淬火硝盐的劣化和再生

Degradation and regeneration of quenched nitrate

使用扫描电镜及能谱分析、化学分析方法,全面分析了使用硝盐浴进行分级淬火和等温淬火时,淬火硝盐劣化产物。结果表明:硝盐反应生成物(Na2CO3、NaOH),设备(主要是盐槽、盐泵、管道)、夹具、料盘及工件等氧化产物(FeO·Fe2O3·Fe3O4),外来物(灰尘,炭黑)是造成硝盐劣化的主要原因。据此,提出了预防淬火硝盐劣化措施:选用品质好的基盐;选用热稳定性较高的混合盐;保持淬火盐浴温度均匀,淬火前后温升可控,尽量避免"瞬间"过热使用;尽量避免外来杂质进入;做好日常维护。并简要介绍了淬火硝盐再生处理方法。

The deterioration products of nitrate bath used for step quenching or austempering were comprehensively analyzed by means of SEM,EDS and chemical analysis. The results show that nitrate degradation is mainly caused by the reaction products of nitrate( Na2CO3,Na OH),oxidation products( FeO·Fe2O3·Fe3O4) of equipment( mainly salt bath,salt pump,pipeline and roller),fixtures,pans and workpieces and foreign substances( dust,carbon black) during the use of nitrate. Accordingly,the counter-measures to prevent deterioration of quenched nitrate are put forward,including choosing base salt with good quality or mixed salt with high thermal stability,keeping the temperature of the quenching salt bath uniform,controlling the temperature rise before and after quenching,trying to avoid"instantaneous"overheating and foreign impurities,and doing daily maintenance well. And the method of regeneration of quenched nitrate is also briefly introduced.