JPH02213498A - Method for reforming metallic material surface - Google Patents

Abstract

PURPOSE:To reform the surface of a metallic material and to impart excellent wear resistance and lubricity to the material by dispersing hard powdery fine particles having specified hardness and the fine particles of BN, graphite, etc., in the metallic plating layer of Ni, Co, etc., in specified amts. CONSTITUTION:The composite plating film is formed on the surface of a metallic material as follows by dispersing powdery fine particles in the metallic plating film. Namely, the hard particles of SiC, etc., having 1-5mum grain size and >=900 Vickers hardness and the self-lubricating fine particles of >=1 kind among the BN, graphite and mica having 1-5mum grain size are dispersed in the metallic plating layer of Ni, Ni-P, hard chromium or Co. In this case, the weight ratio of the hard fine particles to the self-lubricating fine particles is controlled to (80:20)-(50:50), and the total content of both fine particles of the metallic plating layer is controlled to 10-25wt.%. The surface-reformed metallic material is specially utilized to improve the wear resistance of a work roll for cold rolling.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for surface modification of metal materials. The invention finds application in materials requiring surfaces with excellent wear resistance and lubrication properties. It is especially used to improve the wear resistance and lubrication properties of work rolls for cold rolling.

(Prior Art) The metal materials of the sliding parts wear out due to friction as the usage time increases. In particular, the wear resistance of the surface of steel sheet rolling work rolls is one of the important roll characteristics in order to improve the surface quality of sheet products and improve the efficiency of rolling operations. Surface roughness, which is one of the indicators, is used as a control standard for the life of rolling work rolls.

Furthermore, materials used in environments where large loads are applied, such as rolling rolls, undergo more rapid wear than normal sliding materials. To increase wear resistance, it is sufficient to increase the hardness of the material itself. Common methods for increasing hardness include quenching/tempering, carburizing, nitriding, and work hardening, but since the entire material is treated, they are time-consuming and tend to be expensive. However, wear resistance is required only in the vicinity of the sliding surface of the material, and therefore, the application of surface modification methods that harden only the vicinity of the sliding surface is currently being considered.

Surface modification methods include thermal spraying, physical vapor deposition, chemical vapor deposition, and plating, in which the surface of the base material is coated with a metal material or ceramic that satisfies the required functionality, and the coating is applied only near the surface. Composite plating (for example, Japanese Patent Publication No. 5B-1808) is known as one of the surface modification methods capable of imparting properties such as good wear resistance and heat resistance. Composite plating is a surface modification method that forms a composite plating film on the surface of a base metal using a plating bath in which eutectoid fine particles are suspended. The composite plating film exhibits excellent properties such as wear resistance, corrosion resistance, and lubricity depending on the physical or chemical properties of the eutectoid fine particles.

On the other hand, as a method to improve lubrication properties, lubricating oil or solid lubricant (graphite,
A common method is to supply a lubricant containing mica (mica, etc.), and various types of lubricant oil are already used everywhere depending on the purpose of use.

(Problem to be Solved by the Invention) However, in order to impart excellent wear resistance to metal materials, high hardness ceramic or cermet coatings are produced using the above thermal spraying method, physical vapor deposition method, chemical vapor deposition method, etc. When it is formed on a metal material, the properties of the coating and the base material (hardness, modulus of elasticity, etc.) are significantly different, so the coating is likely to peel off, making it impractical. When metals or alloys are coated by thermal spraying or plating,
Peeling of the film is less likely to occur compared to the above cases, but it cannot be expected to significantly improve wear resistance compared to conventional materials.Composite plating in which only hard particles are dispersed improves wear resistance, but The lubrication properties are not improved, and a composite plating film in which only self-lubricating powder is dispersed improves the lubrication properties but deteriorates the wear resistance. On the other hand, using lubricating oil may cause problems such as dirt on the surface of the metal material, so it is desirable to use a lubrication method other than lubricating oil for such materials. The present invention provides a method for modifying the surface of a metal material so that it has both excellent wear resistance and excellent lubrication properties.

(Means and effects for solving the problems) The present invention provides a method for forming a composite plating film on the surface of a metal material in which fine powder particles are dispersed in the metal plating film.
-P,octa-dochrome or Co metal plating layer has a particle size of 1 to 5 μm and a hardness of 90 on the Vickers scale.
0 or more fine particles and fine particles consisting of one or more types of ON, graphite, and mica having a particle size of 1 to 5 μI are dispersed in a weight ratio of 80:20 to 50:50, and metal plating is performed. The total content of the fine particles in the layer is 1
The present invention relates to a method for surface modification of a metal material, characterized in that the amount is 0 to 25 wt%.

FIG. 1 shows a schematic cross-sectional view near the surface of a metal material that has been subjected to composite plating. When another mating material comes into contact with the surface of a metal material having such a cross-sectional structure, the actual contact occurs at the outermost surface of the metal material, the powder particles (1).In the case of the present invention, the powder particles are hard particles ( For example, it is a mixed particle of fine powder particles such as SIG (with a Vickers hardness of 900 or more) and particles with high self-lubricating properties (BN, graphite, mica). Hard powder particles, which are harder than metal matrix plating, support surface pressure during sliding and improve wear resistance.
Lubricating properties can be improved by using fine powder particles that are highly self-lubricating. Figure 2 shows the relationship between the abundance ratio of hard powder particles and self-lubricating powder particles in the coating and the wear weight, and Figure 3 shows the relationship between the hard powder particles and self-lubricating powder particles in the coating. The relationship between the abundance ratio and the friction coefficient is shown. When the ratio of hard powder particles to powder particles rich in self-lubricating properties is 50:50 in the film, if more powder particles rich in self-lubricating properties are present, the wear weight will be lower than that of conventional materials (base materials). The larger the size, the worse the wear resistance. If the ratio of hard powder particles to self-lubricating powder particles in the film is greater than 80:20, the coefficient of friction will be higher than that of conventional materials and the lubricating properties will deteriorate. On the other hand, if the total amount of fine powder particles dispersed in the plating film is less than 10 wt%, the effect of the dispersed fine powder particles becomes small and the desired function cannot be achieved. 25
When the content is greater than wt%, the powder particles reduce the strength of the plating film, making it easy for the plating film to peel off. Fourth
The figure shows the relationship between the average particle diameter of hard powder and the wear weight. If the particle size of the hard powder is 5 μm or more, the matrix plating cannot support the particles, and the particles are released from the coating and scratch the plated coating, conversely worsening the wear resistance. Also, the average particle size is 1μ
Powders with a particle diameter of less than m are actually difficult to obtain and expensive, and cannot fully exhibit the effects of the present invention. The metal used for matrix plating can be arbitrarily selected depending on the operating environment conditions of the rolling work roll, and it is necessary to select a metal that has excellent adhesion to the work roll base material. Old, Ni-P, hard chrome, G
o is considered optimal.

Composite plating that achieves the object of the present invention, which is to improve the wear resistance and lubrication properties of metal materials by surface modification of the metal materials, includes electrolytic methods and electroless methods. However, this method is not essential to achieving the object of the present invention, and there is no need to specifically limit the method according to the present invention.

(Example) Example 1 A work roll with a diameter of 400 mm and a barrel length of 100 mg+ was plated with Ni-P+ (SiC, BN) composite plating, and a rolling experiment was conducted. The roll material used is ordinary forged steel roll material for cold-rolled work rolls, and Ni-P + (Sin
, BN) dispersion plating was applied to a film thickness of 10 μm. The finished surface roughness was adjusted to 0.05 μI with R1. The plating bath contained 830 g/l of 60% nickel sulfamate solution, 5 g/l of nickel chloride, 45 g/l of boric acid, 3 g/l of saccharin soda, and 150 g/l of SiC (average particle size 2 μm).
Composite plating is performed using a mixed solution of g/text, BN (average particle size 3 μm) 120 g/, Q, while preventing agglomeration of solid particles by gas agitation with an inert gas, the temperature of the plating bath is 57 ° C. pH is 4.0, current density is 20A/d
It was set as m'. The ratio of hard powder particles and highly self-lubricating powder particles in the composite plating film was 87:33. Using the thus composite plated work roll, a stainless steel plate (SUS430, plate thickness 3.1oon) was rolled using a 3% emulsion using a 4-Hi cold rolling machine for testing (backup roll: diameter φ480mm, barrel length 100mm1). When rolled at a rolling speed of 30%, which was 1.6 times faster than the rolling speed using conventional rolling rolls, no grains or heat streaks were observed, and the surface quality of the product was good.

Example-2 Ring-shaped test piece assuming a rolling roll (size: φ3
0x8m+o; forged steel) is formed with a composite plating film by the method of surface modification of metal materials of the present invention, and a mating piece (size: φ30 x 10 ff1) corresponding to the rolled material is prepared.
A rolling friction test was conducted using a 545G (Test Conditions 2 Table 1). Table 2 shows the composite plating film, solid lubricant, wear amount, and friction coefficient. It was found that all combinations had less wear and a lower coefficient of friction than conventional forged steel.

Table 1 Test conditions (effects of the invention) In the method of the present invention for forming a composite plating film on the surface of a metal material in which fine powder particles are dispersed in a metal plating film, Nl, Ni-P, and hard chromium are The metal plating layer contains hard powder fine particles with a particle size of 1 to 5 μI and a hardness of 900 or more on the Vickers scale, and one or more of BN, graphite, and mica with a particle size of 1 to 5 μm. fine particles with a weight ratio of 80
Abrasion resistance can be improved by a surface modification method for a metal material, characterized in that the fine particles are dispersed in a ratio of 10 to 25:50 and the total content of the fine particles in the metal plating layer is 10 to 25 t6A. This enables surface modification with excellent lubrication properties, reducing product costs and improving productivity and work efficiency. This effect is particularly remarkable in rolling work rolls.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view of the surface of a work roll coated with the composite plating of the present invention, and Figure 2 shows the relationship between the abundance ratio of hard powder particles and highly self-lubricating powder particles in the coating and the wear weight. Figure 3 is a diagram showing the relationship between the abundance ratio of hard powder particles and highly self-lubricating powder particles in the film and the coefficient of friction, and Figure 4 is a diagram showing the relationship between the average particle diameter of the powder and the abrasion weight. It is. 1... Powder fine particles Figure 1 Figure and 4 others wt"10B-- A: Hard powder fine particles B: Powder fine particles rich in self-lubricating properties Figure f Average particle size (m) A:, @7ff;, W, 7g-1 solder powder fine particles The following matters in the specification of this application are amended.Indication of 1° incident on page 3, line 11 Heisei @=4@/ Patent Application No. 3, 8 .37 ``Special Publication No. 5B-1808'' is corrected to ``Special Publication No. 56-18080.'' ” Name: Nippon Steel Corporation 4th Generation / DirectorAddress: 3305° Shigesu Building, 2-6-2 Marunouchi, Chiyoiro-ku, Tokyo Date of Correction Order: 7°Subject of Correction

Claims (1)

[Claims] 1. A method for forming a composite plating film on the surface of a metal material in which fine powder particles are dispersed in the metal plating film,
, Ni-P, hard chromium or Co metal plating layer contains hard powder fine particles with a particle size of 1 to 5 μm and a hardness of 900 or more on the Vickers scale, and a particle size of 1 to 5 μm.
Fine particles made of one or more of BN, graphite, and mica are dispersed in a weight ratio of 80:20 to 50:50, and the total content of the fine particles in the metal plating layer is 10 to 50:50. A method for surface modification of a metal material, characterized in that the content is 25 wt%.