JPS59195584A - Heat resistant ceramic flame spray material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-resistant ceramic sprayed material used in high-temperature atmospheres such as heating furnaces, scorching furnaces, and annealing furnaces.

For example, hearth rolls for heat treatment furnaces for steel plates, stainless steel plates, etc. are made of various heat-resistant steels with a smooth finish, but during use, oxidized scale picks up on the roll surface, which can damage the product and cause the product to become unusable. It may reduce the value.

However, among ceramic materials, chromium carbide exhibits unique properties when compared to other materials, and in particular exhibits extremely excellent corrosion resistance against molten metals, and exhibits excellent characteristics that make it difficult to pick up. There are ceramic materials. When this chromium carbide is used as a thermal spray powder, the strength of the thermal spray coating decreases at high temperatures and is likely to cause cracks and peeling.
It cannot be used for the purpose of improving pick-up resistance in harsh operating environments such as eight-throttles where dynamic stress acts under high temperatures.

In order to solve the above-mentioned problems, the present invention provides a thermal spraying material containing chromium carbide as a main component, which does not easily react with the metal to be heated or its scale, and forms a tough thermal spray coating. The gist of the material is a heat-resistant ceramic thermal spray material having a composition of 3 to 40% of one or more selected from aluminum oxide, zirconium oxide, calcium oxide, and magnesium oxide, and the balance being chromium carbide.

The thermal spray material of the present invention can be obtained by blending various material powders within the above-mentioned composition range, granulating and firing, and the firing method depends on a reducing atmosphere or a vacuum atmosphere.

Next, the tests that led to the development of the thermal spray material of the present invention and their results will be shown. That is, 3 parts by weight of paraffin was added to 100 parts by weight of a mixture of chromium carbide powder with a purity of 99% and a particle size of 5 μm and other various additives (2 to 3 μ1 Tl) as shown in Table 1 below. was used as the raw material powder. The raw material obtained as in (B) was granulated into 150 to 350 meshes and fired in a hydrogen gas atmosphere for 1 hour to obtain semi-baked granulated powder.

Nickel-chromium thermal spray powder, which is commonly used as a base material for ceramic thermal spraying, was sprayed onto a steel material to a thickness of 0.1 mm, and this thermal spray powder was further plasma sprayed to a thickness of 0.5 mm, and a pick-up resistance test was conducted. Changes in adhesive strength after holding were measured. The results are shown in Table 1 below. Among these, the pick-up resistance test was conducted with the specimen at 1000℃ in the atmosphere.
45C material for a contact area of 20mm x 20mm
After holding for 6 hours under a load of kg, both were pulled with a member and judged based on the fact that the oxide scale that had formed on the surface of the 545C material had adhered to the sprayed surface. The results in the table indicate that there is no scale adhesion at all; 01 indicates that there is some adhesion; Those that can be used sufficiently are indicated as △, and those that are unusable due to excessive adhesion are indicated as ×.

Changes in adhesive strength after holding at high temperature were determined by holding at 900°C in the atmosphere for 6 hours, cooling to room temperature, and measuring adhesive strength.

Regarding the amounts of the various oxides added in Table 1, unless they are used in an amount of at least 3% by weight, the effect will be insufficient, and the adhesive strength of the film will deteriorate significantly due to temperature cycles from high temperature holding to cooling. On the other hand, if too many of these oxides are added, and the amount exceeds 40% by weight, the adhesive strength will deteriorate again after high temperature use, so the amount of these oxides added should be 3 to 40% by weight. .

As mentioned above, the ceramic sprayed material of the present invention has excellent pick-up resistance and adhesive strength against high-temperature cycles, and the sprayed coating is dense and good, so it can be used in various types of materials used in high-temperature environments. Ideal as a thermal spray material for parts.

Claims (1)

[Claims] 1. 3 to 4 at least one selected from aluminum oxide, zirconium oxide, calcium oxide, and magnesium oxide
A heat-resistant ceramic thermal spray material with a composition of 0% by weight and the balance being chromium carbide.