe,M)e,R指取代稀土Nd的轻稀土元素;RH指Tb、Dy、Ho、Er、Y等重稀土元素,优选Tb、Dy;M指取代Fe的Ga、Co、Al、Cu、Nb、Ti、W、Mo等元素中的一种或几种。
优选的,步骤7中加压低温烧结分成两个阶段,第一阶段采用高真空低温烧结,炉内压力低于10-1Pa,温度500~850℃,温度到达指定温度后保温0.5~1h;第二阶段采用加压烧结,通入纯度为9.9999%的氩气,完成重稀土元素的熔渗和坯体的致密化。
本方案与现有技术相比较至少具有以下有益效果之一:
1.主相合金原料纯度高于99.5%,氧含量低于300pmm,添加相原料纯度高于99.5%,可大大减少稀土损失及降低氧元素对磁体矫顽力的负面影响,有利于制得高矫顽力磁体;
2.主相合金采用低硼配方,添加相不含硼,磁体硼含量小于0.9%,申请人研究分析表明,这样在烧结的过程可以析出熔点较低的富稀土铁晶界相,有利于降低烧结温度,缩短烧结时间,有效的避免磁体在烧结过程晶粒的长大,有效保证了制得磁体的剩磁、最大磁能积等磁性能优异。这样还可抑制非铁磁性富硼相的生成,也有效保证了制得磁体的剩磁、最大磁能积等磁性能优异。缩短烧结时间,可提高生产效率,同时也增强了材料的抗腐蚀性能和加工性能;
3.主相合金不添加铽、镝等重稀土元素,而将重稀土元素设置在添加相中,因添加相仅占主相的0.1-2.0%,使得整体重金属添加量足够少,减少了重稀土的消耗和且能降低对磁体的剩磁Br和最大磁能积(BH)max等磁性能的影响;并且,添加相为含Tb、Dy、Ho、Er、Y等重稀土元素碳酸盐的细粉末,有利于烧结过程形成含重稀土的富稀土晶界相,申请人试验表明,与传统技术比较,可提高磁体的矫顽力的同时整个磁体的重稀土元素含量降低70%,有利于降低生产成本。另外,申请人发现,稀土金属元素碳酸盐在预烧结过程热分解释放气体,可形成具有一定孔隙的生坯,为浸重稀土碳酸盐纳米粉末浆料后的烧结过程,重稀土的熔渗创造条件,提高效率,提高矫顽力。预烧结过程加入一定的磁场进行“诱导”,可提高磁体的取向度,提高磁体剩磁Br、最大磁能积(BH)max、矫顽力HcJ/HcB等磁性能;
4.将制得的生坯浸入由重稀土碳酸盐纳米粉末制成的浆料中,粒度更细的纳米粉末有利于重稀土元素向坯体内部的渗入,另外在烧结过程中,纳米稀土碳酸盐能在较低的温度下分解,其粒度进一步变小,同样有利于重稀土元素向坯体内部的熔渗,最终在重稀土元素含量大幅降低的前提下,矫顽力大大提高;
5.采用加压烧结,可以大幅提高重稀土元素向坯体内部熔渗的效率,同时,也有利于在较低的温度和较短的时间完成磁体的致密化烧结,避免烧结过程晶粒的长大,有利制得高矫顽力磁体。
具体实施方式
下面结合实施例进一步说明本发明,但实施例仅为示例性表述,而不限制本发明。
实施例1
一种低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法,包含以下步骤:
1.以纯度大于99.5%、氧含量低于250ppm的稀土金属钕、稀土金属镨、金属铁、金属钴、金属铜、金属铝、硼铁合金为原料,按(Nd23.4%Pr5.5%)28.9%(Fe68.62%Co0.8%Cu0.5%Al0.3%)70.22%B0.88%进行主相合金的成分设计,采用速凝薄片工艺制成速凝薄片后,再采用氢破法破碎并通过气流磨破碎,制成1.5~3.5μm的粉末;
2.以纯度大于99.5%的稀土金属钕、稀土金属镧、金属铁、铌铁合金、碳酸镝为原料,按{Nd40%La6.5%[Dy2(CO3)3]9.65%}56.15%(Fe33.85%Nb10%)43.85%进行添加相的成分设计,采用速凝薄片工艺制成速凝薄片后,再采用氢破法破碎并通过气流磨破碎,制成0.06~0.3μm的粉末;
3.将添加相粉末加入主相合金粉末中,添加比例为总粉末量的1.5%,后在纯度为9.9999%的氩气保护下混合3h,混合均匀;
4.以取向磁场强度为1.5T,压制压力为60MPa取向并压制成型,再进行冷等静压,压力100MPa,保压20min;
5.以温度为850℃、炉内压力低于6.67×10-2Pa、取向磁场强度为0.4T、烧结时间为2h,进行预烧结,制得生坯;
6.将生坯浸入由碳酸镝纳米粉末制成的浆料中,浸泡时间10h;
7.将生坯放入炉内后,先抽真空,再以5℃/min的升温速率升温至800℃,保温30min后,通入纯度为9.9999%的氩气,加压至4Mpa,并以10℃/min的升温速率升温至1050℃、保温1h,最后进行热处理,温度500℃,时间6h,制得永磁体毛坯。对毛坯的主要磁性能进行测量结果如下表1:
表1.实施例1中永磁体毛坯20℃时主要磁性能测试结果
实施例2
一种低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法,包含以下步骤:
1.以纯度大于99.5%、氧含量低于300ppm的稀土金属钕、稀土金属镨、稀土金属镧、金属铁、金属钴、金属铝、硼铁合金为原料,按(Nd22.7%Pr4.5%La2.4%)29.6%(Fe67.83%Co1.2%Al0.5%)69.53%B0.87%进行主相合金的成分设计,采用速凝薄片工艺制成速凝薄片后,再采用氢破法破碎并通过气流磨破碎,制成1.5~3.5μm的粉末;
2.以纯度大于99.5%的稀土金属钕、稀土金属镧、金属铁、铌铁合金、金属钴、碳酸镝为原料,按{Nd35%La8.25%[Dy2(CO3)3]12%}55.25%(Fe39.85%Nb3%Co2.5%)44.75%进行添加相的成分设计,采用速凝薄片工艺制成速凝薄片后,再采用氢破法破碎并通过气流磨破碎,制成0.06~0.3μm的粉末;
3.将添加相粉末加入主相合金粉末中,添加比例为总粉末量的2%,后在纯度为9.9999%的氩气保护下混合3h,混合均匀;
4.以取向磁场强度为1.8T,压制压力为40MPa取向并压制成型,再进行冷等静压,压力80MPa,保压20min;
5.以温度为750℃、炉内压力低于6.67×10-2Pa、取向磁场强度为0.4T、烧结时间为2h,进行预烧结,制得生坯;
6.将生坯浸入由碳酸镝纳米粉末制成的浆料中,浸泡时间12h;
7.将生坯放入炉内后,先抽真空,再以5℃/min的升温速率升温至750℃压力,保温20min后,通入纯度为9.9999%的氩气,加压至4Mpa,并以10℃/min的升温速率升温至1050℃、保温2h,最后进行热处理,温度550℃,时间5h,制得永磁体毛坯。对毛坯的主要磁性能进行测量结果如下表2:
表2.实施例2中永磁体毛坯20℃时主要磁性能测试结果
实施例3
一种低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法,包含以下步骤:
1.以纯度大于99.5%、氧含量低于200ppm的稀土金属钕、稀土金属镨、金属铁、金属钴、铌铁合金、硼铁合金为原料,按(Nd26.65%Pr2.5%)29.15%(Fe67.9%Co1.5%Nb0.6%)70%B0.85%进行主相合金的成分设计,采用速凝薄片工艺制成速凝薄片后,再采用氢破法破碎并通过气流磨破碎,制成1.5~3.5μm的粉末;
2.以纯度大于99.5%的稀土金属钕、稀土金属镧、金属铁、铌铁合金、金属钴、碳酸铽为原料,按{Nd43.72%[Tb2(CO3)3]8.5%}52.22%(Fe42.28%Nb3.5%Co2.0%)47.78%进行添加相的成分设计,采用速凝薄片工艺制成速凝薄片后,再采用氢破法破碎并通过气流磨破碎,制成0.06~0.3μm的粉末;
3.将添加相粉末加入主相合金粉末中,添加比例为总粉末量的2%,后在纯度为9.9999%的氩气保护下混合4h,混合均匀;
4.以取向磁场强度为2.0T,压制压力为50MPa取向并压制成型,再进行冷等静压,压力85MPa,保压15min;
5.以温度为850℃、炉内压力低于6.67×10-2Pa、取向磁场强度为0.5T、烧结时间为3h,进行烧结制得生坯;
6.将生坯浸入由碳酸镝纳米粉末制成的浆料中,浸泡时间18h;
7.将生坯放入炉内后,先抽真空,再以5℃/min的升温速率升温至650℃压力,保温40min后,通入纯度为9.9999%的氩气,加压至3.5Mpa,并以10℃/min的升温速率升温至1030℃、保温1h,最后进行热处理,温度550℃,时间4h,制得永磁体毛坯。对毛坯的主要磁性能进行测量结果如下表3:
表3.实施例3中永磁体毛坯20℃时主要磁性能测试结果
对比分析:
按照案例3中毛坯的成分进行配料设计,并加入B元素,将B的含量提高到1.01%,按传统方法制得毛坯,并对其主要磁性能进行测量结果如下表4:
表4.对比分析中永磁体毛坯20℃时主要磁性能测试结果
对比可知,上述实施例3中,剩磁Br、最大磁能积(BH)max的性能和对比例相当,而矫顽力HcJ/HcB具有显著的提高。取得该效果主要归功于本申请的配比和加工制备方式:
主相合金原料纯度高于99.5%,氧含量低于300pmm,添加相原料纯度高于99.5%,可大大减少稀土损失及降低氧元素对磁体矫顽力的负面影响,有利于制得高矫顽力磁体;
主相合金采用低硼配方,添加相不含硼,磁体硼含量小于1.0%,这样在烧结的过程可以析出熔点较低的富稀土铁晶界相,有利于降低烧结温度,缩短烧结时间,有效的避免磁体在烧结过程晶粒的长大,有效保证了制得磁体的剩磁、最大磁能积等磁性能优异。这样还可抑制非铁磁性富硼相的生成,也有效保证了制得磁体的剩磁、最大磁能积等磁性能优异。缩短烧结时间,可提高生产效率,同时也增强了材料的抗腐蚀性能和加工性能;
主相合金不添加铽、镝等重稀土元素,而将重稀土元素设置在添加相中,因添加相仅占主相的0.1-2.0%,使得整体重金属添加量足够少,减少了重稀土的消耗和且能降低对磁体的剩磁Br和最大磁能积(BH)max等磁性能的影响;并且,添加相为含Tb、Dy、Ho、Er、Y等重稀土元素碳酸盐的细粉末,有利于烧结过程形成含重稀土的富稀土晶界相,与传统技术比较,可提高磁体的矫顽力的同时整个磁体的重稀土元素含量降低70%,有利于降低生产成本。稀土金属元素碳酸盐在预烧结过程热分解释放气体,可形成具有一定孔隙的生坯,为浸重稀土碳酸盐纳米粉末浆料后的烧结过程,重稀土的熔渗创造条件,提高效率,提高矫顽力。预烧结过程加入一定的磁场进行“诱导”,可提高磁体的取向度,提高磁体剩磁Br、最大磁能积(BH)max、矫顽力HcJ/HcB等磁性能;
将制得的生坯浸入由重稀土碳酸盐纳米粉末制成的浆料中,粒度更细的纳米粉末有利于重稀土元素向坯体内部的渗入,另外在烧结过程中,纳米稀土碳酸盐能在较低的温度下分解,其粒度进一步变小,同样有利于重稀土元素向坯体内部的熔渗,最终在重稀土元素含量大幅降低的前提下,矫顽力大大提高;
采用加压烧结,可以大幅提高重稀土元素向坯体内部熔渗的效率,同时,也有利于在较低的温度和较短的时间完成磁体的致密化烧结,避免烧结过程晶粒的长大,有利制得高矫顽力磁体。
Claims (8)
1.一种低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法,其特征包括以下步骤:
步骤1:主相合金(Nd,R)a-(Fe,M)b-Bc,以纯度高于99.5%、氧含量低于300ppm的原料进行成分设计,采用速凝薄片工艺制成速凝薄片后,再采用氢破法破碎并通过气流磨破碎,制成1.5~3.5μm的粉末;
步骤2:添加相(Nd,R,RH2(CO3)3)d-(Fe,M)e,以纯度高于99.5%的原料采用速凝薄片工艺制成速凝薄片后,再采用氢破法破碎并通过气流磨破碎,制成0.06~0.3μm的粉末;
步骤3:将添加相粉末加入主相合金粉末中,添加比例为总粉末量的0.1~2.0%,后在氩气或氮气保护下混合2~4h,混合均匀;
步骤4:取向并压制成型,压制压力40~80MPa,再进行冷等静压,压力60~120MPa;
步骤5:高真空低温取向预烧结,温度500~850℃、炉内压力低于10-1Pa、取向磁场强度0.3T以上、烧结时间1~3h,制得生坯;
步骤6:将生坯浸入由重稀土碳酸盐纳米粉末制成的浆料中,浸泡时间6~36h;
步骤7:加压低温烧结,压力0.5~6Mpa、温度800~1050℃、烧结时间1~2h;
步骤8:热处理,温度400~650℃,时间4~8h,制得烧结钕铁硼系永磁体。
2.根据权利要求1所述的低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法,其特征在于:步骤1中的主相合金(Nd,R)a-(Fe,M)b-Bc,R指取代稀土Nd的轻稀土元素。
3.根据权利要求1或2所述的低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法,其特征在于:
M指取代Fe的Ga、Co、Al、Cu、Nb、Ti、W、Mo中的一种或几种。
4.根据权利要求1所述的低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法,其特征在于:步骤1中的主相合金(Nd,R)a-(Fe,M)b-Bc,采用c<0.9%的低硼配方。
5.根据权利要求1所述的低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法,其特征在于:步骤2中的添加相(Nd,R,RH2(CO3)3)d-(Fe,M)e,R指取代稀土Nd的轻稀土元素。
6.根据权利要求1或5所述的低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法,其特征在于:
RH指重稀土元素Tb、Dy、Ho、Er、Y;M指取代Fe的Ga、Co、Al、Cu、Nb、Ti、W、Mo元素中的一种或几种。
7.根据权利要求6所述的低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法,其特征在于:RH指Tb或Dy。
8.根据权利要求1所述的低硼低重稀土高矫顽力烧结钕铁硼系永磁体的制备方法,其特征在于:在步骤7中加压低温烧结之前先采用高真空低温烧结,炉内压力低于10-1Pa,温度500~850℃,温度到达指定温度后保温0.5~1h;然后通入氩气进行步骤7的加压低温烧结,完成重稀土元素的熔渗和坯体的致密化。
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