Abstract：Cobalt-chromium-tungsten (Co-Cr-W) alloy is a kind of cobalt-based hard alloy. It has excellent comprehensive performance including abrasive wear resistance, erosive wear resistance, high temperature wear resistance, high temperature oxidation resistance and thermal fatigue resistance. So far, there is no related detection standard method for Co-Cr-W alloy powder, and there are also only few reports about this at domestic and abroad. Nickel is the major component in Co-Cr-W alloy powder, and it is urgent to develop a method for determination of nickel, thus providing guidance for the production, use and trade of Co-Cr-W alloy. The sample was treated by microwave digestion with 10 mL of hydrochloric acid, 3 mL of nitric acid and 2 mL of hydrofluoric acid. Potassium sodium tartrate was selected as the masking agent and ammonium persulfate was selected as the oxidant. Nickel could form a soluble wine-red complex with dimethylglyoxime in a strong alkaline medium of sodium hydroxide. The complex was determined with spectrophotometer at 530 nm. Thus, a method for determination of nickel in Co-Cr-W alloy powder was established by dimethylglyoxime spectrophotometry. According to the content range of each element in sample, the interference tests of coexisting elements were conducted by adding 2 or 5 times of maximum content. The results showed that the recoveries of nickel were between 100% and 101%, indicating that the coexisting elements in sample had no interference with the determination of nickel. The experimental method was applied for determination of nickel in actual sample of Co-Cr-W alloy powder, and the addition standard recovery test was conducted. The relative deviations (RSD, n=11) of determination results were between 0.26% and 1.8%, and the recoveries were between 97% and 102%. According to the composition range of elements in sample, the simulated samples of Co-Cr-W alloy powder were synthesized and determined by the experimental method. The results of nickel content were consistent with the theoretical values.
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