JPS60228706A - Wear resisting blade - Google Patents

Abstract

PURPOSE:To improve ash erosion resistance in a blade for an axial-flow machine in a coal thermal power plant, by bonding a composite boride hard alloy to the front edge of the blade. CONSTITUTION:A composite boride hard alloy 2 is bonded to the front edge of a cast steel base material 1 of a blade for an axial-flow machine such as an exhauster in a coal thermal power plant. Thus, ash erosion resistance of the blade may be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a wear-resistant blade for, for example, an axial flow machine that handles gas containing abrasive particles, and in particular to a wear-resistant blade for an axial flow machine that handles gas containing abrasive particles, and in particular for use in a wear-resistant blade such as an exhaust fan for a coal-fired power plant. The present invention relates to a wear-resistant blade suitable for axial flow machines that require ash erosion properties.

[Background of the invention]

Exhaust fans in coal-fired power plants handle combustion exhaust gas from the boiler that contains fly ash, so this fly ash causes wear in the flow passages, and the wear on the blades, which rotate at high speeds, is particularly noticeable. The wear of the blades of smoke exhaust fans is also discussed in Japanese Patent Publication No. 54-51010 ``Method of Manufacturing Smoke Exhaust Fan Blades''. The state of blade wear will be explained using the rotor blades of an axial fan shown in FIGS. 1 and 2.

Fly ash in the gas flowing in the direction of arrow X collides with the leading edge 1a of the rotor blade base material 1 at high speed,
is the most severely worn. Broken line 1a and solid line 1 in the same figure
ali indicates the shape of the leading edge portion 1a before and after wear, respectively. If the blade shape is damaged due to wear of the leading edge 1a, the fluid performance of the fan will decrease, causing serious problems in the operation of the plant where the equipment is installed.To prevent this, the leading edge 1a will be damaged. It is necessary to improve wear resistance and extend life.

Since the fluid performance deteriorates due to wear of the blades, there is a drawback that maintenance and inspection must be carried out in a short period of time.

[Purpose of the invention]

An object of the present invention is to provide a wear-resistant blade for an axial flow machine that eliminates the above-mentioned conventional drawbacks, has excellent ash erosion resistance, and can maintain a long service life.

[Summary of the invention]

In order to achieve the above object, the present invention provides a wear-resistant blade that handles gas containing abrasive particles, in which a separate member made of a hard alloy is bonded to the front part of the blade, and the separate member is made of complex boride in weight ratio. Hard alloy; 40-65%, B; 4-8%, Mo
; 40-60%, Fa; 25-45%, Cr; 5-20
%, Ni: 15% or less, Mo: 40 to 60%, W: 1% or less, and other impurities.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 3 and 4 are plan views showing the shape of the wear-resistant mat according to the present invention. Further, FIG. 5 is a cross-sectional view taken at the position marked ``■'' shown in FIGS. 3 and 4.

In FIG. 3, FIG. 4, and FIG. 5, 1 is a cast steel blade matrix, and the leading edge part 2 of this blade matrix 1 is made of a complex boride-based hard alloy;
50%, B; 5.6%, Fe; 30%, Cr; 10%,
MO; 50%, Ni; 2.5%, W; 0.5%,
It is made by joining a sintered alloy containing other impurities.

In FIG. 3, separately manufactured members 2 are joined over the entire length of the blade 1.

Further, in FIG. 4, a part of the wing 1 is hollowed out so that the member 2 can be inserted therein, and the member 2 is fitted therein and joined. The feature of this joining method is that while the fan is rotating,
Since the force applied to the blade 1 is received by the convex portion at the tip of the hollowed out portion of the blade 1, the force applied to the joint surface is reduced.

FIG. 6 shows the results of a constant time wear test using fly ash with a particle size of 17 μm. The figure shows 18 types of materials separated by function on the vertical axis, and the amount of wear on the horizontal axis. From the figure, it can be seen that the compound boride hard alloy No. 10 shows the best value for the leading edge member, followed by the material No. 3.

As a coating material, it can be seen that hard chrome plating No. 16 showed the best value, followed by chromium oxide No. 13.

The conventional bonding material shown in number 18 uses silver solder, but the amount of wear is large, indicating that the ash erosion resistance is low.

If a material with low ash erosion resistance is used for bonding, the silver solder parts may be selectively worn out when the device is installed and operated.

Not.

Therefore, material number 3 shown in FIG. 6 is preferable because it is a self-fusing alloy that exhibits high ash erosion resistance as a leading edge member.

Using the shape shown in Figure 4, the leading edge of the wing base 1 is hollowed out so that the leading edge 2 separately manufactured from a complex boride hard alloy can be inserted therein, and the leading edge 2 is fitted into the space. In the case of joining, the difference in thermal expansion coefficient between the surface materials of the steel of the blade base 1 and the compound boride hard alloy of the leading edge 2 was used for joining. That is, assuming that the respective thermal expansion coefficients of the steel and the compound hard alloy of the blade base are α9 α□, the relationship between the two is α6>α□. Therefore, the hollowed-out dimensions of the wing matrix at room temperature, the dimensions of the leading edge 2, and the hollowed-out dimensions of the wing matrix when heated to a temperature for joining the blade matrix are αmB and α-9α?, respectively. ml, these three are α−〈αan＜α! The dimensions of the leading edge 2 are determined so as to satisfy the relationship 1.

When manufacturing a blade by joining the blade matrix and the leading edge 2, the blade matrix is first inserted into a heating furnace (not shown), and while inert gas such as argon is flowed into the furnace, the temperature of the wax liquid is increased. 850～
After heating to 1000°C, attach the leading edge part 2 to the hollowed out part of the wing base, being careful not to shift it. Thereafter, metal powder or silver solder number 3 shown in FIG. 6 is placed at the joint, and heating is performed again while flowing an inert gas such as argon into the furnace. Through metal or silver solder number 3 shown in FIG. 6, the hollowed-out remaining convex portion is tightened by force to join the blade base body and the leading edge portion 2 together to produce a wear-resistant pure piece. After this, hard chrome plating is applied to the entire surface of the wing base in order to protect the wing surface.

In addition, a wear-resistant pure body fabricated by diffusion bonding the leading edge of a complex boride hard alloy and the blade base will be described with reference to FIG.

First, the leading edge portion 2 of a complex boride hard alloy and the blade base body 1 are assembled. The assembled product is then inserted into a diffusion bonding furnace (not shown) under a reduced pressure of io-''l'orr at a bonding temperature of 900-1000°C and a bonding pressure of 0.5-5.0k.
Diffusion bonding is performed for 10 to 180 minutes at a temperature of 100 g/+m'', and the blade base 1 and the leading edge 2 are integrally bonded to produce a wear-resistant pure material.

Fig. 7 shows a comparison of the wear status of the wear-resistant pure blade with that of blades manufactured using other conventional techniques.

For the experimental results shown in Figure 7, an experimental loop device was created, and the fan was attached to it and rotated at the same rotational speed as the actual machine. In addition, since the concentration of fly ash contained in the airflow in the loop accelerates the erosion test, the amount of fly ash supplied was adjusted so that the concentration was maintained at about 50 times the capacity of the electrostatic precipitator.

After starting the experiment, the experimental equipment was stopped at regular intervals, the fan was disassembled, the blade span was measured, and the wear dimension of the most worn part was taken as the blade span reduction dimension, and the experimental time was plotted on the vertical axis of Figure 7. shown on each axis.

The numbers shown in each wear curve in FIG. 7 are the materials with the numbers shown in FIG. Here, number 17 is the blade span wear curve number 3, 6, 7, 8 of the wing made with material equivalent to 820C raw material.
, 9 and 10 show the span wear curves of blades made by overlaying the leading edge with materials having the same composition as the numbers shown in FIG.

The relationship between the above experiment time and the blade span reduction dimension (ΔL) of each material is as shown in FIG. From this diagram number 17 8
It can be seen that a material equivalent to 20C green material causes extremely large wear on the blade, but when wear-resistant overlay is applied to the front part of the blade, the amount of wear decreases rapidly. In particular, it is easy to understand that the reduction in the wing span varies depending on the material of the overlay, and that it is necessary to use an appropriate material. The wear-resistant pure material No. 10 exhibits zero reduction in blade span, and is clearly effective in ash erosion resistance.

[Effects of the Invention] As explained above, according to the present invention, the life of the blade is extended by dramatically improving the ash erosion resistance of the blade, and the blade is strong in strength and has stable quality. Therefore, the labor and cost of maintenance and inspection can be significantly reduced.

[Brief explanation of the drawing]

Fig. 1 is a side view showing the state in which the leading edge of the blade of the smoke exhaust fan is worn out, Fig. 2 is a sectional view taken along the line nn in Fig. 1, and Figs. Figure 5 is a side view of a wing to which one embodiment is applied, Figure 5 is a sectional view taken along the line ■-■ in Figures 3 and 4, and Figure 6 is a comparison of the ash erosion resistance of various materials using a basic testing machine. FIG. 7 is a comparison diagram of the ash erosion resistance of blades made of various materials. 1...Blade matrix, 1a...Blade leading edge, la,...Leading edge shape before wear, lag...Leading edge shape after wear, 2...
...Front edge made of complex boride hard alloy.

Claims (1)

[Scope of Claims] 1. In a wear-resistant blade that handles gas containing abrasive particles, in which a separate member made of a hard alloy is joined to the leading edge of the blade, the separate member is made of complex boride-based hard metal with heavy tc. Alloy; 40-65
%, Ij; 4-8%. Mq: 40-60%, F, 15-45%. Or; 5 to 20%, Ni; 5% or less, Mo; 4
A wear-resistant blade characterized by being made of a sintered alloy containing 0 to 60%, W: 1% or less, and other impurities. 2. A wear-resistant blade according to claim 1, characterized in that the entire surface of the blade or the surface in contact with the abrasive particles is plated with chrome or nickel-chromium.