The invention relates to a special hot-dip plating alloy for a coating on the surface of a titanium alloy part, wherein the hot-dip plating alloy contains the following components by mass percentage: 8-24% of Si, 1. The decoding method includes: when demodulated data in a buffer space is enough to form a second predetermined number of CB data, reading the demodulated data to form the second predetermined number of CB data from the buffer space; decoding the second predetermined number of CB data. Front and rear walls are included. The magnetic orientation of the free layer switches relative to that of the fixed layer.