JPS62253747A - Composite lining material for cylinder - Google Patents

Abstract

PURPOSE:To improve the corrosion and wear resistances by dispersing a prescribed percentage of NbC grains in a Co alloy matrix contg. prescribed percentages of Cr, B, Si and Mn. CONSTITUTION:An alloy consisting of, by weight, 5-10% Cr, 2.5-4% B, 0.2-2% Si, 0.2-2% Mn and the balance Co is refined and 10-30% NbC grains as a wear resistant reinforcing material are dispersed in a matrix of the Co alloy having corrosion resistance. The resulting composite lining material for a cylinder has superior wear resistance as well as superior corrosion resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lining material for lining the inner peripheral surface of a cylinder of a plastic molding machine, a slurry pump, a compressor, etc. by centrifugal casting.

[Prior art]

Cylinders for plastic molding machines are required to have corrosion resistance and wear resistance to prevent corrosion and wear due to the resin or reinforcing additives added to the resin. In this case, a Co-based alloy lined with a centrifugal casting method was used. However, cylinders lined with these alloys have the disadvantage that when used in plastic molding that contains a high proportion of reinforcing materials such as glass fiber, they suffer significant wear and tear after a few months of use, making them unusable. Ta.

In order to improve this drawback, there is also a composite lining material in which WC particles are dispersed in a Ni-based alloy.

[Problem that the invention seeks to solve]

However, although this composite lining material has improved corrosion resistance and wear resistance, it has the following drawbacks. In other words, the specific gravity of WC, which is a wear-resistant reinforcing material, is about twice as large as that of the matrix alloy, so during lining, the WC particles are pressed against the cylinder base material due to the difference in centrifugal force based on the difference in specific gravity, causing the WC particles to become densely packed. The layer is separated into a layer containing a small amount of WC particles or a layer containing no WC particles. Therefore, there is a problem in that after lining, it is necessary to remove an extra layer from the inner circumferential surface of the cylinder in which the Ni-based alloy matrix contains a trace amount or no reinforcing WC particles. Another disadvantage is that in order to control the boundary between the layer containing WC particles and the layer not containing WC particles to be near the inner circumferential surface of a cylinder of a predetermined size, it is necessary to make the lining treatment conditions very strict.

The object of the present invention is to eliminate the above-mentioned drawbacks, and is to provide a composite lining material for cylinders that has particularly high wear resistance in addition to the corrosion resistance inherent to Co-based alloys.

[Means for solving problems]

In order to achieve the above object, the present invention uses a corrosion-resistant metal as a matrix in a composite lining material for cylinders, and contains niobium carbide (which has almost the same hardness as WC and has a specific gravity extremely close to that of the matrix) in the matrix. NbC) particles are dispersed therein as a wear-resistant reinforcing material.

That is, the composite lining material for cylinders of the present invention has chemical components in weight ratio of 5 to 10% Cr, 2.5 to 4% B, and S.
A corrosion-resistant Co-based alloy consisting of i 0.2-2%, Mn 0.2-2%, the balance eo and unavoidable impurities is used as a matrix, and NbC particles are added as a wear-resistant reinforcing material in the matrix by weight ratio. It is characterized by being dispersed by 10 to 30%.

The hardness of NbC, which is a hard particle, is around Hv2400, which is almost the same as that of WC. Further, its specific gravity is 7.7 to 7.8. Furthermore, the matrix of the composite lining material of the present invention is a conventional Co-C matrix.
It is an r-B alloy and is described in Japanese Patent Publication No. 51-7126 (Japanese Patent Application No. 46-94456).

That is, the chemical components are 5 to 10% Cr and 2.5 to 10% by weight.
4%, Si 0.2-2%, Mn 0.2-2%, and the remainder Co and unavoidable impurities. This alloy contains high amounts of Cr and Co and has excellent corrosion resistance, and has a specific gravity of 7.
．． 8-8.5, close to NbC. Since niobium boride is crystallized or precipitated in the matrix of this alloy, H
It has a hardness of v 400 to 800 and has excellent wear resistance.

The reason why the blending ratio of NbC particles is limited to 10 to 30% is as follows. If the content of NbC particles is less than 10% by weight, sufficient wear resistance cannot be obtained, and if it exceeds 30% by weight, the viscosity of the lining material increases, making it impossible to form a uniform lining layer by centrifugal casting.

When the composite lining material of the present invention is lined on the inner peripheral surface of a steel cylinder by centrifugal casting, the result will be as follows. In other words, since the difference in specific gravity between the matrix and NbC is small, NbC is not unevenly distributed due to centrifugal force, and the fibers are dispersed throughout the lining layer. However, the distribution density is slightly larger on the surface side of the lining layer (innermost surface of the cylinder) than on the cylinder base material side. The way NbC is dispersed in this lining layer depends on the composition of the composite lining material, temperature,
Varies depending on facing conditions such as centrifugal force.

As described above, in a cylinder in which the inner peripheral surface of a steel cylinder is lined with the composite lining material according to the present invention by centrifugal casting, NbC, which is a hard particle, is almost uniformly dispersed over the entire surface of the lining layer. A cylinder with excellent corrosion and wear resistance can be easily obtained by simply cutting and grinding the layer to a desired inner diameter using a boron nitride tool.

〔Example〕

The present invention will be explained in further detail by the following examples.

Example 1 Cr 7.5%, 33.0%, Si 0.8% by weight
, a matrix material consisting of 1.0% Mn and the remainder substantially Co and 20% by weight NbC powder is melted in a high frequency induction furnace to create an alloy, which is cooled to form an alloy of size 51 or less. It was crushed. This pulverized alloy material was placed in a cylinder made of SCM440 with an outer diameter of 1605 mm and an inner diameter of 65 mm. After enclosing the necessary amount to obtain an Oa+a lining layer, heat it to 1200 ° C in a heating furnace,
It was held at 1200°C for 30 minutes. Thereafter, the cylinder was taken out of the heating furnace and immediately installed in a centrifugal casting machine, and the cylinder was rotated at 157 Or, p, m. Then, after sintering, it was allowed to cool in the air.

A ring sample was taken from the Shinrida and the condition of the lining layer was investigated. As a result, the lining layer has a side thickness of 3.2 mm.
It was found that the inner circumferential wall of the SCM440 cylinder had a thickness of 100 ml, and that the NbC particles were almost uniformly dispersed throughout the lining layer. In addition, the hardness at 1.5 ms from the innermost diameter part of the lining layer + outer layer position is H*e57~58
Met.

Next, as shown in Table 1, samples of the composite lining material according to the present invention and the conventional Co-based alloy lining material were taken from the thin lidar after lining and subjected to a wear test and a corrosion test.

Wear test Each sample (sample number 1.2) measuring 1Qmm x 15mm x 10mm in height was pressed against a 200φ abrasive paper whose main component was SiC with a grain size of No. 800 with a load of 2.5 kg, and the abrasive paper was rotated. I let it happen. Abrasive paper is 560r, p, a+
The test time was 3 minutes. The wear amount of each sample was measured by weight loss. Figure 1 shows the wear test results for each sample, and the figure shows that the composite lining material of the present invention (sample number 2) has nearly 10 times more wear resistance than the conventional alloy lining material (sample number 1). It shows.

Table 1 [Effects of the Invention] As explained above, in the composite lining material for cylinders according to the present invention, a corrosion-resistant Ni-based alloy is used as a matrix, and NbC particles are added to the matrix as a wear-resistant reinforcing material. By dispersing the resin by 10 to 30% in terms of ratio, it is possible to improve not only corrosion resistance but also wear resistance several times compared to conventional cylinder materials, and the life of the cylinder is extended (and therefore economical).

[Brief explanation of drawings]

FIG. 1 is a diagram showing abrasion test results of samples taken from a composite lining layer according to an embodiment of the present invention and a conventional lining layer.

Claims (1)

[Claims] Chemical components are Cr5-10%, B2.5-4% by weight,
A corrosion-resistant Co-based alloy consisting of 0.2-2% Si, 0.2-2% Mn, the balance Co and unavoidable impurities is used as a matrix, and NbC particles are added as a wear-resistant reinforcing material in the matrix at a weight ratio of 10-2%. A composite lining material for cylinders characterized by being made by dispersing 30%.