JPS6239224B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] 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 resin or reinforcing additives added to the resin. The inner peripheral surface of the cylinder was lined with a Ni-based alloy using a centrifugal casting method. However, cylinders lined with these alloys have the disadvantage that when used for plastic molding that contains a high proportion of reinforcing agents such as glass fibers, they suffer significant wear and tear after only 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. [Problems to be solved by the invention] However, this composite lining material has poor corrosion resistance and
Although the wear resistance has improved, it has the following drawbacks. In other words, since the specific gravity of WC, which is a wear-resistant reinforcing material, is approximately twice as large as that of the matrix alloy, the difference in centrifugal force due to the difference in specific gravity during lining
The WC particles are pressed against the cylinder base material side, and the WC
The layer is separated into a layer with dense particles and a layer with only a small amount of WC particles or no WC particles. Therefore, in order to obtain a corrosion-resistant and wear-resistant composite lining layer on the inner peripheral surface of the cylinder after lining, in which reinforcing WC particles are dispersed in a Ni-based alloy matrix, it is necessary to Alternatively, there was a problem of having to remove an extra layer that was not present at all. Another drawback 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 peripheral surface of a cylinder of a predetermined size, it is necessary to make the lining treatment conditions very strict. The purpose of the present invention is to eliminate the above-mentioned drawbacks, and is to provide a composite lining material for cylinders that is particularly high in wear resistance in addition to corrosion resistance. [Means for Solving the Problems] In order to achieve the above object, the present invention uses a matrix of corrosion-resistant metal in a composite lining material for cylinders, and has hardness in the matrix.
It is characterized by the fact that niobium carbide (NbC) particles, which are almost the same as WC and whose specific gravity is extremely close to that of the matrix, are dispersed as a wear-resistant reinforcing material. That is, the composite lining material for cylinders of the present invention has chemical components of Cr5 to 10% and B2.5 to 4% by weight.
%, Si2.5~10%, Co5~40%, Mn0.2~2%, balance Ni and unavoidable impurities. It is characterized by having particles dispersed in a weight ratio of 10 to 30%. The hardness of NbC, which is a hard particle, is around Hv2400, which is almost the same as that of WC. Moreover, its specific gravity is 7.7 to 7.8. Furthermore, the matrix of the composite lining material of the present invention is a conventionally used Ni-Cr-B-Si-Co alloy, which is described in Japanese Patent Publication No. 56-53626 (Japanese Patent Application No. 161354-1983). ing. In other words, the chemical composition is Cr5 in weight ratio.
~10%, 2.5~4%, Si2.5~10%, Co5~40%,
Consisting of 0.2-2% Mn, the balance being Ni and unavoidable impurities. This alloy contains high amounts of Ni and Cr and has excellent corrosion resistance, and has a specific gravity of 7.8 to 8.5, which is close to NbC.
Since niobium boride is crystallized or precipitated in the matrix of this alloy, it has a hardness of 400 to 800 Hv and excellent wear resistance. The reason why the blending ratio of NbC particles is limited to 10 to 30% by weight 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, a structure in which NbC is dispersed throughout the lining layer without being unevenly distributed due to centrifugal force is created. 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. NbC in this lining layer
The method of dispersion 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 lining layer to a desired inner diameter using a boron nitride tool. [Example] The present invention will be explained in more detail with reference to the following example. Example 1 Outer diameter 115 mm heated to 1200°C for 20 minutes in a heating furnace,
The inner circumferential surface of an SCM440 cylinder with an inner diameter of 45 mm (one end is sealed and the other end has a pouring port) contains 7.2% Cr, 2.8% B, 3.0% Si, 15% Co, and 1.0 Mn by weight.
%, 18 wt.
The material weighed to obtain a lining layer of mm was melted in a high frequency induction furnace and injected at 1350°C, immediately installed in a centrifugal casting machine, and the cylinder was rotated at 1890 rpm. Next, the cylinder was cooled to 700° C. while rotating, and then taken out from the centrifugal casting machine, slowly cooled in diatomaceous earth for 48 hours, and then left to cool in air. Thereafter, a ring-shaped sample was taken from the cylinder and the state of the lining layer was investigated. As a result, the lining layer had a thickness of 3.1 mm per side and was diffusion-welded to the inner peripheral wall of the SCM440 cylinder, and the NbC particles were almost uniformly dispersed throughout the lining layer.
Further, the hardness at the outer layer position of 1.5 mm from the innermost diameter portion of the lining layer was H _RC 58 to 59. Example 2 Outer diameter 115 mm heated at 1200°C for 20 minutes in a heating furnace,
The inner surface of an SCM440 cylinder with an inner diameter of 28 mm (one end is sealed and the other end has a spout) was melted using a high-frequency induction furnace by melting a matrix material with the same composition as in Example 1 and 25% by weight of NbC powder. It was injected at ℃ and immediately installed in a centrifugal casting machine and rotated at 2200 rpm. After the cylinder was cooled while rotating to 700°C, it was taken out from the centrifugal casting machine and cooled in exactly the same manner as in Example 1. A ring sample was taken from the cylinder and the state of the lining layer was investigated. As a result, the lining layer was diffusion-welded to the inner circumferential wall of the SCM440 cylinder with a thickness of 3 mm per side, and the NbC particles were almost uniformly dispersed throughout the lining layer. From the innermost diameter of the lining layer
The hardness at the 1.5 mm outer layer position was H _RC 60-62. Next, as shown in Table 1, samples of the composite lining material according to the present invention and the conventional Ni-based alloy lining material were taken from the thin lids after lining and subjected to wear tests and corrosion tests. Wear test Each sample of 10 mm x 15 mm x height 10 mm (sample number 1 ~
4) was pressed against a 200φ abrasive paper whose main component is SiC with a particle size of No. 800 under a load of 2.5 kg, and the abrasive paper was rotated. The abrasive paper was rotated at a speed of 560 rpm, and the test time was 3 minutes. The amount of wear of each sample was measured by weight loss. Figure 1 shows the abrasion test results for each sample. In the figure, the composite lining materials of the present invention (sample numbers 3 and 4) were 7% lower than the conventional alloy lining materials (sample numbers 1 and 2).
~10 times more abrasion resistant. Corrosion test Each sample (sample numbers 1 to 4) with a thickness of 2 mm x width of 7 mm x length of 18 mm was placed in a 50% by volume formic acid aqueous solution at 85°C for 24 hours.
The corrosion weight loss was measured after soaking for a certain period of time. Figure 2 shows the corrosion test results for each sample, and as seen in the figure, the corrosion resistance of the composite lining materials of the present invention (sample numbers 3 and 4) was higher than that of conventional alloy lining materials (sample numbers 1 and 2). ) shows characteristics that are equivalent to or better than.

〔Effect of the invention〕

As explained above, the composite lining material for cylinders according to the present invention has corrosion resistance.
A Ni-based alloy is used as a matrix, and NbC particles are added as a wear-resistant reinforcement in this matrix in terms of weight ratio.
By dispersing it by 10 to 30%, it is possible to improve not only corrosion resistance but also wear resistance several times compared to conventional cylinder materials, extending the life of the cylinder and making it economical.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the wear test results of samples taken from the composite lining layer of the embodiment of the present invention and the conventional lining layer, and FIG. 2 is a diagram showing the corrosion test results as well.

Claims (1)

[Claims] 1 Chemical components are Cr5-10% by weight, B2.5-4
%, Si2.5~10%, Co5~40%, Mn0.2~2%, balance Ni and unavoidable impurities. A composite lining material for cylinders characterized by dispersing particles at a weight ratio of 10 to 30%.