管式炉加热—红外吸收法测定内螺纹铜管内表面残碳量

Determination of residual carbon on the inner surface of inner grooved copper tubes by tubular furnace heating-infrared absorption method

在没有铜管内表面残碳标样的情况下,以合成碳样校准仪器,内螺纹铜管内表面碳参考样验证测定结果,成功地用管式炉加热-红外吸收法测定了内螺纹铜管内表面残碳量。对影响测定结果的诸多因素,例如试样的处理、流量的选择、温度常数和仪器空白的设定、仪器的校准等进行了试验和讨论。结果表明,当试验温度为400～600℃、氧气流量为750mL/min时,铜管内表面碳释放完全,并得到理想的积分曲线。对内螺纹铜管内表面碳参考样进行测定,结果与管式炉加热非水滴定法一致,相对标准偏差为3.7%。通过加入合成碳样品进行回收试验,测得回收率为98%～103%。

Since there was no standard sample for inner surface residual carbon in copper tube, the instrument was calibrated by synthetic carbon sample. The determination results were verified using reference sample of inner surface carbon of inner grooved copper tube. The content of inner surface re- sidual carbon in inner grooved copper tube was successfully determined by tubular furnace heating - infrared absorption. Several factors influencing the determination results were tested and discussed, for instance, the sample treatment, the flow selection of oxygen, the temperature constant, the setting of instrumental blank and the calibration of instrument. The results showed that, when the testing temperature was 400--600℃ and the flow rate of oxygen was 750 mL/min, the inner surface carbon in copper tube was completely released. The determination results were consistent with those obtained by tubular furnace heating-nonaqueous titration, with relative standard deviation （RSD） of 3.7 %. The synthetic carbon sample was added for recovery test and the recoveries were found as 98%--103%.