JP2015218353A - Nozzle and attachment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further atomize raw material particles.SOLUTION: A nozzle comprises: an inlet through which raw material particles and gas flow in; an internal passage through which the raw material particles and gas having flown in pass; an outlet that injects the raw material particles and the gas through the internal passage; and a throat that has a flow passage cross section smaller than that of the outlet and is provided in the internal passage. The flow passage cross section of the internal passage becomes larger toward the outlet from the throat. Projections are provided on the inner surface of the nozzle between the throat and the outlet.

Description

  The present invention relates to a nozzle and an attachment that collide and deposit a solid, semi-molten material powder particle on a base material together with an accelerated gas flow to form a film.

  Composite coatings are widely produced by combining metals with plastic deformation, brittle materials such as ceramics and semiconductors, and metals. Among composite materials, composite coatings such as composite sprayed coating of titanium and dissimilar metals (molybdenum, nickel), composite sprayed coating of nickel and aluminum, etc. have been developed as functional materials, and are macroscopically dispersed in a matrix. In recent years, attention has been focused on composite coatings in which finer particles are dispersed.

  However, the fine powder is expensive and requires strict storage management to prevent surface oxidation. For example, in Patent Document 1, raw material particles such as ceramics and metal are aerosolized, aerosols injected from a plurality of nozzles are caused to collide with each other in a space away from the substrate surface, and the aerosolized raw material particles are pulverized into fine particles. Is described.

JP 2009-249720 JP

  However, the raw material particles are accelerated in the nozzle and decelerated as they exit the nozzle. In the above-mentioned patent document, since the raw material particles collide outside the nozzle, the collision speed becomes insufficient, and there is room for improvement in making the raw material particles fine.

  An object of the present invention is to make raw material particles finer.

  The above object can be achieved by the invention described in the claims.

  According to the present invention, the raw material particles can be made finer.

It is an example of the sectional side view of a nozzle. It is an example of the top view of a nozzle. It is another example of the sectional side view of a nozzle. It is a figure which shows a mode that it forms into a film using a some nozzle.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, this invention is not limited to embodiment taken up here, A combination and improvement are possible suitably in the range which does not change a summary.

  FIG. 1 is an example of a side sectional view of the nozzle of the present embodiment. A mixture of gas and raw material powder (gas and particle flow G) is supplied to the nozzle inlet 2 in the direction of the arrow, and after passing through the throat 3 having the smallest flow path cross-sectional area inside the nozzle 5, the gas and particle flow G Is ejected from the nozzle outlet 1. The cross-sectional area of the nozzle outlet 1 is larger than the cross-sectional area of the throat 3, and the gas and the particle flow G are accelerated from the throat 3 to the nozzle outlet 1.

  In the nozzle of this embodiment, a convex portion 4 is provided on the inner surface in the vicinity of the nozzle outlet in the acceleration space between the throat and the nozzle outlet where the gas and particle flow are sufficiently accelerated. By providing a convex portion on the inner side of the nozzle tip, particles collide with each other and turbulent flow occurs without substantially reducing the velocity in the nozzle, and the particles can be miniaturized. When a plurality of convex portions are provided in the circumferential direction of the nozzle, the raw material powder is easily miniaturized and the deposited film is likely to be uniform. If the protruding protrusions are tall, the nozzles are clogged due to the adhesion of the particles to the protrusions. Therefore, the protrusions are desirably high enough to prevent particles from attaching. The shape of the convex part is not particularly limited, but (a) hemispherical, (b) conical, (c) columnar and conical, (d) columnar as shown in the plan view of the nozzle shown in FIG. (E) The convex part etc. which continued in the circumferential direction may be sufficient. Moreover, as shown in FIG. 1, the convex part may be installed in multiple stages in the axial direction of the nozzle.

  When the length from the throat to the nozzle outlet is A, and the convex portion is installed in the range B in which the length from the nozzle outlet is 30% of A, the particle does not extremely decrease in speed. The film can be deposited on the substrate after being refined and formed into a film. The reason can be explained as follows. A gas heated up to 800 ° C is made into a supersonic flow by a Laval nozzle (a shape that expands once the inner diameter is reduced), and raw material powder is put into it and accelerated to collide with the substrate to form a film. . As the hot gas expands, the velocity of the gas flow increases rapidly in the vicinity of the throat, and after passing through the nozzle outlet, gradually decreases due to the viscosity of the atmospheric gas. For this reason, when a convex portion is provided in the throat portion, the powder cannot be sufficiently refined due to insufficient gas flow velocity, and the powder tends to adhere to the convex portion, and the nozzle hole is eventually closed. Since the gas flow velocity between the nozzle outlet and the throat at a length of 30% is maintained at a substantially maximum speed, it is desirable to provide a convex portion between the nozzle outlet and the throat at a length of 30%. The powder of the highest speed gas flow collides with the convex portion, so that the powder can be refined. Further, the convex portion is in the vicinity of the nozzle outlet, and there is no fear of blocking the nozzle hole.

  Instead of installing the convex part from the nozzle outlet to the throat part with a length of 30%, the material powder particles to be injected collide with the gas pressure supplied from the gas supply part to the nozzle tip part and refined. It can be deposited on the material to form a film. The position of the gas supply unit for supplying the gas is preferably provided within a length of 30% from the nozzle outlet to the throat in consideration of the gas flow speed injected from the nozzle inlet. The gas pressure supplied from the gas supply unit is preferably much lower than the gas pressure injected from the nozzle inlet, so that collision between the injected powder particles is possible.

  In addition, as shown in FIG. 3, by connecting the external nozzle 15 provided with the convex portion 14 of the present embodiment to the conventional nozzle 16, a fine structure composite film can be formed on the substrate. The externally attached nozzle of this embodiment corresponds to the length of the convex part or the gas supply part installed between the nozzle outlet and the throat at a length of 30%. By connecting externally to the conventional nozzle, the cost is reduced. It can be easily replaced and repaired.

  The raw material powder is not particularly limited as long as it is a material for which a film is to be formed, and examples thereof include metals and ceramics. You may mix and use these multiple types. Conventional raw material powders generally have an average particle diameter of 10 to 100 μm, and when the nozzle of this embodiment is used, a finer powder is injected, and the particles in the formed film are further refined. . In the present embodiment, the particle surface is atomized by the nozzle of the present embodiment without performing powder storage management, and the atomized powder is instantaneously deposited on the substrate to form a film, so that the oxidation of the particle surface is suppressed. .

Examples of the present invention will be described below, but the present invention is not limited to these examples.
(Observation of cross-sectional structure of film)
Using a scanning electron microscope (S-4300; manufactured by Hitachi High-Technology), the cross-sectional structure of the film was observed, and fine particles were measured from the obtained observation photograph.
(Injection conditions)
The method for forming the microstructure film is shown below. The carrier gas is nitrogen gas of 3.0 MPa, the injection distance (distance from the tip of the nozzle to the film formation surface) is 30 mm, the carrier gas temperature is 700 ° C, and the mixed powder is passed almost vertically on the nickel substrate surface for 10 passes. Injected 10 times.

As the mixed powder, nickel powder (manufactured by High Purity Chemical Laboratory; -63 μm) and molybdenum powder (manufactured by High Purity Chemical Laboratory; -63 μm) were used.
(nozzle)
The cross-sectional view and plan view of the nozzle used were those shown in FIGS. The material of the nozzle and the convex portion is not particularly limited, but a material having wear resistance and hardness and a material that is difficult to adhere is desirable. For example, carbon steel, silicon carbide, tungsten carbide, alumina, zirconia and the like are desirable.
(Example)
A film was formed by cold spraying with the nozzle convex shape changed. Example 1 is the first stage in FIG. 2 (a), Example 2 is the same shape and the second stage is shifted by 45 ° in the circumferential direction, and Example 3 is the first stage in FIG. 2 (b). Example 4 uses three stages of (c) in FIG. 2, Example 5 uses one stage of (d) in FIG. 2, and Example 6 uses two stages of (e).

  Although the molybdenum raw material powder was agglomerated, the molybdenum powder particles were refined and dispersed to a diameter of 10 μm or less in the formed film. When observed with an electron microscope, it was confirmed that the molybdenum aggregates in the film were loosened and dispersed as primary particles. As a comparative example, as a result of forming a film using a conventional nozzle, most of the molybdenum powder particles in the film were 50 to 20 μm. As for the convex part of the external nozzle, as a result of adopting the same form as in Examples 1 to 6, the molybdenum powder particles in the film had a diameter of 10 μm or less.

  In Example 7, the apparatus shown in FIG. 4 was used. The nozzle 46 on the right side has a convex shape in one stage in FIG. 1A, and an external nozzle shown in FIG. 2 was used. As the powder, molybdenum powder was used. A conventional nozzle 46 was used on the left side, and a mesh 45 was provided between the nozzle outlet and the substrate. Nickel powder was used as the powder. The wire diameter of the mesh is desirably large enough to withstand supersonic gas and particle flow. A slit may be used instead of the mesh. Slits and meshes are used to refine powders by collisions between ejected particles and the resulting turbulence, and there is no need for openings and slits on the order of micrometers. The material is not particularly limited, but a material having wear resistance and hardness and a material that is difficult to adhere is desirable. For example, carbon steel, silicon carbide, tungsten carbide, alumina, zirconia and the like are desirable. As a result, the molybdenum powder particles in the coating were finely dispersed to 10 μm or less. Thus, fine particles can be deposited even when the nozzle of this embodiment and the conventional nozzle are used in combination.

1 ... Nozzle outlet, 2 ... Nozzle inlet, 3 ... Throat, 4, 14 ... Convex, 5 ... Nozzle, G ... Gas and particle flow, A ... Throat-nozzle outlet length, B ... Throat- nozzle outlet length 15 ... external nozzle, 16 ... conventional nozzle, 41 ... base material, 42 ... film, 43 ... raw powder, 44 ... fine powder, 45 ... mesh, slit, 46 ... nozzle

Claims (7)

An inlet through which the raw material powder and gas flow, an internal passage through which the raw material powder and the gas flow in, an outlet through which the raw material powder and the gas are injected through the internal passage, and an internal passage In a nozzle provided with a throat having a smaller channel cross-sectional area than the outlet,
The internal passage has a channel cross-sectional area that increases from the throat toward the outlet, and has a convex portion on the inner surface of the nozzle between the throat and the outlet.   The nozzle according to claim 1, comprising a plurality of the convex portions in a circumferential direction of the nozzle.   The nozzle according to claim 1, wherein the convex portion is provided in multiple stages in the axial direction of the nozzle.   4. The nozzle according to claim 1, wherein the convex portion is provided between 30% of a length from the outlet of the nozzle to the throat. 5.   In an attachment that is removably attached to the tip of a nozzle from which the raw material powder and gas are injected, an inlet through which the raw material powder and the gas flow from the tip of the nozzle, and the raw material powder and the gas that flow in An internal space between the inflow port and the outflow port, an outflow port in which the raw material powder and the gas are injected through the internal space and the flow passage cross-sectional area is larger than the inflow port. An attachment characterized by comprising a convex part.   The attachment according to claim 5, wherein a plurality of the convex portions are provided in a circumferential direction of the attachment.   The attachment according to claim 5 or 6, wherein the protrusion is provided in multiple stages in the axial direction of the attachment.