Determination of Carbon in Ni-Al Powder by the Pure Chemical Substance Calibration-high Frequency Combustion Infrared Absorption Method

The carbon in Ni-based powder directly influences the property of the material. However, there is no national standard method to determine carbon content in Ni-based powder, according to the wide content range of carbon, different interferences and inconsistent optimal measuring conditions. The High Frequency Combustion-Infrared Absorption Method is already widely used to determine carbon and sulfur in new materials (such as carbon ferro-silico-manganese). Based on the preliminary study on Ni-based brazing material and Ni-based self-fluxing alloy, the high frequency combustion infrared absorption method is used to determine carbon content in Ni-Al powder. The sample is burned at high-temperature and decomposed by adding the flux of Fe and W-Sn fluxes. The measurement conditions such as flux adding amounts, sequence and sample weight have been optimized to obtain accurate results. The method has been applied to the determination of practical samples with the relative standard deviation of less than 1.2% and recovery rate of 98.0%-105.0%. The flux used by the method solves the problems of bad conductivity and splashing during burning. As new materials fall short of standard materials, the calibration curve is prepared by standard sodium carbonate relating to the carbon content, which solves the problem of no reference material and also improves the accuracy. The provided analytical method is not only suitable for the analysis of carbon in Ni-Al power within the carbon content range of 0.005%-0.60%, but also provides the basis for the development of a carbon standard analysis method for nickel-based powder.