JPH02200763A - Member for refiner - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance and wear resistance of a member by providing a sprayed deposit of carbide-metal cermet on the surface of the grinding surface of a refiner for dissociating and crushing fibers. CONSTITUTION:A sprayed deposit of carbide-metal cermet is provided on the surface of the grinding surface of a member for refiner used for dissociating and crushing water-containing pulp fibers, or, a two-layer sprayed deposit consisting of a primary metallic thermally sprayed layer and a secondary carbide thermally sprayed layer is provided on the above grinding surface. It is desirable to regulate the surface roughness of the outermost layer of the above sprayed deposits to Ra0.01-5mum. As the carbide in the sprayed deposit, at least one kind selected from WC, TiC, WC-TiC, Cr3C2, ZrC, TaC, NbC, VC, B4C, and Mo2C is used. The above member for refiner has superior pulp fiber crushing function, and further, the property can be maintained over a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a so-called refiner member, which controls the beating of pulp fibers in a paper manufacturing process.

The refiner member of the present invention is suitable for use in refining not only virgin pulp fibers but also waste paper fibers, synthetic fibers, animal fibers such as wool, and the like.

Furthermore, the member of the present invention is also applicable to devices used for crushing grains, seeds, and the like.

[Conventional technology]

Pulp produced in the pulping process is sent to the papermaking process in a state dispersed in water, but paper made as is has a lot of fluff and is weak in strength, so it is usually sent to a refiner before the papermaking process. The pulp is beaten (beating and kneading the pulp) using a device called Through this treatment, the outer layer of the pulp fibers is torn, the inner layer is exposed to water, and the water completely penetrates into the pulp, causing it to swell significantly. As a result, the fibers become significantly plasticized and flexible, allowing them to be easily deformed during the dewatering process of papermaking, and also improve the bonding strength between fibers. As the beating progresses further, hair-like substances are generated on the surface of the fibers, increasing the ability of the fibers to intertwine with each other, strengthening the bonds between the fibers, and increasing the strength.
do.

As described above, the beating treatment of pulp has a great influence on the properties of paper and plays an important role in the paper manufacturing process.

Currently, there are two types of refiners used for this purpose: disk type refiners and conical type refiners. The conical refiner uses a rotating plug (
The rotor (rotor) and its housing (stator) are equipped with longitudinally arranged metal bars, to which the fibers are beaten while flowing parallel to them.

In addition, disk-type refiners include: ■ those equipped with a fixed disk and a rotating disk facing it, ■ those equipped with two opposing rotating disks, and ■ those consisting of two fixed disks and a rotating double-sided disk placed between them. and so on.

In any case, in both the °C, disc type and conical type, the grinding surface that beats the fibers is provided with tooth shapes and grooves, and rotates at high speed (600 to 120 rpm) to produce pulp. The fibers are subjected to a beating action by passing through gaps where such uneven grinding surfaces approach each other.

For this reason, the surface of the ground surface is required to have excellent chemical resistance (corrosion resistance) to water, as well as a high beating effect and excellent abrasion resistance.

By the way, currently the refiner members are 1.7
Precipitation hardening stainless steel such as Cr-4Ni P Il steel is used, but its wear resistance is not sufficient, and the tooth profile on the grinding surface wears out after 1 to 3 months of continuous use. However, due to the damage, the beating performance deteriorated significantly, and it had to be replaced.

(Problems to be Solved by the Invention) The present invention advantageously solves the above-mentioned problems, and aims to provide a member for a refiner that has extremely excellent wear resistance as well as corrosion resistance.

[Failure to solve the problem]

The inventors of the present invention have conducted extensive research to achieve the above object, and have found that the grinding surface of a refiner member is coated with a thermally sprayed coating of carbide-metal cermet or a two-layer coating consisting of a metal base layer and a carbide surface layer. It has been found that applying a thermal spray coating is extremely effective in achieving the intended purpose.

That is, the coating thus obtained is much harder than current materials (Hv 1100-1300),
In addition to being excellent in corrosion resistance, the coating surface has fine irregularities, which effectively hook pulp fibers and have found that the beating function is significantly improved.

The present invention is based on the above findings.

That is, the present invention provides a member that controls the beating of pulp fibers containing moisture, and the ground surface of the member is coated with: (1) a carbide-metallic-method sprayed coating, or (2) a metal sprayed first layer and a carbide sprayed second layer. This is a refiner member comprising a two-layer thermal sprayed coating consisting of two layers.

In this invention, the carbide in the sprayed coating is WC
, TiC, WC-Tic, Cr, C, , ZrC, Ta
C, NbC.

At least one selected from VC, B, C and MO2C, and the metal is Co, Ni, Ni-
At least one selected from Cr and Ni-At are each advantageously suited.

In the carbide-metal cermet thermal spray coating of the first invention, the metal content in the coating is preferably 5 to 40-L% (hereinafter simply expressed in %).

This is because if the metal content is less than 51%, the adhesion between the sprayed coating and the object to be treated will be reduced, and the mutual bonding force of the particles forming the coating will be reduced. On the other hand, if it exceeds 40%, the inherent high hardness of carbide and the surface ability to beat fibers will deteriorate.

Further, it is preferable that the H thickness of this carbide-metal cermet thermal spray coating is about 30 to 300 .mu.m.

This is because when the film thickness is less than 30 μm, the sprayed film has many pores, and therefore the object to be treated is likely to be corroded.

On the other hand, if it exceeds 300 μ-, the residual stress of the sprayed coating becomes large and the adhesion to the object to be treated becomes low.
This is because there is a cost disadvantage due to the use of expensive thermal spray materials.

Next, in the two-layer thermal spray coating of the second invention, the metal coating thickness and the carbide coating thickness are 10 to 200 μm and 10 μm, respectively.
It is desirable that the thickness be approximately 200 μm. This is because, if the metal coating thickness is less than 10 μm, its original function as an undercoat will be insufficient.

- On the other hand, if the thickness exceeds 200 μm, the function as an undercoat will reach a saturated state and there will be no value in increasing the film. Further, if the carbide film thickness is less than 10 μm, the surface of the undercoat cannot be completely covered. On the other hand, 200
This is because if it exceeds μI, it will only increase the cost and will have little effect in increasing the film as a refiner film.

Further, the surface roughness of the outermost layer of the thermal spray coatings of the first and second inventions is desirably in the range of Ra 0.01 to Ra 5 μm. The reason for this is that Ra O, 01 μm
Below, the polishing process requires a great deal of effort and expense.
On the other hand, if the surface roughness is Ra5 or more, the fibers will adhere excessively, and the power cost will increase due to the increase in water resistance.

As the thermal spraying method, any conventionally known method can be used, such as an atmospheric pressure plasma spraying method, a reduced pressure plasma spraying method, and a thermal spraying method using a combustion flame of hydrocarbon gas as a heat source.

FIG. 1a schematically shows the main part of one side of a disc-type refiner equipped with a refiner member according to the present invention. In the figure, numeral 1 is a rotating shaft, 2 is a rotating disk, and 3 and 4 are refiner members attached to the rotating disk 2 and a housing (not shown), respectively. As shown in the figure, the surfaces of these refiner members 3.4 are provided with a tooth-shaped uneven pattern in this example to form a grinding surface.

5 is a thermally sprayed coating formed on the surface of the ground surface.

Note that 6 shows the flow of water containing pulp fibers.
The gap between the refiner members 3 and 4 consisting of toothed disks (
The fibers are beaten while passing through the fibers (usually about 0, i to 1.0+n).

[For production]

BACKGROUND ART The uneven pattern, such as a tooth pattern, formed on the surface of precipitation-hardened stainless steel, which is used as a conventional disc-shaped or conical refiner member, is a smooth metal surface when viewed microscopically. Now, when water containing pulp fibers passes through the gap formed by the two teeth, if the fibers are torn by the pressure of the two teeth, the fibers will easily slip on a smooth metal surface, and moreover, the large amount of coexisting fibers will tear. Since water acts as a lubricant, the beating effect is extremely low. One possible solution to this problem is to narrow the gap between the two tooth impressions, but if the gap is made smaller, there will be more opportunities for the tooth impressions to come into contact with each other, resulting in mechanical damage to the tooth impressions. .

In this regard, the surface of the carbide-metal cermet thermal spray coating according to the present invention has a state in which fine carbide particles that are microscopically arranged in a forest are fixed by metal, so that the adhesion efficiency of pulp fibers is high, and the surface of both teeth is Since there is little escape from the pressure, the fibers are effectively beaten.

In addition, there is no need to make the refiner 0 teeth particularly narrow, and an appropriate spacing is maintained, so there is no risk of mechanical damage as seen with existing tooth forms.

In addition, increasing the rotation speed of the refiner increases the contact resistance of the fibers attached to the surface of the sprayed coating with water, and this resistance alone can promote the fluffing phenomenon of the fibers, making the overall refining effect even more effective. improves.

Furthermore, the carbide-metallic thermal sprayed coating of the present invention has good adhesion to the substrate, and is far superior in corrosion resistance and hardness to the current precipitation-hardening stainless steel, so it can withstand high-speed rotation underwater. It does not peel off and can be used stably for a long period of time.

The above explanation has mainly focused on the case where a carbide-metal cermet thermal spray coating is formed, but even in a two-layer thermal spray coating structure consisting of a metal spray coating first layer and a carbide spray coating second layer, the surface is covered with a forest of fine carbide particles. Therefore, the same effect as above can be obtained.

〔Example〕

Example 1 Using the refiner shown in FIG. 1, an experiment was conducted under the following conditions.

- Experimental conditions (1,1 tooth type disk material: 17Cr-4Ni precipitation hardening stainless steel (JIS GJ303 SO5630) was used and finished to a hardness of Hv 330 to 350.

(2) Pulp fiber used and its concentration: water containing 5% virgin pulp fiber (3) Rotation speed of disk: 800 rp (4)
Type of thermal spray coating: WC, TiC, WC-TiC,
Cr3C,.

Carbide-metal cermet (5) Sprayed coating FJ: 100u100u Sprayed by combining ZrC, TaC, NbC, VC, B, C, Mo, and C carbides with Co, Ni, and Ni-Cr metals as shown in Table 1 Surface roughness of coating: Ra: 0.3 to 5 μm (7) Comparative Example ■ S, US630 was used without treatment.

■ A1.0. , Zr5iO, to a thickness of 100 pm; N1-Cr (80/20) alloy coated with 10
0. Table 1 shows the results of examining changes in tooth profile when the refiner was operated for 5 months under the above conditions. During the operation period, after 1 month and 3 months, the effectiveness of the thermal spray coating was evaluated by visually observing the tooth shape of the disc. The fiber-beating effect was also evaluated by collecting the fiber-containing water that had passed through the device and observing the kneading state of the fibers contained therein using a magnifying glass.

As is clear from the same table, the refiner member (block 1) coated with the carbide-metal cermet spray coating according to the present invention
- 10), the sprayed coatings remained in good condition even after 5 months of operation, and no change was observed in the shape of the teeth. Further, the pulp fibers treated with the refiner member of the present invention were well loosened and had a good dispersion state in water.

Table 1 (611 considerations) The metal content in the thermal spray coatings of fil' NQ I to Positive 10 is within the range of 6 to 40 wt%.

(2) The evaluation criteria for the change in the shape of the tooth profile of the refiner member are as follows.

0: No change observed △: Some change observed ×:
Large change (3) The beating effect was expressed by comparing the fractional state of the pulp fibers based on an untreated refiner member (1 m 14).

○: Better dispersion than the standard Δ: Poor dispersion than the standard This is thought to be the result of the fibers adhering well to the fine irregularities on the surface, increasing the beating effect.

In contrast, 5. conventional untreated refiner members (m
14), deformation was observed in the tooth profile after 1 month of operation, and large deformation was observed after 3 months of operation. Also, even with thermal spray coating, A
120i (Fill) or 21751.04 (Na12)
Products using oxide-based ceramics, such as
After 3 months, most of the coating has peeled off.

This tendency was also observed in No. 13, which was thermally sprayed with Nt-Cr alloy, and the pulp fiber loosening effect was only low. The reason for this is thought to be that the surfaces of oxide ceramics and N-Cr alloy thermally sprayed coatings are microscopically aggregates of molten particles, so the adhesion of pulp fibers is weak, and therefore the beating efficiency is low. .

Example 2 Using the same refiner shown in FIG. 1 above, experiments were conducted under the following conditions to investigate changes in tooth profile and beating effect, and the results are shown in Table 2.

・Experimental conditions (1) Type of thermal spray coating 1st layer: Co, Ni, Ni-Cr, Ni-Al
2nd layer: WC, TiC, WCTiC, Cr, , C, Zr
C.

TaC, NbC, VC, B4C, MozC (2) Sprayed coating thickness 1st layer: 80-100 μm 2nd layer: 50-70 pm (3) Surface roughness of sprayed coating: Ra 0.3-5 μm (4)
Comparative Example ■ 5US630 was used without treatment.

■ Ni-Al alloy thermally sprayed coating with a thickness of 150 μm (5
1 Evaluation items and methods: Same as Example 1 Table 2 As is clear from the same table, refiner members coated with a two-layer sprayed coating consisting of a first metal sprayed layer and a second carbide sprayed layer were also evaluated. It was also found that the product had excellent durability and beating effect.

On the other hand, the comparative examples of no treatment (llkl, 12) and those with only metal spraying (mll) have the same drawbacks as Example 1, such as changes in the tooth shape and poor beating effect. It was done.

As can be understood from the examples described above, the beating effect in refiner members is
It was found that this depended on the action of hard and fine forest particles. That is, both the cermet coating in a mixed state of carbide and metal in Example 1 and the second layer carbide coating in contact with the pulp fibers in Example 2 satisfied the above-mentioned conditions, and each exhibited excellent performance. It is thought that
It was confirmed that not only a carbide-metal mixed cermet but also a carbide alone is effective. In addition, since all thermal spray particles form a coating after passing through a high-temperature environment, the coating sprayed on the ground surface contains a small amount of carbide, metal reactants, and oxides in which carbide and metal have changed. Although it is considered to be a problem, it hardly affects the working mechanism as a refiner member.

Similarly, in the metals and alloys that are mixed with carbides, it is possible that some impurities may be mixed in or the ratio of alloy components may fluctuate during the respective manufacturing and refining processes. As long as it does not adversely affect the working mechanism of the sprayed coating on the member, it can be ignored and does not limit the gist of the present invention in any way.

In the embodiment described in f, the case where a disc-shaped refiner is used was mainly explained, but since the pulp fiber beating mechanism is exactly the same even in a conical refiner, the present invention is not limited to the disc-shaped refiner. Needless to say, it is not.

[Effects of the Invention] As described above, the refiner member according to the present invention has the following features:
It has an excellent beating effect on pulp fibers and can maintain its performance over a long period of time, so it can improve the efficiency of beating pulp fibers and improve the quality of the product. In addition, as the lifespan of refiner parts is extended, the plant can operate continuously, which greatly reduces the need for complicated operations such as repairing refiner parts and replacing them with new parts, thereby reducing product manufacturing costs. can also be expected to be highly efficient.

[Brief explanation of the drawing]

Figure 1 (al is a schematic diagram of the main part of a disc-type refiner equipped with a refiner member according to the present invention;
b) is a sectional view of the grinding surface. ■... Rotating shaft, 2... Rotating disk, 3.4... Refiner member, 5... Thermal spray coating,
6...Flow of water containing pulp fibers.

Claims (1)

[Claims] 1. A member that controls the beating of pulp fibers containing moisture,
A member for a refiner, characterized in that the grinding surface thereof is provided with a sprayed coating of carbide-metal cermet. 2. A member that controls the beating of pulp fibers containing moisture,
A member for a refiner, characterized in that a two-layer sprayed coating consisting of a first sprayed metal layer and a second sprayed carbide layer is provided on the ground surface. 3. The carbide in the thermal spray coating is WC, TiC, WC-Ti
C, Cr_3C_2, ZrC, TaC, NbC, VC,
The refiner member according to claim 1 or 2, which is at least one selected from B_4C and Mo_2C. 4. The refiner member according to claim 1 or 2, wherein the metal in the thermal spray coating is at least one selected from Co, Ni, Ni-Cr, and Ni-Al.