Quantitative analysis of micro-corrosion on magnetic recording disk using TOF SIMS

For corrosion study, time-of-flight secondary ion mass spectroscopy (TOF SIMS) provides qualitative composition information of the corrosion products with very high sensitivity. However, when this technique is used for quantitative analysis, a standard must be set up. This work aims to establish TOF SIMS quantitative analysis standard for Co or Ni related corrosion products on magnetic hard disk surfaces. Three approaches to measuring Co or Ni hydroxide corrosion products on hard disk media surfaces have been proposed and the detection limit of each method is discussed. The first method is to measure the ion counts of Co⁺ or Ni⁺. The detection limit can be as low as ppm level. The second method is to measure the ion counts of CoOH⁺ or NiOH⁺. The detection limit is around 0.1% (100 ppm), and the third method is to measure the ion counts of CoF⁺ or NiF⁺. The detection limit is lower than CoOH⁺ or NiOH⁺, but higher than Co⁺ or Ni⁺.