JPH01136957A - High temperature durable thermal sprayed film material - Google Patents

Abstract

PURPOSE:To improve the wear resistance and thermal shock resistance of the above material by forming a thermal sprayed layer of ZrO2 consisting essentially of ZrO2 and to which Cr2O3 or further other oxide is fused to incorporate. CONSTITUTION:The ZrO2-Cr2O3 ceramics having the compsn. to which 10-70wt.% Cr2O3 or one or more kinds among 1-18wt.% oxide such as CaO, MgO, Y2O3 and CeO2 are fused and consisting of the balance ZrO2 is thermal sprayed by plasma thermal spraying method, etc., on the surface of hearth roll, etc., to be used in a high temp. atmosphere of a heat treatment furnace, by which the thermal sprayed layer having excellent wear resistance and thermal shock resistance in the range of high temp. is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention applies to the surfaces of mechanical parts that require wear resistance and low reactivity with metals in high temperature ranges (SOO to 1700°C).
It relates to thermal spray coating materials that are coated to provide such functions, and is applied to steelmaking equipment such as rolls installed in heat treatment furnaces (hereinafter referred to as eight-rolls) and mud gun nozzles for blast furnaces. It is something that should be done.

<Prior art> For example, the hearth roll of an annealing heat treatment furnace has a diameter of 600 to 13
Because steel sheets that have been work-hardened in the cold-rolling process are conveyed at temperatures as high as 00°C for long periods of time, the surfaces of these rolls wear out, and contact with the steel sheets causes oxides and build-up on the surface of the steel sheets. Adhesion and accumulation of iron powder occurs. The wear marks and build-up generated on the roll surface in this way cause surface scratches on the steel plate passing through it, which significantly reduces the quality of the product. Therefore, the operation must be periodically interrupted, the heat treatment furnace must be cooled, and the eight-roll surfaces must be ground and cleaned, or the rolls must be replaced.

As a countermeasure against this problem, the roll surface is coated with a ceramic or carbon material, and methods of fitting a sleeve-shaped molded body or a thermal spraying method are used as coating methods.

<Problems to be solved by the invention> In the case of thermal spraying, many oxide ceramics, such as A
Thermal sprayed coatings of I, 0□ and Cr-03 have excellent wear resistance and low reactivity with metals, but when the material is metal such as steel, rapid cooling from high temperatures may cause the coating to peel off, and the coating may peel off when exposed to high-temperature atmospheres. Currently, it cannot be used. In addition, non-oxide ceramic thermal spray coatings have problems with oxidation resistance, so
Similarly, they often cannot be used in high-temperature environments. In addition,
As an example of Zr0J type thermal spray coating, for example, JP-A-62-1
There is a technology as shown in Japanese Patent No. 09980, but such ZrO2-based materials have excellent thermal shock resistance and low reactivity with metals, but have the drawbacks of low hardness and poor wear resistance. there were.

The present invention aims to improve the abrasion resistance, which is a drawback of the ZrO2-based thermal spray coating mentioned above, and to provide a thermal spray coating material that also has thermal shock resistance and low reactivity with metals.

<Means for Solving the Problems> The present invention uses 0.0% Cr to increase wear resistance and provide high-temperature durability. The composition contains 10 to 70% by weight of ZrO, and the remainder consists essentially of ZrO.
Thermal spray coating materials have fused O, and optionally CaO, MgO, yJo3. The gist is a thermal spray coating material in which one or more types of CeOs are added in an amount of 1 to 18 weight percent, and the respective compositions are fused.

<Function> The present invention will be described in detail below. In addition, the component content of the thermal spray coating material in the following description is not shown, and unless otherwise specified, % is weight %.

ZrO2 is a material that hardly reacts with metals, but it has three allotropic anisomorphies, monoclinic, tetragonal, and cubic, depending on the temperature.At about 1100℃, the monoclinic-tetragonal system A volume change occurs due to crystal transformation, and when the temperature reaches high temperatures, the sprayed coating is destroyed. For this reason, CaO, MgO.

Y, Oj, or Cab is added in amounts ranging from several percent to several dozen, and is used as stabilized silcornia or partially stabilized silcornia in thermal spray coatings.

The inventor used trivalent C as a stabilizing material for the crystal structure of ZrO.
At the same time as focusing on r ions, Cr+ 03 has excellent wear resistance and is a material that hardly reacts with metals.
A thermal shock test was carried out in which a thermal spraying material containing R-03 added in various proportions was prepared, which was then thermally sprayed onto a stainless steel material to form a thermal spray coating, heated at 1000°C for 30 minutes, and dropped into water. A friction test was conducted in which a rotating disk was pressed against the test piece.

In the Zr0a -Cra 03 binary system, the component range that has high wear resistance and good thermal shock resistance is Cr2O.
The composition contained ZrO in an amount of 10 to 70%, with the remainder consisting essentially of ZrO. The thermal shock resistance of the sprayed coating with the Zr02-CrY03 composition is due to the partially stabilized phase including the high-temperature phase, as well as the addition of a toughening effect due to the eutectic reaction or solid solution reaction. it is conceivable that.

In addition, in the binary crystal structure mentioned above, CaO, MgO, Y AO3, Ce0 are stabilized in the high temperature phase.
) further improves thermal shock resistance. Its component range is Cr, 10-70% wl, CaO, M
gO.

1-18% of one or more types of Y Yu Og Cab Yu
The remainder was substantially composed of ZrO.

However, even with the above component range, 5 to 5
If particles sprayed with a particle size of 0 μm were present independently, the effect of improving thermal shock resistance would be small. Therefore, at the stage of making thermal spray materials, by processing such as electric melting in advance,
It is important that each thermal spray particle becomes homogeneous during film formation, such as by fusing each component or by granulating particles of each component of 1 μm or less and then subjecting them to a sintering reaction.

Furthermore, when forming a thermal spray coating on the surface of a hearth roll or mud gun nozzle, providing a bond coat layer and a cermet layer is effective in further improving thermal shock resistance.
As its alloy component, CoCrAl! In addition to heat-resistant alloys such as Y, FeCrJY, N1CoCrAJY,
Ni-Cr alloy etc. can be used. Regarding the thermal spraying method, methods using electrical energy such as gas plasma spraying and air plasma spraying are preferred, but film formation is also possible by flame spraying and explosive spraying.

Next, an example will be described in which the reason for limiting the component range according to the present invention was obtained.

<Example> Table 1 shows the components of the thermal spray coating used in the experiment and the results of the thermal shock test and abrasion test.

The sample material is 5US304 and the shape is 50X 30X 5 (
Co-based alloy is thermally sprayed onto this material to a thickness of 0.1 mm, and cermet (50% Co-based alloy + 50% Co-based alloy
% top layer material) to a thickness of 0.15 mm, and test samples were prepared so that the top layer had a sprayed coating of the present invention and a comparative sprayed coating with a thickness of 0.15 mm.

From Table 1, if ZrOλ is less than 30%, the thermal shock resistance will be poor, and if it exceeds 90%, the wear resistance will be poor.
It can be seen that the preferred amount of ZrO is 30 to 90%.

Furthermore, if Cr, 03 is less than 10%, the wear resistance will be insufficient, and if it exceeds 70%, the thermal shock resistance will be poor.

Next, CaO, MgO, YU03. The amount of one or more types of Ce0a, but these oxides are ZrO
It acts to stabilize the crystal structure of Yu.
For this purpose, it is necessary to have a content of 1% or more, but if it exceeds 18%, the wear resistance will deteriorate significantly, so the content should be in the range of 1 to 18%.

<Effects of the Invention> As described above, the thermal spray coating material according to the present invention has excellent abrasion resistance and also excellent thermal shock resistance. Therefore, by forming the thermal spray coating according to the present invention on the surface of a material, it becomes possible to impart high-temperature wear resistance, thereby extending the life of various equipment members and contributing to cost reduction.

Claims (1)

[Claims] 1. A composition containing 10 to 70% by weight of Cr_2O_3, with the remainder substantially consisting of ZrO_2;
A high temperature resistant thermal spray coating material characterized by a fusion of ZrO_2 and ZrO_2. 2. Contains 10 to 70% by weight of Cr_2O_3, and further contains C
Contains 1 to 18% by weight of one or more of aO, MgO, Y_2O_3 and CeO_2, and the remainder is substantially Zr.
Composition consisting of O_2, and also Cr_2O_3 and CaO
, MgO, Y_2O_3 and CeO_2, and one or more of them and ZrO_2 are fused.