JPS60262954A - Powder for spraying - Google Patents

Abstract

PURPOSE:To obtain an inexpensive material for spraying giving a sprayed film having superior heat, corrosion and wear resistances and capable of undergoing smooth finishing by mixing ferrochrome powder with stainless steel powder so that iron and Ni contain prescribed amounts of Cr and C. CONSTITUTION:About 40-80wt% ferrochrome powder is mixed with about 10-50% stainless steel powder to obtain a material for spraying having a composition consisting of 27-70% Cr, 1.6-6.5% C and the balance Fe and Ni. The material for spraying contains C in the form of Cr-Fe carbide, and it is necessary that Cr and Ni are in the form of a Cr-Ni-Fe alloy. A sprayed film having especially superior abrasive wear resistance is obtd. by using the material for spraying.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a powder material for thermal spraying for forming a film on the surface of a metal material, and in particular, it has excellent abrasion resistance, abrasive wear resistance,
The present invention relates to an inexpensive thermal spray powder suitable for obtaining coatings with excellent corrosion resistance.

In recent years, there has been an increasing demand for internal combustion engines to be smaller and lighter and to have higher output, and internal combustion engine components are now required to have higher wear resistance and seizure resistance.

Conventionally, in order to meet such requirements, porous chrome plating has been applied to the surface of the member, which has been used as a material having a high melting point φ, high hardness, excellent corrosion resistance, and retains lubricating oil appropriately. However, the current situation is that, among the recent requirements for materials, properties that satisfy the wear resistance, particularly abrasive wear resistance, have not been obtained.

In order to meet these demands, many attempts have been made to form thermal spray coatings on the surfaces of metal materials to improve wear resistance, corrosion resistance, and lubricity. Conventionally, thermal spray materials include various metal powders, oxide powders, and composite powders thereof, depending on the characteristics required for the coating. Among these thermal spraying materials, metals such as molybdenum, cobalt, and nickel have the hardness, wear resistance, and corrosion resistance that can be used for mechanical parts, and can provide a good thermal sprayed surface finish. , nickel, chromium-based self-fusing alloys, various cermets, and chromia.

There are ceramic materials such as titanium carbide. However, the ceramic sprayed materials currently in use have the disadvantage that although they have high hardness, they are brittle and wear out significantly in environments where high loads and impacts are applied. Further, among various metal materials, molybdenum and self-fusing alloys are easy to thermal spray and have excellent performance, and have obtained fairly good results in terms of relative wear. However, in terms of oxidation resistance and wear resistance at high temperatures, they cannot withstand the harsh conditions imposed on modern internal combustion engines, and even better wear resistance and seizure resistance are required.

The purpose of the present invention is to provide a thermal sprayed coating that exhibits excellent heat resistance, corrosion resistance, and abrasion resistance, and in particular exhibits excellent performance in abrasive wear resistance, and that is easy to spray and can be finished with a smooth coating surface. The purpose is to provide inexpensive thermal spray materials.

Since the thermal spray material of the present invention has the above-mentioned properties, it is suitable for coating the surfaces of mechanical parts, particularly sliding parts such as pistons and cylinders of internal combustion engines.

The present invention uses chromium-iron carbide ((Or, Fe)7c3) in ferrochrome, which has high hardness and is inexpensive, as a hard phase component that contributes to wear resistance. In order to compensate for this deficiency, stainless steel, which has low hardness but excellent toughness and corrosion resistance, is mixed as a binder phase component to prevent the occurrence of cracks caused by the lack of toughness of chromium and iron carbide, and to improve wear resistance and This makes it possible to obtain a tough thermal sprayed coating with excellent corrosion resistance. For example, coatings made from thermal spray materials made of high carbon ferrochrome (FCrH) and molybdenum (MO) that have been used so far have high hardness but lack toughness and have poor wear resistance under heavy loads. Also, low carbon ferrochrome (FCrL) and FGtH,N.

Similarly, coatings using thermal sprayed materials consisting of FCrL and FCrL had problems in wear resistance due to lack of toughness. That is, it is necessary to use some kind of binder phase to prevent the particles from falling off due to insufficient toughness of the hard, wear-resistant phase. The tendency for wear-resistant particles to fall off due to lack of toughness is greater in highly hard materials, and this also depends on the original properties of the material.

For example, the hardness of l1lO as a thermal spray coating is Hmer4.
00 to 600, which is not very large, but the inherent brittleness of MO causes the film to fall off, resulting in increased wear under heavy loads, or abrasion wear.

On the other hand, in order to improve these points, there are also attempts to use a self-fusing alloy phase as a binder component.

The self-fusing alloy phase has a hardness of Hmer 400 to 600, and the alloy itself has good toughness, but because the melting point is low and the strength is high, the tension of the sprayed coating is large and the bonding force between particles is weak. When observing the film, )lo and FCr)
In the case of l, the fracture due to cracks progresses within the grains of the individual coatings and they fall off, but in self-fusing alloys, the unit of this fracture is large, and the shedding is larger under heavy loads. Significant wear will occur under dynamic friction.

In order to eliminate the above-mentioned drawbacks, the present invention uses a stainless copper phase as a binder phase, which has a relatively low hardness of 200 to 400 but has excellent toughness, and has a relatively low tension within the film. The objective is to improve the wear resistance under the

Furthermore, stainless steel itself has excellent oxidation resistance, heat resistance, corrosion resistance, and thermal sprayability.

The thermal spraying material of the present invention is obtained by mixing 40 to 80% heavy electric ferrochrome powder and 10 to 50% by weight stainless steel powder, and its composition is 27 to 70% chromium and 1.6 to 8% carbon. .5% by weight, with the remainder being iron or iron and nickel and incidental impurities. In this case, carbon must be contained as a carbide of chromium and iron, and chromium and nickel must be alloyed with iron.

The reasons for limiting each component are as follows.

Carbon forms carbide with chromium-iron and contributes to wear resistance, so if it is less than 6% by weight, there is a lack of carbide, low hardness and poor abrasive wear resistance.
If the carbon content is 8.5% by weight or more, there will be too much carbide and the film will become brittle.

Since chromium exists as chromium-iron carbide and also forms an alloy with iron and contributes to improving toughness, it is necessary to include the total amount of 27 to 70% by weight. chrome is 2
If it is less than 7% by weight, the hardness is insufficient, and if it is more than 70% by weight, it becomes brittle.

The remainder of the sprayed material is iron or iron and nickel and incidental metals.
It consists of a blunt material, and iron or iron and nickel are mainly alloyed with chromium.

Ni has the effect of increasing toughness and improving abrasive wear resistance, so it may be included in an appropriate amount.The appropriate amount of Ni is 5 to 13% by weight, and if too much is added, the wear resistance will deteriorate.

Even if other components are included to the extent that they are added to stainless steel, there is no particular problem in obtaining the effects of the present invention.

The ferrochrome powder used in the present invention is chromium.
Since iron carbide is used, it is essential to use commercially available high carbon ferrochrome. In addition, medium-carbon ferrochrome or low-carbon ferrochrome may be used as long as the requirements of the present invention are met. These ferrochrome powders can be prepared by mechanically crushing an ingot or by blowing gas onto a molten metal. can get. The size of the ferrochrome powder particles is 150 μm or less, preferably 10
Preferably, the particles are sized to 74 gm.

Furthermore, the stainless steel powder used in the present invention is 5 tl.
Ferritic stainless steel represented by S430,
It is also possible to use austenitic stainless steel such as SOS 304, and even stainless steel containing No. such as SOS 31B. Stainless steel powder is generally manufactured by the 7tomizing method, and the preferred particle size of the powder is 1507 tm or less, similar to ferrochrome powder, and preferably sized to 10 to 744 m.

The above powders are blended in a predetermined ratio and mixed uniformly to form a powder for thermal spraying.

In the present invention, the mixture is used as it is for economical reasons, but it is also possible to use it as a composite powder using an appropriate binder. In that case, the particle size is 150I.
Lm or less, preferably 10~? It goes without saying that thermal spraying workability improves when the particles are sized to 4#Lm.

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

Examples Ferrochrome powder, stainless steel powder, and ferromolybdenum powder as shown in Table 1 were uniformly mixed in the proportions shown in Table 2 to prepare a thermal spraying material.

(Left below) Next, a thermal spray coating was made using the above thermal spray material, and the hardness was measured (
B), Blast erosion test (B).

E, Te5t), a lap test (LP Text) was conducted.

The conditions for each test were as follows.

1. Thermal spraying material Thermal spraying equipment; Thermal spraying equipment manufactured by Plasmadyne SG-100 Conditions; Ar= 4 (IQ/win,)le=
155L/win.

powder gas (At) = 7.5Jl/sin
.

powder = 50g/sin.

Input = eooA, 35V.

Spraying distance = 100 mm, thermal spraying 2, test conditions (1) Cross-sectional hardness measurement (Hw (θ, 5)) Q, ls-sprayed on normal steel material, cut and polished, and measured with a Micro Vickers hardness meter manufactured by Shimadzu Corporation. Measured with a load of 500g (2) Blast erosion test (B, E, Text)
■Sample size 3 0.3mmt thermal spraying on X50XBO steel ■Spraying flame test last equipment: Fuji Seisakusho l FIIK-2yJ.

Nozzle inner diameter = 91. Distance = 100m intestine.

Blasting pressure = 4.0kg/crn'.

Blast material: Showa Denko A-40.

Particle size = -32 mesh + 80 mesh.

Test piece nozzle angle = 30°.

Blasting time = 10 sec (3) Lap test (LP Te5t) Sample size Outer diameter + 10v + eX Inner diameter 101s + s
kg, test time = 2 (twin.

Abrasive: Showa Denko A-Boo cloud, 20g/Amount of cross abrasive used: Table 2 shows the measurement results when using IOg/10ml or more.
Also listed in

As is clear from the results, it can be seen that the thermal sprayed coating using the solvent material according to the present invention has superior wear resistance compared to the thermal sprayed coating made of ferrochrome alone or stainless steel alone. This is a unique effect resulting from not only matching the composition, but also combining the effects of chromite carbide and stainless steel.

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

Claims (1)

[Claims] l) Ferrochrome powder and stainless steel having a composition containing 27 to 70% by weight of chromium, 1.8 to 6.5% by weight of carbon, and the balance consisting of iron or iron and nickel and incidental impurities. A thermal spray powder characterized by being mixed with steel powder. 2) The thermal spraying powder according to claim 1, wherein the ferrochrome powder is a high carbon ferrochrome powder. 3) The thermal spraying powder according to claim 1, wherein the ferrochrome powder is comprised of a high carbon ferrochrome powder and a low carbon ferrochrome powder. 4) The thermal spraying powder according to claim 1, wherein the stainless steel powder is a ferritic stainless steel powder. 5) The thermal spraying powder according to claim 1, wherein the stainless steel powder is austenitic stainless steel.