Discussion of Problems of Measurement Carbon on the Inner Surface of Inner Grooved Copper Tube by Infrared Absorption Method

The inner surface carbon in the inner grooved copper tube was determined by tube furnace heating-infrared absorption method. Some factors which influenced the determination such as sample preparation and cleaning, flow rate, furnace constants, blank value, calibration constant were tested and optimized. The inner surface carbon of copper tube was released completely while the experiment temperature was chosen as 400~600°C and the flow rate of oxygen was 750 mL/min. And the obtained integral calculus curve was ideal. The method has been applied to the determination of inner surface carbon in the inner grooved copper tube with carbon content of 0.24 mg/dm2. The result of the RSD was 3.7％. And the recovery experiment through joining in synthesize carbon sample was carried on, the recovery was 98～103%.