JPS59126772A - Melt spraying material having build-up resistance - Google Patents

Abstract

PURPOSE:To provide a titled metal spraying material having an excellent effect for preventing scale deposition by making the same substantially consist of a ceramic of Cr7C3 and/or Cr3C2 and mixing the same adequately with other ceramics or heat resistant metals. CONSTITUTION:A melt spraying material having build-up resistance contains >=50wt% Cr7C3 and/or Cr3C2 as a ceramic, and consists of a mixture composed of other ceramics or heat resistant metals and is used to form a coating layer on the surface of, for example, a roll for conveyance in a heat treating furnace for iron and steel in order to provide the effect of preventing scale deposition on the surface of such roll. Oxide, nitride, carbide, boride, etc. of Si, Al, Zr, Cr, Ti, Mg, Mo, etc. are used as the ceramics to be incorporated into said material in addition to the above-mentioned Cr7C3 or Cr3C2. On the other hand, heat resistant metals such as Ni, Cr, Mo, Co or their alloy, etc. are suitable for the metal. The melt spraying is accomplished by a method of heating to melt the melt spraying material by a high temp. heat source such as the flame of combustion gas or the like and forming the coating layer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal spray material with excellent build-up resistance made of ceramic or a mixture of ceramic and metal.
For example, by forming a coating layer on the surface of a transport roll in a steel heat treatment furnace, the effect of preventing scale adhesion on the roll surface is provided.

Since the transport rolls that carry and transport the heat-treated material in the steel heat treatment furnace are exposed to a high-temperature atmosphere, a so-called pick-up phenomenon occurs in which scale (oxide) of the heat-treated material adheres to the roll surface. This phenomenon is particularly noticeable in silicon steel plate heat treatment furnaces. When scale adheres to the roll surface, the surface of the subsequent heat-treated material is scratched, which causes surface defects in the rolled product.

Conventionally, as a countermeasure, a coating layer made of ceramic or cermet, which is a mixture of ceramic and metal, was formed on the roll surface by thermal spraying in order to provide build-up resistance (ability to prevent scale adhesion). It is being done. The ceramics include M2O3, ZrO
2,0r20B, WC, etc. are used, and the cermets include the above ceramics, Or, Ni, Co1Mo.
A mixture of these and other ingredients is used.

However, although these conventional coating layers made of ceramic or cermet are effective in improving heat resistance and abrasion resistance, they are still not sufficiently effective in terms of build-up resistance. An immediate solution is strongly requested.

The present invention is based on the knowledge, as a result of various experiments conducted in order to meet the above-mentioned requirements, that among various ceramics, chromium carbide, especially 0r70a and CrBO2, are effective in improving the build-up resistance. It has been done.

The build-up resistant thermal spray material of the present invention may be one or two types.
Consisting of more than one ceramic or a mixture of ceramic and metal, its essential components are 0r7Q3 and 0r
It is characterized in that it contains one or both of BO2 and its content is 50% by weight or more.

The present invention will be explained in detail below. In addition, in the following description, all "%" indicating the content of the constituent components of the thermal spray material are weight %.

In addition to 0r70B and 0rBO2, chromium carbides include 0r2BO6 and Cr80, but 0r70B and 0rBC2 have a remarkable effect on improving the hilt resistance, and 0r2BO6 and Cr3C
None of them come close to these. Therefore, the present invention provides 0r
70B and OrB 02 or both (
Hereinafter, this will be referred to as [CrC*l] as an essential component.

The build-up resistant thermal spray material of the present invention consists essentially of CrC.
In addition to being composed only of *, it is also composed of a mixture of CrC* and other ceramics and metals. As a mixture, a mixture of CrC* and other ceramics, C
Examples include a mixture of rC* and a metal, or a mixture of CrC*, another ceramic, and a metal.

C when the build-up resistant thermal sprayed material of the present invention is composed of a mixture of CrC* and other ceramics or metals
The content of rC* is 50% to ensure build-up resistance.
% or more.

When 0r70B and Cr3C2 are used together, the total amount may be 50% or more. When a metal is used as a component, the metal in the mixture serves as a bonding metal between the ceramic particles and contributes to improving toughness and the like. The blending amount should be determined by taking into consideration the desired heat resistance, abrasion resistance, etc. of the target thermal spray material.
The amount may be adjusted appropriately within the range of 0% or less.

Ceramics other than CrC* constituting the mixture include:
For example, Si-, A1% Zr% Cjr-, T1
% average, oxides such as MO, nitrides, carbides, borides, etc., while metals include, for example, NiN11CrS, CO
1 or alloys thereof (Ni--Cjr, etc.), and one or more of these ceramics and metals are appropriately selected depending on the intended use and required performance.

The build-up resistant thermal sprayed material of the present invention is used as a coating layer on a conveyor roll in a heat treatment furnace, for example, to prevent scale adhesion on the roll surface. As is well known, there are various thermal spraying methods for forming the coating layer, but in short, the thermal spraying material is heated and melted using a high-temperature heat source such as a combustion gas flame, high-frequency generated heat, or plasma flame, and the melting A coating layer is formed by spraying particles at high speed onto the base metal surface (which has been roughened by sandblasting or grid blasting as a pretreatment) to a desired thickness. It is. Any method may be used to form the coating layer made of the thermal spray material of the present invention. The thermal spraying material may include a ceramic powder consisting essentially only of CrC*, a mixed ceramic powder consisting of Orb* and other ceramics, and a ceramic powder prepared to meet the provisions of the present invention.
The metal powder may be a cermet powder made of CrC*, other ceramics, and metals, or may be formed into a linear or rod shape.

Furthermore, the build-up resistant thermal sprayed material of the present invention can be used to form heat treatment furnace components such as conveyor rolls and other various components for high-temperature applications that require build-up resistance. These parts are manufactured by powder metallurgy using ceramic powder made of Cra* as described above, or a ceramic powder or cermet powder mixture made of CrC* and other constituents, by a conventional method, compacting, molding, and molding. It can be manufactured by subjecting it to various sintering processes. Of course, the raw material powder may be appropriately mixed with known forming aids and sintering aids as necessary, as in the case of ordinary powders.

Next, the hilt and swelling resistance of the material of the present invention will be specifically explained with reference to Examples.

Example substrates (steel plates) having thermal sprayed coatings having various compositions shown in Table 1 on their surfaces were used as test materials, and a build-up resistance test was conducted on each of them.

Flavoring (1) to (10) are examples of the present invention, (101) to (10)
7) is a comparative example. The manufacturing conditions and build-up resistance test conditions for the sample materials are as follows.

(AI) Production of compact test pieces Raw material powders include CrC* powder, other ceramic powders, or metal powders (particle size: 50 to 150 μm)
are blended to have a predetermined component composition, mixed uniformly to form a thermal spraying material, and this is used as a base material (SOI (22,50 mm x 50 mm).
Thermal spraying is applied to the surface of
A sprayed layer of xm was formed.

CB) Build-up resistance test procedure 8841 material (10ff
Heat and hold at °C for 1 hour to generate scale on the surface.
This was placed on the surface of each of the molded body test pieces, and 500y□
In the state of pressing with a load of 2, heat the furnace (atmosphere: temperature 12
00°C 195%N2-5%02, containing water vapor), 2
Leave it for 4 hours. Next, a molded product test piece is taken out and the amount of scale adhering to its surface is measured.

The test results are shown in the right column of Table 1. However, the scale adhesion amount is expressed as the weight increase (%) of the molded product test piece.

As is clear from the same table, the examples of the present invention have almost no scale adhesion and have excellent build-up resistance. Incidentally, among the comparative examples, fragrance 106 and 1
07 (containing a small amount of OrC!*) has less scale adhesion than other comparative examples, but OrC! *Due to insufficient amount, the build-up resistance does not match that of the present invention.

As described above, the build-up resistant thermal spray material of the present invention is
Compared to conventional ceramics and cermets, it has a significantly superior ability to prevent scale adhesion. For example, by forming a coating layer on the conveyor rolls associated with heat treatment furnaces by thermal spraying, etc.
It almost completely eliminates scale adhesion, improves and stabilizes the surface quality of steel materials, increases roll durability, and greatly contributes to stable and efficient furnace operation. Of course, its use is not limited to rolls, but in other words, it is applied to various high-temperature parts that require build-up resistance, and is not limited to simply being used as a coating layer, but also as a molded body to form high-temperature parts. This produces the same effects as above. In addition to build-up resistance, the material of the present invention has various properties similar to those of ordinary ceramic materials and cermet materials, such as wear resistance, heat resistance, and corrosion resistance, making it suitable for applications that require these characteristics. Needless to say, it is suitable.

Agent: Patent Attorney Shinhachibe Miyazaki

Claims (1)

[Claims] (1) One or more types of ceramic or a mixture of ceramic and heat-resistant metal, which as a ceramic,
A build-up resistant thermal spray material characterized by containing 50% by weight or more of 0r7C8 and/or CrBO2.