JPS6058293B2 - Wear-resistant and corrosion-resistant Ni-Co-based alloy for centrifugal coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wear-resistant and corrosion-resistant alloy that is used by being applied to worn parts of the inner surface of a cylindrical cylinder of a plastic molding machine or the like by a centrifugal coating method.

The inner layer of a cylinder for a plastic molding machine requires an alloy material that has both abrasion resistance and corrosion resistance to prevent corrosion caused by the resin during molding or the flame retardant added to the resin.

Although conventionally known wear-resistant alloys, such as iron-based alloys, are inexpensive, they cannot be used in the molding of plastics, which require wear resistance and corrosion resistance, which have increased significantly in recent years.

In order to solve this difficulty, various alloys have been developed as adherend alloys for centrifugal coating.

Among these, Co-based alloys have excellent wear resistance and corrosion resistance, but because the content of Co, an expensive metal, is 85% by weight or more, the manufacturing cost of the cylinder is extremely high. Although the base alloy has excellent corrosion resistance, Si and B
Since a large amount of is added to improve hardness and wear resistance, it becomes extremely brittle and difficult to finish after centrifugal coating. Conventional Ni-Co-based alloys have excellent corrosion resistance and are inexpensive
Although it is cheaper than o-based alloys, its wear resistance is inferior, so attempts are made to increase the amount of B and Si to improve hardness, but adding a large amount of these elements increases the solidification zone temperature of the alloy and causes dendrite-like primary crystals. This growth impedes the flow of the metal and impairs the integrity of the inner layer, resulting in a decrease in material yield. Here, the solidification zone temperature refers to the difference between the liquidus temperature and solidus temperature of the alloy measured by differential thermal analysis.

An object of the present invention is to provide an alloy for centrifugal coating that has performance equivalent to or better than that of the Ni-Co-based alloy without deteriorating wear resistance and corrosion resistance, and is less expensive and does not deteriorate solidification retention. It is in.

The present inventor has discovered that by adding Cu to a Ni-Co-based alloy, it is possible to improve the hardness due to the synergistic effect with 51, and by reducing the solidification zone to 30°C or less due to the action of Cu. It has been found that the material yield J can be greatly improved.

That is, the alloy of the present invention has Ni of 38.0 to 44.0% by weight.
0%, Cr6.0-11.0%, B2.0-4.0%,
5i0.8-3.0%, Mn0.5-1.2%, Cu0
．． 5 to 2.0%, C 0.1 to 0.4%, Fel, 0% or less, the balance Co and inevitable impurities.

The reasons for limiting the components of the alloy of the present invention will be described below.

Hereinafter, % represents weight %. Cr combines with Co and B to give the alloy high hardness and corrosion resistance, but if it is less than 6%, the effect is not sufficient, and if it exceeds 11%, brittleness increases, so the range is set to 6 to 11%.

B is effective in precipitating high hardness borides in the structure and improving the hardness of the alloy, but B2. If it is less than 0%, the hardness is insufficient, and if it exceeds 4%, the hardness improves but the brittleness increases and the solidification zone exceeds 30°C, so the range is set to 2.
The content was set at 0 to 4.0%.

Si combines with Nl and Cu to improve the hardness of the alloy, but if it is less than 0.8%, the effect is not sufficient, and if it is more than 3%, brittleness increases and the solidification period exceeds 30°C, so the range is limited. The content was set at 0.8 to 3.0%. Mn is necessary as a deoxidizing agent, but its effect is not sufficient if it is less than 0.5%, and if it is contained in more than 1.2%, it deteriorates the corrosion resistance of the alloy, so the range is set to 0.5 to 1.2%. did. Cu reduces the solidification zone and is effective in increasing hardness, but S
The effect differs depending on the content of i.

In the composition shown in Table 1 C below, Si is 2.5% and 1.0
In experiments in which the Cu content was varied in terms of % and the amount of CO was increased or decreased in response to changes in Si and Cu, results as shown in Figure 1 were obtained regarding the effects of Si and Cu on the hardness of the alloy.

In Figure 1, the solid line indicates SI content of 1.0%, and the dotted line indicates S content.
This is the case when i is 2.5%. It is clear from FIG. 1 that there is a synergistic effect of S1 and Cu on the hardness of the alloy. In addition, in the composition of Table 1 C below, the Si content is 2.
From experiments in which the Cu content was changed to 5% and the amount of CO was changed accordingly, results as shown in FIG. 2 were obtained regarding the influence of Cu on the solidification zone of the alloy. It is clear from FIG. 2 that Cu has a great effect of reducing the solidification zone of the alloy. Therefore, the Cu content was set in the range of 0.5 to 2.0%. When Fe is contained in an amount exceeding 1%, the hardness decreases.
Degrades corrosion resistance.

Ni is B, . It combines with Si and contributes to increasing the hardness of the alloy.
It is also effective in improving the corrosion resistance of the alloy compared to CO-based alloys.

If it is less than 38%, the effect is not sufficient and the CO
Since the amount of C increases, there is a problem in terms of economic efficiency, and if the content exceeds 44%, the hardness decreases, so the above range was set.

C is effective in improving the hardness of the alloy, but if it is less than 0.1%, the effect is not sufficient, and if it is contained in more than 0.4%, it reduces the corrosion resistance of the alloy.

Next, the alloy of the present invention will be explained based on examples.

EXAMPLE 7 kg of each of an alloy within the alloy composition range of the present invention and a conventional Cu-free Ni--CO based alloy were melted in a high-frequency atmospheric melting furnace to form rod-shaped castings.

The components of these alloys are shown in Table 1. Next, a test piece with a diameter of 4Trr1n and a length of 5cm was taken from a portion of each alloy shown in Table 1, and differential thermal analysis was performed using a differential thermal analyzer.

The test conditions were to place the sample in an alumina crucible and raise the temperature to 900°C at a rate of 10°C per minute in a nitrogen atmosphere.
The temperature was further increased from 0.degree. C. to 1150.degree. C. at a rate of 2.degree. C./min, and the solidus temperature was determined.

Next, the temperature was lowered from 1150°C to 900°C at a rate of 2°C per minute, and the liquidus temperature was determined. Table 2 shows the results of Vickers hardness and coagulation retention of each sample. Figure 3 shows a micrograph (400x magnification) of the invention alloy A, and the same invention alloy C.
A microscopic photograph is shown in Fig. 4.

It can be seen from the photograph that the structure of the alloy of the present invention consists mostly of eutectic parts, and the solidification zone is narrow. The alloy of the present invention is a conventional N1 alloy.
It has hardness comparable to -CO-based alloys and CO-based alloys, and has a melting point about 100°C lower than CO-based alloys, making heating during deposition economical and reducing material costs.
Rod-shaped castings of alloys B and C of the present invention and conventional alloy D shown in Table 1 were coated on the inner surface of a copper cylinder by a centrifugal coating method.

That is, the rod-shaped casting was crushed to have an outer diameter of 125 Twt,
The amount necessary for coating 4wm thick was placed in an S45C cylinder with an inner diameter of 507m and a length of 410mm, and iron lids were placed on both ends of the cylinder. Alloys B and C of the present invention or conventional alloy D were placed in a furnace maintained at about 1160° C. to melt the adherend alloy, and then taken out from the furnace and immediately placed in a centrifuge and the cylinder was rotated at 1800 r'Pm.

After the cylinder was cooled to 850° C., rotation was stopped, and the cylinder was placed in a furnace maintained at 800%° C. and slowly cooled to room temperature over a period of time. After this, when finishing cutting was performed on the inner surface, in order to obtain a sound surface, alloys B and C of the present invention
requires cutting of 1.2 TnIn and 11.0 TfrIn in thickness, and conventional alloy D required cutting of 2.2 mm. When the cylinder was cut and a test piece was taken and examined under a microscope, the adhesion to the S45C cylinder was found to be good for both the inventive alloy and the conventional alloy. It was found that this material is superior to conventional Ni--CO based alloys as it has a smaller chipping amount as an adherend. As detailed above,
The alloy of the present invention has excellent wear resistance and solidification retention,
Excellent performance is achieved by coating the inner surface of plastic molding cylinders using the centrifugal coating method. Also,
It can be manufactured at a lower cost than the conventional Ni--CO based alloy, which is the mainstream coating alloy.

Therefore, the present invention makes a great contribution to industry from both the viewpoints of performance and economy.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between hardness and Cu for different Si contents.

Claims (1)

[Claims] 1% by weight, Ni38.0-44.0%, Cr6.0
~11.0%, B2.0~4.0%, Si0.8~3.
0%, Mn0.5-1.2%, Cu0.5-2.0%,
A wear-resistant and corrosion-resistant N for centrifugal coating consisting of 0.1 to 0.4% C, 1.0% or less Fe, the balance Co and inevitable impurities.
i-Co based alloy.