二苯卡巴肼光度法测定镀铬板表面铬氧化物含量  

Determination of chromium oxides in chrome plate surface by diphenyicarbazide spectrophotometry

作　　者：李江文[1] 于录军[1] 余卫华[1] 李杰[1] 易丽红[1] 

机构地区：[1]武钢研究院,湖北武汉430080

出　　处：《冶金分析》2016年第3期11-16,共6页Metallurgical Analysis

摘　　要：测定镀铬板表面镀层中铬氧化物及金属铬意义重大,但以往测定的大都是镀铬板表面铬氧化物量(以铬计,下同)和金属铬量的总和。实验在A657/A657M-03标准附录中测定镀铬板表面铬氧化物方法的基础上,通过采用辉光光谱法对氢氧化钠溶液浸泡镀铬板前后的表面进行对比分析,证实了氢氧化钠溶液仅对镀铬板表面的铬氧化物有溶解作用,而不能溶解金属铬,同时优化了铬氧化物的溶解条件和光度法测定条件。实验表明:将镀铬板浸泡到300g/L90℃的NaOH溶液中20min可将镀铬板表面铬氧化物溶解完全;在样品溶液中加入H_2SO_4(1+1)中和至pH为7,再加入5.0mL硫磷混酸(3+3+4)、2.0mL AgNO_3溶液以及5.0mL(NH4)2S2O8溶液,加热至沸腾并保持约10min以破坏过氧化物,冷却至室温后加入3.0mL二苯卡巴肼溶液并稀释至100mL,在542nm处于2cm比色皿中测定,Cr质量在0.24~100μg之间有较好的线性关系,其线性方程为A=0.002 1+0.013 mCr(μg),相关系数为0.999 7。方法检出限为0.24μg,测定下限为1.2μg。将最终所测得镀铬板表面铬氧化物的量除以镀铬板试样面积,最终可计算出单位面积内镀铬板表面铬氧化物的含量。采用实验方法对两类镀铬板表面铬氧化物进行测定,所得平均含量分别为12.8mg/m^2和11.1mg/m^2,其相对标准偏差分别为3.1%(n=5)和3.6%(n=5)。对镀铬板试样进行加标回收,测得铬氧化物的加标回收率在92%~101%之间。The determination of chromium oxides and metallic chromium in coating surface of chrome plate is very important.However,the total content of chromium oxides(in chromium,similarly hereinafter)and metallic chromium was usually determined in previous studies.On the basis of determination method of chromium oxides in chrome plate surface in appendix of A657/A657M-03 standard,the surface of chrome plate before and after immersion in sodium hydroxide solution was analyzed and compared by glow discharge spectrometry.It proved that the chromium oxides in coating surface of chrome plate could be dissolved by NaOH solution,while the metallic chromium could not be dissolved.The dissolution conditions of chromium oxides and the determination conditions by spectrophotometry were optimized.The results indicated that the chromium oxides in coating surface of chrome plate could be dissolved completely in 300g/L NaOH solution at 90 ℃for 20 min.Then,H_2SO_4(1+1)was added into sample solution for neutralization at pH 7.After addition of 5.0mL of mixed sulfuric acid-phosphoric acid solution(3+3+4),2.0mL of AgNO_3 solution and 5.0mL of(NH_4)2S_2O_8 solution,the solution was heated to boiling and kept for 10 min to decompose the oxides.After cooling to room temperature,3.0mL of diphenylcarbazide solution was added.Then,the sample solution was diluted to 100 mL.The content of chromium was determined at 542 nm with 2cm cuvette.It was found that the content of chromium showed good linearity in range of 0.24-100μg.The linear equation was A=0.002 1+0.013 mCr(μg)with correlation coefficient of0.999 7.The detection limit of method was 0.24μg,and the low limit of determination was 1.2μg.The measured amount of chromium oxides in coating surface of chrome plate was divided by sample area to finally obtained the content of chromium oxides in unit area of coating surface of chrome plate.The proposed method was applied to the determination of chromium oxides in coating surface of two types of chrome plate.The results were 12.8mg/m^2 and 11.1

关 键 词：二苯卡巴肼 光度法 镀铬板 铬氧化物 

分 类 号：TG115.33[金属学及工艺—物理冶金]