JPS5867804A - Method and apparatus for forming anti-wear film - Google Patents

Abstract

PURPOSE:To form an anti-wear film with high density easily in the thickness control thereof, by a method wherein the layer of a metal powder prepared by containing B, Si, Fe and C in Ni-Cr or Cr-Co-Ni is formed on the surface of a metal and this powder layer is sintered under pressure. CONSTITUTION:A recessed part 3 is formed to the inside surface 2 of a cylindrical metal body 1 and a metal powder prepared by containing B, Si, Fe and C in a Ni-Cr base alloy or a Cr-Co-Ni base alloy as essential components is coated to the formed recessed part by using a binder to form a metal powder layer 4. To the entire periphery of the inside surface 2, a cylinder 5 comprising a thin plate is fixed to hold the metal powder layer 4 in a gastight state. This metal body 1 is contained in a container 8 and the metal powder layer 4 is subjected to compression treatment by supplying a high pressure gas such as an Ar gas from a bomb 10 by using a pressure increasing device 11. In this case, the metal body 1 is heated by a high frequency induction coil 9 and the gas contained in the powder layer 4 is degassed through an exhaust orifice 7 by operating vacuum pump 12. After cooling, the exhaust orifice 7, the cylinder 5 and a protruded part are removed by cutting.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a wear-resistant coating and an apparatus used therefor, and more particularly, the present invention relates to a method for forming a wear-resistant coating and an apparatus used therefor. The present invention relates to a method for forming an abrasion-resistant coating that is easy to obtain, requires a short processing step, and has a high product yield, and an apparatus used therefor.

In various machines and mechanisms, there are many component parts that are forced to slide against each other during their operation, and the solid metal surfaces that make up these parts naturally require a high degree of wear resistance. One example of this is the control rod drive mechanism of a zero-boiling watercolor reactor (BWR). Since the parts such as these slide, it is also desirable that they have wear resistance.

Therefore, the sliding surfaces of the control rod drive mechanism parts of the BWR, such as the inner surface of the spacer, are coated with a coating to increase the wear resistance of the surface. Conventionally, such a method involves forming a wear-resistant metal coating on the surface of a metal body using a thermal spraying method or a thermal spray welding method. However, 1. Thermal spraying requires steps such as sandblasting the surface to be treated, applying VK of wear-resistant metal powder by thermal spraying, and welding, making it difficult to control the coating layer thickness. There was a drawback that the yield was low because voids were likely to be formed in the coating metal layer.

Thermal spray welding uses a self-fluxing alloy and performs spraying and welding of metal powder in one step, making the process a little simpler, but it takes a long time to process, resulting in extremely low processing efficiency, and the coating metal layer It has the disadvantage that voids are easily formed and the yield is low (80% at most).

It is an object of the present invention to overcome the above-mentioned drawbacks of conventional methods for forming wear-resistant coatings, to form a high-density coating layer whose thickness is easy to control, and to form a coating layer in one processing step. The object of the present invention is to provide a method for forming a wear-resistant coating that has a short time and a high product yield, and an apparatus used therefor.

That is, the method for forming a wear-resistant coating of the present invention is a method for forming a wear-resistant coating on the surface of a metal body, and the method includes forming a wear-resistant coating on the surface of a metal body. (Cr), cobalt (Co) and nickel (Ni) as main components, boron (B), silicon (Si), iron (Fe)
After forming a metal powder layer containing carbon (C) and carbon (C), the powder layer is pressure sintered.

As mentioned above, the metal powder used in the present invention is Ni-
Cr group (Ni: 70-90 lit%, Cr
10 to 30% by weight) or Cr-Co-Ni groups (Cr
: 15-25% by weight, Co: 45-65% by weight, Ni: 20-30% by weight). 3i,
It contains Fe and C as essential components. Ni-Cr or Cr-Co-Ni contained as main components
F! About 80-90% by weight or 1 it% is preferred. In addition, B is 1-4%, Sl is 3-5'vNh1%, and Fe is 4-4%.
Preferably, the content is 1% by weight and C is 0.6 to 0.9 m%. In addition to the ingredients listed below, the metal powder contains fj
A(Cu) may be added to the coating, and adding kneading improves the bonding strength between the surface to be treated and the coating metal. Furthermore, molybdenum (Vo), tungsten (W), and tungsten carbide (WC) may be added, and these have the effect of further improving wear resistance.

The metal powder used may be a mixture of powders of the above-mentioned component metals, or may be a powder obtained by alloying some or all of the component metals.

In addition, when the metal body is a component M of a nuclear reactor such as a control rod drive mechanism of a BWR, it is not preferable to include conomalt, so it is preferable to use a Ni-Cr based metal powder. Unless there are other special circumstances, Ni
Either a -Cr group or a Cr-Co-Ni group can be used to form a sufficiently wear-resistant coating.

The particle size of the metal powder is preferably 100 to 325 mesh,
In order to obtain a uniform coating layer, the width of the particle size distribution is preferably 111Iφ.

When applying the method of the present invention to form a wear-resistant coating on a flat surface of a metal body having a simple shape such as a plate or a column, for example, the metal Forming a metal powder layer on the surface of the metal body by contacting a powder compact in the form of a thin layer or root shape, or by applying a mixed powder obtained by adding an appropriate binder to the metal powder, A method of pressure sintering the powder using a hot F-press is applicable. In this case, sintering is preferably carried out in vacuum or in an inert gas such as argon or helium.

In addition to the above-mentioned planar parts of metal bodies such as plates and columns, the individual iJ function can also be applied to surfaces to be treated that have relatively rough shapes, such as the inner surface of a cylindrical metal body. In the method of the present invention, a metal powder layer is formed by applying a mixed powder obtained by adding an appropriate binder to the metal powder on the surface of the metal body. Examples include a method in which the layer is heated while applying high-pressure gas, and then the powder layer is sintered under pressure.

In this case, it is preferable to cap the metal powder layer with a thin plate made of mild steel or the like and apply high pressure gas through the thin plate because the entire metal powder layer is compressed under equal pressure. Further, if the metal powder layer is kept in an airtight state by the thin plate,
Densification of the metal powder layer by pressure sintering is well achieved.

In this method, the powder layer has high UE at room temperature.
Mit in the pressure sintering process by applying gas, etc.
1. When the powder layer is compressed in advance, the contact area between the metal powders increases, the thermal conductivity improves, and the sinterability of the metal powder layer increases. Furthermore, if the gas contained in the metal powder layer made into an airtight state is degassed before and/or during the pressure sintering process, air will be removed, which causes the formation of impurities such as sulfides. Alternatively, a gaseous component such as a binder can be removed from the powder layer. ``During pressure sintering, the inside of the metal powder layer becomes a vacuum state, and pressurization with high-pressure gas can be performed efficiently, which is preferable.

The high pressure gas is preferably an inert gas such as argon or helium. The sintering temperature is lower than the temperature at which crystal grains of the metal powder grow, that is, 1020 to 10
The temperature is preferably 80°C, more preferably 1025 to 1050°C.

Next, in the case where the surface to be treated is the inner surface of a cylindrical metal body, such as a spacer used in a control rod drive mechanism of a BWR, an embodiment of the method of the present invention will be described below in accordance with the attached drawings. will be explained in detail.

FIG. 1 is a schematic diagram showing a state in which a metal powder layer is formed on the inner surface of a cylindrical metal forming unit by applying the method of the present invention.

FIG. 2 is a schematic diagram illustrating the configuration of the wear-resistant coating forming apparatus 1'' of the present invention and the state in which a metal powder layer is subjected to pressure sintering using the electric generator.

In the example of FIG. 1, the entire 1r of the inner surface 2 of the cylindrical whole body
, l, a four part 3 is formed, and within the four part 3,
For example, if Cal is added to the metal powder, oxymethyl tenululose salt (
A mixed powder obtained by adding an appropriate binder such as CMC) is implanted and filled to form a metal powder layer 4.

A cylinder 5 made of a thin plate of mild steel or the like is fixedly attached by welding to each of the convex parts 6 and 6' at the upper and lower ends of the inner surface over the entire circumference of the inner surface 2, and by the circle 115. , the metal powder layer 4 is in an airtight state. When the airtightness of the powder layer 4 is inspected using, for example, a Freon or helium leak detector, it is found that the protrusion 6 at the upper end of the powder layer 4 is provided with an exhaust hole 7 for degassing the gas contained in the powder layer. There is.

Thus, the apparatus of the present invention for pressurizing and sintering the metal powder layer formed on the surface of the gold body includes: an airtight container that houses the gold body with a metal powder layer formed on the surface thereof; It basically consists of a heater that heats the metal body contained therein, and a gas supply source that supplies high-pressure gas into the container.

The same elements as in FIG. 1 are represented by the same symbols. In the example of FIG. 2, a high-frequency induction coil 9 is provided in an airtight container 8 made of steel for high-temperature, high-pressure vessels, alloy steel, etc.
The metal body IK on which the metal powder layer 4 is formed is arranged so as to surround the metal body IK. An argon gas tank 10 is placed outside Kld of the container 9, and supplies high pressure gas into the container via a pressure intensifier 11. 12IIi, a vacuum pump connected to the exhaust hole of the metal body housed in the container to evacuate the gas in the metal powder layer 4;

Forming a wear-resistant coating using the apparatus shown in Figure 2
In this case, the metal body 1 on which the metal powder layer 4 has been formed is housed in a predetermined position in the container 8, and the exhaust hole 7 is connected to the vacuum bonder 1.
After connecting with 2, using cylinder 1° and pressure intensifier 11,
High-pressure gas is supplied into the container 8 at room temperature to compress the metal powder layer 4.

Next, the vacuum bonder 12 is operated to remove the gas contained in the powder layer 4. At this time, it is preferable to use the coil 9 and heat the metal body to 400 to 500 degrees Celsius because oxygen, binder, etc. contained in the powder layer can be easily discharged. The degree of vacuum in the layer is I
It is preferable to carry out the process at a temperature of 10-” torr or less,
After the treatment, the exhaust hole may be sealed by pressure welding.

After performing the room temperature compression treatment and deaeration treatment, the +
While supplying high pressure gas from the R pump 10 into the container 8,
The metal powder layer 4 is heated by the coil 9 and sintered under pressure. During this pressure sintering, the powder layer 4 may be deaerated by operating the vacuum bonnet 12.

The example in Fig. 2 is for the case of one piece of metal to be processed, but for example, if multiple heaters are provided in the same airtight container, two or more metal pieces can be pressure sintered at the same time. It can also be processed.

Next, after cooling, the metal body with the metal powder layer subjected to pressure sintering treatment is taken out from the container, and the exhaust hole, cylinder, and convex portion are removed by cutting force ILL, etc., and the inner surface is A cylindrical metal body provided with a wear-resistant coating is obtained.

According to the method for forming a wear-resistant coating of the present invention and the apparatus used therefor, the thickness can be easily controlled and a high-density coating can be formed on the surface of a metal body, usually in the range of 1 to layers can be formed. Further, according to a method in which pressure sintering is performed by heating the powder layer while applying high-pressure gas, a coating layer with high density and less segregation can be obtained.

In addition, the process of sandblasting is omitted, and by adjusting the thickness of the powder layer and the pressing force during sintering, it is possible to obtain a coating layer with a desired thickness in just one process. In addition to being simple, the carbide is fine and uniformly distributed in the coating layer that is formed, resulting in uniform performance over the entire cross section, and the inconvenience of creating pores in the coating layer is eliminated. Therefore, the product yield is also high.

Therefore, the method of the present invention is as follows: 1. Applying a wear-resistant coating to sliding parts that require wear resistance, such as the above-mentioned spacers and other parts used in the control rod drive mechanism of the BWR.
This is an extremely useful method.

EXAMPLE A wear-resistant coating was formed on the inner surface of a spacer using the method and apparatus of the present invention, illustrated schematically in FIGS. 1 and 2.

il), the same elements as in Figures 1 and 2 are represented by the same symbols, and are made of 5US304 and have an outer diameter of 1061Jl's.
87 yen, 74% Ni (weight it%, the same applies hereinafter) to the four parts 3 formed on the inner surface 2 of the spacer l with a length of 130 mm
, Cr 13.5%, B 3.0%, St 4.25
%, CO, 75%, and p'e 4.0%, and the average particle size is 3f1m. A metal powder layer 4 was obtained by applying and filling powder.

Next, a cylinder 5 made of a thin flat plate is attached over the entire circumference of the inner surface 2, and is attached by welding to the (!1 parts 6 and 6'), and an exhaust hole 7 is made in the mortar &6. Crotch "Rita."

Thus, the metal body 1 with the gold powder layer 4 formed thereon is housed in an airtight chamber 8, and the argon gas pump 10 and the pressure intensifier 11 are placed inside the airtight chamber 8.
Apply an FF force of 300 kliJ to the container at room temperature using
/aI of argon gas is supplied to transfer the powder layer 4 to the cylinder 5.
After isobaric compression via high 1. ! 1. Wave induction coil 9
The powder layer was heated to 450° C. using a vacuum tube 7'12, and the powder layer was heated to
The degree of vacuum was set to rr. Next, the thus cold-pressed and degassed metal powder layer was made into 1025'C1aML,
Argon gas at a pressure of 1ooky/al was supplied into the container and maintained for 30 minutes to sinter the powder layer under pressure.

After the spacer with the metal powder layer subjected to pressure sintering is cooled, it is taken out from the container, and the exhaust hole, cylinder, protrusion, etc. are removed by cutting, and a wear-resistant coating is formed on the inner surface of the spacer. I got 20 pieces.

Next, we cut 20 of the obtained spacers and observed the cross section of the coating layer under a microscope. It was found that the coating layer was firmly bonded to stainless steel, had little segregation, and was uniformly distributed over the entire coating layer. Carbide was distributed. Product yield is 95
% or more.

Thus, by the method of the present invention, a wear-resistant layer can be formed into J&L.
20 fQ spacers and, as a comparative example, a wear-resistant outer covering M layer with a thickness of 1.5 to 211 m was made using the conventional stone printing method.
After cutting the spacer, a fixed test piece for the Amsler set wear test was prepared by machining, and the test piece was hung in the Amsler adhesion test, and the wear resistance was tested under the following stripes. Ta. Figure 3 shows the relationship between the travel distance (m) and the number of ejaculations.

<Abrasion test conditions> Counterpart material Nysterite weight: 4 Yu/d Lin i = 2.5 m/sec From Figure 3, it is clear that the carbonate layer obtained by the method of the present invention is It has superior stain resistance compared to coatings obtained by conventional thermal spraying methods.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a pongee in which a metal powder layer is formed on the inner surface of a cylindrical metal body by applying the method of the present invention. Figures 81' and 32 are schematic diagrams illustrating the state in which the wear-resistant coating of the present invention is formed on iron. FIG. 3 is a curve diagram comparing the wear resistance of the coated metal layer according to the present invention (curve mA) and the coated metal layer formed by the conventional thermal spraying method (curve B). DESCRIPTION OF SYMBOLS 1... Cylindrical metal body S2... Inner surface, 3... Recessed part, 4... Metal powder layer, 5... Cylinder, 6... Convex part, 7... Exhaust hole, 8 ... Airtight reactor, 9 ... High frequency induction coil, 1° ... Gas tank, 11 ... Pressure intensifier, 12 ... Vacuum bonder. Shoulder rubbing vinegar (xlo'in)

Claims (1)

[Claims] 1. A method of forming a wear-resistant coating on the surface of a metal body, which coats the surface of the metal body with nickel, norrom, or hachrome, cobalt, and nickel as main components, boron, A method for forming a JIl wear-resistant coating, which comprises forming a metal powder layer containing silicon, iron, and carbon, and then pressure-sintering the powder layer. 2. Method 1 according to claim 11 JIJf, in which pressure sintering is performed by heating the powder layer through a thin layer capped on the metal powder layer while applying high-pressure gas to the powder layer. 2. The method according to claim 1, wherein a compression treatment is performed at a high temperature before the pressure sintering step. 4. The method according to claim 1, characterized in that gas is contained in the metal powder layer before and/or during the pressure sintering step. 5. An apparatus for forming a wear-resistant coating on the surface of a metal body, comprising: an airtight container that houses the metal body with a metal powder layer formed on the surface thereof; and a metal housed in the container. An apparatus for pressurizing and sintering a metal powder layer formed on the surface of the metal body, comprising: a heater for heating the body; and a gas supply source for supplying high-pressure gas into the container.