JPH0323623B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a wear-resistant member having a sprayed layer containing fine ceramic powder, particularly a hot or cold wear member having a sprayed layer of a mixture of a metal sprayed layer and ceramic fine powder. The present invention relates to wear-resistant members such as rolling rolls and methods of manufacturing the same.

(Prior art) In recent years, surface coating technologies for improving the wear resistance of metal parts include a sintering method in which WC or various ceramic powder is sintered and fixed on the surface of the metal member, a thermal spraying method in which WC or various ceramic powders are sintered and fixed on the surface of the metal member, and a thermal spraying method in which WC or various ceramic powders are sintered and fixed on the surface of the metal member. There are overlay methods such as overlaying with high carbon steel, etc. Of course, the metal member itself may also be constructed from a wear-resistant alloy such as V-containing high Cr steel.

However, each of the above-mentioned wear-resistant members in the prior art has advantages and disadvantages; for example, those using wear-resistant alloys have high material costs and can only be used for special purposes; In the thermal spraying method, peeling of the sprayed layer is often observed during use, and sufficient wear resistance cannot be obtained. Despite the many economic advantages of ceramic spraying, the frequent occurrence of such flaking has hindered its practical application, especially for rolling rolls used in steel production, which are subject to high loads and high temperatures. .

(Problems to be Solved by the Invention) Thus, an object of the present invention is to provide a wear-resistant member that is much cheaper than conventional ones and has excellent wear resistance, especially high-temperature wear resistance, and its manufacture. The purpose is to provide a method.

Another object of the present invention is to provide a wear-resistant member having a surface coating formed by thermal spraying or projection of fine ceramic powder, and a method for manufacturing the same.

Another more specific object of the present invention is to provide a mill roll that further improves the wear resistance of conventional mill rolls provided with a sprayed layer of ceramic powder, and a method for manufacturing the same.

(Means for Solving the Problems) Therefore, the present inventors investigated the conventional ceramic spraying technique in general in order to achieve the above object, and obtained the following findings.

In other words, the thickness of the ceramic layer with wear-resistant strength is limited to a certain extent in order to exhibit the wear-resistant effect.
For example, since it was said that 100 μm or more was preferable,
In conventional ceramic spraying methods, it was common to spray to a thickness of 100 to 500 μm. however,
Rather, since such a thick film was thermally sprayed, the problem of peeling of the surface sprayed layer under high loads was unavoidable, and therefore it was not used for manufacturing wear-resistant parts.

So, after considering this point further, I found that
It is sufficient for the thermal sprayed ceramic layer to function as a high-temperature wear-resistant protective coating, and for that purpose, it is sufficient to effectively utilize the inherent heat resistance and wear resistance of ceramic materials, and it is not necessarily necessary to make the film thicker. The thinner the entire coating is, the more flexible it becomes, which ultimately improves the peeling resistance of the sprayed layer. The inventors discovered that it is useful to disperse ultrafine ceramic powder in a soft metal thermal spray layer to reduce the thickness of the film, and completed the present invention.

Therefore, the gist of the present invention is to apply 0.5 μm to the base surface of a wear-resistant member with a surface roughness of 0.5 to 10 μm Ra.
This is a wear-resistant member comprising a sprayed metal layer with a thickness of ~20 μm and a sprayed layer of ceramic with an average particle size of 30 μm or less, and the thickness of the sprayed mixed layer is adjusted to 50 μm or less.

According to another feature of the present invention, the surface of the base of the wear-resistant member is finished to a surface roughness of 0.5 to 10 μm Ra; the surface of the wear-resistant member is provided with a metal sprayed layer with a thickness of 0.5 to 20 μm; Simultaneously or subsequently with the metal spraying, ceramic fine powder with an average particle size of 30 μm or less is sprayed or projected to form a mixed sprayed layer of the metal sprayed layer and ceramic; and the thickness of the mixed sprayed layer is 50 μm or less. This is a method of manufacturing a wear-resistant member comprising the following steps.

Here, the ceramic fine powder with an average particle size of 30 μm or less is usually obtained by pulverizing ceramic, and preferably has an average particle size of 5 to 15 μm.
It is m. Zirconia powder (ZrO ₂ ), alumina powder (Al ₂ O ₃ ), alumina + titanium oxide (TiO ₂ ) mixed powder, magnesium oxide powder (MgO), silicon nitride powder (Si ₃ N ₄ ), tungsten carbide powder (WC), Chromium carbide powder (Cr ₃ C ₂ ), chromium oxide powder (Cr ₂ O ₃ ), chromium boride powder (CrB ₂ ), titanium boride powder (TiB ₂ ), titanium nitride powder (TiN), titanium carbide powder (TiC ), and others, and can be selected as appropriate depending on the usage conditions of the intended wear-resistant member and the type of base metal.

In this specification, the sprayed layer thickness is determined by the average value of actual measurements at several locations using an electromagnetic film thickness meter or an ultrasonic film thickness meter, and the average particle size is determined by a sieving method. do.

As described above, according to the present invention, as a measure against peeling, minute irregularities are provided on the surface of the workpiece; as a measure against peeling, a thin film of soft metal is added to improve the adhesion between the surface of the workpiece and ceramic spraying. Metal spraying; and To prevent peeling and to fully demonstrate the wear resistance effect, spraying or projecting ultrafine ceramic powder with an average particle size of 30 μm or less to form a mixed sprayed layer; For example, it is possible to produce an inexpensive wear-resistant member that does not peel off even when used on steel rolling rolls under high temperatures and high loads and exhibits excellent wear resistance.

In the present invention, wear-resistant members include, in addition to the above-mentioned rolling rolls, bride rolls, cylinders, bits, piercer rolls, and the like. Although the present invention is not limited to any particular roll, hot and cold rolling rolls are particularly preferred since they are used under high loads.

For hot wear-resistant members, measures against peeling are taken by selecting fine ceramic powder that has a certain degree of thermal expansion coefficient at high temperatures. Preferably, ceramic powder having a coefficient of thermal expansion of 6.0×10 ^-6 /°C or more at 500°C or higher is used, and
Among the ceramic fine powders mentioned above, such fine ceramic powders include zirconia powder, alumina powder,
Chromium oxide powder, titanium oxide powder, chromium boride powder,
There are titanium boride powder, magnesium oxide powder, etc.

(Function) The attached drawings are explanatory diagrams schematically showing the surface properties of the wear-resistant member according to the present invention, taking a rolling roll as an example.

In the figure, the surface roughness of the base surface of the wear-resistant member indicated by reference numeral 10 is reduced to 0.5 to 0.5 by shot blasting, ball blasting, or etching.
Adjusted to 10μRa, with metal sprayed layer 1 on top.
1 and ceramic 12 is provided, and the entire sprayed layer has a final finished surface 14 as shown by the thick line in the figure, and its thickness is 50 μm.
m or less.

As can be clearly seen from the figure, due to the surface roughness provided on the surface of the substrate, the metal sprayed layer provided thereon has a kind of mechanical anchoring effect, and the interfacial adhesion between the two is significantly reduced. Improved. Then,
Alternatively, ceramic fine powder is thermally sprayed or projected at the same time as the above-mentioned thermal spraying, but since the metal sprayed layer is made of a soft metal, the thermally sprayed ceramic fine powder is injected into this metal sprayed layer and is in a buried form. The peeling resistance of the mixed sprayed layer is significantly improved. Of course, since the ceramic fine powder is embedded, the wear resistance, especially at high temperatures, is significantly improved.

The reason for the above-mentioned numerical limitations in the present invention will be described below.

First, the reason why a surface roughness of 0.5 to 10 μRa is applied to the surface of the workpiece is to prevent the ceramic sprayed layer from peeling off and to improve adhesion by exerting an anchor effect as mentioned above. ,
On the other hand, if it exceeds 10μRa, the PPI (number of peaks) will decrease as a result, and it will not be possible to improve the adhesion. In other words, the anchor effect is reduced. Furthermore, despite its effectiveness, an unnecessarily large amount of ceramic powder is required, resulting in high costs. It is also unfavorable for peeling.

The reason for setting the thickness of the metal sprayed layer to 0.5 to 20 μm is also to improve adhesion as a measure against peeling. If the thickness is less than 0.5 μm, it will not be effective, while if it exceeds 20 μm, any metal layer will be a soft metal spray layer, so even if the ceramic fine powder is dispersed, it will not be effective under high loads. This results in plastic flow and no wear-resistance effect.

Here, the soft sprayed metals include Ni, Al, Mo,
Cu, Cr, W, Ti, V, etc. are preferable in terms of wear resistance or cost.

Such metal spraying may be carried out by conventional means, such as gas spraying using oxygen-acetylene gas.

Next, or simultaneously with the above thermal spraying, ceramic powder with an average particle size of 30 μm or less is thermally sprayed or projected onto the surface of the metal sprayed layer. This is because the film inevitably becomes thick, which weakens the anchoring effect produced by creating minute irregularities on the surface of the substrate at the beginning of processing, and at the same time makes it easier to peel off.

Further, the reason why the thickness of the mixed sprayed layer is set to 50 μm or less is to improve the peel strength by setting the sprayed thickness to 50 μm or less.

Ceramic thermal spraying is generally performed using, for example, (H ₂ +
This can be done by plasma spraying using N ₂ ) gas or N ₂ gas as a plasma gas. Ceramic spraying can generally be carried out by entraining ceramic powder in a high-pressure gas such as compressed air at the same time as the metal spraying described above. Although the present invention is not particularly limited thereto, the amount of ceramic powder sprayed or sprayed is preferably such that the thickness of the sprayed or sprayed layer is 50 μm or less.

Note that in a preferred embodiment of the present invention, as described above,
Ceramic fine powder with a thermal expansion coefficient of 6.0 x 10 ^-6 /℃ or more at temperatures above 500℃ can be used for hot applications by thermal spraying, since it is possible to use it for hot applications by spraying ceramic powder with a thermal expansion coefficient of 6.0 × 10 -6 /℃ or more at temperatures above 500℃. This is because, in general, the difference between the base metal and the base metal becomes too large, and the resulting thermal strain causes peeling.

Further, the surface roughness of the mixed sprayed layer is preferably adjusted to 10 μRa or less. This reduces the frictional resistance between the steel material and the mixed thermal spray layer during steel rolling, etc.
This is because the peel strength of the mixed sprayed layer is improved and the surface of the steel material can be smoothed.

The surface roughness in this specification is measured using a normal surface roughness meter, and is the center line average roughness (Ra).
Displayed according to the law (JIS B 0616).

Next, the present invention will be described in more detail with reference to Examples. In each of the following Examples, the present invention will be explained using a rolling roll as an example of a wear-resistant member, but it should be understood that the present invention is not limited thereto.

Example 1 In this example, the present invention was applied to a cold rolling roll for thin plates used in steel manufacturing.

Workpiece: Cold rolling roll (high Cr roll) with a diameter of 610 mm and a roll barrel of 1710 mm. The stand used was the final #5 stand. The roll surface was given a surface roughness of 10 μRa by shot blasting. Next, 15 μm thick metal Mo
The layer is formed by oxygen-acetylene gas spraying,
On top of this obtained metal spray layer, an average particle size of 10 μm was applied.
Next, plasma spray ZrO ₂ ceramic fine powder.
A mixed sprayed layer was formed in which fine ceramic powder was dispersed within the metal sprayed layer. After thermal spraying, the surface is polished with a grindstone.
The roughness of the sprayed layer was adjusted to 3μRa and the total thickness of the sprayed layer was 25μm.

The above-mentioned rolling roll manufactured in this manner was actually used in an operating line. As a result, the wear resistance effect was dramatically improved compared to ordinary forged steel rolls, the roll change interval was 15 times longer, and there were no problems such as peeling of the ceramic. In addition, the processing cost per roll can be significantly reduced, making it possible to significantly reduce costs compared to conventional WC and ceramic spraying methods.

Example 2 This example was carried out using a hot rolling roll instead of the cold rolling roll of Example 1 in the following manner.

Workpiece: Hot rolling roll (Adamite roll) with a diameter of 760 mm and a roll barrel of 1780 mm Stand used Finishing #2 stand The surface of the roll was given a surface roughness of 5 μRa by steel ball blasting. Next, a 7 μm thick Ni layer was formed by oxygen-acetylene gas spraying, and on top of the metal spray layer was a Ni layer with an average particle size of 10 μm.
Ceramic fine powder of Al ₂ O ₃ was then plasma sprayed to form a sprayed mixed layer. After thermal spraying, the surface of the sprayed mixed layer was adjusted to a roughness of 1μRa using a grindstone, and
The total thickness of the sprayed layer was 20 μm.

When the above hot rolling roll manufactured in this way was used on an actual production line for 50 hours, the results showed that the wear resistance effect was dramatically improved compared to ordinary Adamite rolls, and the roll replacement pitch was 10 times faster. In particular, there were no problems such as peeling of the ceramic mixed sprayed layer. In addition, the processing cost per roll can be significantly reduced, and conventional WC,
It has become possible to significantly reduce costs compared to ceramic spraying.

Example 3 This example was carried out as follows.

Workpiece: Work roll (forged steel roll) of a tension leveler for scale breaking of a hot rolled steel strip with a diameter of 80 mm and a roll barrel of 1750 mm. First, the roll surface was given a surface roughness of 3 μRa by chemical electrolytic etching. Next, a Ni-Al layer with a thickness of 5 μm was formed by oxygen-acetylene gas spraying, and a mixed ceramic fine powder of Al ₂ O ₃ and TiO ₂ with an average particle size of 5 μm was subsequently sprayed by plasma spraying to form a mixed sprayed layer. did. After thermal spraying, the surface of this mixed thermal sprayed layer was adjusted to a roughness of 1 μRa using a grindstone, and the thickness of the entire thermal sprayed layer was 10 μm.

When the roll manufactured in this way was used for 500 hours on an actual production line, it was found that it not only has a wear-resistant effect but also has corrosion resistance (water spray is applied to wash away scale). Compared to ordinary forged steel rolls, this is a dramatic improvement, the roll change pitch is 30 times longer, and there are no problems such as peeling of the ceramic mixed thermal spray layer.

Moreover, the throughput per roll can be significantly reduced in this example, compared to the conventional
Compared to WC and ceramic spraying methods, it has become possible to significantly reduce costs.

Example 4 This example was carried out as follows.

Workpiece: Seamless steel pipe manufacturing line piercer roll with a diameter of 1400 mm and a roll barrel of 900 mm.The above roll surface is coated with shot blasting.
A surface roughness of 10μRa was given. Then 10μm thick
A Ni-Cr-Al alloy layer was formed by gas spraying, and at the same time, ceramic fine powder of Al ₂ O ₃ + ZrO ₂ with an average particle size of 15 μm was sprayed with compressed air at 5 kg/cm ² to form a mixed sprayed layer. .

After thermal spraying, the surface was adjusted to a roughness of 5 μRa using a grindstone, and the thickness of the entire sprayed layer was 25 μm.

The above-mentioned piercer roll manufactured in this manner was used for 1000 hours in an actual facility. the result,
The wear resistance effect was dramatically improved compared to ordinary forged steel rolls, the roll change pitch was 10 times longer, and there were no problems such as peeling of the ceramic mixed thermal spray layer.

[Brief explanation of the drawing]

The accompanying drawings are schematic illustrations showing the structure of the surface of the wear-resistant member according to the present invention. 10: Base surface portion, 11: Metal sprayed layer, 12:
Ceramic, 13: mixed sprayed layer, 14: final finished surface.

Claims (1)

[Claims] 1. A metal sprayed layer with a thickness of 0.5 to 20 μm and an average particle size on the base surface of a wear-resistant member with a surface roughness of 0.5 to 10 μRa.
Equipped with a mixed thermal spray layer with ceramic of 30μm or less,
A wear-resistant member in which the thickness of the thermally sprayed mixed layer is adjusted to 50 μm or less. 2. Finishing the base surface of the wear-resistant member to a surface roughness of 0.5 to 10 μRa; Providing a metal sprayed layer with a thickness of 0.5 to 20 μm on the surface of the wear-resistant member; At the same time as or following the above metal spraying, coat the surface with an average particle size of 30 μm. A method for producing a wear-resistant member, comprising: spraying or projecting the following ceramic fine powder to form a mixed sprayed layer of the metal sprayed layer and ceramic; and setting the thickness of the mixed sprayed layer to 50 μm or less.