JPH024953A - Flame spray-coating method - Google Patents

Abstract

PURPOSE:To improve the adhesion of a flame sprayed layer by using an anodic arc flame to heat a coating region at the time of locally coating the surface of a metallic material with a flame spraying material. CONSTITUTION:When the surface of a metallic material is locally coated with a flame spraying material, the region to be coated is heated over the whole period of flame spraying with the anodic arc flame. The flame spraying surface is melted or quasi-melted by the arc flame, and highly adhesive coating film is obtained. Since the flame spraying surface can be melted or quasi-melted, the degreasing and roughening of the material surface, which are vital as the pretreatment for flame spraying in the conventional process, can be omitted. In addition, since the heating region of the arc flame can be easily controlled by the shape of a cathode, the flame spraying even on a narrow region can be accurately followed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a thermal spray coating method, and particularly to a thermal spray coating method that allows a local surface of a metal material to be coated with a thermal spray material with good adhesion.

(Prior Art) Recently, thermal spray coating has been widely used as a method for improving the surface properties of metal materials, such as wear resistance, corrosion resistance, heat resistance and heat insulation.

However, thermal spray coatings have poor adhesion, so
Even among metal materials that require wear resistance, such as rolling rolls, it has been practically impossible to apply them to areas where strong stresses such as compressive stress, bending stress, and shear force are applied.

As a solution to the above problem, for example, JP-A-59
Although Japanese Patent No. 153506 proposes a method of performing heat treatment after the film is formed, this method has a high risk of deforming the metal material as a raw material due to thermal strain.

Furthermore, JP-A No. 63-15343 proposes a method of imparting a negative charge to the material and increasing the adhesion strength through its cleaning action. The adhesion between the material and the sprayed layer is
It still wasn't enough.

(Problems to be Solved by the Invention) This invention advantageously solves the above-mentioned problems, and improves not only the bonding force between sprayed particles but also the adhesion between the sprayed layer and the material surface. The purpose is to propose a thermal spray coating method.

(Means for Solving the Problems) In other words, the present invention uses a positive polarity arc flame over the entire thermal spraying period when locally coating the surface of a metal material with a thermal spraying material by a thermal spraying method. This is a thermal spray coating method that involves applying heat treatment.

(Function) According to the present invention, by heating the sprayed surface using a positive arc flame, the sprayed surface can be brought into a melted or nearly melted state, and therefore a coating with strong adhesion can be obtained.

Furthermore, since the sprayed surface can be brought into a molten or nearly melted state, degreasing and surface roughening treatments of the material, which were conventionally indispensable as pre-treatment for thermal spraying, can be omitted.

Furthermore, since the heating area of the positive polarity arc flame can be easily controlled by the shape of the cathode, thermal spraying in a narrow area can be accurately followed.

In this invention, there are no limitations on the type of thermal spraying material or thermal spraying method, and any conventionally known materials can be used. The thermal spraying atmosphere is preferably a low-pressure inert atmosphere of about 20 to 100 Torr in order to prevent oxidation due to heating.

Furthermore, in order to reduce distortion during thermal spraying, it is desirable to preheat the material prior to thermal spraying, and the preferred temperature is around 200°C.

(Example) Local surfaces of various metal materials shown in Table 1 were coated with thermal spray materials having various compositions shown in Table 2 by plasma spraying or gas spraying. During this thermal spraying process, the thermal spraying area was heated with a positive arc flame (cathode diameter: 2.4 mmφ, W electrode,
Heated using voltage: 60 V'% current: 90 A).

Table 3 shows the results of examining the adhesion of the sprayed coating layer thus obtained.

As is clear from the table, the thermal spray coating obtained according to the present invention has much better adhesion than the comparative example.

(Effects of the Invention) Thus, according to the present invention, it is possible to coat a thermal spray material with good adhesion, and it is particularly useful for thermal spray coating of an abrasion resistant material on areas where stress is strongly applied.

Claims (1)

[Claims] 1. A thermal spray coating characterized in that when locally coating the surface of a metal material with a thermal spray material by a thermal spray method, the thermal spray coating area is subjected to heat treatment using a positive arc flame for the entire thermal spraying period. Law.