Methods for preparing magnetostrictive powder and magnetostrictive coating

A method for preparing a magnetostrictive coating, comprising:

• depositing the magnetostrictive powder prepared by a method for preparing the magnetostrictive powder on a surface of a piece to be detected by surface coating, to form a magnetostrictive coating attached to the surface of the piece,
• wherein the method for preparing the magnetostrictive powder comprises putting metals for preparing magnetostrictive powder into a vacuum melting furnace to be melted into a solution, wherein the putting metals for preparing magnetostrictive powder into a vacuum melting furnace to be melted into a solution comprises putting iron and one or more metals selected from the group consisting of gallium, cobalt, aluminum, and nickel into a vacuum smelting furnace to be melted into an alloy solution;
• keeping a temperature of the alloy solution at 350° C. above a melting point of the alloy solution for 10 to 30 minutes;
• and
• atomizing the solution into fine droplets by ultrasonic atomization, so that the fine droplets are cooled and solidified into magnetostrictive powder,
• wherein atomizing the solution into fine droplets by ultrasonic atomization comprises:
• outputting high-frequency electric energy with an ultrasonic generator in an atomization furnace, so that a crystal transducer at the bottom of a cavity of the atomization furnace generates ultrasonic sound energy;
• pouring the solution into the atomization furnace, wherein the sound energy vibrates a sound-transparent film at the bottom of the atomization furnace to act on the liquid in the atomization furnace, which destroys a surface tension and inertia of molten metals;
• and
• impacting a liquid metal flow formed by the solution with an airflow with a frequency of 85 kHz to 95 kHz and a velocity of 2.2 Mach to 2.4 Mach by ultrasonic atomization, so that the molten metals are broken and atomized into fine droplets, wherein particle sizes of the magnetostrictive powder are 15 μm to 22 μm, and an average particle size of the magnetostrictive powder is 20 μm.