Abstract: A liquid jet discharge device including an ejection section, a pressure generation section, and an impulse force impartation means. The ejection section is open at both end portions and internally houses a liquid such that a contact angle between the liquid and at least an inner face of the ejection section is less than 90°. The pressure generation section is in communication with one end portion of the ejection section, has a cross-sectional area larger than a cross-sectional area of the ejection section, has a length in a discharge direction of a liquid jet that is longer than a length in the discharge direction from the one end portion of the ejection section to a surface of the liquid, and houses the liquid at least at a bottom face side onto which the one end portion opens. The impulse force impartation means is configured to impart an impulse force to the pressure generation section.

Abstract: A coating structure for a metal member includes a surface-smoothing layer formed on the metal member for smoothing a surface of the metal member, and a fluorine-based film formed on the surface-smoothing layer. The fluorine-based film can be formed by applying a fluorine-containing solution on the surface-smoothing layer, and by drying the fluorine-containing solution. The coating structure can be suitably used for a fuel injection nozzle.