Abstract: A coating material is allowed to contain a sulfate having a higher degree of solubility in water than that of calcium sulfate. The sulfate is an additive for coating materials which is used for reducing the consumption of zinc (including zinc oxide) in a coating film formed from the coating material and the corrosion of a base material when the coating film is scratched. The content of the sulfate can be 0.004 to 0.65 mol per 100 g of the content of zinc. Alternatively, the content of the sulfate may be 0.006 to 0.186 mol per 100 g of a heating residue (except for the sulfate added) of a coating film.

Abstract: An ultra-directional speaker having a modulator 33 for modulating an ultrasonic carrier signal with an input electric signal from an audible sound signal source, and an emitter 44 for emitting an output of the modulator 33 is mounted in a moving object 1 having a target tracking system for sensing a target in a surrounding space in real time using the above-mentioned emitter 44. The moving object equipped with ultra-directional speaker can therefore transmit a voice only to a specific target through parametric action caused by the nonlinearity of finite amplitude of ultrasonic wave.