JPS58193357A - Method for surface hardening of metal - Google Patents

Abstract

PURPOSE:To obtain a hardened film on the surface of a metal material, by an easy method wherein a paste containing an autogenous alloy is applied to the surface of a metal and the whole is heated to the m.p. of the autogenous alloy or higher. CONSTITUTION:A homogenous paste consisting of an autogenous alloy powder obtained by adding B and Si to a Ni base, or a Ni-Cr base or a Ni-Co base alloys, a solvent such as alpha-terpineol and a binder such as methyl cellulose is prepared. This paste is applied to the surface of a metal material by a screen printing method, a dripping method, a brush coating method or a spray method. After the obtained coating is dried, it is heated to the m.p. of the autogenous alloy or higher and the solvent and the binder are removed to obtain an autogenous alloy film.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of hardening a metal surface using a self-fusing alloy, and more particularly to a method of hardening a metal surface using a paste containing a self-fusing alloy.

Self-fusing alloys have excellent wear resistance and corrosion resistance, so they are used as surface treatment techniques for the purpose of partially modifying metal materials, such as by thermal spraying and overlay welding. However, when using the thermal spraying method, (1) it is necessary to roughen the surface of the base material by blasting, etc., which may cause deformation of the base material;
(2) The particle size of the powder used must be sharply classified to 44 to 105 microns, resulting in poor powder manufacturing yield.

(3) During thermal spraying, the powder scatters or adheres to areas other than the target, so the efficiency of powder utilization is poor (less than 50% in some cases). (4) Expensive gas is required.

(5) Requires expensive equipment for thermal spraying. (6) It has drawbacks such as a complicated process for surface hardening the coating after thermal spraying.

In addition, when using the overlay welding method, it is difficult to apply to minute parts or to form a thin film, and there is a risk of localized thermal distortion in the base material, which often limits the range of application.

As another method, the use of sheets or tapes made of self-fusing alloys processed with thermoplastic resin has been proposed, but this method is effective for flat parts, but it is not suitable for curved parts or parts with complex shapes. Difficult to apply. Additionally, there are drawbacks such as the need to pressurize the luco to increase its adhesion.

The present invention has been made in order to eliminate all of the above-mentioned drawbacks, and it is possible to obtain the desired self-fusing alloy film by applying a paste containing self-fusing alloy powder and heating it above the melting temperature of the self-fusing alloy. be. According to the present invention, it is possible to obtain a hardened film on the surface of a metal material using a method that is easier than conventional methods.

Further, according to the present invention, there is almost no loss of self-fusing alloy, and the thickness of the coating can be freely adjusted, making it extremely economical. Furthermore, the advantage of the present invention is that coating or printing techniques can be applied, so the shape of the member is not limited, and the range of use is extremely wide, and productivity can also be improved.

Next, the present invention will be explained in detail.

The self-fusing alloy used in the present invention is a Ni-based, Ni-Cr-based or Ni-Co-based alloy with B and Si added, and is made into a paste and heated to 100 to 1100°C after application.
By melting and floating the B and St in the alloy as an amorphous phase with a low melting point, it becomes a car (a film with pores and low oxidation) and has excellent corrosion resistance and wear resistance. These alloys are used after being pulverized to 20 microns or less, preferably 10 microns or less.Particularly when screen printing is used, the smaller the particle size, the better.

The solvent controls the viscosity and ductility of the paste.
It must have good wettability with metal powder, be completely volatilized at a temperature of 200°C or less, and have low toxicity. These include α-terpineol, butyl carpitol, butyl carpitol acetate, butyl cellosolve, turpentine oil, laxalol (2,2,4) dimethyl 1.3bentanediol monoisobutyrate), toluene. , acetone, methyl ethyl ketone, methyl isobutyl ton, butyl glycidyl ether, etc. can be used. The binder should be one that completely decomposes below the melting temperature of the self-fusing alloy and does not leave any carbon in the film after surface hardening. Specifically, methyl cellulose, ethyl cellulose, polyvinyl butyral, dibu, 1-thilphthalate, and abietic acid resin are recommended. , CMC, etc. can be used. If a thermoplastic resin is used as a binder, carbon may remain in the film after surface hardening, and large pores may be formed that deteriorate wear resistance and corrosion resistance, which is not preferable. According to the invention, such drawbacks can be avoided.

Furthermore, it is effective to use a surfactant as a dispersant for the purpose of improving the wettability of the alloy powder with the solvent or uniformly blending the powder binder in the solvent.

Next, the self-fusing alloy powder, a solvent, a binder and, if necessary, a dispersant are blended according to the purpose of use of the film, and thoroughly kneaded to obtain a homogeneous paste. The kneading method may be any commonly used kneading device such as a three-roll mill. .

Next, the paste is applied by screen printing method, drudding (
It is applied to the surface of a metal material using a method such as a dropping method, a printing method, a brush coating, or a spray coating.

At this time, there is no need to roughen the material W1 by blasting or the like, and it is sufficient to keep it clean. The desired thickness of the film can be arbitrarily selected by adjusting the coating thickness of the paste. According to the present invention, it is possible to easily obtain a thin uniform film of 20 microns or less and about 5 microns, which cannot be produced by thermal spraying, by adjusting the viscosity of the paste.

After drying, the film thus obtained is heated to a temperature equal to or higher than the melting point of the self-fusing alloy, and the solvent, binder, dispersant, etc. are removed to obtain a self-fusing alloy film. The heating method may be in an oxidizing air stream, a reducing air stream, or an inert air stream, and may be appropriately selected depending on the target material and the type of target self-fusing alloy. The heating temperature and heating time are not particularly limited either, as long as they are higher than the melting temperature of the self-fluxing alloy and do not adversely affect the material. The melting temperature of self-fusing alloys is usually about 900°C to 1100°C, a temperature at which solvents, binders, dispersants, etc. are completely decomposed.

Next, the present invention will be explained with reference to Examples.

Example 1 100 parts of terpineol as a solvent, 7 parts of ethyl cellulose as a binder, and 2 parts of a dispersant (surfactant S-80 manufactured by Toho Chemical Co., Ltd.) were thoroughly kneaded with three bottles of [ff-lumil] and mixed with a vehicle (base). agent).

C by weight for 20 parts of the vehicle thus produced.
r=10% B=2%, 5i=2%, C-05%, N
80 parts of Ni-based self-fusing alloy powder (particle size of 10 μm or less) consisting of the remainder of i- was added and thoroughly kneaded in a three-roll mill to form a paste.

100rran x 10 with oil and other dirt removed in advance
It was printed on a 100m7iX2 mild steel surface by a screen method, leveled for 15 minutes, and then dried at 80°C for 30 minutes. This was heated to about 1050° C. with oxygen and acetylene flame to obtain a cured film layer with a uniform thickness of about 25 μm. When the cross-sectional structure of this was observed under a microscope, a coating layer that was exactly the same as the thermally sprayed coating layer in which fine hard particles were evenly distributed was obtained.

Example 2 A paste with the same composition as in Example 1 was diluted with α-tervineol to a solid concentration of 30 parts, and this was mixed into a 108-g plate in the center of a 100-100 mm x 1002 am stainless steel plate from which oil and other stains had been removed. It was dotted (dropped) into the recess of 311n using a dispenser. then 8
It was dried at 0°C for 30 minutes. This was heated to 900°C in a soaking furnace.
When heat treated for 1 hour, a cured film layer with a uniform thickness of about 7 μm could not be obtained.

When the cross-sectional structure of this was observed under a microscope, a coating layer that was exactly the same as the thermally sprayed coating layer in which fine hard particles were evenly distributed was obtained.

Example 3 A paste having the same composition as in Example 1 was applied with a brush to a stainless steel plate with a thickness of 2 mm, from which oil and other stains had been removed in advance.

Thereafter, it was dried at 80° C. for 30 minutes. This was placed on a net conveyor and passed through a heating furnace in a nitrogen stream atmosphere at a peak temperature of 900° C. for 45 minutes, resulting in a cured film layer with a uniform thickness of approximately 1301 tons. When the cross-sectional structure of this was observed under a microscope, a coating layer that was exactly the same as the thermally sprayed coating layer in which fine hard particles were evenly distributed was obtained.

Example 4 Texanol (2,2,4) riftyl 1 as a solvent,
To 100 parts of 3-bentanediol monoisobutylene), 5 parts of ethyl cellulose as a binder and 2 parts of a dispersant (S.80 manufactured by Toho Chemical Industry Co., Ltd.) were added and kneaded well with a three-roll mill. Something was used as a vehicle.

The weight ratio of Cr to 15 parts of the vehicle thus prepared was
= 10%, B = 2%, 5i = 2.2%, Fe = 25%, C = 0.45%, 85 parts of Ni-based self-fusing alloy powder (particle size 10μ or less) consisting of residual Ni was added and three more The mixture was thoroughly kneaded with a roll mill to form a paste.

This is 100 + lll x 10 with oil and other dirt removed in advance.
Printed on a Q m x 2 m mild steel surface using the screen method.
After leveling for 5 minutes, it was dried at 80° C. for 30 minutes.

When this was heated to about 1050° C. with an oxygen/acetylene flame, a cured film layer with a uniform thickness of about 75 μm was obtained. When the cross-sectional structure of this was observed under a microscope, it was found that the structure was exactly the same as that obtained by the thermal spray welding method, in which fine hard particles were scooped and distributed.

Patent applicant: Showa Denko Co., Ltd. 3111 Patent Attorney Sei Kikuchi

Claims (1)

[Claims] A metal surface characterized in that a homogeneous paste composed of a self-fusing alloy powder, a solvent, and a binder is applied to the metal surface, and then heated to a temperature higher than the melting temperature of the self-fusing alloy to obtain a hardened coating layer. curing method.