The highest sintering temperature was 900 c , and the sintering lasted 70 seconds . the conventional sintered magnets were sintered at 1000 c for 1h 常規(guī)燒結(jié)的溫度為1000 ,燒結(jié)時(shí)間為1h ,并分別在800和600各進(jìn)行1h的回火。
The comparison between the magnetic properties of ndfeb magnet by microwave magnetic field sintering and those of magnet by conventional sintering technology shows that the brwas improved 50 % , the hcb was improved 8 % , and the ms was improved 40 % 將微波磁場燒結(jié)的磁體與常規(guī)燒結(jié)磁體進(jìn)行磁性能比較表明:微波磁場燒結(jié)出的磁體剩磁提高了將近50 ,矯頑力提高了8 ,飽和磁化強(qiáng)度提高了40 。
The microwave magnetic sintering can not only lower the sintering temperature and shorten the sintering time , but also decrease the micro - grain size of magnets and make intergranular phase and grain boundary of main phase distributed well . the abnormal grain growth was found in conventional sintered ndfeb magnets , which may be due to the greater particle size and uneven distribution of powder , and higher sintering temperature and longer sintering time . of course , the abnormal grain growth would deteriorate the magnetic properties 微波磁場燒結(jié)的不但降低燒結(jié)溫度,縮短燒結(jié)時(shí)間,而且使磁體整體加熱,受熱更均勻,因而磁體晶粒更細(xì)小,并且主相晶粒邊界趨于規(guī)則化,晶間相的分布更均勻;在常規(guī)燒結(jié)的磁體中則出現(xiàn)了晶粒異常長大現(xiàn)象,造成這一現(xiàn)象的原因,一方面可能是燒結(jié)溫度過高或燒結(jié)時(shí)間過長,另一方面可能是磨制的粉體均勻性較差,存在的大顆粒被許多細(xì)小顆粒包圍,在燒結(jié)過程中,大顆粒不斷吞并小顆粒,逐漸長大,而異常長大的晶粒自然會(huì)導(dǎo)致磁體性能的惡化。