再制造清洗熔盐配方改进及去除作用研究

Formulation improvement and removal mechanism of cleaning molten salts

针对原有再制造清洗熔盐配方热稳定性低、毒性强的缺陷,进行配方改进及去除作用研究。将原有配方中易分解的NaNO2替换为Na2CO3,使用混料实验设计获得13组不同比例配方,并对其熔点进行理论计算及试验测试,获得熔点计算值与实测值的响应曲面及等值线图,利用响应变量优化器获得二者最低熔点及组分比例。验证最优配方清洗效果及清洗前后机械性能,并利用傅里叶红外光谱(FTIR)、X射线能谱(EDS)、气相色谱质谱(GC-MS)分析油漆及气体产物组分,阐释去除作用机制。结果表明,熔点计算值与实测值的响应曲面及等值线图变化趋势相同,二者熔点最大绝对值误差为3.5%,最优熔点相差5.70℃,误差率为2.74%,吻合程度高;同时依据FTIR、EDS显示的油漆主要为含酯基、羧基、硝基及芳香类基团的有机物的结果及GC-MS确定的气体产物成分,将改进配方去除作用阐释为包含裂解、氧化反应的化学作用及高温作用;此配方可在4 min内完全去除油漆,清洗前后抗拉强度和硬度变化率分别为1.68%和0.83%,表面粗糙度为0.21和0.25μm,均符合使用要求。

Cleaning molten salts have low thermal stability and high toxicity.The formulation of cleaning molten salts was improved and the removal effect was discussed.NaNO2 in the original formulation was replaced by Na2CO3 and 13 proportions were obtained by mixture experimental design.The melting points were calculated and measured.All results were analyzed and related response surface figures and contour plots were obtained for the study of melting point trends.The minimal value and related ratio were gained by Variable Optimizer of Minitab.The cleaning effect and mechanical performance were verified.Moreover,the components of paint and gas production were analyzed by Fourier infrared spectrum(FTIR),X-ray energy spectrum(EDS)and gas chromatography-mass spectrometry(GC-MS).The results show that the calculated and measured points display the same trends with the maximal absolute error of 3.5%.The difference of optimal melting points is 5.70℃and the error rate is 2.74%,which indicates a high degree of agreement between calculated and measured points.Meanwhile,FTIR and EDS results show that the paints are organic compounds containing ester group,carboxyl group,nitro group and aromatic group.The gas composition was determined by GC-MS.The removal effects were described as thermal effects and chemical reactions containing oxidation and pyrolysis.Paints can be completely removed within 4min.The changing rates of tensile strength and hardness are 1.68%and 0.83%respectively,and the surface roughness changes from 0.21μm to 0.25μm,all of which meet the requirements.